commit 85366acf15bdcc48a36457513c2bd317a2078a60
author David Blaikie <dblaikie@gmail.com> Sat Apr 22 07:53:44 2017 +0000
committer David Blaikie <dblaikie@gmail.com> Sat Apr 22 07:53:44 2017 +0000
tree 5ed12296f75b235d6b92dde7da32734a106abfb8
parent 6cce69020cf1034749a2abfee87ac0ac45293bcb

Avoid using relocations for ref_addr in .dwo files

In dwo files the fixed offset can be used - if the dwos are linked into
a dwp, the dwo consumer must use the dwp tables to find out where the
original range of the debug_info was and resolve the "section relative"
value relative to that original range - effectively
avoiding/reimplementing the relocation handling.

llvm-svn: 301072

llvm/lib/CodeGen/AsmPrinter/DIE.cpp

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
index 31c2b3b..30bfd7c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -655,20 +655,12 @@
   case dwarf::DW_FORM_ref_addr: {
     // Get the absolute offset for this DIE within the debug info/types section.
     unsigned Addr = Entry->getDebugSectionOffset();
-    if (AP->MAI->doesDwarfUseRelocationsAcrossSections()) {
-      const DwarfDebug *DD = AP->getDwarfDebug();
-      if (DD)
-        assert(!DD->useSplitDwarf() &&
-               "TODO: dwo files can't have relocations.");
-      const DIEUnit *Unit = Entry->getUnit();
-      assert(Unit && "CUDie should belong to a CU.");
-      MCSection *Section = Unit->getSection();
-      if (Section) {
-        const MCSymbol *SectionSym = Section->getBeginSymbol();
-        AP->EmitLabelPlusOffset(SectionSym, Addr, SizeOf(AP, Form), true);
-        return;
-      }
+    if (const MCSymbol *SectionSym =
+            Entry->getUnit()->getCrossSectionRelativeBaseAddress()) {
+      AP->EmitLabelPlusOffset(SectionSym, Addr, SizeOf(AP, Form), true);
+      return;
     }
+
     AP->OutStreamer->EmitIntValue(Addr, SizeOf(AP, Form));
     return;
   }

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index bac0c20..16fb20d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1595,3 +1595,11 @@
                                   const DIScope *Context) {
   getCU().addGlobalTypeUnitType(Ty, Context);
 }
+
+const MCSymbol *DwarfUnit::getCrossSectionRelativeBaseAddress() const {
+  if (!Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+    return nullptr;
+  if (isDwoUnit())
+    return nullptr;
+  return getSection()->getBeginSymbol();
+}

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index d141acc..e84df46 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -335,6 +335,7 @@
   void setIndexTyDie(DIE *D) { IndexTyDie = D; }
 
   virtual bool isDwoUnit() const = 0;
+  const MCSymbol *getCrossSectionRelativeBaseAddress() const override;
 };
 
 class DwarfTypeUnit final : public DwarfUnit {