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a179bd461b4a07bf2defe91e68f1bb9edfa60551
carbon-lang/toolchain/lower/testdata/interop/cpp/enum.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/full.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/interop/cpp/enum.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/interop/cpp/enum.carbon
// --- enum_member.h
struct C {
enum E : short {
a,
b = 7,
c
};
static void F(E);
};
// --- pass_as_arg.carbon
library "[[@TEST_NAME]]";
import Cpp library "enum_member.h";
fn Pass() {
Cpp.C.F(Cpp.C.a);
Cpp.C.F(Cpp.C.a);
Cpp.C.F(Cpp.C.b);
Cpp.C.F(Cpp.C.c);
Cpp.C.F(Cpp.C.E.a);
Cpp.C.F(Cpp.C.E.b);
Cpp.C.F(Cpp.C.E.c);
}
// --- convert.carbon
library "[[@TEST_NAME]]";
import Cpp library "enum_member.h";
fn TakeI16(n: i16);
fn PassEnum() {
TakeI16(Cpp.C.b as i16);
}
fn ConvertEnumToI16(e: Cpp.C.E) {
TakeI16(e as i16);
}
fn ConvertI16ToEnum(n: i16) {
Cpp.C.F(n as Cpp.C.E);
}
// --- bitmask.h
enum Bits {
A = 1 << 0,
B = 1 << 1,
C = 1 << 2,
};
void Take(Bits b);
// --- use_bitmask.carbon
library "[[@TEST_NAME]]";
import Cpp library "bitmask.h";
// TODO: Once we support interop with C++-defined operators, we should be able
// to use `|` below rather than declaring our own builtin.
fn BitOr(a: Cpp.Bits, b: Cpp.Bits) -> Cpp.Bits = "int.or";
fn Call() {
Cpp.Take(BitOr(Cpp.A, Cpp.C));
}
// CHECK:STDOUT: ; ModuleID = 'pass_as_arg.carbon'
// CHECK:STDOUT: source_filename = "pass_as_arg.carbon"
// CHECK:STDOUT: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
// CHECK:STDOUT: target triple = "x86_64-unknown-linux-gnu"
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CPass.Main() #0 !dbg !7 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc7_16.1.temp = alloca i16, align 2, !dbg !10
// CHECK:STDOUT: %.loc8_16.1.temp = alloca i16, align 2, !dbg !11
// CHECK:STDOUT: %.loc9_16.1.temp = alloca i16, align 2, !dbg !12
// CHECK:STDOUT: %.loc10_16.1.temp = alloca i16, align 2, !dbg !13
// CHECK:STDOUT: %.loc11_18.1.temp = alloca i16, align 2, !dbg !14
// CHECK:STDOUT: %.loc12_18.1.temp = alloca i16, align 2, !dbg !15
// CHECK:STDOUT: %.loc13_18.1.temp = alloca i16, align 2, !dbg !16
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc7_16.1.temp), !dbg !10
// CHECK:STDOUT: store i16 0, ptr %.loc7_16.1.temp, align 2, !dbg !10
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc7_16.1.temp), !dbg !17
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc8_16.1.temp), !dbg !11
// CHECK:STDOUT: store i16 0, ptr %.loc8_16.1.temp, align 2, !dbg !11
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc8_16.1.temp), !dbg !18
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc9_16.1.temp), !dbg !12
// CHECK:STDOUT: store i16 7, ptr %.loc9_16.1.temp, align 2, !dbg !12
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc9_16.1.temp), !dbg !19
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc10_16.1.temp), !dbg !13
// CHECK:STDOUT: store i16 8, ptr %.loc10_16.1.temp, align 2, !dbg !13
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc10_16.1.temp), !dbg !20
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc11_18.1.temp), !dbg !14
// CHECK:STDOUT: store i16 0, ptr %.loc11_18.1.temp, align 2, !dbg !14
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc11_18.1.temp), !dbg !21
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc12_18.1.temp), !dbg !15
// CHECK:STDOUT: store i16 7, ptr %.loc12_18.1.temp, align 2, !dbg !15
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc12_18.1.temp), !dbg !22
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc13_18.1.temp), !dbg !16
// CHECK:STDOUT: store i16 8, ptr %.loc13_18.1.temp, align 2, !dbg !16
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc13_18.1.temp), !dbg !23
// CHECK:STDOUT: ret void, !dbg !24
// 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
// CHECK:STDOUT: define dso_local void @_ZN1C1FENS_1EE.carbon_thunk(ptr %0) #2 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.addr = alloca ptr, align 8
