Debug Info: Support DW_AT_calling_convention on composite types.
This implements the DWARF 5 feature described at
http://www.dwarfstd.org/ShowIssue.php?issue=141215.1
This allows a consumer to understand whether a composite data type is
trivially copyable and thus should be passed by value instead of by
reference. The canonical example is being able to distinguish the
following two types:
// S is not trivially copyable because of the explicit destructor.
struct S {
~S() {}
};
// T is a POD type.
struct T {
~T() = default;
};
This patch adds two new (DI)flags to LLVM metadata: TypePassByValue
and TypePassByReference.
<rdar://problem/36034922>
Differential Revision: https://reviews.llvm.org/D41743
llvm-svn: 321844
diff --git a/llvm/test/DebugInfo/Generic/pass-by-value.ll b/llvm/test/DebugInfo/Generic/pass-by-value.ll
new file mode 100644
index 0000000..b650e42
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/pass-by-value.ll
@@ -0,0 +1,63 @@
+; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
+;
+; // S is not trivially copyable.
+; struct S {
+; ~S() {}
+; };
+;
+; // T is a POD.
+; struct T {
+; ~T() = default;
+; };
+;
+; S s;
+; T t;
+;
+; CHECK: DW_TAG_structure_type
+; CHECK-NEXT: DW_AT_calling_convention (DW_CC_pass_by_reference)
+; CHECK-NEXT: DW_AT_name ("S")
+;
+; CHECK: DW_TAG_structure_type
+; CHECK-NEXT: DW_AT_calling_convention (DW_CC_pass_by_value)
+; CHECK-NEXT: DW_AT_name ("T")
+
+source_filename = "pass.cpp"
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.13.0"
+
+%struct.S = type { i8 }
+%struct.T = type { i8 }
+
+@s = global %struct.S zeroinitializer, align 1, !dbg !0
+@__dso_handle = external hidden global i8
+@t = global %struct.T zeroinitializer, align 1, !dbg !6
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!20, !21, !22, !23}
+!llvm.ident = !{!24}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "s", scope: !2, file: !3, line: 9, type: !14, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 7.0.0 (trunk 321763) (llvm/trunk 321758)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "pass.cpp", directory: "/")
+!4 = !{}
+!5 = !{!0, !6}
+!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
+!7 = distinct !DIGlobalVariable(name: "t", scope: !2, file: !3, line: 10, type: !8, isLocal: false, isDefinition: true)
+!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "T", file: !3, line: 5, size: 8, elements: !9, identifier: "_ZTS1T", flags: DIFlagTypePassByValue)
+!9 = !{!10}
+!10 = !DISubprogram(name: "~T", scope: !8, file: !3, line: 6, type: !11, isLocal: false, isDefinition: false, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: false)
+!11 = !DISubroutineType(types: !12)
+!12 = !{null, !13}
+!13 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!14 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !3, line: 1, size: 8, elements: !15, identifier: "_ZTS1S", flags: DIFlagTypePassByReference)
+!15 = !{!16}
+!16 = !DISubprogram(name: "~S", scope: !14, file: !3, line: 2, type: !17, isLocal: false, isDefinition: false, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false)
+!17 = !DISubroutineType(types: !18)
+!18 = !{null, !19}
+!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !14, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!20 = !{i32 2, !"Dwarf Version", i32 4}
+!21 = !{i32 2, !"Debug Info Version", i32 3}
+!22 = !{i32 1, !"wchar_size", i32 4}
+!23 = !{i32 7, !"PIC Level", i32 2}
+!24 = !{!"clang version 7.0.0 (trunk 321763) (llvm/trunk 321758)"}