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Use the value representation of T as that of MaybeUnformed(T) where possible (#6334)

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If the value representation of `T` is a copy representation, but it
copies all of the bits of `T`'s object representation, then it's OK to
use that as the value representation of `MaybeUnformed(T)` too.

This fixes the behavior of interop with nullable pointers, which are
represented as an adapter of `MaybeUnformed(T*)`, and need to be passed
to and returned from functions on the Carbon / C++ boundary as `T*`s.
This commit is contained in:
Richard Smith
2025-11-07 16:25:27 +00:00
committed by GitHub
parent d6c19442b2
commit 8f19f7a7c0
14 changed files with 417 additions and 322 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/lower/testdata/interop/cpp/pointer.carbon
Vendored
+58 -47
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@@ -68,6 +68,8 @@ fn PassPtr(p: Core.Optional(Cpp.C*)) {
}
fn PassNonnullPtr(p: Cpp.C*) {
// TODO: The `value_of_initializer` optimization doesn't get used here, so we
// unnecessarily round-trip this value through memory.
Cpp.TakePtr(p);
}
@@ -188,23 +190,25 @@ fn ReturnPtrWithThunk() -> Core.Optional(Cpp.C*) {
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CPassNonnullPtr.Main(ptr %p) #0 !dbg !11 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc20_15.1.temp = alloca ptr, align 8, !dbg !12
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc20_15.1.temp), !dbg !12
// CHECK:STDOUT: call void @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422"(ptr %.loc20_15.1.temp, ptr %p), !dbg !12
// CHECK:STDOUT: call void @_Z7TakePtrP1C(ptr %.loc20_15.1.temp), !dbg !13
// CHECK:STDOUT: %.loc22_15.2.temp = alloca ptr, align 8, !dbg !12
// CHECK:STDOUT: %U.binding.as_type.as.ImplicitAs.impl.Convert.call = call ptr @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422"(ptr %p), !dbg !12
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc22_15.2.temp), !dbg !12
// CHECK:STDOUT: store ptr %U.binding.as_type.as.ImplicitAs.impl.Convert.call, ptr %.loc22_15.2.temp, align 8, !dbg !12
// CHECK:STDOUT: %.loc22_15.4 = load ptr, ptr %.loc22_15.2.temp, align 8, !dbg !12
// CHECK:STDOUT: call void @_Z7TakePtrP1C(ptr %.loc22_15.4), !dbg !13
// CHECK:STDOUT: ret void, !dbg !14
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_Z7TakePtrP1C(ptr)
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CReturnPtr.Main(ptr sret(ptr) %return) #0 !dbg !15 {
// CHECK:STDOUT: define ptr @_CReturnPtr.Main() #0 !dbg !15 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @_Z9ReturnPtrv(ptr %return), !dbg !16
// CHECK:STDOUT: ret void, !dbg !17
// CHECK:STDOUT: %ReturnPtr.call = call ptr @_Z9ReturnPtrv(), !dbg !16
// CHECK:STDOUT: ret ptr %ReturnPtr.call, !dbg !17
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_Z9ReturnPtrv(ptr sret(ptr))
// CHECK:STDOUT: declare ptr @_Z9ReturnPtrv()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CPassPtrWithThunk.Main(ptr %p) #0 !dbg !18 {
@@ -215,45 +219,50 @@ fn ReturnPtrWithThunk() -> Core.Optional(Cpp.C*) {
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CPassNonnullPtrWithThunk.Main(ptr %p) #0 !dbg !20 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc33_24.1.temp = alloca ptr, align 8, !dbg !21
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc33_24.1.temp), !dbg !21
// CHECK:STDOUT: call void @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422"(ptr %.loc33_24.1.temp, ptr %p), !dbg !21
// CHECK:STDOUT: call void @_Z16TakePtrWithThunkP1Ci.carbon_thunk1(ptr %.loc33_24.1.temp), !dbg !22
// CHECK:STDOUT: %.loc35_24.2.temp = alloca ptr, align 8, !dbg !21
// CHECK:STDOUT: %U.binding.as_type.as.ImplicitAs.impl.Convert.call = call ptr @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422"(ptr %p), !dbg !21
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc35_24.2.temp), !dbg !21
// CHECK:STDOUT: store ptr %U.binding.as_type.as.ImplicitAs.impl.Convert.call, ptr %.loc35_24.2.temp, align 8, !dbg !21
