From 4abb6100e740ee5dda07e4e769208b0aea906816 Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
Date: Fri, 30 Oct 2026 01:22:12 +0000
Subject: [PATCH] Define exported C++ thunks in the LLVM function Clang uses
 for them (#8060)

Carbon gives the C++ declaration of an exported Carbon thunk an asm
label that
includes the target's global symbol prefix (`_` on Mach-O). Clang names
a
declaration with an asm label `\01<label>` in the IR, so that LLVM uses
the
label verbatim as the symbol name, while Carbon lowered the thunk
definition
under its unprefixed name. Both name the same symbol, but they were
distinct
globals in the IR, so LLVM couldn't see that the C++ calls refer to the
Carbon
definition. That only works while the definition is never discarded.

Mark the Carbon thunk as a `CppThunk` (as described in
`toolchain/docs/check/cpp/thunks.md`), record its C++ declaration in
`clang_decls`, and when lowering the thunk, ask Clang for its function
(creating it if necessary) and define the thunk in that function. This
means
that the thunk and the C++ calls to it always use the same IR global,
with
Clang's name and signature.

The thunk takes all of its parameters by reference, so Clang lowers its
parameters the same way Carbon does, but some C++ ABIs (such as Apple
arm64)
return `this` from constructors. In that case, return the parameter that
Clang
marks `returned`.

On targets without a global prefix, the IR names already matched, so the
only
change is that the thunk definitions now carry Clang's parameter and
function
attributes.
---
 toolchain/check/cpp/export.cpp                |  23 +-
 toolchain/lower/file_context.cpp              |  75 +++-
 toolchain/lower/file_context.h                |   7 +
 .../lower/testdata/interop/cpp/array.carbon   |   3 +-
 .../interop/cpp/class/export/class.carbon     |   7 +-
 .../interop/cpp/class/export/method.carbon    |   9 +-
 .../interop/cpp/class/import/dynamic.carbon   |  27 +-
 .../interop/cpp/class/virtual_fn.carbon       |   4 +-
 .../cpp/class/virtual_fn_carbon_only.carbon   |  17 +-
 .../cpp/function/export/constructor.carbon    |  13 +-
 .../cpp/function/export/default_values.carbon |   9 +-
 .../cpp/function/export/function.carbon       |  34 +-
 .../cpp/function/export/generic.carbon        |   5 +-
 .../function/export/macho_asm_label.carbon    | 368 ++++++++++++++++++
 .../cpp/function/import/function_ptr.carbon   |  28 +-
 .../cpp/function/import/method_ptr.carbon     |  22 +-
 .../testdata/interop/cpp/issue7142.carbon     |  17 +-
 17 files changed, 577 insertions(+), 91 deletions(-)
 create mode 100644 toolchain/lower/testdata/interop/cpp/function/export/macho_asm_label.carbon

diff --git a/toolchain/check/cpp/export.cpp b/toolchain/check/cpp/export.cpp
index 08052418e67b..7a2204a72d7f 100644
--- a/toolchain/check/cpp/export.cpp
+++ b/toolchain/check/cpp/export.cpp
@@ -1607,8 +1607,10 @@ static auto BuildCarbonToCarbonThunk(Context& context, SemIR::LocId loc_id,
   // If this thunk will be exposed as a C++ constructor, we put the output
   // parameter first to match the Itanium constructor ABI.
   //
-  // TODO: use `clang::CodeGen::CGCXXABI::HasThisReturn` to determine if the
-  // constructor's `this` should be a return value instead of an output param.
+  // Some C++ ABIs also return `this` from constructors. We don't model that
+  // here; instead, lowering defines the thunk in the LLVM function Clang
+  // creates for its C++ declaration, and returns `this` if Clang's signature
+  // does. See `FileContext::GetCppThunkLLVMFunction`.
   if (target.export_as_constructor) {
     CARBON_CHECK(target.return_type_id != SemIR::TypeId::None);
     std::rotate(thunk_param_type_ids.begin(), thunk_param_type_ids.end() - 1,
@@ -1626,6 +1628,9 @@ static auto BuildCarbonToCarbonThunk(Context& context, SemIR::LocId loc_id,
            .param_type_ids = thunk_param_type_ids,
            .param_kinds = thunk_param_kinds})
           .second;
+  context.functions()
+      .Get(carbon_thunk_function_id)
+      .SetCppThunk(target.function.first_decl_id());
 
   BuildThunkDefinitionForExport(
       context, carbon_thunk_function_id, target.function_id,
@@ -1673,6 +1678,20 @@ static auto BuildCppToCarbonThunk(Context& context, SemIR::LocId loc_id,
     return;
   }
 
+  // Map the Carbon thunk to its C++ declaration, so that lowering can define
+  // the thunk in the same LLVM function that Clang uses to call it.
+  SemIR::ClangDeclSignature carbon_function_signature{
+      .kind = SemIR::ClangDeclSignature::Normal,
+      .num_params = static_cast<int32_t>(carbon_function_decl->getNumParams())};
+  carbon_function_signature.passing_modes.assign(
+      carbon_function_signature.num_params,
+      SemIR::ClangDeclSignature::PassingMode::ByValue);
+  context.clang_decls().Add(
+      {.key = SemIR::ClangDeclKey::ForFunctionDecl(
+           carbon_function_decl, context.clang_decl_signatures().Add(
+                                     std::move(carbon_function_signature))),
+       .inst_id = carbon_thunk_target.function.first_decl_id()});
+
   // Build the thunk function body.
   clang::Sema& sema = context.clang_sema();
   clang::Sema::ContextRAII context_raii(sema, thunk_function_decl);
diff --git a/toolchain/lower/file_context.cpp b/toolchain/lower/file_context.cpp
index d4714ea0940e..d0b1063c64c8 100644
--- a/toolchain/lower/file_context.cpp
+++ b/toolchain/lower/file_context.cpp
@@ -16,6 +16,7 @@
 #include "common/vlog.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Sequence.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/Linker/Linker.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
@@ -335,6 +336,45 @@ auto FileContext::HandleReferencedCppFunction(clang::FunctionDecl* cpp_decl)
   return function_address;
 }
 
+auto FileContext::GetCppThunkLLVMFunction(
+    const FunctionTypeInfo& function_type_info, clang::FunctionDecl* cpp_decl)
+    -> llvm::Function* {
+  // Ask Clang for its function for the thunk, creating its declaration if it
+  // doesn't exist yet. Clang names it based on the thunk's asm label, which
+  // may differ from Carbon's name for it in the IR (for example, `\01`-prefixed
+  // on targets with a global symbol prefix). Using Clang's function means that
+  // C++ calls to the thunk refer to its definition in the IR.
+  // TODO: This code generator can be for the wrong AST if we're not using
+  // --share-cpp-ast.
+  auto* llvm_function =
+      dyn_cast<llvm::Function>(context().cpp_code_generator()->GetAddrOfGlobal(
+          CreateGlobalDecl(cpp_decl), /*isForDefinition=*/false));
+  CARBON_CHECK(llvm_function);
+
+  // The thunk takes all of its parameters by reference, so Clang should lower
+  // them the same way we do. However, some C++ ABIs return `this` from
+  // constructors; `BuildFunctionBody` handles that.
+  auto* cpp_type = llvm_function->getFunctionType();
+  auto* carbon_type = function_type_info.type;
+  CARBON_CHECK(llvm::equal(cpp_type->params(), carbon_type->params()),
+               "C++ thunk parameter types don't match: {0} vs {1}", *cpp_type,
+               *carbon_type);
+  CARBON_CHECK(
+      cpp_type->getReturnType() == carbon_type->getReturnType() ||
+          (carbon_type->getReturnType()->isVoidTy() &&
+           llvm_function->hasParamAttribute(0, llvm::Attribute::Returned)),
+      "C++ thunk return types don't match: {0} vs {1}", *cpp_type,
+      *carbon_type);
+  CARBON_CHECK(function_type_info.sret_type == nullptr,
+               "C++ thunks return through an explicit output parameter");
+
+  for (auto [name_id, arg] : llvm::zip_equal(function_type_info.param_name_ids,
+                                             llvm_function->args())) {
+    arg.setName(sem_ir().names().GetIRBaseName(name_id));
+  }
+  return llvm_function;
+}
+
 auto FileContext::HandleReferencedSpecificFunction(
     SemIR::FunctionId function_id, SemIR::SpecificId specific_id,
     llvm::Type* llvm_type) -> void {
@@ -371,6 +411,13 @@ auto FileContext::GetOrCreateLLVMFunction(
                      "Specific functions cannot have C++ definitions");
         return HandleReferencedCppFunction(clang_decl->decl()->getAsFunction());
       }
+      if (function.special_function_kind ==
+          SemIR::Function::SpecialFunctionKind::CppThunk) {
+        CARBON_CHECK(!specific_id.has_value(),
+                     "Specific functions cannot be C++ thunks");
+        return GetCppThunkLLVMFunction(function_type_info,
+                                       clang_decl->decl()->getAsFunction());
+      }
     }
   }
 
@@ -686,6 +733,23 @@ auto FileContext::BuildFunctionBody(SemIR::FunctionId function_id,
     lower_block(block_id);
   }
 
+  // Some C++ ABIs return `this` from constructors. If Clang's declaration of a
+  // C++ thunk does that, return the parameter it marks as `returned` instead
+  // of returning nothing.
