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carbon-lang/toolchain/lower/testdata/function/generic/call_recursive_impl.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/function/generic/call_recursive_impl.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/function/generic/call_recursive_impl.carbon
import Core library "io";
interface I {
fn F();
}
class X {}
impl X as I {
fn F() { Core.Print(1); }
}
class Y {}
impl Y as I {
fn F() { Core.Print(2); }
}
// Builds on "call_different_impls.carbon", cannot lower a single G due to
// different calls to F. Additionally, add recursion so the function
// fingerprint is dependent on itself.
fn G(T:! I, count: i32) -> i32 {
T.F();
if (count > 0) {
return count;
}
return G(T, count + 1);
}
fn Run() {
G(X, 0);
G(Y, 0);
}
// CHECK:STDOUT: ; ModuleID = 'call_recursive_impl.carbon'
// CHECK:STDOUT: source_filename = "call_recursive_impl.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: @printf.int.format = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @"_CF.X.Main:I.Main"() #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %Print.call = call i32 (ptr, ...) @printf(ptr @printf.int.format, i32 1), !dbg !7
// CHECK:STDOUT: ret void, !dbg !8
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @"_CF.Y.Main:I.Main"() #0 !dbg !9 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %Print.call = call i32 (ptr, ...) @printf(ptr @printf.int.format, i32 2), !dbg !10
// CHECK:STDOUT: ret void, !dbg !11
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @main() #0 !dbg !12 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %G.call.loc40 = call i32 @_CG.Main.4d3c36eeac175c1f(i32 0), !dbg !13
// CHECK:STDOUT: %G.call.loc41 = call i32 @_CG.Main.7abe23e63361d139(i32 0), !dbg !14
// CHECK:STDOUT: ret void, !dbg !15
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare i32 @printf(ptr, ...)
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr i32 @_CG.Main.4d3c36eeac175c1f(i32 %count) #0 !dbg !16 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @"_CF.X.Main:I.Main"(), !dbg !22
// CHECK:STDOUT: %Int.as.OrderedWith.impl.Greater.call = icmp sgt i32 %count, 0, !dbg !23
// CHECK:STDOUT: br i1 %Int.as.OrderedWith.impl.Greater.call, label %if.then, label %if.else, !dbg !24
// CHECK:STDOUT:
// CHECK:STDOUT: if.then: ; preds = %entry
// CHECK:STDOUT: ret i32 %count, !dbg !25
// CHECK:STDOUT:
// CHECK:STDOUT: if.else: ; preds = %entry
// CHECK:STDOUT: %Int.as.AddWith.impl.Op.call = add i32 %count, 1, !dbg !26
// CHECK:STDOUT: %G.call = call i32 @_CG.Main.4d3c36eeac175c1f(i32 %Int.as.AddWith.impl.Op.call), !dbg !27
// CHECK:STDOUT: ret i32 %G.call, !dbg !28
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr i32 @_CG.Main.7abe23e63361d139(i32 %count) #0 !dbg !29 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: call void @"_CF.Y.Main:I.Main"(), !dbg !32
// CHECK:STDOUT: %Int.as.OrderedWith.impl.Greater.call = icmp sgt i32 %count, 0, !dbg !33
// CHECK:STDOUT: br i1 %Int.as.OrderedWith.impl.Greater.call, label %if.then, label %if.else, !dbg !34
// CHECK:STDOUT:
// CHECK:STDOUT: if.then: ; preds = %entry
// CHECK:STDOUT: ret i32 %count, !dbg !35
// CHECK:STDOUT:
// CHECK:STDOUT: if.else: ; preds = %entry
// CHECK:STDOUT: %Int.as.AddWith.impl.Op.call = add i32 %count, 1, !dbg !36
// CHECK:STDOUT: %G.call = call i32 @_CG.Main.7abe23e63361d139(i32 %Int.as.AddWith.impl.Op.call), !dbg !37
// CHECK:STDOUT: ret i32 %G.call, !dbg !38
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: ; uselistorder directives
// CHECK:STDOUT: uselistorder ptr @printf, { 1, 0 }
// CHECK:STDOUT:
// CHECK:STDOUT: attributes #0 = { nounwind }
// 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: "call_recursive_impl.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "F", linkageName: "_CF.X.Main:I.Main", scope: null, file: !3, line: 20, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{null}
// CHECK:STDOUT: !7 = !DILocation(line: 20, column: 12, scope: !4)
// CHECK:STDOUT: !8 = !DILocation(line: 20, column: 3, scope: !4)
// CHECK:STDOUT: !9 = distinct !DISubprogram(name: "F", linkageName: "_CF.Y.Main:I.Main", scope: null, file: !3, line: 24, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !10 = !DILocation(line: 24, column: 12, scope: !9)
// CHECK:STDOUT: !11 = !DILocation(line: 24, column: 3, scope: !9)
// CHECK:STDOUT: !12 = distinct !DISubprogram(name: "Run", linkageName: "main", scope: null, file: !3, line: 39, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !13 = !DILocation(line: 40, column: 3, scope: !12)
// CHECK:STDOUT: !14 = !DILocation(line: 41, column: 3, scope: !12)
// CHECK:STDOUT: !15 = !DILocation(line: 39, column: 1, scope: !12)
// CHECK:STDOUT: !16 = distinct !DISubprogram(name: "G", linkageName: "_CG.Main.4d3c36eeac175c1f", scope: null, file: !3, line: 30, type: !17, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !20)
// CHECK:STDOUT: !17 = !DISubroutineType(types: !18)
// CHECK:STDOUT: !18 = !{!19, !19}
// CHECK:STDOUT: !19 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
// CHECK:STDOUT: !20 = !{!21}
// CHECK:STDOUT: !21 = !DILocalVariable(arg: 1, scope: !16, type: !19)
// CHECK:STDOUT: !22 = !DILocation(line: 31, column: 3, scope: !16)
// CHECK:STDOUT: !23 = !DILocation(line: 33, column: 7, scope: !16)
// CHECK:STDOUT: !24 = !DILocation(line: 33, column: 6, scope: !16)
// CHECK:STDOUT: !25 = !DILocation(line: 34, column: 5, scope: !16)
// CHECK:STDOUT: !26 = !DILocation(line: 36, column: 15, scope: !16)
// CHECK:STDOUT: !27 = !DILocation(line: 36, column: 10, scope: !16)
// CHECK:STDOUT: !28 = !DILocation(line: 36, column: 3, scope: !16)
// CHECK:STDOUT: !29 = distinct !DISubprogram(name: "G", linkageName: "_CG.Main.7abe23e63361d139", scope: null, file: !3, line: 30, type: !17, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !30)
// CHECK:STDOUT: !30 = !{!31}
// CHECK:STDOUT: !31 = !DILocalVariable(arg: 1, scope: !29, type: !19)
// CHECK:STDOUT: !32 = !DILocation(line: 31, column: 3, scope: !29)
// CHECK:STDOUT: !33 = !DILocation(line: 33, column: 7, scope: !29)
// CHECK:STDOUT: !34 = !DILocation(line: 33, column: 6, scope: !29)
// CHECK:STDOUT: !35 = !DILocation(line: 34, column: 5, scope: !29)
// CHECK:STDOUT: !36 = !DILocation(line: 36, column: 15, scope: !29)
// CHECK:STDOUT: !37 = !DILocation(line: 36, column: 10, scope: !29)
// CHECK:STDOUT: !38 = !DILocation(line: 36, column: 3, scope: !29)
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