// CHECK:STDOUT: store ptr %0, ptr %.addr, align 8
// CHECK:STDOUT: %1 = load ptr, ptr %.addr, align 8
// CHECK:STDOUT: %2 = load i16, ptr %1, align 2
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE(i16 signext %2)
// CHECK:STDOUT: ret void
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_ZN1C1FENS_1EE(i16 signext) #3
// CHECK:STDOUT:
// CHECK:STDOUT: ; uselistorder directives
// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 6, 5, 4, 3, 2, 1, 0 }
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="0" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
// CHECK:STDOUT: attributes #3 = { "no-trapping-math"="true" "stack-protector-buffer-size"="0" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
// CHECK:STDOUT: !llvm.dbg.cu = !{!5}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = !{i32 1, !"wchar_size", i32 4}
// CHECK:STDOUT: !3 = !{i32 8, !"PIC Level", i32 0}
// CHECK:STDOUT: !4 = !{i32 7, !"PIE Level", i32 2}
// CHECK:STDOUT: !5 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !6, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !6 = !DIFile(filename: "pass_as_arg.carbon", directory: "")
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "Pass", linkageName: "_CPass.Main", scope: null, file: !6, line: 6, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
// CHECK:STDOUT: !9 = !{null}
// CHECK:STDOUT: !10 = !DILocation(line: 7, column: 11, scope: !7)
// CHECK:STDOUT: !11 = !DILocation(line: 8, column: 11, scope: !7)
// CHECK:STDOUT: !12 = !DILocation(line: 9, column: 11, scope: !7)
// CHECK:STDOUT: !13 = !DILocation(line: 10, column: 11, scope: !7)
// CHECK:STDOUT: !14 = !DILocation(line: 11, column: 11, scope: !7)
// CHECK:STDOUT: !15 = !DILocation(line: 12, column: 11, scope: !7)
// CHECK:STDOUT: !16 = !DILocation(line: 13, column: 11, scope: !7)
// CHECK:STDOUT: !17 = !DILocation(line: 7, column: 3, scope: !7)
// CHECK:STDOUT: !18 = !DILocation(line: 8, column: 3, scope: !7)
// CHECK:STDOUT: !19 = !DILocation(line: 9, column: 3, scope: !7)
// CHECK:STDOUT: !20 = !DILocation(line: 10, column: 3, scope: !7)
// CHECK:STDOUT: !21 = !DILocation(line: 11, column: 3, scope: !7)
// CHECK:STDOUT: !22 = !DILocation(line: 12, column: 3, scope: !7)
// CHECK:STDOUT: !23 = !DILocation(line: 13, column: 3, scope: !7)
// CHECK:STDOUT: !24 = !DILocation(line: 6, column: 1, scope: !7)
// CHECK:STDOUT: ; ModuleID = 'convert.carbon'
// CHECK:STDOUT: source_filename = "convert.carbon"
// CHECK:STDOUT: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
// CHECK:STDOUT: target triple = "x86_64-unknown-linux-gnu"
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CTakeI16.Main(i16)
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CPassEnum.Main() #0 !dbg !7 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @_CTakeI16.Main(i16 7), !dbg !10
// CHECK:STDOUT: ret void, !dbg !11
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CConvertEnumToI16.Main(i16 %e) #0 !dbg !12 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @_CTakeI16.Main(i16 %e), !dbg !18
// CHECK:STDOUT: ret void, !dbg !19
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CConvertI16ToEnum.Main(i16 %n) #0 !dbg !20 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.loc17_13.3.temp = alloca i16, align 2, !dbg !23
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %.loc17_13.3.temp), !dbg !23
// CHECK:STDOUT: store i16 %n, ptr %.loc17_13.3.temp, align 2, !dbg !23
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE.carbon_thunk(ptr %.loc17_13.3.temp), !dbg !24
// CHECK:STDOUT: ret void, !dbg !25
// 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
// CHECK:STDOUT: define dso_local void @_ZN1C1FENS_1EE.carbon_thunk(ptr %0) #2 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %.addr = alloca ptr, align 8
// CHECK:STDOUT: store ptr %0, ptr %.addr, align 8
// CHECK:STDOUT: %1 = load ptr, ptr %.addr, align 8
// CHECK:STDOUT: %2 = load i16, ptr %1, align 2