+  if (declaration_function.special_function_kind ==
+          SemIR::Function::SpecialFunctionKind::CppThunk &&
+      !function_info->llvm_function->getReturnType()->isVoidTy() &&
+      function_info->type->getReturnType()->isVoidTy()) {
+    auto* this_arg = function_info->llvm_function->getArg(0);
+    for (auto& llvm_block : *function_info->llvm_function) {
+      auto* ret = dyn_cast<llvm::ReturnInst>(llvm_block.getTerminator());
+      if (ret && !ret->getReturnValue()) {
+        llvm::ReturnInst::Create(llvm_context(), this_arg, ret->getIterator());
+        ret->eraseFromParent();
+      }
+    }
+  }
+
   // LLVM requires that the entry block has no predecessors.
   auto* entry_block = &function_info->llvm_function->getEntryBlock();
   if (entry_block->hasNPredecessorsOrMore(1)) {
@@ -715,8 +779,17 @@ auto FileContext::BuildDISubprogram(const SemIR::Function& function,
   }
   auto loc = GetLocForDI(function.definition_id);
   llvm::DISubroutineType* subroutine_type = function_info.di_type;
+  // A function named by Clang from an asm label has a `\01` marker followed
+  // by the target's global prefix, if any. Use the unprefixed name, matching
+  // other functions.
+  llvm::StringRef linkage_name = function_info.llvm_function->getName();
+  if (linkage_name.consume_front("\1")) {
+    if (char global_prefix = llvm_module().getDataLayout().getGlobalPrefix()) {
+      linkage_name.consume_front(llvm::StringRef(&global_prefix, 1));
+    }
+  }
   auto* subprogram = context().di_builder().createFunction(
-      context().di_compile_unit(), name, function_info.llvm_function->getName(),
+      context().di_compile_unit(), name, linkage_name,
       /*File=*/context().di_builder().createFile(loc.filename, ""),
       /*LineNo=*/loc.line_number, subroutine_type,
       /*ScopeLine=*/0, llvm::DINode::FlagZero,
diff --git a/toolchain/lower/file_context.h b/toolchain/lower/file_context.h
index 035baa7eaf90..de885ee1e149 100644
--- a/toolchain/lower/file_context.h
+++ b/toolchain/lower/file_context.h
@@ -211,6 +211,13 @@ class FileContext {
   auto HandleReferencedCppFunction(clang::FunctionDecl* cpp_decl)
       -> llvm::Function*;
 
+  // Gets the LLVM function that Clang uses for a Carbon thunk exported to C++,
+  // given the thunk's C++ declaration. The thunk's definition is lowered into
+  // this function.
+  auto GetCppThunkLLVMFunction(const FunctionTypeInfo& function_type_info,
+                               clang::FunctionDecl* cpp_decl)
+      -> llvm::Function*;
+
   // Notes that a specific function has been referenced for the first time.
   // Updates the fingerprint to include the function's type, and adds the
   // function to the list of specific functions whose definitions should be
diff --git a/toolchain/lower/testdata/interop/cpp/array.carbon b/toolchain/lower/testdata/interop/cpp/array.carbon
index 7c170ca40e6b..0dbfc4b1ce96 100644
--- a/toolchain/lower/testdata/interop/cpp/array.carbon
+++ b/toolchain/lower/testdata/interop/cpp/array.carbon
@@ -87,7 +87,7 @@ int H() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.Main(ptr %_, ptr %_1) #3 !dbg !40 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.Main(ptr noundef nonnull align 4 dereferenceable(20) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #4 !dbg !40 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %F.call = call i32 @_CF.Main(ptr %_), !dbg !43
 // CHECK:STDOUT:   store i32 %F.call, ptr %_1, align 4, !dbg !43
@@ -98,6 +98,7 @@ int H() {
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #3 = { nounwind }
+// CHECK:STDOUT: attributes #4 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!25}
 // CHECK:STDOUT: !llvm.module.flags = !{!51, !52, !53, !6, !7}
diff --git a/toolchain/lower/testdata/interop/cpp/class/export/class.carbon b/toolchain/lower/testdata/interop/cpp/class/export/class.carbon
index d79e02e5cf21..95a40e859ee1 100644
--- a/toolchain/lower/testdata/interop/cpp/class/export/class.carbon
+++ b/toolchain/lower/testdata/interop/cpp/class/export/class.carbon
@@ -301,7 +301,7 @@ fn G() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CCallLayoutA__carbon_thunk.Main(ptr %_) #5 !dbg !67 {
+// CHECK:STDOUT: define void @_CCallLayoutA__carbon_thunk.Main(ptr noundef nonnull align 8 dereferenceable(8) %_) #6 !dbg !67 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc21 = load ptr, ptr %_, align 8, !dbg !69
 // CHECK:STDOUT:   call void @_CCallLayoutA.Main(ptr %.loc21), !dbg !69
@@ -336,7 +336,7 @@ fn G() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CCallLayoutB__carbon_thunk.Main(ptr %_) #5 !dbg !83 {
+// CHECK:STDOUT: define void @_CCallLayoutB__carbon_thunk.Main(ptr noundef nonnull align 8 dereferenceable(8) %_) #6 !dbg !83 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc22 = load ptr, ptr %_, align 8, !dbg !85
 // CHECK:STDOUT:   call void @_CCallLayoutB.Main(ptr %.loc22), !dbg !85
@@ -371,7 +371,7 @@ fn G() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CCallLayoutC__carbon_thunk.Main(ptr %_) #5 !dbg !99 {
+// CHECK:STDOUT: define void @_CCallLayoutC__carbon_thunk.Main(ptr noundef nonnull align 8 dereferenceable(8) %_) #6 !dbg !99 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc23 = load ptr, ptr %_, align 8, !dbg !101
 // CHECK:STDOUT:   call void @_CCallLayoutC.Main(ptr %.loc23), !dbg !101
@@ -418,6 +418,7 @@ fn G() {
 // CHECK:STDOUT: attributes #3 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { alwaysinline nounwind }
 // CHECK:STDOUT: attributes #5 = { nounwind }
+// CHECK:STDOUT: attributes #6 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!49}
 // CHECK:STDOUT: !llvm.module.flags = !{!43, !44, !45, !19, !20}
diff --git a/toolchain/lower/testdata/interop/cpp/class/export/method.carbon b/toolchain/lower/testdata/interop/cpp/class/export/method.carbon
index 85313134e569..5337db5feb08 100644
--- a/toolchain/lower/testdata/interop/cpp/class/export/method.carbon
+++ b/toolchain/lower/testdata/interop/cpp/class/export/method.carbon
@@ -124,7 +124,7 @@ fn CallCallF() { Cpp.CallStaticF(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.A.Main(ptr %self) #4 !dbg !35 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.A.Main(ptr noundef nonnull align 1 %self) #6 !dbg !35 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.A.Main(ptr %self), !dbg !37
 // CHECK:STDOUT:   ret void, !dbg !37
@@ -141,6 +141,7 @@ fn CallCallF() { Cpp.CallStaticF(); }
 // CHECK:STDOUT: attributes #3 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { nounwind }
 // CHECK:STDOUT: attributes #5 = { alwaysinline nounwind }
+// CHECK:STDOUT: attributes #6 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!21}
 // CHECK:STDOUT: !llvm.module.flags = !{!51, !52, !53, !4, !5}
@@ -247,7 +248,7 @@ fn CallCallF() { Cpp.CallStaticF(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.ArgsA.Main(ptr %self, ptr %_, ptr %_1) #4 !dbg !81 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.ArgsA.Main(ptr noundef nonnull align 1 %self, ptr noundef nonnull align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #6 !dbg !81 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc6_29.2 = load i32, ptr %_, align 4, !dbg !85
 // CHECK:STDOUT:   %ArgsA.F.call = call i32 @_CF.ArgsA.Main(ptr %self, i32 %.loc6_29.2), !dbg !85
@@ -273,6 +274,7 @@ fn CallCallF() { Cpp.CallStaticF(); }
 // CHECK:STDOUT: attributes #3 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { nounwind }
 // CHECK:STDOUT: attributes #5 = { alwaysinline nounwind }
+// CHECK:STDOUT: attributes #6 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!58}
 // CHECK:STDOUT: !llvm.module.flags = !{!51, !52, !53, !4, !5}
@@ -362,7 +364,7 @@ fn CallCallF() { Cpp.CallStaticF(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.StaticA.Main() #2 !dbg !112 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.StaticA.Main() #4 !dbg !112 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.StaticA.Main(), !dbg !113
 // CHECK:STDOUT:   ret void, !dbg !113
@@ -384,6 +386,7 @@ fn CallCallF() { Cpp.CallStaticF(); }
 // CHECK:STDOUT: attributes #1 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #2 = { nounwind }
 // CHECK:STDOUT: attributes #3 = { alwaysinline nounwind }
+// CHECK:STDOUT: attributes #4 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!103}
 // CHECK:STDOUT: !llvm.module.flags = !{!51, !52, !53, !4, !5}
diff --git a/toolchain/lower/testdata/interop/cpp/class/import/dynamic.carbon b/toolchain/lower/testdata/interop/cpp/class/import/dynamic.carbon
index 9c769ae0d976..cde108a4d60c 100644
--- a/toolchain/lower/testdata/interop/cpp/class/import/dynamic.carbon
+++ b/toolchain/lower/testdata/interop/cpp/class/import/dynamic.carbon
@@ -125,14 +125,14 @@ fn DoThing() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_Cfunc__carbon_thunk.Derived.Main(ptr %self) #2 !dbg !74 {
+// CHECK:STDOUT: define void @_Cfunc__carbon_thunk.Derived.Main(ptr noundef nonnull align 8 dereferenceable(12) %self) #4 !dbg !74 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_Cfunc.Derived.Main(ptr %self), !dbg !76
 // CHECK:STDOUT:   ret void, !dbg !76
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_Cother_func__carbon_thunk.Derived.Main(ptr %self) #2 !dbg !78 {