// CHECK:STDOUT: %.loc35_24.4 = load ptr, ptr %.loc35_24.2.temp, align 8, !dbg !21
// CHECK:STDOUT: call void @_Z16TakePtrWithThunkP1Ci.carbon_thunk1(ptr %.loc35_24.4), !dbg !22
// CHECK:STDOUT: ret void, !dbg !23
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CReturnPtrWithThunk.Main(ptr sret(ptr) %return) #0 !dbg !24 {
// CHECK:STDOUT: define ptr @_CReturnPtrWithThunk.Main() #0 !dbg !24 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @_Z18ReturnPtrWithThunki.carbon_thunk0(ptr %return), !dbg !25
// CHECK:STDOUT: ret void, !dbg !26
// CHECK:STDOUT: %ReturnPtrWithThunk__carbon_thunk.call = call ptr @_Z18ReturnPtrWithThunki.carbon_thunk0(), !dbg !25
// CHECK:STDOUT: ret ptr %ReturnPtrWithThunk__carbon_thunk.call, !dbg !26
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr ptr @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422"(ptr %self) #0 !dbg !27 {
// CHECK:STDOUT: %1 = call ptr @"_CConvert.8d16edc1dfe20a7c:OptionalAs.Core.b5eba8f3f1d9af5a"(ptr %self), !dbg !29
// CHECK:STDOUT: ret ptr %1, !dbg !30
// 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: nounwind
// CHECK:STDOUT: define linkonce_odr void @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422"(ptr sret(ptr) %return, ptr %self) #0 !dbg !27 {
// CHECK:STDOUT: call void @"_CConvert.8d16edc1dfe20a7c:OptionalAs.Core.b5eba8f3f1d9af5a"(ptr %return, ptr %self), !dbg !29
// CHECK:STDOUT: ret void, !dbg !30
// CHECK:STDOUT: define linkonce_odr ptr @"_CConvert.8d16edc1dfe20a7c:OptionalAs.Core.b5eba8f3f1d9af5a"(ptr %self) #0 !dbg !31 {
// CHECK:STDOUT: %1 = call ptr @_CSome.Optional.Core.b5eba8f3f1d9af5a(ptr %self), !dbg !32
// CHECK:STDOUT: ret ptr %1, !dbg !33
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr void @"_CConvert.8d16edc1dfe20a7c:OptionalAs.Core.b5eba8f3f1d9af5a"(ptr sret(ptr) %return, ptr %self) #0 !dbg !31 {
// CHECK:STDOUT: call void @_CSome.Optional.Core.b5eba8f3f1d9af5a(ptr %return, ptr %self), !dbg !32
// CHECK:STDOUT: ret void, !dbg !33
// CHECK:STDOUT: define linkonce_odr ptr @_CSome.Optional.Core.b5eba8f3f1d9af5a(ptr %value) #0 !dbg !34 {
// CHECK:STDOUT: %1 = call ptr @"_CSome.4f0b5cc38af595d2:OptionalStorage.Core.f53db17714b9f655"(ptr %value), !dbg !35
// CHECK:STDOUT: ret ptr %1, !dbg !36
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr void @_CSome.Optional.Core.b5eba8f3f1d9af5a(ptr sret(ptr) %return, ptr %value) #0 !dbg !34 {
// CHECK:STDOUT: call void @"_CSome.4f0b5cc38af595d2:OptionalStorage.Core.f53db17714b9f655"(ptr %return, ptr %value), !dbg !35
// CHECK:STDOUT: ret void, !dbg !36
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr void @"_CSome.4f0b5cc38af595d2:OptionalStorage.Core.f53db17714b9f655"(ptr sret(ptr) %return, ptr %self) #0 !dbg !37 {
// CHECK:STDOUT: store ptr %self, ptr %return, align 8, !dbg !38
// CHECK:STDOUT: ret void, !dbg !39
// CHECK:STDOUT: define linkonce_odr ptr @"_CSome.4f0b5cc38af595d2:OptionalStorage.Core.f53db17714b9f655"(ptr %self) #0 !dbg !37 {
// CHECK:STDOUT: %1 = alloca ptr, align 8, !dbg !38
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %1), !dbg !38
// CHECK:STDOUT: store ptr %self, ptr %1, align 8, !dbg !39
// CHECK:STDOUT: %2 = load ptr, ptr %1, align 8, !dbg !40
// CHECK:STDOUT: ret ptr %2, !dbg !41
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: alwaysinline mustprogress
@@ -278,8 +287,8 @@ fn ReturnPtrWithThunk() -> Core.Optional(Cpp.C*) {
// CHECK:STDOUT: declare ptr @_Z18ReturnPtrWithThunki(i32) #3
// CHECK:STDOUT:
// CHECK:STDOUT: ; uselistorder directives
// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
// CHECK:STDOUT: uselistorder ptr @"_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422", { 1, 0 }
// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 0, 2, 1 }
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
@@ -301,21 +310,21 @@ fn ReturnPtrWithThunk() -> Core.Optional(Cpp.C*) {
// CHECK:STDOUT: !9 = !{}
// CHECK:STDOUT: !10 = !DILocation(line: 14, column: 1, scope: !7)
// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "PassNonnullPtr", linkageName: "_CPassNonnullPtr.Main", scope: null, file: !6, line: 19, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !12 = !DILocation(line: 20, column: 15, scope: !11)
