From 34fa5640b805e6bc7a8259e181eed64051c09b4e Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
Date: Fri, 7 Mar 2014 01:30:55 +0000
Subject: [PATCH] DebugInfo: Emit DW_TAG_subprogram's DW_AT_high_pc as an
 offset from the low_pc

This removes a relocation from each subprogram, reducing link times,
etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203187 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/DwarfDebug.cpp    | 3 ++-
 lib/CodeGen/AsmPrinter/DwarfUnit.cpp     | 6 ++++++
 lib/CodeGen/AsmPrinter/DwarfUnit.h       | 4 ++++
 test/DebugInfo/AArch64/dwarfdump.ll      | 2 +-
 test/DebugInfo/X86/dbg-value-location.ll | 2 +-
 5 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index d30be282361..7abd2f1dc73 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -413,7 +413,8 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(DwarfCompileUnit *SPCU,
   }
 
   SPCU->addLabelAddress(SPDie, dwarf::DW_AT_low_pc, FunctionBeginSym);
-  SPCU->addLabelAddress(SPDie, dwarf::DW_AT_high_pc, FunctionEndSym);
+  SPCU->addLabelDelta(SPDie, dwarf::DW_AT_high_pc, FunctionEndSym,
+                      FunctionBeginSym);
 
   const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
   MachineLocation Location(RI->getFrameRegister(*Asm->MF));
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index ddc1c2f4bc0..e046bf417b6 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -320,6 +320,12 @@ void DwarfUnit::addSectionDelta(DIE *Die, dwarf::Attribute Attribute,
     Die->addValue(Attribute, dwarf::DW_FORM_data4, Value);
 }
 
+void DwarfUnit::addLabelDelta(DIE *Die, dwarf::Attribute Attribute,
+                              const MCSymbol *Hi, const MCSymbol *Lo) {
+  DIEValue *Value = new (DIEValueAllocator) DIEDelta(Hi, Lo);
+  Die->addValue(Attribute, dwarf::DW_FORM_data4, Value);
+}
+
 /// addDIEEntry - Add a DIE attribute data and value.
 ///
 void DwarfUnit::addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry) {
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.h b/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 937a607fa88..af465c006ed 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -359,6 +359,10 @@ public:
   void addSectionDelta(DIE *Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
                        const MCSymbol *Lo);
 
+  /// addLabelDelta - Add a label delta attribute data and value.
+  void addLabelDelta(DIE *Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
+                     const MCSymbol *Lo);
+
   /// addDIEEntry - Add a DIE attribute data and value.
   void addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry);
 
diff --git a/test/DebugInfo/AArch64/dwarfdump.ll b/test/DebugInfo/AArch64/dwarfdump.ll
index 3325f30293a..b30bd33ea3a 100644
--- a/test/DebugInfo/AArch64/dwarfdump.ll
+++ b/test/DebugInfo/AArch64/dwarfdump.ll
@@ -12,7 +12,7 @@
 ; A couple of ABS64s similarly:
 
 ; CHECK: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
-; CHECK: DW_AT_high_pc [DW_FORM_addr] (0x0000000000000008)
+; CHECK: DW_AT_high_pc [DW_FORM_data4] (0x00000008)
 
 define i32 @main() nounwind {
   ret i32 0, !dbg !8
diff --git a/test/DebugInfo/X86/dbg-value-location.ll b/test/DebugInfo/X86/dbg-value-location.ll
index 1e21c6a00ae..83907b1cb13 100644
--- a/test/DebugInfo/X86/dbg-value-location.ll
+++ b/test/DebugInfo/X86/dbg-value-location.ll
@@ -4,7 +4,7 @@ target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f3
 target triple = "x86_64-apple-darwin10.0.0"
 ;Radar 8950491
 
-;CHECK: .long Lset5
+;CHECK: .long Lset6
 ;CHECK-NEXT:        ## DW_AT_decl_file
 ;CHECK-NEXT:        ## DW_AT_decl_line
 ;CHECK-NEXT:        ## DW_AT_type