+// CHECK:STDOUT: define void @_Cother_func__carbon_thunk.Derived.Main(ptr noundef nonnull align 8 dereferenceable(12) %self) #4 !dbg !78 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %Derived.other_func.call.vtable = load ptr, ptr %self, align 8, !dbg !80
 // CHECK:STDOUT:   %Derived.other_func.call = call ptr @llvm.load.relative.i32(ptr %Derived.other_func.call.vtable, i32 8), !dbg !80
@@ -158,7 +158,7 @@ fn DoThing() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZN4BaseC1Ev.carbon_thunk.(ptr noundef %return) #4 {
+// CHECK:STDOUT: define internal void @_ZN4BaseC1Ev.carbon_thunk.(ptr noundef %return) #5 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %return.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %return, ptr %return.addr, align 8, !tbaa !4
@@ -179,13 +179,13 @@ fn DoThing() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: read)
-// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #5
+// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #6
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #6
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #7
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZNR6Carbon4Main7Derived4funcEv(ptr noundef nonnull align 8 dereferenceable(12) %this) unnamed_addr #4 align 2 {
+// CHECK:STDOUT: define internal void @_ZNR6Carbon4Main7Derived4funcEv(ptr noundef nonnull align 8 dereferenceable(12) %this) unnamed_addr #5 align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !110
@@ -195,7 +195,7 @@ fn DoThing() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZNK6Carbon4Main7Derived10other_funcEv(ptr noundef nonnull align 8 dereferenceable(12) %this) unnamed_addr #4 align 2 {
+// CHECK:STDOUT: define internal void @_ZNK6Carbon4Main7Derived10other_funcEv(ptr noundef nonnull align 8 dereferenceable(12) %this) unnamed_addr #5 align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !110
@@ -205,7 +205,7 @@ fn DoThing() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN4BaseC2Ev(ptr noundef nonnull align 8 dereferenceable(12) %this) unnamed_addr #7 comdat align 2 {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN4BaseC2Ev(ptr noundef nonnull align 8 dereferenceable(12) %this) unnamed_addr #8 comdat align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !4
@@ -216,7 +216,7 @@ fn DoThing() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN11FurtherBaseC2Ev(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #7 comdat align 2 {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN11FurtherBaseC2Ev(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #8 comdat align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !108
@@ -234,10 +234,11 @@ fn DoThing() {
 // CHECK:STDOUT: attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #2 = { nounwind }
 // CHECK:STDOUT: attributes #3 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #4 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #5 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
-// CHECK:STDOUT: attributes #6 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #7 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #4 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #5 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #6 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
+// CHECK:STDOUT: attributes #7 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #8 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!40}
 // CHECK:STDOUT: !llvm.module.flags = !{!115, !116, !117, !7, !8}
diff --git a/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon b/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon
index b340b53ede3b..4a8a617e7079 100644
--- a/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon
+++ b/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon
@@ -231,7 +231,7 @@ void delete_new_Base() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.Final.Main(ptr %self) #8 !dbg !49 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.Final.Main(ptr noundef nonnull align 8 dereferenceable(8) %self) #7 !dbg !49 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.Final.Main(ptr %self), !dbg !51
 // CHECK:STDOUT:   ret void, !dbg !51
@@ -262,7 +262,7 @@ void delete_new_Base() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.Base.Main(ptr %self) #8 !dbg !66 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.Base.Main(ptr noundef nonnull align 8 dereferenceable(8) %self) #7 !dbg !66 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.Base.Main(ptr %self), !dbg !68
 // CHECK:STDOUT:   ret void, !dbg !68
diff --git a/toolchain/lower/testdata/interop/cpp/class/virtual_fn_carbon_only.carbon b/toolchain/lower/testdata/interop/cpp/class/virtual_fn_carbon_only.carbon
index c30acc92d969..4e6eed9ed660 100644
--- a/toolchain/lower/testdata/interop/cpp/class/virtual_fn_carbon_only.carbon
+++ b/toolchain/lower/testdata/interop/cpp/class/virtual_fn_carbon_only.carbon
@@ -101,7 +101,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_Cf__carbon_thunk.Z.Main(ptr %self) #1 !dbg !41 {
+// CHECK:STDOUT: define void @_Cf__carbon_thunk.Z.Main(ptr noundef nonnull align 8 dereferenceable(8) %self) #3 !dbg !41 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_Cf.Z.Main(ptr %self), !dbg !43
 // CHECK:STDOUT:   ret void, !dbg !43
@@ -122,7 +122,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZN1XC1Ev.carbon_thunk.(ptr noundef %return) #3 {
+// CHECK:STDOUT: define internal void @_ZN1XC1Ev.carbon_thunk.(ptr noundef %return) #4 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %return.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %return, ptr %return.addr, align 8, !tbaa !69
@@ -143,10 +143,10 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #4
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #5
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZN6Carbon4Main1Z1fEv(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #3 align 2 {
+// CHECK:STDOUT: define internal void @_ZN6Carbon4Main1Z1fEv(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #4 align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !73
@@ -156,7 +156,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN1XC2Ev(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #5 comdat align 2 {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN1XC2Ev(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #6 comdat align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !69
@@ -172,9 +172,10 @@ fn F() {
 // CHECK:STDOUT: attributes #0 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #1 = { nounwind }
 // CHECK:STDOUT: attributes #2 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #3 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #4 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #5 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #4 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #5 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #6 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!13}
 // CHECK:STDOUT: !llvm.module.flags = !{!76, !77, !78, !2, !3}
diff --git a/toolchain/lower/testdata/interop/cpp/function/export/constructor.carbon b/toolchain/lower/testdata/interop/cpp/function/export/constructor.carbon
index 663101edd84c..5c4252f12cf6 100644
--- a/toolchain/lower/testdata/interop/cpp/function/export/constructor.carbon
+++ b/toolchain/lower/testdata/interop/cpp/function/export/constructor.carbon
@@ -39,10 +39,10 @@ void f() {
 // CHECK:STDOUT: define dso_local void @_Z1fv() #0 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %a = alloca %"class.Carbon::Main::OneArg", align 1
-// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %a) #5
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %a) #6
 // CHECK:STDOUT:   call void @_ZN6Carbon4Main6OneArgC2Ei(ptr noundef nonnull align 1 %a, i32 noundef 42)
-// CHECK:STDOUT:   call void @_ZN6Carbon4Main6OneArgD2Ev(ptr noundef nonnull align 1 %a) #5
-// CHECK:STDOUT:   call void @llvm.lifetime.end.p0(ptr %a) #5
+// CHECK:STDOUT:   call void @_ZN6Carbon4Main6OneArgD2Ev(ptr noundef nonnull align 1 %a) #6
+// CHECK:STDOUT:   call void @llvm.lifetime.end.p0(ptr %a) #6
 // CHECK:STDOUT:   ret void
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -84,7 +84,7 @@ void f() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_COneArg__carbon_thunk.OneArg.Main(ptr %_, ptr %_1) #5 !dbg !19 {
+// CHECK:STDOUT: define void @_COneArg__carbon_thunk.OneArg.Main(ptr noundef nonnull align 1 %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) unnamed_addr #5 !dbg !19 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc6_28.2 = load i32, ptr %_1, align 4, !dbg !22
 // CHECK:STDOUT:   call void @_COneArg.OneArg.Main(ptr %_, i32 %.loc6_28.2), !dbg !22
@@ -92,7 +92,7 @@ void f() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.f5db22251d2a7ef4(ptr %t) #5 !dbg !25 {
+// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.f5db22251d2a7ef4(ptr %t) #6 !dbg !25 {
 // CHECK:STDOUT:   ret void, !dbg !30
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -101,7 +101,8 @@ void f() {
 // CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #3 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #5 = { nounwind }
+// CHECK:STDOUT: attributes #5 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #6 = { nounwind }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!6}
