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a179bd461b4a07bf2defe91e68f1bb9edfa60551
carbon-lang/toolchain/lower/testdata/function/definition/destroy.carbon
T
David BlaikieandDana Jansens a179bd461b Start plumbing through debug info type information with function parameters/return value (#6410) 
This adds just enough debug info for i32/int parameters and return
values, with a path forward for adding DWARF type metadata for other
types.

As it happens, return type information is carried separately from
parameter information:
* Return type information is carried in the `type` of the `DISubprogram`
  (as a `DISubroutineType` - which does carry parameter type information
  as well, but that's unused when the DWARF is emitted by LLVM)
* Parameter information is carried by `DILocalVariable`s with a non-zero
  `arg` value (representing the order of function parameters)

In the absence of locations for the parameters (future work), nothing
would usually keep the `DILocalVariable` live/reachable when emitting
DWARF - so for cases where this can happen (for clang, this happens in
optimized builds where all references to the parameter variable might be
optimized away) the variables can be "retained" in a list on the
`DISubprogram` - achieved by passing `AlwaysPreserve` parameter to
`createParameterVariable` (adds them to a list, then that list gets
attached to the `DISubprogram` when it's finalized later)

For now, any unsupported types are emitted as `void*` (except void
return, which is implemented as void) as a placeholder.

Given this example:
```
import Core library "io";
class MyClass {
}
fn Unsupported(v: MyClass) {
}
fn Ret() -> i32 {
  return 42;
}
fn Arg(x: i32) {
  Core.Print(x);
}
fn Run() {
}
```
this is the resulting DWARF:
```
DW_TAG_compile_unit
  DW_AT_name    ("test.carbon")
  DW_TAG_subprogram
    DW_AT_name  ("Unsupported")
    DW_TAG_formal_parameter
      DW_AT_type        (0x00000066 "void *")
  DW_TAG_subprogram
    DW_AT_name  ("Ret")
    DW_AT_type  (0x00000062 "int")
  DW_TAG_subprogram
    DW_AT_name  ("Arg")
    DW_TAG_formal_parameter
      DW_AT_type        (0x00000062 "int")
  DW_TAG_subprogram
    DW_AT_name  ("Run")
  DW_TAG_base_type
    DW_AT_name  ("int")
  DW_TAG_pointer_type
```
And the debugger:
```
(gdb) p Ret()
$1 = 42
(gdb) p Arg(4)
4
$2 = void
```

I'm not sure if there's a way this logic should be merged with the logic
for making the `llvm::Function` type (which the `DISubroutineType`
building code was inspired by/copied from) - since they're done at
different times/places, I don't think there's an easy way to do it in
one pass, but maybe the code can be shared (even if it's run twice) in
some generic `SemIR::Function` type walker.