// CHECK:STDOUT: !13 = !DILocation(line: 20, column: 3, scope: !11)
// CHECK:STDOUT: !12 = !DILocation(line: 22, column: 15, scope: !11)
// CHECK:STDOUT: !13 = !DILocation(line: 22, column: 3, scope: !11)
// CHECK:STDOUT: !14 = !DILocation(line: 19, column: 1, scope: !11)
// CHECK:STDOUT: !15 = distinct !DISubprogram(name: "ReturnPtr", linkageName: "_CReturnPtr.Main", scope: null, file: !6, line: 23, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !16 = !DILocation(line: 24, column: 10, scope: !15)
// CHECK:STDOUT: !17 = !DILocation(line: 24, column: 3, scope: !15)
// CHECK:STDOUT: !18 = distinct !DISubprogram(name: "PassPtrWithThunk", linkageName: "_CPassPtrWithThunk.Main", scope: null, file: !6, line: 27, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !19 = !DILocation(line: 27, column: 1, scope: !18)
// CHECK:STDOUT: !20 = distinct !DISubprogram(name: "PassNonnullPtrWithThunk", linkageName: "_CPassNonnullPtrWithThunk.Main", scope: null, file: !6, line: 32, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !21 = !DILocation(line: 33, column: 24, scope: !20)
// CHECK:STDOUT: !22 = !DILocation(line: 33, column: 3, scope: !20)
// CHECK:STDOUT: !23 = !DILocation(line: 32, column: 1, scope: !20)
// CHECK:STDOUT: !24 = distinct !DISubprogram(name: "ReturnPtrWithThunk", linkageName: "_CReturnPtrWithThunk.Main", scope: null, file: !6, line: 36, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !25 = !DILocation(line: 37, column: 10, scope: !24)
// CHECK:STDOUT: !26 = !DILocation(line: 37, column: 3, scope: !24)
// CHECK:STDOUT: !15 = distinct !DISubprogram(name: "ReturnPtr", linkageName: "_CReturnPtr.Main", scope: null, file: !6, line: 25, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !16 = !DILocation(line: 26, column: 10, scope: !15)
// CHECK:STDOUT: !17 = !DILocation(line: 26, column: 3, scope: !15)
// CHECK:STDOUT: !18 = distinct !DISubprogram(name: "PassPtrWithThunk", linkageName: "_CPassPtrWithThunk.Main", scope: null, file: !6, line: 29, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !19 = !DILocation(line: 29, column: 1, scope: !18)
// CHECK:STDOUT: !20 = distinct !DISubprogram(name: "PassNonnullPtrWithThunk", linkageName: "_CPassNonnullPtrWithThunk.Main", scope: null, file: !6, line: 34, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !21 = !DILocation(line: 35, column: 24, scope: !20)
// CHECK:STDOUT: !22 = !DILocation(line: 35, column: 3, scope: !20)
// CHECK:STDOUT: !23 = !DILocation(line: 34, column: 1, scope: !20)
// CHECK:STDOUT: !24 = distinct !DISubprogram(name: "ReturnPtrWithThunk", linkageName: "_CReturnPtrWithThunk.Main", scope: null, file: !6, line: 38, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !25 = !DILocation(line: 39, column: 10, scope: !24)
// CHECK:STDOUT: !26 = !DILocation(line: 39, column: 3, scope: !24)
// CHECK:STDOUT: !27 = distinct !DISubprogram(name: "Convert", linkageName: "_CConvert.f82b7327366b1770:ImplicitAs.Core.78b0d6e062ff6422", scope: null, file: !28, line: 82, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !28 = !DIFile(filename: "{{.*}}/prelude/types/optional.carbon", directory: "")
// CHECK:STDOUT: !29 = !DILocation(line: 83, column: 12, scope: !27)
@@ -327,5 +336,7 @@ fn ReturnPtrWithThunk() -> Core.Optional(Cpp.C*) {
// CHECK:STDOUT: !35 = !DILocation(line: 30, column: 12, scope: !34)
// CHECK:STDOUT: !36 = !DILocation(line: 30, column: 5, scope: !34)
// CHECK:STDOUT: !37 = distinct !DISubprogram(name: "Some", linkageName: "_CSome.4f0b5cc38af595d2:OptionalStorage.Core.f53db17714b9f655", scope: null, file: !28, line: 125, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !38 = !DILocation(line: 127, column: 5, scope: !37)
// CHECK:STDOUT: !39 = !DILocation(line: 128, column: 5, scope: !37)
// CHECK:STDOUT: !38 = !DILocation(line: 126, column: 14, scope: !37)
// CHECK:STDOUT: !39 = !DILocation(line: 127, column: 5, scope: !37)
// CHECK:STDOUT: !40 = !DILocation(line: 126, column: 18, scope: !37)
// CHECK:STDOUT: !41 = !DILocation(line: 128, column: 5, scope: !37)