 // CHECK:STDOUT: !llvm.module.flags = !{!39, !40, !41, !3, !4}
diff --git a/toolchain/lower/testdata/interop/cpp/function/export/default_values.carbon b/toolchain/lower/testdata/interop/cpp/function/export/default_values.carbon
index 81f16fc36496..3d6ca07762d6 100644
--- a/toolchain/lower/testdata/interop/cpp/function/export/default_values.carbon
+++ b/toolchain/lower/testdata/interop/cpp/function/export/default_values.carbon
@@ -125,7 +125,7 @@ void CallF() {
 // CHECK:STDOUT: declare void @_CF.OtherFunction(i32)
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.OtherFunction(ptr %_) #2 !dbg !41 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.OtherFunction(ptr noundef nonnull align 4 dereferenceable(4) %_) #2 !dbg !41 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.1 = load i32, ptr %_, align 4, !dbg !43
 // CHECK:STDOUT:   call void @_CF.OtherFunction(i32 %.1), !dbg !43
@@ -135,7 +135,7 @@ void CallF() {
 // CHECK:STDOUT: declare void @_CF.FirstFunction(i32)
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.FirstFunction(ptr %_) #2 !dbg !45 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.FirstFunction(ptr noundef nonnull align 4 dereferenceable(4) %_) #2 !dbg !45 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.1 = load i32, ptr %_, align 4, !dbg !47
 // CHECK:STDOUT:   call void @_CF.FirstFunction(i32 %.1), !dbg !47
@@ -143,7 +143,7 @@ void CallF() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define internal void @_C__global_init.Main() #2 !dbg !51 {
+// CHECK:STDOUT: define internal void @_C__global_init.Main() #3 !dbg !51 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   store i32 23, ptr @_C__carbon_default_value__CF.OtherFunction_0.Main, align 4
 // CHECK:STDOUT:   store i32 0, ptr @_C__carbon_default_value__CF.FirstFunction_0.Main, align 4
@@ -152,7 +152,8 @@ void CallF() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #1 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #2 = { nounwind }
+// CHECK:STDOUT: attributes #2 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { nounwind }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!40}
 // CHECK:STDOUT: !llvm.module.flags = !{!53, !54, !55, !6, !7}
diff --git a/toolchain/lower/testdata/interop/cpp/function/export/function.carbon b/toolchain/lower/testdata/interop/cpp/function/export/function.carbon
index 009bb60ae6cb..c3fcc682403e 100644
--- a/toolchain/lower/testdata/interop/cpp/function/export/function.carbon
+++ b/toolchain/lower/testdata/interop/cpp/function/export/function.carbon
@@ -221,7 +221,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: declare void @_CBoolArg.Other(i1)
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CBoolArg__carbon_thunk.Other(ptr %_) #2 !dbg !44 {
+// CHECK:STDOUT: define void @_CBoolArg__carbon_thunk.Other(ptr noundef nonnull align 1 dereferenceable(1) %_) #2 !dbg !44 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.1 = load i8, ptr %_, align 1, !dbg !46
 // CHECK:STDOUT:   %.11 = trunc i8 %.1 to i1, !dbg !46
@@ -232,7 +232,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: declare void @_CIntArg.Other(i32)
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CIntArg__carbon_thunk.Other(ptr %_) #2 !dbg !48 {
+// CHECK:STDOUT: define void @_CIntArg__carbon_thunk.Other(ptr noundef nonnull align 4 dereferenceable(4) %_) #2 !dbg !48 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.1 = load i32, ptr %_, align 4, !dbg !50
 // CHECK:STDOUT:   call void @_CIntArg.Other(i32 %.1), !dbg !50
@@ -242,7 +242,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: declare void @_CFloatArg.Other(float)
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CFloatArg__carbon_thunk.Other(ptr %_) #2 !dbg !52 {
+// CHECK:STDOUT: define void @_CFloatArg__carbon_thunk.Other(ptr noundef nonnull align 4 dereferenceable(4) %_) #2 !dbg !52 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.1 = load float, ptr %_, align 4, !dbg !54
 // CHECK:STDOUT:   call void @_CFloatArg.Other(float %.1), !dbg !54
@@ -252,7 +252,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: declare i32 @_CIntReturn.Other()
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CIntReturn__carbon_thunk.Other(ptr %_) #2 !dbg !56 {
+// CHECK:STDOUT: define void @_CIntReturn__carbon_thunk.Other(ptr noundef nonnull align 4 dereferenceable(4) %_) #2 !dbg !56 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %IntReturn.call = call i32 @_CIntReturn.Other(), !dbg !58
 // CHECK:STDOUT:   store i32 %IntReturn.call, ptr %_, align 4, !dbg !58
@@ -261,7 +261,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #1 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #2 = { nounwind }
+// CHECK:STDOUT: attributes #2 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!41}
 // CHECK:STDOUT: !llvm.module.flags = !{!68, !69, !70, !2, !3}
@@ -329,7 +329,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.Main() #0 !dbg !77 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.Main() #1 !dbg !77 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.Main(), !dbg !78
 // CHECK:STDOUT:   ret void, !dbg !78
@@ -343,29 +343,30 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_Z2G2v() #1 comdat {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_Z2G2v() #2 comdat {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_Z2G1v()
 // CHECK:STDOUT:   ret void
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_Z2G1v() #1 comdat {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_Z2G1v() #2 comdat {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_ZN6Carbon4MainL1FEv()
 // CHECK:STDOUT:   ret void
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZN6Carbon4MainL1FEv() #2 {
+// CHECK:STDOUT: define internal void @_ZN6Carbon4MainL1FEv() #3 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF__carbon_thunk.Main()
 // CHECK:STDOUT:   ret void
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { inlinehint mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { inlinehint mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!74}
 // CHECK:STDOUT: !llvm.module.flags = !{!68, !69, !70, !2, !3}
@@ -408,7 +409,7 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_Cbase__carbon_thunk.Main() #0 !dbg !86 {
+// CHECK:STDOUT: define void @_Cbase__carbon_thunk.Main() #1 !dbg !86 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_Cbase.Main(), !dbg !87
 // CHECK:STDOUT:   ret void, !dbg !87
@@ -422,22 +423,23 @@ fn CallCallBase() { Cpp.CallBase(); }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_Z8CallBasev() #1 comdat {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_Z8CallBasev() #2 comdat {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_ZN6Carbon4MainL4baseEv()
 // CHECK:STDOUT:   ret void
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal void @_ZN6Carbon4MainL4baseEv() #2 {
+// CHECK:STDOUT: define internal void @_ZN6Carbon4MainL4baseEv() #3 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_Cbase__carbon_thunk.Main()
 // CHECK:STDOUT:   ret void
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { inlinehint mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { inlinehint mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!83}
 // CHECK:STDOUT: !llvm.module.flags = !{!68, !69, !70, !2, !3}
diff --git a/toolchain/lower/testdata/interop/cpp/function/export/generic.carbon b/toolchain/lower/testdata/interop/cpp/function/export/generic.carbon
index 7c0ae588321c..9da8ac8d2297 100644
--- a/toolchain/lower/testdata/interop/cpp/function/export/generic.carbon
+++ b/toolchain/lower/testdata/interop/cpp/function/export/generic.carbon
@@ -196,14 +196,14 @@ fn Run() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.26f2099a79512a5d.Main(ptr %_) #4 !dbg !42 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.26f2099a79512a5d.Main(ptr noundef nonnull align 1 %_) #6 !dbg !42 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.Main.6662a1ffb773360a(ptr %_), !dbg !44
 // CHECK:STDOUT:   ret void, !dbg !44
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CF__carbon_thunk.7a3b9f04ddf4269e.Main(ptr %_) #4 !dbg !46 {
+// CHECK:STDOUT: define void @_CF__carbon_thunk.7a3b9f04ddf4269e.Main(ptr noundef nonnull align 1 %_) #6 !dbg !46 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CF.Main.d53b17eed3ce903c(ptr %_), !dbg !48
 // CHECK:STDOUT:   ret void, !dbg !48
@@ -252,6 +252,7 @@ fn Run() {
 // CHECK:STDOUT: attributes #3 = { inlinehint mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { nounwind }
 // CHECK:STDOUT: attributes #5 = { alwaysinline nounwind }
+// CHECK:STDOUT: attributes #6 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!15}
 // CHECK:STDOUT: !llvm.module.flags = !{!86, !87, !88, !4, !5}
diff --git a/toolchain/lower/testdata/interop/cpp/function/export/macho_asm_label.carbon b/toolchain/lower/testdata/interop/cpp/function/export/macho_asm_label.carbon
new file mode 100644
index 000000000000..55167d4b4bd6
--- /dev/null
+++ b/toolchain/lower/testdata/interop/cpp/function/export/macho_asm_label.carbon
@@ -0,0 +1,368 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/full.carbon
+// Mach-O has a global symbol prefix (`_`), so Clang refers to Carbon functions
+// exported to C++ using an `\01`-prefixed asm label name. Check that those
+// references resolve to the Carbon definitions in the IR.