// CHECK:STDOUT: call void @_ZN1C1FENS_1EE(i16 signext %2)
// CHECK:STDOUT: ret void
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_ZN1C1FENS_1EE(i16 signext) #3
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
// CHECK:STDOUT: attributes #2 = { alwaysinline mustprogress "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="0" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
// CHECK:STDOUT: attributes #3 = { "no-trapping-math"="true" "stack-protector-buffer-size"="0" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
// CHECK:STDOUT: !llvm.dbg.cu = !{!5}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = !{i32 1, !"wchar_size", i32 4}
// CHECK:STDOUT: !3 = !{i32 8, !"PIC Level", i32 0}
// CHECK:STDOUT: !4 = !{i32 7, !"PIE Level", i32 2}
// CHECK:STDOUT: !5 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !6, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !6 = !DIFile(filename: "convert.carbon", directory: "")
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "PassEnum", linkageName: "_CPassEnum.Main", scope: null, file: !6, line: 8, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
// CHECK:STDOUT: !9 = !{null}
// CHECK:STDOUT: !10 = !DILocation(line: 9, column: 3, scope: !7)
// CHECK:STDOUT: !11 = !DILocation(line: 8, column: 1, scope: !7)
// CHECK:STDOUT: !12 = distinct !DISubprogram(name: "ConvertEnumToI16", linkageName: "_CConvertEnumToI16.Main", scope: null, file: !6, line: 12, type: !13, spFlags: DISPFlagDefinition, unit: !5, retainedNodes: !16)
// CHECK:STDOUT: !13 = !DISubroutineType(types: !14)
// CHECK:STDOUT: !14 = !{null, !15}
// CHECK:STDOUT: !15 = !DIBasicType(name: "int", size: 16, encoding: DW_ATE_signed)
// CHECK:STDOUT: !16 = !{!17}
// CHECK:STDOUT: !17 = !DILocalVariable(arg: 1, scope: !12, type: !15)
// CHECK:STDOUT: !18 = !DILocation(line: 13, column: 3, scope: !12)
// CHECK:STDOUT: !19 = !DILocation(line: 12, column: 1, scope: !12)
// CHECK:STDOUT: !20 = distinct !DISubprogram(name: "ConvertI16ToEnum", linkageName: "_CConvertI16ToEnum.Main", scope: null, file: !6, line: 16, type: !13, spFlags: DISPFlagDefinition, unit: !5, retainedNodes: !21)
// CHECK:STDOUT: !21 = !{!22}
// CHECK:STDOUT: !22 = !DILocalVariable(arg: 1, scope: !20, type: !15)
// CHECK:STDOUT: !23 = !DILocation(line: 17, column: 11, scope: !20)
// CHECK:STDOUT: !24 = !DILocation(line: 17, column: 3, scope: !20)
// CHECK:STDOUT: !25 = !DILocation(line: 16, column: 1, scope: !20)
// CHECK:STDOUT: ; ModuleID = 'use_bitmask.carbon'
// CHECK:STDOUT: source_filename = "use_bitmask.carbon"
// CHECK:STDOUT: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
// CHECK:STDOUT: target triple = "x86_64-unknown-linux-gnu"
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CCall.Main() #0 !dbg !7 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @_Z4Take4Bits(i32 5), !dbg !10
// CHECK:STDOUT: ret void, !dbg !11
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_Z4Take4Bits(i32)
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT:
// CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
// CHECK:STDOUT: !llvm.dbg.cu = !{!5}
// CHECK:STDOUT:
// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
// CHECK:STDOUT: !2 = !{i32 1, !"wchar_size", i32 4}
// CHECK:STDOUT: !3 = !{i32 8, !"PIC Level", i32 0}
// CHECK:STDOUT: !4 = !{i32 7, !"PIE Level", i32 2}
// CHECK:STDOUT: !5 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !6, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
// CHECK:STDOUT: !6 = !DIFile(filename: "use_bitmask.carbon", directory: "")
// CHECK:STDOUT: !7 = distinct !DISubprogram(name: "Call", linkageName: "_CCall.Main", scope: null, file: !6, line: 10, type: !8, spFlags: DISPFlagDefinition, unit: !5)
// CHECK:STDOUT: !8 = !DISubroutineType(types: !9)
// CHECK:STDOUT: !9 = !{null}
// CHECK:STDOUT: !10 = !DILocation(line: 11, column: 3, scope: !7)
// CHECK:STDOUT: !11 = !DILocation(line: 10, column: 1, scope: !7)
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