[ThinLTO] Metadata linking for imported functions

Summary:
Second patch split out from http://reviews.llvm.org/D14752.

Maps metadata as a post-pass from each module when importing complete,
suturing up final metadata to the temporary metadata left on the
imported instructions.

This entails saving the mapping from bitcode value id to temporary
metadata in the importing pass, and from bitcode value id to final
metadata during the metadata linking postpass.

Depends on D14825.

Reviewers: dexonsmith, joker.eph

Subscribers: davidxl, llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D14838

llvm-svn: 255909

1 files changed, 71 insertions, 0 deletions

diff --git a/llvm/test/Linker/thinlto_funcimport_debug.ll b/llvm/test/Linker/thinlto_funcimport_debug.ll
new file mode 100644
index 00000000000..6c33caacf9e
--- /dev/null
+++ b/llvm/test/Linker/thinlto_funcimport_debug.ll
@@ -0,0 +1,71 @@
+; Do setup work for all below tests: generate bitcode and combined index
+; RUN: llvm-as -function-summary %s -o %t.bc
+; RUN: llvm-as -function-summary %p/Inputs/thinlto_funcimport_debug.ll -o %t2.bc
+; RUN: llvm-lto -thinlto -o %t3 %t.bc %t2.bc
+
+; Confirm that we link the metadata for the imported module.
+; RUN: llvm-link %t2.bc -functionindex=%t3.thinlto.bc -import=func1:%t.bc -S | FileCheck %s
+
+; CHECK: declare i32 @func2
+; CHECK: define available_externally i32 @func1
+; CHECK: distinct !DISubprogram(name: "func1"
+; CHECK: distinct !DISubprogram(name: "func2"
+
+; ModuleID = 'dbg.o'
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readnone uwtable
+define i32 @func1(i32 %n) #0 !dbg !4 {
+entry:
+  tail call void @llvm.dbg.value(metadata i32 %n, i64 0, metadata !9, metadata !17), !dbg !18
+  tail call void @llvm.dbg.value(metadata i32 5, i64 0, metadata !10, metadata !17), !dbg !19
+  %cmp = icmp sgt i32 %n, 10, !dbg !20
+  %. = select i1 %cmp, i32 10, i32 5, !dbg !22
+  tail call void @llvm.dbg.value(metadata i32 %., i64 0, metadata !10, metadata !17), !dbg !19
+  ret i32 %., !dbg !23
+}
+
+; Function Attrs: nounwind readnone uwtable
+define i32 @func2(i32 %n) #0 !dbg !11 {
+entry:
+  tail call void @llvm.dbg.value(metadata i32 %n, i64 0, metadata !13, metadata !17), !dbg !24
+  ret i32 %n, !dbg !25
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
+
+attributes #0 = { nounwind readnone 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 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!14, !15}
+!llvm.ident = !{!16}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 251407) (llvm/trunk 251401)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "dbg.c", directory: ".")
+!2 = !{}
+!3 = !{!4, !11}
+!4 = distinct !DISubprogram(name: "func1", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, variables: !8)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !7}
+!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!8 = !{!9, !10}
+!9 = !DILocalVariable(name: "n", arg: 1, scope: !4, file: !1, line: 1, type: !7)
+!10 = !DILocalVariable(name: "x", scope: !4, file: !1, line: 2, type: !7)
+!11 = distinct !DISubprogram(name: "func2", scope: !1, file: !1, line: 8, type: !5, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: true, variables: !12)
+!12 = !{!13}
+!13 = !DILocalVariable(name: "n", arg: 1, scope: !11, file: !1, line: 8, type: !7)
+!14 = !{i32 2, !"Dwarf Version", i32 4}
+!15 = !{i32 2, !"Debug Info Version", i32 3}
+!16 = !{!"clang version 3.8.0 (trunk 251407) (llvm/trunk 251401)"}
+!17 = !DIExpression()
+!18 = !DILocation(line: 1, column: 15, scope: !4)
+!19 = !DILocation(line: 2, column: 7, scope: !4)
+!20 = !DILocation(line: 3, column: 9, scope: !21)
+!21 = distinct !DILexicalBlock(scope: !4, file: !1, line: 3, column: 7)
+!22 = !DILocation(line: 3, column: 7, scope: !4)
+!23 = !DILocation(line: 5, column: 3, scope: !4)
+!24 = !DILocation(line: 8, column: 15, scope: !11)
+!25 = !DILocation(line: 9, column: 3, scope: !11)