+// EXTRA-ARGS: --target=arm64-apple-macosx14.0
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/interop/cpp/function/export/macho_asm_label.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/interop/cpp/function/export/macho_asm_label.carbon
+
+// --- function.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp;
+
+fn F(i: i32) -> i32 { return i; }
+
+inline Cpp '''
+int G() {
+  return Carbon::F(1);
+}
+''';
+
+fn H() -> i32 { return Cpp.G(); }
+
+// --- constructor.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp;
+
+class C {
+  fn C(i: i32) -> Self {
+    return {.i = i};
+  }
+
+  var i: i32;
+}
+
+inline Cpp '''
+int G() {
+  Carbon::C c(42);
+  return c.i;
+}
+''';
+
+fn H() -> i32 { return Cpp.G(); }
+
+// CHECK:STDOUT: ; ---
+// CHECK:STDOUT: ; ModuleID = 'function.carbon'
+// CHECK:STDOUT: source_filename = "function.carbon"
+// CHECK:STDOUT: target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32"
+// CHECK:STDOUT: target triple = "arm64-apple-macosx14.0.0"
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: mustprogress ssp uwtable(sync)
+// CHECK:STDOUT: define noundef i32 @_Z1Gv() #0 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %call = call noundef i32 @_ZN6Carbon4MainL1FEi(i32 noundef 1)
+// CHECK:STDOUT:   ret i32 %call
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind ssp uwtable(sync)
+// CHECK:STDOUT: define internal noundef i32 @_ZN6Carbon4MainL1FEi(i32 noundef %0) #1 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %retval = alloca i32, align 4
+// CHECK:STDOUT:   %.addr = alloca i32, align 4
+// CHECK:STDOUT:   store i32 %0, ptr %.addr, align 4, !tbaa !36
+// CHECK:STDOUT:   call void @"\01__CF__carbon_thunk.Main"(ptr noundef nonnull align 4 dereferenceable(4) %.addr, ptr noundef nonnull align 4 dereferenceable(4) %retval)
+// CHECK:STDOUT:   %1 = load i32, ptr %retval, align 4
+// CHECK:STDOUT:   ret i32 %1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define i32 @_CF.Main(i32 %i) #2 !dbg !18 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   ret i32 %i, !dbg !24
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @"\01__CF__carbon_thunk.Main"(ptr noundef nonnull align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #3 !dbg !26 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.loc6 = load i32, ptr %_, align 4, !dbg !29
+// CHECK:STDOUT:   %F.call = call i32 @_CF.Main(i32 %.loc6), !dbg !29
+// CHECK:STDOUT:   store i32 %F.call, ptr %_1, align 4, !dbg !29
+// CHECK:STDOUT:   ret void, !dbg !29
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define i32 @_CH.Main() #2 !dbg !31 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %G.call = call i32 @_Z1Gv(), !dbg !34
+// CHECK:STDOUT:   ret i32 %G.call, !dbg !35
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: attributes #0 = { mustprogress ssp uwtable(sync) "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #1 = { alwaysinline mustprogress nounwind ssp uwtable(sync) "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #2 = { nounwind }
+// CHECK:STDOUT: attributes #3 = { nounwind "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT:
+// CHECK:STDOUT: !llvm.dbg.cu = !{!10}
+// CHECK:STDOUT: !llvm.module.flags = !{!37, !38, !39, !7, !8}
+// CHECK:STDOUT: !llvm.errno.tbaa = !{!41}
+// CHECK:STDOUT:
+// CHECK:STDOUT: !0 = !{!"Simple C++ TBAA"}
+// CHECK:STDOUT: !1 = !{!"omnipotent char", !0, i64 0}
+// CHECK:STDOUT: !2 = !{!"int", !1, i64 0}
+// CHECK:STDOUT: !7 = !{i32 7, !"Dwarf Version", i32 5}
+// CHECK:STDOUT: !8 = !{i32 2, !"Debug Info Version", i32 3}
+// CHECK:STDOUT: !9 = !DIFile(filename: "function.carbon", directory: "")
+// CHECK:STDOUT: !10 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !9, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+// CHECK:STDOUT: !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+// CHECK:STDOUT: !12 = !{!11, !11}
+// CHECK:STDOUT: !13 = !DISubroutineType(types: !12)
+// CHECK:STDOUT: !14 = !{null, !11, !11}
+// CHECK:STDOUT: !15 = !DISubroutineType(types: !14)
+// CHECK:STDOUT: !16 = !{!11}
+// CHECK:STDOUT: !17 = !DISubroutineType(types: !16)
+// CHECK:STDOUT: !18 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main", scope: null, file: !9, line: 6, type: !13, spFlags: DISPFlagDefinition, unit: !10, retainedNodes: !25)
+// CHECK:STDOUT: !19 = !DILocalVariable(arg: 1, scope: !18, type: !11)
+// CHECK:STDOUT: !24 = !DILocation(line: 6, column: 23, scope: !18)
+// CHECK:STDOUT: !25 = !{!19}
+// CHECK:STDOUT: !26 = distinct !DISubprogram(name: "F__carbon_thunk", linkageName: "_CF__carbon_thunk.Main", scope: null, file: !9, line: 6, type: !15, spFlags: DISPFlagDefinition, unit: !10, retainedNodes: !30)
+// CHECK:STDOUT: !27 = !DILocalVariable(arg: 1, scope: !26, type: !11)
+// CHECK:STDOUT: !28 = !DILocalVariable(arg: 2, scope: !26, type: !11)
+// CHECK:STDOUT: !29 = !DILocation(line: 6, column: 1, scope: !26)
+// CHECK:STDOUT: !30 = !{!27, !28}
+// CHECK:STDOUT: !31 = distinct !DISubprogram(name: "H", linkageName: "_CH.Main", scope: null, file: !9, line: 14, type: !17, spFlags: DISPFlagDefinition, unit: !10)
+// CHECK:STDOUT: !34 = !DILocation(line: 14, column: 24, scope: !31)
+// CHECK:STDOUT: !35 = !DILocation(line: 14, column: 17, scope: !31)
+// CHECK:STDOUT: !36 = !{!2, !2, i64 0}
+// CHECK:STDOUT: !37 = !{i32 8, !"PIC Level", i32 2}
+// CHECK:STDOUT: !38 = !{i32 7, !"uwtable", i32 1}
+// CHECK:STDOUT: !39 = !{i32 7, !"frame-pointer", i32 4}
+// CHECK:STDOUT: !40 = !{!"__libc_errno", !2, i64 0}
+// CHECK:STDOUT: !41 = !{!40, !2, i64 0}
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; ---
+// CHECK:STDOUT: ; ModuleID = 'constructor.carbon'
+// CHECK:STDOUT: source_filename = "constructor.carbon"
+// CHECK:STDOUT: target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32"
+// CHECK:STDOUT: target triple = "arm64-apple-macosx14.0.0"
+// CHECK:STDOUT:
+// CHECK:STDOUT: %"class.Carbon::Main::C" = type { i32 }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: mustprogress ssp uwtable(sync)
+// CHECK:STDOUT: define noundef i32 @_Z1Gv() #0 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %c = alloca %"class.Carbon::Main::C", align 4
