From: David Blaikie <dblaikie@gmail.com>
Date: Tue, 25 Mar 2014 05:34:24 +0000 (+0000)
Subject: DebugInfo: Add GNU_addr_base and GNU_ranges_base only when there are addresses or... 
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=9d5961d0d89b561be9ef91ea6cca81ef00672d17

DebugInfo: Add GNU_addr_base and GNU_ranges_base only when there are addresses or ranges

Based on code review feedback from Eric in r204672.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204702 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index a9ed9dbcb5b..f4182d0b79b 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -956,6 +956,17 @@ void DwarfDebug::finalizeModuleInfo() {
                       dwarf::DW_FORM_data8, ID);
         SkCU->addUInt(SkCU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
                       dwarf::DW_FORM_data8, ID);
+
+        // We don't keep track of which addresses are used in which CU so this
+        // is a bit pessimistic under LTO.
+        if (!InfoHolder.getAddrPool()->empty())
+          addSectionLabel(Asm, SkCU, SkCU->getUnitDie(),
+                          dwarf::DW_AT_GNU_addr_base, DwarfAddrSectionSym,
+                          DwarfAddrSectionSym);
+        if (!TheU->getRangeLists().empty())
+          addSectionLabel(Asm, SkCU, SkCU->getUnitDie(),
+                          dwarf::DW_AT_GNU_ranges_base,
+                          DwarfDebugRangeSectionSym, DwarfDebugRangeSectionSym);
       }
 
       // If we have code split among multiple sections or non-contiguous
@@ -2660,19 +2671,6 @@ DwarfCompileUnit *DwarfDebug::constructSkeletonCU(const DwarfCompileUnit *CU) {
 
   initSkeletonUnit(CU, Die, NewCU);
 
-  // Relocate to the beginning of the addr_base section, else 0 for the
-  // beginning of the one for this compile unit.
-  // We could shave off some space if we deferred adding these attributes until
-  // the end of the CU to see if we have a non-empty debug_addr and debug_ranges
-  // sections so we don't bother with extra attributes and relocations.
-  if (Asm->MAI->doesDwarfUseRelocationsAcrossSections()) {
-    NewCU->addSectionLabel(Die, dwarf::DW_AT_GNU_addr_base, DwarfAddrSectionSym);
-    NewCU->addSectionLabel(Die, dwarf::DW_AT_GNU_ranges_base, DwarfDebugRangeSectionSym);
-  } else {
-    NewCU->addSectionOffset(Die, dwarf::DW_AT_GNU_addr_base, 0);
-    NewCU->addSectionOffset(Die, dwarf::DW_AT_GNU_ranges_base, 0);
-  }
-
   return NewCU;
 }
 
diff --git a/test/DebugInfo/X86/fission-cu.ll b/test/DebugInfo/X86/fission-cu.ll
index 543b7874406..7f176986394 100644
--- a/test/DebugInfo/X86/fission-cu.ll
+++ b/test/DebugInfo/X86/fission-cu.ll
@@ -59,8 +59,6 @@
 ; CHECK-NEXT: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x00000000)
 ; CHECK-NEXT: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x00000000] = "baz.dwo")
 ; CHECK-NEXT: DW_AT_comp_dir [DW_FORM_strp]     ( .debug_str[0x00000008] = "/usr/local/google/home/echristo/tmp")
-; CHECK-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]                   (0x00000000)
-; CHECK-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]                   (0x00000000)
 ; CHECK-NEXT: DW_AT_GNU_dwo_id [DW_FORM_data8]  (0x1f1f859683d49324)
 
 ; Check that the rest of the compile units have information.
@@ -108,7 +106,6 @@
 ; OBJ-NEXT: R_X86_64_32 .debug_str
 ; OBJ-NEXT: R_X86_64_32 .debug_str
 ; OBJ-NEXT: R_X86_64_32 .debug_addr
-; OBJ-NEXT: R_X86_64_32 .debug_ranges
 ; OBJ-NEXT: }
 
 ; HDR-NOT: .debug_aranges
diff --git a/test/DebugInfo/X86/fission-ranges.ll b/test/DebugInfo/X86/fission-ranges.ll
index a48896f5a55..416e7cb2a2f 100644
--- a/test/DebugInfo/X86/fission-ranges.ll
+++ b/test/DebugInfo/X86/fission-ranges.ll
@@ -2,6 +2,15 @@
 ; RUN: llvm-dwarfdump %t | FileCheck %s
 ; RUN: llvm-objdump -h %t | FileCheck --check-prefix=HDR %s
 
+; CHECK: .debug_info contents:
+; CHECK: DW_TAG_compile_unit
+; CHECK-NEXT: DW_AT_stmt_list
+; CHECK-NEXT: DW_AT_GNU_dwo_name
+; CHECK-NEXT: DW_AT_comp_dir
+; CHECK-NEXT: DW_AT_GNU_dwo_id
+; CHECK-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]                   (0x00000000)
+
+
 ; CHECK: .debug_info.dwo contents:
 ; CHECK: DW_AT_location [DW_FORM_sec_offset]   ([[A:0x[0-9a-z]*]])
 ; CHECK: DW_AT_location [DW_FORM_sec_offset]   ([[E:0x[0-9a-z]*]])
diff --git a/test/DebugInfo/empty.ll b/test/DebugInfo/empty.ll
index 1fb18166146..cf40523e7e4 100644
--- a/test/DebugInfo/empty.ll
+++ b/test/DebugInfo/empty.ll
@@ -1,6 +1,7 @@
 ; REQUIRES: object-emission
 
 ; RUN: %llc_dwarf < %s -filetype=obj | llvm-dwarfdump - | FileCheck %s
+; RUN: %llc_dwarf -split-dwarf=Enable < %s -filetype=obj | llvm-dwarfdump - | FileCheck --check-prefix=FISSION %s
 
 ; darwin has a workaround for a linker bug so it always emits one line table entry
 ; XFAIL: darwin
@@ -17,6 +18,9 @@
 ; CHECK: .debug_pubtypes contents:
 ; CHECK-NOT: Offset
 
+; Don't emit DW_AT_addr_base when there are no addresses.
+; FISSION-NOT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]
+
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!5}