[PATCH] ARM: use relocation type tlsldo in debug info (PR18554)

[Kai Nacke]

Hi all!

The attached patch enables use of relocation type tlsldo in debug info 
for tls data.
This fixes PR18554.

Please review.

Regards,
Kai
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diff --git a/lib/Target/ARM/ARMTargetObjectFile.cpp b/lib/Target/ARM/ARMTargetObjectFile.cpp
index 1c5dc51..e6b8cce 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.cpp
+++ b/lib/Target/ARM/ARMTargetObjectFile.cpp
@@ -51,3 +51,9 @@ getTTypeGlobalReference(const GlobalValue *GV, Mangler *Mang,
                                  MCSymbolRefExpr::VK_ARM_TARGET2,
                                  getContext());
 }
+
+const MCExpr *ARMElfTargetObjectFile::
+getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
+  return MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_ARM_TLSLDO,
+                                 getContext());
+}
diff --git a/lib/Target/ARM/ARMTargetObjectFile.h b/lib/Target/ARM/ARMTargetObjectFile.h
index 7f60727..cb86896 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.h
+++ b/lib/Target/ARM/ARMTargetObjectFile.h
@@ -36,6 +36,9 @@ public:
   virtual const MCSection *getAttributesSection() const {
     return AttributesSection;
   }
+
+  /// \brief Describe a TLS variable address within debug info.
+  virtual const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const;
 };
 
 } // end namespace llvm
diff --git a/test/DebugInfo/ARM/tls.ll b/test/DebugInfo/ARM/tls.ll
new file mode 100644
index 0000000..1a613d2
--- /dev/null
+++ b/test/DebugInfo/ARM/tls.ll
@@ -0,0 +1,26 @@
+; RUN: llc -O0 -filetype=asm -mtriple=armv7-linux-gnuehabi < %s | FileCheck %s
+;
+; Generated with clang with source
+; __thread int x;
+
+ at x = thread_local global i32 0, align 4
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7, !8}
+
+; 6 byte of data
+; CHECK: .byte 6 @ DW_AT_location
+; DW_OP_const4u
+; CHECK: .byte 12
+; The debug relocation of the address of the tls variable
+; CHECK: .long x(tlsldo)
+
+!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"clang version 3.5 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !2, metadata !3, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/tmp/arm.c] [DW_LANG_C99]
+!1 = metadata !{metadata !"arm.c", metadata !"/tmp"}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786484, i32 0, null, metadata !"x", metadata !"x", metadata !"", metadata !5, i32 1, metadata !6, i32 0, i32 1, i32* @x, null} ; [ DW_TAG_variable ] [x] [line 1] [def]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/tmp/arm.c]
+!6 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!7 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!8 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}