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a179bd461b4a07bf2defe91e68f1bb9edfa60551
carbon-lang/toolchain/driver/testdata/compile/optimize/optimize_debug.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
//
// ARGS: compile --optimize=debug foo.carbon --target=x86_64-unknown-linux-gnu --phase=optimize --dump-llvm-ir --exclude-dump-file-prefix=%{core}
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/driver/testdata/compile/optimize/optimize_debug.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/driver/testdata/compile/optimize/optimize_debug.carbon
// --- foo.carbon
import Core library "range";
fn Rand() -> i32;
fn NoInlineWithOz() -> i32 {
return Rand() + Rand();
}
fn CallNoInlineWithOptSize() -> i32 {
// Should not be inlined with --optimize=size, because the body is larger than the call.
return NoInlineWithOz();
}
fn VectorizedWithOptSpeed(a: array(i32, 65536)*) {
// Should be vectorized with --optimize=speed, but not in other modes.
var n: i32 = 0;
while (n < 65536) {
(*a)[n] *= 2;
++n;
}
}
// CHECK:STDOUT: ; ModuleID = 'foo.carbon'
// CHECK:STDOUT: source_filename = "foo.carbon"
// CHECK:STDOUT: target triple = "x86_64-unknown-linux-gnu"
// CHECK:STDOUT:
// CHECK:STDOUT: declare i32 @_CRand.Main() local_unnamed_addr
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define i32 @_CNoInlineWithOz.Main() local_unnamed_addr #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %Rand.call.loc7_15 = tail call i32 @_CRand.Main() #0, !dbg !8
// CHECK:STDOUT: %Rand.call.loc7_24 = tail call i32 @_CRand.Main() #0, !dbg !9
// CHECK:STDOUT: %Int.as.AddWith.impl.Op.call = add i32 %Rand.call.loc7_24, %Rand.call.loc7_15, !dbg !8
// CHECK:STDOUT: ret i32 %Int.as.AddWith.impl.Op.call, !dbg !10
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define i32 @_CCallNoInlineWithOptSize.Main() local_unnamed_addr #0 !dbg !11 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %Rand.call.loc7_15.i = tail call i32 @_CRand.Main() #0, !dbg !12
// CHECK:STDOUT: %Rand.call.loc7_24.i = tail call i32 @_CRand.Main() #0, !dbg !14
// CHECK:STDOUT: %Int.as.AddWith.impl.Op.call.i = add i32 %Rand.call.loc7_24.i, %Rand.call.loc7_15.i, !dbg !12
// CHECK:STDOUT: ret i32 %Int.as.AddWith.impl.Op.call.i, !dbg !15
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nofree norecurse nosync nounwind memory(argmem: readwrite)
// CHECK:STDOUT: define void @_CVectorizedWithOptSpeed.Main(ptr captures(none) %a) local_unnamed_addr #1 !dbg !16 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: br label %while.body, !dbg !22
// CHECK:STDOUT:
// CHECK:STDOUT: while.body: ; preds = %entry, %while.body
// CHECK:STDOUT: %n.var.03 = phi i32 [ 0, %entry ], [ %1, %while.body ]
// CHECK:STDOUT: %0 = zext nneg i32 %n.var.03 to i64, !dbg !23
// CHECK:STDOUT: %.loc19_11.array.index = getelementptr inbounds nuw i32, ptr %a, i64 %0, !dbg !23
// CHECK:STDOUT: %Int.as.MulAssignWith.impl.Op.call = load i32, ptr %.loc19_11.array.index, align 4, !dbg !23
// CHECK:STDOUT: %Int.as.MulAssignWith.impl.Op.call1 = shl i32 %Int.as.MulAssignWith.impl.Op.call, 1, !dbg !23
// CHECK:STDOUT: store i32 %Int.as.MulAssignWith.impl.Op.call1, ptr %.loc19_11.array.index, align 4, !dbg !23
// CHECK:STDOUT: %1 = add nuw nsw i32 %n.var.03, 1, !dbg !24
// CHECK:STDOUT: %Int.as.OrderedWith.impl.Less.call = icmp samesign ult i32 %n.var.03, 65535, !dbg !39
// CHECK:STDOUT: br i1 %Int.as.OrderedWith.impl.Less.call, label %while.body, label %while.done, !dbg !22
// CHECK:STDOUT:
// CHECK:STDOUT: while.done: ; preds = %while.body
// CHECK:STDOUT: ret void, !dbg !40
// CHECK:STDOUT:
// CHECK:STDOUT: ; uselistorder directives
// CHECK:STDOUT: uselistorder label %while.body, { 1, 0 }
// CHECK:STDOUT: uselistorder i32 %n.var.03, { 0, 2, 1 }
// CHECK:STDOUT: uselistorder ptr %.loc19_11.array.index, { 1, 0 }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// CHECK:STDOUT: attributes #1 = { nofree norecurse nosync nounwind 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: "foo.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "NoInlineWithOz", linkageName: "_CNoInlineWithOz.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 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
// CHECK:STDOUT: !8 = !DILocation(line: 7, column: 10, scope: !4)
// CHECK:STDOUT: !9 = !DILocation(line: 7, column: 19, scope: !4)
// CHECK:STDOUT: !10 = !DILocation(line: 7, column: 3, scope: !4)
// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "CallNoInlineWithOptSize", linkageName: "_CCallNoInlineWithOptSize.Main", scope: null, file: !3, line: 10, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !12 = !DILocation(line: 7, column: 10, scope: !4, inlinedAt: !13)
// CHECK:STDOUT: !13 = distinct !DILocation(line: 12, column: 10, scope: !11)
// CHECK:STDOUT: !14 = !DILocation(line: 7, column: 19, scope: !4, inlinedAt: !13)
// CHECK:STDOUT: !15 = !DILocation(line: 12, column: 3, scope: !11)
// CHECK:STDOUT: !16 = distinct !DISubprogram(name: "VectorizedWithOptSpeed", linkageName: "_CVectorizedWithOptSpeed.Main", scope: null, file: !3, line: 15, type: !17, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !20)
// CHECK:STDOUT: !17 = !DISubroutineType(types: !18)
// CHECK:STDOUT: !18 = !{null, !19}
// CHECK:STDOUT: !19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 8)
// CHECK:STDOUT: !20 = !{!21}
// CHECK:STDOUT: !21 = !DILocalVariable(arg: 1, scope: !16, type: !19)
// CHECK:STDOUT: !22 = !DILocation(line: 18, column: 9, scope: !16)
// CHECK:STDOUT: !23 = !DILocation(line: 19, column: 5, scope: !16)
// CHECK:STDOUT: !24 = !DILocation(line: 275, column: 3, scope: !25, inlinedAt: !32)
// CHECK:STDOUT: !25 = distinct !DISubprogram(name: "Op", linkageName: "_COp:thunk.Int.Core:AddAssignWith.Core.5dfb78ae56583d8e", scope: null, file: !26, line: 275, type: !27, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !29)
// CHECK:STDOUT: !26 = !DIFile(filename: "{{.*}}/prelude/types/int.carbon", directory: "")
// CHECK:STDOUT: !27 = !DISubroutineType(types: !28)
// CHECK:STDOUT: !28 = !{null, !7, !7}
// CHECK:STDOUT: !29 = !{!30, !31}
// CHECK:STDOUT: !30 = !DILocalVariable(arg: 1, scope: !25, type: !7)
// CHECK:STDOUT: !31 = !DILocalVariable(arg: 2, scope: !25, type: !7)
// CHECK:STDOUT: !32 = distinct !DILocation(line: 341, column: 5, scope: !33, inlinedAt: !38)
// CHECK:STDOUT: !33 = distinct !DISubprogram(name: "Op", linkageName: "_COp.Int.Core:Inc.Core.be1e879c1ad406d8", scope: null, file: !26, line: 339, type: !34, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !36)
// CHECK:STDOUT: !34 = !DISubroutineType(types: !35)
// CHECK:STDOUT: !35 = !{null, !7}
// CHECK:STDOUT: !36 = !{!37}
// CHECK:STDOUT: !37 = !DILocalVariable(arg: 1, scope: !33, type: !7)
// CHECK:STDOUT: !38 = distinct !DILocation(line: 20, column: 5, scope: !16)
// CHECK:STDOUT: !39 = !DILocation(line: 18, column: 10, scope: !16)
// CHECK:STDOUT: !40 = !DILocation(line: 15, column: 1, scope: !16)
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