---------

Co-authored-by: Dana Jansens <danakj@orodu.net>
2025-11-25 23:25:09 +00:00

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// 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/convert.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/function/definition/destroy.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/function/definition/destroy.carbon
// --- let_param.carbon
library "[[@TEST_NAME]]";
class C {}
fn F(x: C) {
}
fn G();
fn CallF() {
F({});
// TODO: The `C` instance is destroyed after the call to `G()`, and
// should be destroyed before.
G();
}
// --- var_param.carbon
library "[[@TEST_NAME]]";
class C {}
fn F(var x: C) {
}
fn G();
fn CallF() {
F({});
// TODO: The `C` instance is destroyed after the call to `G()`, and
// should be destroyed before.
G();
}
// --- return_slot.carbon
library "[[@TEST_NAME]]";
class C {}
fn F() -> C {
return {};
}
fn G();
fn Forward() -> C {
return F();
}
fn InitVar() {
var local: C = F();
G();
}
fn InitLet() {
let local: C = F();
G();
}
// CHECK:STDOUT: ; ModuleID = 'let_param.carbon'
// CHECK:STDOUT: source_filename = "let_param.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: @C.val.loc12_6.3 = internal constant {} zeroinitializer
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CF.Main(ptr %x) #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: ret void, !dbg !10
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CG.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CCallF.Main() #0 !dbg !11 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc12_6.2.temp = alloca {}, align 8, !dbg !14
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc12_6.2.temp), !dbg !14
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc12_6.2.temp, ptr align 1 @C.val.loc12_6.3, i64 0, i1 false), !dbg !14
// CHECK:STDOUT: call void @_CF.Main(ptr %.loc12_6.2.temp), !dbg !15
// CHECK:STDOUT: call void @_CG.Main(), !dbg !16
// CHECK:STDOUT: ret void, !dbg !17
// 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: nocallback nofree nounwind willreturn memory(argmem: readwrite)
// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !3 = !DIFile(filename: "let_param.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main", scope: null, file: !3, line: 6, type: !5, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !8)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{null, !7}
// CHECK:STDOUT: !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 8)
// CHECK:STDOUT: !8 = !{!9}
// CHECK:STDOUT: !9 = !DILocalVariable(arg: 1, scope: !4, type: !7)
// CHECK:STDOUT: !10 = !DILocation(line: 6, column: 1, scope: !4)
// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main", scope: null, file: !3, line: 11, type: !12, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !12 = !DISubroutineType(types: !13)
// CHECK:STDOUT: !13 = !{null}
// CHECK:STDOUT: !14 = !DILocation(line: 12, column: 5, scope: !11)
// CHECK:STDOUT: !15 = !DILocation(line: 12, column: 3, scope: !11)
// CHECK:STDOUT: !16 = !DILocation(line: 15, column: 3, scope: !11)
// CHECK:STDOUT: !17 = !DILocation(line: 11, column: 1, scope: !11)
// CHECK:STDOUT: ; ModuleID = 'var_param.carbon'
// CHECK:STDOUT: source_filename = "var_param.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: @C.val.loc6_6.2 = internal constant {} zeroinitializer
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CF.Main(ptr %x) #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: ret void, !dbg !10
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CG.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CCallF.Main() #0 !dbg !11 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc6_6.1.temp = alloca {}, align 8, !dbg !14
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc6_6.1.temp), !dbg !14
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc6_6.1.temp, ptr align 1 @C.val.loc6_6.2, i64 0, i1 false), !dbg !14
// CHECK:STDOUT: call void @_CF.Main(ptr %.loc6_6.1.temp), !dbg !15
// CHECK:STDOUT: call void @_CG.Main(), !dbg !16
// CHECK:STDOUT: ret void, !dbg !17
// 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: nocallback nofree nounwind willreturn memory(argmem: readwrite)
// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !3 = !DIFile(filename: "var_param.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main", scope: null, file: !3, line: 6, type: !5, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !8)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{null, !7}
// CHECK:STDOUT: !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 8)
// CHECK:STDOUT: !8 = !{!9}
// CHECK:STDOUT: !9 = !DILocalVariable(arg: 1, scope: !4, type: !7)
// CHECK:STDOUT: !10 = !DILocation(line: 6, column: 1, scope: !4)
// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main", scope: null, file: !3, line: 11, type: !12, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !12 = !DISubroutineType(types: !13)
// CHECK:STDOUT: !13 = !{null}
// CHECK:STDOUT: !14 = !DILocation(line: 6, column: 6, scope: !11)
// CHECK:STDOUT: !15 = !DILocation(line: 12, column: 3, scope: !11)
// CHECK:STDOUT: !16 = !DILocation(line: 15, column: 3, scope: !11)
// CHECK:STDOUT: !17 = !DILocation(line: 11, column: 1, scope: !11)
// CHECK:STDOUT: ; ModuleID = 'return_slot.carbon'
// CHECK:STDOUT: source_filename = "return_slot.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: @C.val.loc7_12 = internal constant {} zeroinitializer
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CF.Main(ptr sret({}) %return) #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %return, ptr align 1 @C.val.loc7_12, i64 0, i1 false), !dbg !8
// CHECK:STDOUT: ret void, !dbg !8
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CG.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CForward.Main(ptr sret({}) %return) #0 !dbg !9 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @_CF.Main(ptr %return), !dbg !10
// CHECK:STDOUT: ret void, !dbg !11
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CInitVar.Main() #0 !dbg !12 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %local.var = alloca {}, align 8, !dbg !15
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %local.var), !dbg !15
// CHECK:STDOUT: call void @_CF.Main(ptr %local.var), !dbg !16
// CHECK:STDOUT: call void @_CG.Main(), !dbg !17
// CHECK:STDOUT: ret void, !dbg !18
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CInitLet.Main() #0 !dbg !19 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc22_20.1.temp = alloca {}, align 8, !dbg !20
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc22_20.1.temp), !dbg !20
// CHECK:STDOUT: call void @_CF.Main(ptr %.loc22_20.1.temp), !dbg !20
// CHECK:STDOUT: call void @_CG.Main(), !dbg !21
// CHECK:STDOUT: ret void, !dbg !22
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
// 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:
// CHECK:STDOUT: ; uselistorder directives
// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !3 = !DIFile(filename: "return_slot.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main", scope: null, file: !3, line: 6, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{!7}
// CHECK:STDOUT: !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 8)
// CHECK:STDOUT: !8 = !DILocation(line: 7, column: 3, scope: !4)
// CHECK:STDOUT: !9 = distinct !DISubprogram(name: "Forward", linkageName: "_CForward.Main", scope: null, file: !3, line: 12, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !10 = !DILocation(line: 13, column: 10, scope: !9)
// CHECK:STDOUT: !11 = !DILocation(line: 13, column: 3, scope: !9)
// CHECK:STDOUT: !12 = distinct !DISubprogram(name: "InitVar", linkageName: "_CInitVar.Main", scope: null, file: !3, line: 16, type: !13, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !13 = !DISubroutineType(types: !14)
// CHECK:STDOUT: !14 = !{null}
// CHECK:STDOUT: !15 = !DILocation(line: 17, column: 3, scope: !12)
// CHECK:STDOUT: !16 = !DILocation(line: 17, column: 18, scope: !12)
// CHECK:STDOUT: !17 = !DILocation(line: 18, column: 3, scope: !12)
// CHECK:STDOUT: !18 = !DILocation(line: 16, column: 1, scope: !12)
// CHECK:STDOUT: !19 = distinct !DISubprogram(name: "InitLet", linkageName: "_CInitLet.Main", scope: null, file: !3, line: 21, type: !13, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !20 = !DILocation(line: 22, column: 18, scope: !19)
// CHECK:STDOUT: !21 = !DILocation(line: 23, column: 3, scope: !19)
// CHECK:STDOUT: !22 = !DILocation(line: 21, column: 1, scope: !19)
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