From 1ad8457570e8641f9729b8cd45d2468bea59a754 Mon Sep 17 00:00:00 2001
From: Eric Christopher <echristo@gmail.com>
Date: Wed, 15 Jan 2014 00:04:29 +0000
Subject: [PATCH] Make sure we emit a relocation to the debug_ranges section in
 the presence of CU ranges.

llvm-svn: 199276
---
 llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp | 9 ++++++---
 llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h   | 6 ++++++
 llvm/test/DebugInfo/X86/cu-ranges.ll       | 4 ++++
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index c895f17931d9..f76e898cfb5a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -209,6 +209,10 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   else
     HasDwarfPubSections = DwarfPubSections == Enable;
 
+  // For now only turn on CU ranges if we've explicitly asked for it
+  // or we have -ffunction-sections enabled.
+  HasCURanges = DwarfCURanges || TargetMachine::getFunctionSections();
+
   DwarfVersion = DwarfVersionNumber
                      ? DwarfVersionNumber
                      : getDwarfVersionFromModule(MMI->getModule());
@@ -1057,8 +1061,7 @@ void DwarfDebug::finalizeModuleInfo() {
       // FIXME: We should use ranges if we have multiple compile units or
       // allow reordering of code ala .subsections_via_symbols in mach-o.
       DwarfCompileUnit *U = SkCU ? SkCU : static_cast<DwarfCompileUnit *>(TheU);
-      if ((DwarfCURanges || TargetMachine::getFunctionSections()) &&
-          TheU->getRanges().size())
+      if (useCURanges() && TheU->getRanges().size())
         addSectionLabel(Asm, U, U->getUnitDie(), dwarf::DW_AT_ranges,
                         Asm->GetTempSymbol("cu_ranges", U->getUniqueID()),
                         DwarfDebugRangeSectionSym);
@@ -2910,7 +2913,7 @@ void DwarfDebug::emitDebugRanges() {
     }
 
     // Now emit a range for the CU itself.
-    if (DwarfCURanges) {
+    if (useCURanges()) {
       Asm->OutStreamer.EmitLabel(
           Asm->GetTempSymbol("cu_ranges", TheCU->getUniqueID()));
       const SmallVectorImpl<RangeSpan> &Ranges = TheCU->getRanges();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 5a2110605542..516def804d15 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -458,6 +458,9 @@ class DwarfDebug : public AsmPrinterHandler {
   // Whether to emit the pubnames/pubtypes sections.
   bool HasDwarfPubSections;
 
+  // Whether or not to use AT_ranges for compilation units.
+  bool HasCURanges;
+
   // Version of dwarf we're emitting.
   unsigned DwarfVersion;
 
@@ -733,6 +736,9 @@ public:
   /// split dwarf proposal support.
   bool useSplitDwarf() { return HasSplitDwarf; }
 
+  /// \brief Returns whether or not to use AT_ranges for compilation units.
+  bool useCURanges() { return HasCURanges; }
+
   /// Returns the Dwarf Version.
   unsigned getDwarfVersion() const { return DwarfVersion; }
 
diff --git a/llvm/test/DebugInfo/X86/cu-ranges.ll b/llvm/test/DebugInfo/X86/cu-ranges.ll
index 77561a4e6333..e582ea733247 100644
--- a/llvm/test/DebugInfo/X86/cu-ranges.ll
+++ b/llvm/test/DebugInfo/X86/cu-ranges.ll
@@ -1,5 +1,6 @@
 ; RUN: llc -split-dwarf=Enable -O0 %s -ffunction-sections -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
 ; RUN: llvm-dwarfdump -debug-dump=all %t | FileCheck --check-prefix=FUNCTION-SECTIONS %s
+; RUN: llvm-readobj --relocations %t | FileCheck --check-prefix=FUNCTION-SECTIONS-RELOCS %s
 
 ; RUN: llc -split-dwarf=Enable -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
 ; RUN: llvm-dwarfdump -debug-dump=all %t | FileCheck --check-prefix=NO-FUNCTION-SECTIONS %s
@@ -12,6 +13,9 @@
 ; With function sections enabled make sure that we have a DW_AT_ranges attribute.
 ; FUNCTION-SECTIONS: DW_AT_ranges
 
+; Check that we have a relocation against the .debug_ranges section.
+; FUNCTION-SECTIONS-RELOCS: R_X86_64_32 .debug_ranges 0x0
+
 ; Without function sections enabled make sure that we have no DW_AT_ranges attribute.
 ; NO-FUNCTION-SECTIONS-NOT: DW_AT_ranges