[PATCH] D15028: [ELF] Enable temporary labels symbol names

[Leny Kholodov via llvm-commits]

lenykholodov created this revision.
lenykholodov added a reviewer: dexonsmith.
lenykholodov added a subscriber: llvm-commits.
lenykholodov set the repository for this revision to rL LLVM.

After revision r236642 compiler prevents emitting of temp label names into object files to save memory. This creates problems for the binutils linker, which analyzes symbol names from the input object files and can skip some local compiler generated labels. As a result linker doesn't see the label names and therefore puts them all into the final binary as global symbols. Binutils require label names to have a prefix '.L'.

This patch fixes temporary label names generation for ELF.

Repository:
  rL LLVM

http://reviews.llvm.org/D15028

Files:
  lib/CodeGen/LLVMTargetMachine.cpp
  test/CodeGen/ARM/elf-debug-label-name.ll

Index: test/CodeGen/ARM/elf-debug-label-name.ll
===================================================================
--- test/CodeGen/ARM/elf-debug-label-name.ll
+++ test/CodeGen/ARM/elf-debug-label-name.ll
@@ -0,0 +1,37 @@
+; RUN: llc < %s -mtriple=armv7l-linux-eabihf -filetype=obj -o %s.o && llvm-objdump -t %s.o | FileCheck %s --check-prefix=CHECK
+; CHECK: .debug_str	00000000 .Linfo_string0
+; Function Attrs: nounwind
+define arm_aapcs_vfpcc i32 @_Z1xi(i32 %a) #0 !dbg !4 {
+entry:
+  %a.addr = alloca i32, align 4
+  store i32 %a, i32* %a.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %a.addr, metadata !13, metadata !14), !dbg !15
+  %0 = load i32, i32* %a.addr, align 4, !dbg !16
+  ret i32 %0, !dbg !17
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9, !10, !11}
+!llvm.ident = !{!12}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "file", directory: "dir")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "x", linkageName: "_Z1xi", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !7}
+!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!8 = !{i32 2, !"Dwarf Version", i32 4}
+!9 = !{i32 2, !"Debug Info Version", i32 3}
+!10 = !{i32 1, !"wchar_size", i32 4}
+!11 = !{i32 1, !"min_enum_size", i32 4}
+!12 = !{!"clang"}
+!13 = !DILocalVariable(name: "a", arg: 1, scope: !4, file: !1, line: 1, type: !7)
+!14 = !DIExpression()
+!15 = !DILocation(line: 1, column: 11, scope: !4)
+!16 = !DILocation(line: 3, column: 10, scope: !4)
+!17 = !DILocation(line: 3, column: 3, scope: !4)
Index: lib/CodeGen/LLVMTargetMachine.cpp
===================================================================
--- lib/CodeGen/LLVMTargetMachine.cpp
+++ lib/CodeGen/LLVMTargetMachine.cpp
@@ -196,8 +196,11 @@
     if (!MCE || !MAB)
       return true;
 
-    // Don't waste memory on names of temp labels.
-    Context->setUseNamesOnTempLabels(false);
+    if (getObjFileLowering()->getObjectFileType() ==
+        MCObjectFileInfo::Environment::IsELF) {
+      // Don't waste memory on names of temp labels.
+      Context->setUseNamesOnTempLabels(false);
+    }
 
     Triple T(getTargetTriple().str());
     AsmStreamer.reset(getTarget().createMCObjectStreamer(


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