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %c) #4
+// CHECK:STDOUT:   %call = call noundef ptr @_ZN6Carbon4Main1CC1Ei(ptr noundef nonnull align 4 dereferenceable(4) %c, i32 noundef 42)
+// CHECK:STDOUT:   %i = getelementptr inbounds nuw %"class.Carbon::Main::C", ptr %c, i32 0, i32 0
+// CHECK:STDOUT:   %0 = load i32, ptr %i, align 4, !tbaa !4
+// CHECK:STDOUT:   %call1 = call noundef ptr @_ZN6Carbon4Main1CD1Ev(ptr noundef nonnull align 4 dead_on_return(4) dereferenceable(4) %c) #4
+// CHECK:STDOUT:   call void @llvm.lifetime.end.p0(ptr %c) #4
+// CHECK:STDOUT:   ret i32 %0
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind ssp uwtable(sync)
+// CHECK:STDOUT: define internal noundef ptr @_ZN6Carbon4Main1CC1Ei(ptr noundef nonnull returned align 4 dereferenceable(4) %this, i32 noundef %0) unnamed_addr #2 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %this.addr = alloca ptr, align 8
+// CHECK:STDOUT:   %.addr = alloca i32, align 4
+// CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !101
+// CHECK:STDOUT:   store i32 %0, ptr %.addr, align 4, !tbaa !36
+// CHECK:STDOUT:   %this1 = load ptr, ptr %this.addr, align 8
+// CHECK:STDOUT:   %call = call noundef ptr @"\01__CC__carbon_thunk.C.Main"(ptr noundef nonnull align 4 dereferenceable(4) %this1, ptr noundef nonnull align 4 dereferenceable(4) %.addr)
+// CHECK:STDOUT:   ret ptr %this1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind ssp uwtable(sync)
+// CHECK:STDOUT: define linkonce_odr noundef ptr @_ZN6Carbon4Main1CD1Ev(ptr noundef nonnull returned align 4 dead_on_return(4) dereferenceable(4) %this) unnamed_addr #3 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %this.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !101
+// CHECK:STDOUT:   %this1 = load ptr, ptr %this.addr, align 8
+// CHECK:STDOUT:   %call = call noundef ptr @_ZN6Carbon4Main1CD2Ev(ptr noundef nonnull align 4 dead_on_return(4) dereferenceable(4) %this1) #4
+// CHECK:STDOUT:   ret ptr %this1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.lifetime.end.p0(ptr captures(none)) #1
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @_CC.C.Main(ptr sret({ i32 }) %return, i32 %i) #4 !dbg !51 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.loc8_19.2.i = getelementptr inbounds nuw { i32 }, ptr %return, i32 0, i32 0, !dbg !57
+// CHECK:STDOUT:   store i32 %i, ptr %.loc8_19.2.i, align 4, !dbg !57
+// CHECK:STDOUT:   ret void, !dbg !58
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: alwaysinline nounwind
+// CHECK:STDOUT: define weak_odr void @"_C__destroy_thunk:thunk.C.Main"(ptr %self) #5 !dbg !60 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CSelfDestruct.Core.356af3b6aef18564(ptr %self), !dbg !62
+// CHECK:STDOUT:   ret void, !dbg !62
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define weak_odr void @"_COp.d424893893628d5b:core.SubobjectDestroy.Core"(ptr %self) #4 !dbg !64 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.loc6_9.1.i = getelementptr inbounds nuw { i32 }, ptr %self, i32 0, i32 0, !dbg !66
+// CHECK:STDOUT:   call void @_CSelfDestruct.Core.f127f30143696d51(ptr %.loc6_9.1.i), !dbg !66
+// CHECK:STDOUT:   ret void, !dbg !66
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define weak_odr void @"_COp.08d9e38b928ba575:core.SubobjectDestroy.Core"(ptr %self) #4 !dbg !70 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.loc6_9.1.i = getelementptr inbounds nuw { i32 }, ptr %self, i32 0, i32 0, !dbg !72
+// CHECK:STDOUT:   call void @_CSelfDestruct.Core.f127f30143696d51(ptr %.loc6_9.1.i), !dbg !72
+// CHECK:STDOUT:   ret void, !dbg !72
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define noundef ptr @"\01__CC__carbon_thunk.C.Main"(ptr noundef nonnull returned align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) unnamed_addr #6 !dbg !74 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.loc7_24.2 = load i32, ptr %_1, align 4, !dbg !77
+// CHECK:STDOUT:   call void @_CC.C.Main(ptr %_, i32 %.loc7_24.2), !dbg !77
+// CHECK:STDOUT:   ret ptr %_
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define i32 @_CH.Main() #4 !dbg !79 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %G.call = call i32 @_Z1Gv(), !dbg !82
+// CHECK:STDOUT:   ret i32 %G.call, !dbg !83
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.356af3b6aef18564(ptr %t) #4 !dbg !85 {
+// CHECK:STDOUT:   call void @"_COp.08d9e38b928ba575:core.SubobjectDestroy.Core"(ptr %t), !dbg !89
+// CHECK:STDOUT:   ret void, !dbg !90
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.f127f30143696d51(ptr %t) #4 !dbg !92 {
+// CHECK:STDOUT:   ret void, !dbg !97
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind ssp uwtable(sync)
+// CHECK:STDOUT: define linkonce_odr noundef ptr @_ZN6Carbon4Main1CD2Ev(ptr noundef nonnull returned align 4 dead_on_return(4) dereferenceable(4) %this) unnamed_addr #3 personality ptr @__gxx_personality_v0 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %this.addr = alloca ptr, align 8
+// CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !101
+// CHECK:STDOUT:   %this1 = load ptr, ptr %this.addr, align 8
+// CHECK:STDOUT:   invoke void @"\01__C__destroy_thunk:thunk.C.Main"(ptr noundef nonnull align 4 dereferenceable(4) %this1)
+// CHECK:STDOUT:           to label %invoke.cont unwind label %terminate.lpad
+// CHECK:STDOUT:
+// CHECK:STDOUT: invoke.cont:                                      ; preds = %entry
+// CHECK:STDOUT:   ret ptr %this1
+// CHECK:STDOUT:
+// CHECK:STDOUT: terminate.lpad:                                   ; preds = %entry
+// CHECK:STDOUT:   %0 = landingpad { ptr, i32 }
+// CHECK:STDOUT:           catch ptr null
+// CHECK:STDOUT:   %1 = extractvalue { ptr, i32 } %0, 0
+// CHECK:STDOUT:   call void @__clang_call_terminate(ptr %1) #9
+// CHECK:STDOUT:   unreachable
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @"\01__C__destroy_thunk:thunk.C.Main"(ptr noundef nonnull align 4 dereferenceable(4)) #7
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare i32 @__gxx_personality_v0(...)
