Emit discriminator for inlined callsites.

Summary: Inlined callsites need to be emitted in debug info so that sample profile can be annotated to the correct inlined instance.

Reviewers: dnovillo, dblaikie

Subscribers: dblaikie, llvm-commits

Differential Revision: http://reviews.llvm.org/D14511

llvm-svn: 252768

4 files changed, 56 insertions, 0 deletions

diff --git a/llvm/include/llvm/Support/Dwarf.h b/llvm/include/llvm/Support/Dwarf.h
index c3312fc80c5..5c79fc125e1 100644
--- a/llvm/include/llvm/Support/Dwarf.h
+++ b/llvm/include/llvm/Support/Dwarf.h
@@ -238,6 +238,7 @@ enum Attribute : uint16_t {
   DW_AT_GNU_addr_base = 0x2133,
   DW_AT_GNU_pubnames = 0x2134,
   DW_AT_GNU_pubtypes = 0x2135,
+  DW_AT_GNU_discriminator = 0x2136,
 
   // LLVM project extensions.
   DW_AT_LLVM_include_path = 0x3e00,
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 687d6ae7441..21bdb0d0c25 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -439,6 +439,8 @@ DIE *DwarfCompileUnit::constructInlinedScopeDIE(LexicalScope *Scope) {
   addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
           getOrCreateSourceID(IA->getFilename(), IA->getDirectory()));
   addUInt(*ScopeDIE, dwarf::DW_AT_call_line, None, IA->getLine());
+  if (IA->getDiscriminator())
+    addUInt(*ScopeDIE, dwarf::DW_AT_GNU_discriminator, None, IA->getDiscriminator());
 
   // Add name to the name table, we do this here because we're guaranteed
   // to have concrete versions of our DW_TAG_inlined_subprogram nodes.
diff --git a/llvm/lib/Support/Dwarf.cpp b/llvm/lib/Support/Dwarf.cpp
index 13a41557a8d..a6d12725ed0 100644
--- a/llvm/lib/Support/Dwarf.cpp
+++ b/llvm/lib/Support/Dwarf.cpp
@@ -201,6 +201,7 @@ const char *llvm::dwarf::AttributeString(unsigned Attribute) {
   case DW_AT_GNU_addr_base:              return "DW_AT_GNU_addr_base";
   case DW_AT_GNU_pubnames:               return "DW_AT_GNU_pubnames";
   case DW_AT_GNU_pubtypes:               return "DW_AT_GNU_pubtypes";
+  case DW_AT_GNU_discriminator:          return "DW_AT_GNU_discriminator";
   }
   return nullptr;
 }
diff --git a/llvm/test/DebugInfo/Generic/discriminator.ll b/llvm/test/DebugInfo/Generic/discriminator.ll
new file mode 100644
index 00000000000..6d0cc5626a6
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/discriminator.ll
@@ -0,0 +1,52 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf < %s -filetype=obj | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; Given the following source, ensure that the discriminator is emitted for
+; the inlined callsite.
+
+;void xyz();
+;static void __attribute__((always_inline)) bar() { xyz(); }
+;void foo() {
+;  bar(); bar();
+;}
+
+;CHECK: DW_TAG_inlined_subroutine
+;CHECK-NOT: DW_AT_GNU_discriminator
+;CHECK: DW_TAG_inlined_subroutine
+;CHECK-NOT: {{DW_TAG|NULL}}
+;CHECK: DW_AT_GNU_discriminator{{.*}}0x01
+
+; Function Attrs: uwtable
+define void @_Z3foov() #0 !dbg !4 {
+  tail call void @_Z3xyzv(), !dbg !11
+  tail call void @_Z3xyzv(), !dbg !13
+  ret void, !dbg !16
+}
+
+declare void @_Z3xyzv() #1
+
+attributes #0 = { uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9}
+!llvm.ident = !{!10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 252497)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "a.cc", directory: "/tmp")
+!2 = !{}
+!3 = !{!4, !7}
+!4 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, variables: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{null}
+!7 = distinct !DISubprogram(name: "bar", linkageName: "_ZL3barv", scope: !1, file: !1, line: 2, type: !5, isLocal: true, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: true, variables: !2)
+!8 = !{i32 2, !"Dwarf Version", i32 4}
+!9 = !{i32 2, !"Debug Info Version", i32 3}
+!10 = !{!"clang version 3.8.0 (trunk 252497)"}
+!11 = !DILocation(line: 2, column: 52, scope: !7, inlinedAt: !12)
+!12 = distinct !DILocation(line: 4, column: 3, scope: !4)
+!13 = !DILocation(line: 2, column: 52, scope: !7, inlinedAt: !14)
+!14 = distinct !DILocation(line: 4, column: 10, scope: !15)
+!15 = !DILexicalBlockFile(scope: !4, file: !1, discriminator: 1)
+!16 = !DILocation(line: 5, column: 1, scope: !4)