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carbon-lang/toolchain/lower/testdata/function/generic/import.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/int.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/import.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/function/generic/import.carbon
// Test that we can import and call generic functions across libraries, both
// when the generic is defined in a directly imported library and when it's
// defined in an indirectly imported library.
// --- indirectly_imported.carbon
library "[[@TEST_NAME]]";
fn IndirectDeclared();
fn IndirectDefined() {}
fn IndirectGeneric(T:! type, x: T*) -> T* {
IndirectDeclared();
IndirectDefined();
return x;
}
// --- directly_imported.carbon
library "[[@TEST_NAME]]";
import library "indirectly_imported";
fn DirectDeclared();
fn DirectDefined() {}
fn DirectGeneric(T:! type, y: T*) -> T* {
DirectDeclared();
DirectDefined();
return IndirectGeneric(T, y);
}
// --- use.carbon
library "[[@TEST_NAME]]";
import library "directly_imported";
fn Call() -> i32 {
var n: i32 = 0;
var p: i32* = DirectGeneric(i32, &n);
return *p;
}
// CHECK:STDOUT: ; ModuleID = 'indirectly_imported.carbon'
// CHECK:STDOUT: source_filename = "indirectly_imported.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CIndirectDeclared.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CIndirectDefined.Main() #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: ret void, !dbg !7
// CHECK:STDOUT: }
// 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: "indirectly_imported.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "IndirectDefined", linkageName: "_CIndirectDefined.Main", scope: null, file: !3, line: 6, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{null}
// CHECK:STDOUT: !7 = !DILocation(line: 6, column: 1, scope: !4)
// CHECK:STDOUT: ; ModuleID = 'directly_imported.carbon'
// CHECK:STDOUT: source_filename = "directly_imported.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CDirectDeclared.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define void @_CDirectDefined.Main() #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: ret void, !dbg !7
// CHECK:STDOUT: }
// 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: "directly_imported.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "DirectDefined", linkageName: "_CDirectDefined.Main", scope: null, file: !3, line: 8, type: !5, spFlags: DISPFlagDefinition, unit: !2)
// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
// CHECK:STDOUT: !6 = !{null}
// CHECK:STDOUT: !7 = !DILocation(line: 8, column: 1, scope: !4)
// CHECK:STDOUT: ; ModuleID = 'use.carbon'
// CHECK:STDOUT: source_filename = "use.carbon"
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define i32 @_CCall.Main() #0 !dbg !4 {
// CHECK:STDOUT: entry:
// CHECK:STDOUT: %n.var = alloca i32, align 4, !dbg !8
// CHECK:STDOUT: %p.var = alloca ptr, align 8, !dbg !9
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %n.var), !dbg !8
// CHECK:STDOUT: store i32 0, ptr %n.var, align 4, !dbg !8
// CHECK:STDOUT: call void @llvm.lifetime.start.p0(ptr %p.var), !dbg !9
// CHECK:STDOUT: %DirectGeneric.call = call ptr @_CDirectGeneric.Main.b88d1103f417c6d4(ptr %n.var), !dbg !10
// CHECK:STDOUT: store ptr %DirectGeneric.call, ptr %p.var, align 8, !dbg !9
// CHECK:STDOUT: %.loc9_11 = load ptr, ptr %p.var, align 8, !dbg !11
// CHECK:STDOUT: %.loc9_10.2 = load i32, ptr %.loc9_11, align 4, !dbg !12
// CHECK:STDOUT: ret i32 %.loc9_10.2, !dbg !13
// 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 ptr @_CDirectGeneric.Main.b88d1103f417c6d4(ptr %y) #0 !dbg !14 {
// CHECK:STDOUT: call void @_CDirectDeclared.Main(), !dbg !21
// CHECK:STDOUT: call void @_CDirectDefined.Main(), !dbg !22
// CHECK:STDOUT: %1 = call ptr @_CIndirectGeneric.Main.b88d1103f417c6d4(ptr %y), !dbg !23
// CHECK:STDOUT: ret ptr %1, !dbg !24
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CDirectDeclared.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CDirectDefined.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: ; Function Attrs: nounwind
// CHECK:STDOUT: define linkonce_odr ptr @_CIndirectGeneric.Main.b88d1103f417c6d4(ptr %x) #0 !dbg !25 {
// CHECK:STDOUT: call void @_CIndirectDeclared.Main(), !dbg !29
// CHECK:STDOUT: call void @_CIndirectDefined.Main(), !dbg !30
// CHECK:STDOUT: ret ptr %x, !dbg !31
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CIndirectDeclared.Main()
// CHECK:STDOUT:
// CHECK:STDOUT: declare void @_CIndirectDefined.Main()
// 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 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: "use.carbon", directory: "")
// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "Call", linkageName: "_CCall.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: 3, scope: !4)
// CHECK:STDOUT: !9 = !DILocation(line: 8, column: 3, scope: !4)
// CHECK:STDOUT: !10 = !DILocation(line: 8, column: 17, scope: !4)
// CHECK:STDOUT: !11 = !DILocation(line: 9, column: 11, scope: !4)
// CHECK:STDOUT: !12 = !DILocation(line: 9, column: 10, scope: !4)
// CHECK:STDOUT: !13 = !DILocation(line: 9, column: 3, scope: !4)
// CHECK:STDOUT: !14 = distinct !DISubprogram(name: "DirectGeneric", linkageName: "_CDirectGeneric.Main.b88d1103f417c6d4", scope: null, file: !15, line: 10, type: !16, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !19)
// CHECK:STDOUT: !15 = !DIFile(filename: "directly_imported.carbon", directory: "")
// CHECK:STDOUT: !16 = !DISubroutineType(types: !17)
// CHECK:STDOUT: !17 = !{!18, !18}
// CHECK:STDOUT: !18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 8)
// CHECK:STDOUT: !19 = !{!20}
// CHECK:STDOUT: !20 = !DILocalVariable(arg: 1, scope: !14, type: !18)
// CHECK:STDOUT: !21 = !DILocation(line: 11, column: 3, scope: !14)
// CHECK:STDOUT: !22 = !DILocation(line: 12, column: 3, scope: !14)
// CHECK:STDOUT: !23 = !DILocation(line: 13, column: 10, scope: !14)
// CHECK:STDOUT: !24 = !DILocation(line: 13, column: 3, scope: !14)
// CHECK:STDOUT: !25 = distinct !DISubprogram(name: "IndirectGeneric", linkageName: "_CIndirectGeneric.Main.b88d1103f417c6d4", scope: null, file: !26, line: 8, type: !16, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !27)
// CHECK:STDOUT: !26 = !DIFile(filename: "indirectly_imported.carbon", directory: "")
// CHECK:STDOUT: !27 = !{!28}
// CHECK:STDOUT: !28 = !DILocalVariable(arg: 1, scope: !25, type: !18)
// CHECK:STDOUT: !29 = !DILocation(line: 9, column: 3, scope: !25)
// CHECK:STDOUT: !30 = !DILocation(line: 10, column: 3, scope: !25)
// CHECK:STDOUT: !31 = !DILocation(line: 11, column: 3, scope: !25)
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