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: noinline noreturn nounwind ssp uwtable(sync)
+// CHECK:STDOUT: define linkonce_odr hidden void @__clang_call_terminate(ptr noundef %0) #8 {
+// CHECK:STDOUT:   %2 = call ptr @__cxa_begin_catch(ptr %0) #4
+// CHECK:STDOUT:   call void @_ZSt9terminatev() #9
+// CHECK:STDOUT:   unreachable
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare ptr @__cxa_begin_catch(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_ZSt9terminatev()
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; uselistorder directives
+// CHECK:STDOUT: uselistorder ptr @_CSelfDestruct.Core.f127f30143696d51, { 1, 0 }
+// CHECK:STDOUT:
+// CHECK:STDOUT: attributes #0 = { mustprogress ssp uwtable(sync) "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress nounwind ssp uwtable(sync) "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #3 = { inlinehint mustprogress nounwind ssp uwtable(sync) "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #4 = { nounwind }
+// CHECK:STDOUT: attributes #5 = { alwaysinline nounwind }
+// CHECK:STDOUT: attributes #6 = { nounwind "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #7 = { "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #8 = { noinline noreturn nounwind ssp uwtable(sync) "frame-pointer"="non-leaf-no-reserve" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="apple-m1" "target-features"="+aes,+altnzcv,+ccdp,+ccidx,+ccpp,+complxnum,+crc,+dit,+dotprod,+flagm,+fp-armv8,+fp16fml,+fptoint,+fullfp16,+jsconv,+lse,+neon,+pauth,+perfmon,+predres,+ras,+rcpc,+rdm,+sb,+sha2,+sha3,+specrestrict,+ssbs,+v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8a" "tune-cpu"="apple-m5" }
+// CHECK:STDOUT: attributes #9 = { noreturn nounwind }
+// CHECK:STDOUT:
+// CHECK:STDOUT: !llvm.dbg.cu = !{!43}
+// CHECK:STDOUT: !llvm.module.flags = !{!37, !38, !39, !7, !8}
+// CHECK:STDOUT: !llvm.errno.tbaa = !{!41}
+// CHECK:STDOUT:
+// CHECK:STDOUT: !0 = !{!"Simple C++ TBAA"}
+// CHECK:STDOUT: !1 = !{!"omnipotent char", !0, i64 0}
+// CHECK:STDOUT: !2 = !{!"int", !1, i64 0}
+// CHECK:STDOUT: !3 = !{!"_ZTSN6Carbon4Main1CE", !2, i64 0}
+// CHECK:STDOUT: !4 = !{!3, !2, i64 0}
+// CHECK:STDOUT: !7 = !{i32 7, !"Dwarf Version", i32 5}
+// CHECK:STDOUT: !8 = !{i32 2, !"Debug Info Version", i32 3}
+// CHECK:STDOUT: !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+// CHECK:STDOUT: !16 = !{!11}
+// CHECK:STDOUT: !17 = !DISubroutineType(types: !16)
+// CHECK:STDOUT: !36 = !{!2, !2, i64 0}
+// CHECK:STDOUT: !37 = !{i32 8, !"PIC Level", i32 2}
+// CHECK:STDOUT: !38 = !{i32 7, !"uwtable", i32 1}
+// CHECK:STDOUT: !39 = !{i32 7, !"frame-pointer", i32 4}
+// CHECK:STDOUT: !40 = !{!"__libc_errno", !2, i64 0}
+// CHECK:STDOUT: !41 = !{!40, !2, i64 0}
+// CHECK:STDOUT: !42 = !DIFile(filename: "constructor.carbon", directory: "")
+// CHECK:STDOUT: !43 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !42, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+// CHECK:STDOUT: !44 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
+// CHECK:STDOUT: !45 = !{!44, !11}
+// CHECK:STDOUT: !46 = !DISubroutineType(types: !45)
+// CHECK:STDOUT: !47 = !{null, !44}
+// CHECK:STDOUT: !48 = !DISubroutineType(types: !47)
+// CHECK:STDOUT: !49 = !{null, !44, !11}
+// CHECK:STDOUT: !50 = !DISubroutineType(types: !49)
+// CHECK:STDOUT: !51 = distinct !DISubprogram(name: "C", linkageName: "_CC.C.Main", scope: null, file: !42, line: 7, type: !46, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !59)
+// CHECK:STDOUT: !52 = !DILocalVariable(arg: 1, scope: !51, type: !11)
+// CHECK:STDOUT: !57 = !DILocation(line: 8, column: 12, scope: !51)
+// CHECK:STDOUT: !58 = !DILocation(line: 8, column: 5, scope: !51)
+// CHECK:STDOUT: !59 = !{!52}
+// CHECK:STDOUT: !60 = distinct !DISubprogram(name: "__destroy_thunk", linkageName: "_C__destroy_thunk:thunk.C.Main", scope: null, file: !42, line: 6, type: !48, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !63)
+// CHECK:STDOUT: !61 = !DILocalVariable(arg: 1, scope: !60, type: !44)
+// CHECK:STDOUT: !62 = !DILocation(line: 6, column: 1, scope: !60)
+// CHECK:STDOUT: !63 = !{!61}
+// CHECK:STDOUT: !64 = distinct !DISubprogram(name: "Op", linkageName: "_COp.d424893893628d5b:core.SubobjectDestroy.Core", scope: null, file: !42, line: 6, type: !48, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !69)
+// CHECK:STDOUT: !65 = !DILocalVariable(arg: 1, scope: !64, type: !44)
+// CHECK:STDOUT: !66 = !DILocation(line: 6, column: 1, scope: !64)
+// CHECK:STDOUT: !67 = !{null, !11}
+// CHECK:STDOUT: !68 = !DISubroutineType(types: !67)
+// CHECK:STDOUT: !69 = !{!65}
+// CHECK:STDOUT: !70 = distinct !DISubprogram(name: "Op", linkageName: "_COp.08d9e38b928ba575:core.SubobjectDestroy.Core", scope: null, file: !42, line: 6, type: !48, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !73)
+// CHECK:STDOUT: !71 = !DILocalVariable(arg: 1, scope: !70, type: !44)
+// CHECK:STDOUT: !72 = !DILocation(line: 6, column: 1, scope: !70)
+// CHECK:STDOUT: !73 = !{!71}
+// CHECK:STDOUT: !74 = distinct !DISubprogram(name: "C__carbon_thunk", linkageName: "_CC__carbon_thunk.C.Main", scope: null, file: !42, line: 7, type: !50, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !78)
+// CHECK:STDOUT: !75 = !DILocalVariable(arg: 1, scope: !74, type: !44)
+// CHECK:STDOUT: !76 = !DILocalVariable(arg: 2, scope: !74, type: !11)
+// CHECK:STDOUT: !77 = !DILocation(line: 7, column: 3, scope: !74)
+// CHECK:STDOUT: !78 = !{!75, !76}
+// CHECK:STDOUT: !79 = distinct !DISubprogram(name: "H", linkageName: "_CH.Main", scope: null, file: !42, line: 21, type: !17, spFlags: DISPFlagDefinition, unit: !43)
+// CHECK:STDOUT: !82 = !DILocation(line: 21, column: 24, scope: !79)
+// CHECK:STDOUT: !83 = !DILocation(line: 21, column: 17, scope: !79)
+// CHECK:STDOUT: !84 = !DIFile(filename: "{{.*}}/prelude/destroy.carbon", directory: "")
+// CHECK:STDOUT: !85 = distinct !DISubprogram(name: "SelfDestruct", linkageName: "_CSelfDestruct.Core.356af3b6aef18564", scope: null, file: !84, line: 36, type: !48, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !91)
+// CHECK:STDOUT: !86 = !DILocalVariable(arg: 1, scope: !85, type: !44)
+// CHECK:STDOUT: !89 = !DILocation(line: 38, column: 5, scope: !85)
+// CHECK:STDOUT: !90 = !DILocation(line: 36, column: 1, scope: !85)
+// CHECK:STDOUT: !91 = !{!86}
+// CHECK:STDOUT: !92 = distinct !DISubprogram(name: "SelfDestruct", linkageName: "_CSelfDestruct.Core.f127f30143696d51", scope: null, file: !84, line: 36, type: !68, spFlags: DISPFlagDefinition, unit: !43, retainedNodes: !98)
+// CHECK:STDOUT: !93 = !DILocalVariable(arg: 1, scope: !92, type: !11)
+// CHECK:STDOUT: !97 = !DILocation(line: 36, column: 1, scope: !92)
+// CHECK:STDOUT: !98 = !{!93}
+// CHECK:STDOUT: !99 = !{!"any pointer", !1, i64 0}
+// CHECK:STDOUT: !100 = !{!"p1 _ZTSN6Carbon4Main1CE", !99, i64 0}
+// CHECK:STDOUT: !101 = !{!100, !100, i64 0}
+// CHECK:STDOUT:
diff --git a/toolchain/lower/testdata/interop/cpp/function/import/function_ptr.carbon b/toolchain/lower/testdata/interop/cpp/function/import/function_ptr.carbon
index a7eb6844ccd6..938dfa2154b8 100644
--- a/toolchain/lower/testdata/interop/cpp/function/import/function_ptr.carbon
+++ b/toolchain/lower/testdata/interop/cpp/function/import/function_ptr.carbon
@@ -196,7 +196,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr %_, ptr %_1) #0 !dbg !36 {
+// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr noundef nonnull align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #1 !dbg !36 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc8 = load float, ptr %_, align 4, !dbg !39
 // CHECK:STDOUT:   %MyCallback.call = call i32 @_CMyCallback.Main(float %.loc8), !dbg !40
@@ -205,7 +205,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.9d0db8a57c58fabc(ptr %t) #0 !dbg !43 {
@@ -213,7 +213,8 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!26}
 // CHECK:STDOUT: !llvm.module.flags = !{!17, !18, !19, !2, !3}
@@ -270,7 +271,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr %_, ptr %_1) #0 !dbg !55 {
+// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr noundef nonnull align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #1 !dbg !55 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc5 = load float, ptr %_, align 4, !dbg !58
 // CHECK:STDOUT:   %MyCallback.call = call i32 @_CMyCallback.Main(float %.loc5), !dbg !58
@@ -278,10 +279,11 @@ fn F() {
 // CHECK:STDOUT:   ret void, !dbg !58
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_Z12TakeCallbackPFifE(ptr noundef) #1
+// CHECK:STDOUT: declare void @_Z12TakeCallbackPFifE(ptr noundef) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!51}
 // CHECK:STDOUT: !llvm.module.flags = !{!17, !18, !19, !2, !3}
@@ -482,14 +484,14 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr %_, ptr %_1) #0 !dbg !108 {
+// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr noundef nonnull align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #1 !dbg !108 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CMyCallback.Main(ptr %_1, ptr %_), !dbg !112
 // CHECK:STDOUT:   ret void, !dbg !112
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.9d0db8a57c58fabc(ptr %t) #0 !dbg !114 {
@@ -497,7 +499,8 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!99}
 // CHECK:STDOUT: !llvm.module.flags = !{!17, !18, !19, !2, !3}
@@ -552,16 +555,17 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr %_, ptr %_1) #0 !dbg !126 {
+// CHECK:STDOUT: define void @_CMyCallback__carbon_thunk.Main(ptr noundef nonnull align 4 dereferenceable(4) %_, ptr noundef nonnull align 4 dereferenceable(4) %_1) #1 !dbg !126 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CMyCallback.Main(ptr %_1, ptr %_), !dbg !129
 // CHECK:STDOUT:   ret void, !dbg !129
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_Z19TakeComplexCallbackPF1CS_E(ptr noundef) #1
+// CHECK:STDOUT: declare void @_Z19TakeComplexCallbackPF1CS_E(ptr noundef) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!122}
 // CHECK:STDOUT: !llvm.module.flags = !{!17, !18, !19, !2, !3}
diff --git a/toolchain/lower/testdata/interop/cpp/function/import/method_ptr.carbon b/toolchain/lower/testdata/interop/cpp/function/import/method_ptr.carbon
index 230c527509ae..5c00c840457f 100644
--- a/toolchain/lower/testdata/interop/cpp/function/import/method_ptr.carbon
+++ b/toolchain/lower/testdata/interop/cpp/function/import/method_ptr.carbon
@@ -194,14 +194,14 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CMethod__carbon_thunk.C.Main(ptr %self) #0 !dbg !44 {
+// CHECK:STDOUT: define void @_CMethod__carbon_thunk.C.Main(ptr noundef nonnull align 1 %self) #2 !dbg !44 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CMethod.C.Main(ptr %self), !dbg !47
 // CHECK:STDOUT:   ret void, !dbg !47
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.9d0db8a57c58fabc(ptr %t) #0 !dbg !49 {
@@ -215,7 +215,8 @@ fn F() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #2 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!35}
 // CHECK:STDOUT: !llvm.module.flags = !{!28, !29, !30, !2, !3}
@@ -287,14 +288,14 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CMethod__carbon_thunk.C.Main(ptr %self) #0 !dbg !73 {
+// CHECK:STDOUT: define void @_CMethod__carbon_thunk.C.Main(ptr noundef nonnull align 1 %self) #2 !dbg !73 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CMethod.C.Main(ptr %self), !dbg !75
 // CHECK:STDOUT:   ret void, !dbg !75
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress uwtable
-// CHECK:STDOUT: define internal void @_Z20TakeGenericMethodPtrIN6Carbon4Main1CEEvMT_KFvvE.carbon_thunk._(ptr noundef %ptr) #2 {
+// CHECK:STDOUT: define internal void @_Z20TakeGenericMethodPtrIN6Carbon4Main1CEEvMT_KFvvE.carbon_thunk._(ptr noundef %ptr) #3 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %ptr.addr = alloca ptr, align 8
 // CHECK:STDOUT:   %coerce = alloca { i64, i64 }, align 8
@@ -311,7 +312,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #3
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #4
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.9d0db8a57c58fabc(ptr %t) #0 !dbg !77 {
@@ -323,13 +324,14 @@ fn F() {
 // CHECK:STDOUT:   ret void, !dbg !89
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_Z20TakeGenericMethodPtrIN6Carbon4Main1CEEvMT_KFvvE(i64, i64) #4
+// CHECK:STDOUT: declare void @_Z20TakeGenericMethodPtrIN6Carbon4Main1CEEvMT_KFvvE(i64, i64) #5
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #4 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #2 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { alwaysinline mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #4 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #5 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!64}
 // CHECK:STDOUT: !llvm.module.flags = !{!28, !29, !30, !2, !3}
diff --git a/toolchain/lower/testdata/interop/cpp/issue7142.carbon b/toolchain/lower/testdata/interop/cpp/issue7142.carbon
index f429bf1fb3ba..45ef9a3adc7a 100644
--- a/toolchain/lower/testdata/interop/cpp/issue7142.carbon
+++ b/toolchain/lower/testdata/interop/cpp/issue7142.carbon
@@ -56,7 +56,7 @@ void f() {
 // CHECK:STDOUT: declare ptr @_CGet.Main()
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define void @_CGet__carbon_thunk.Main(ptr %_) #1 !dbg !12 {
+// CHECK:STDOUT: define void @_CGet__carbon_thunk.Main(ptr noundef nonnull align 8 dereferenceable(8) %_) #1 !dbg !12 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %Get.call = call ptr @_CGet.Main(), !dbg !14
 // CHECK:STDOUT:   store ptr %Get.call, ptr %_, align 8, !dbg !14
@@ -71,7 +71,7 @@ void f() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define weak_odr void @"_COp.daf9f875be2f7080:core.SubobjectDestroy.Core"(ptr %self) #1 !dbg !20 {
+// CHECK:STDOUT: define weak_odr void @"_COp.daf9f875be2f7080:core.SubobjectDestroy.Core"(ptr %self) #3 !dbg !20 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc15_9.1.price = getelementptr inbounds nuw { i32 }, ptr %self, i32 0, i32 0, !dbg !22
 // CHECK:STDOUT:   call void @_CSelfDestruct.Core.f127f30143696d51(ptr %.loc15_9.1.price), !dbg !22
@@ -79,7 +79,7 @@ void f() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define weak_odr void @"_COp.5a23cc09585c55d2:core.SubobjectDestroy.Core"(ptr %self) #1 !dbg !26 {
+// CHECK:STDOUT: define weak_odr void @"_COp.5a23cc09585c55d2:core.SubobjectDestroy.Core"(ptr %self) #3 !dbg !26 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc15_9.1.price = getelementptr inbounds nuw { i32 }, ptr %self, i32 0, i32 0, !dbg !28
 // CHECK:STDOUT:   call void @_CSelfDestruct.Core.f127f30143696d51(ptr %.loc15_9.1.price), !dbg !28
@@ -87,18 +87,18 @@ void f() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.6b8b385dcf82cc70(ptr %t) #1 !dbg !31 {
+// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.6b8b385dcf82cc70(ptr %t) #3 !dbg !31 {
 // CHECK:STDOUT:   call void @"_COp.5a23cc09585c55d2:core.SubobjectDestroy.Core"(ptr %t), !dbg !35
 // CHECK:STDOUT:   ret void, !dbg !36
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
-// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.f127f30143696d51(ptr %t) #1 !dbg !38 {
+// CHECK:STDOUT: define linkonce_odr void @_CSelfDestruct.Core.f127f30143696d51(ptr %t) #3 !dbg !38 {
 // CHECK:STDOUT:   ret void, !dbg !43
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress nounwind uwtable
-// CHECK:STDOUT: define internal noundef ptr @_ZN6Carbon4MainL3GetEv() #3 {
+// CHECK:STDOUT: define internal noundef ptr @_ZN6Carbon4MainL3GetEv() #4 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %retval = alloca ptr, align 8
 // CHECK:STDOUT:   call void @_CGet__carbon_thunk.Main(ptr noundef nonnull align 8 dereferenceable(8) %retval)
@@ -110,9 +110,10 @@ void f() {
 // CHECK:STDOUT: uselistorder ptr @_CSelfDestruct.Core.f127f30143696d51, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #1 = { nounwind }
+// CHECK:STDOUT: attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #2 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #3 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+// CHECK:STDOUT: attributes #3 = { nounwind }
+// CHECK:STDOUT: attributes #4 = { alwaysinline mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
 // CHECK:STDOUT: !llvm.module.flags = !{!52, !53, !54, !2, !3}