commit d4135bbc30de3d3dbd44d64d718fb2169f41bae0
author Peter Collingbourne <peter@pcc.me.uk> Tue Sep 13 01:12:59 2016 +0000
committer Peter Collingbourne <peter@pcc.me.uk> Tue Sep 13 01:12:59 2016 +0000
tree 0b96e34c50822aed89a2272d9e9f3688bc3a0e46
parent efc066758309683482edd289d82ec7670d38931f

DebugInfo: New metadata representation for global variables.

This patch reverses the edge from DIGlobalVariable to GlobalVariable.
This will allow us to more easily preserve debug info metadata when
manipulating global variables.

Fixes PR30362. A program for upgrading test cases is attached to that
bug.

Differential Revision: http://reviews.llvm.org/D20147

llvm-svn: 281284

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 017fc20..91a480e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -2001,6 +2001,14 @@
 }
 
 void CodeViewDebug::emitDebugInfoForGlobals() {
+  DenseMap<const DIGlobalVariable *, const GlobalVariable *> GlobalMap;
+  for (const GlobalVariable &GV : MMI->getModule()->globals()) {
+    SmallVector<MDNode *, 1> MDs;
+    GV.getMetadata(LLVMContext::MD_dbg, MDs);
+    for (MDNode *MD : MDs)
+      GlobalMap[cast<DIGlobalVariable>(MD)] = &GV;
+  }
+
   NamedMDNode *CUs = MMI->getModule()->getNamedMetadata("llvm.dbg.cu");
   for (const MDNode *Node : CUs->operands()) {
     const auto *CU = cast<DICompileUnit>(Node);
@@ -2011,15 +2019,14 @@
     switchToDebugSectionForSymbol(nullptr);
     MCSymbol *EndLabel = nullptr;
     for (const DIGlobalVariable *G : CU->getGlobalVariables()) {
-      if (const auto *GV = dyn_cast_or_null<GlobalVariable>(G->getVariable())) {
+      if (const auto *GV = GlobalMap.lookup(G))
         if (!GV->hasComdat() && !GV->isDeclarationForLinker()) {
           if (!EndLabel) {
             OS.AddComment("Symbol subsection for globals");
             EndLabel = beginCVSubsection(ModuleSubstreamKind::Symbols);
           }
-          emitDebugInfoForGlobal(G, Asm->getSymbol(GV));
+          emitDebugInfoForGlobal(G, GV, Asm->getSymbol(GV));
         }
-      }
     }
     if (EndLabel)
       endCVSubsection(EndLabel);
@@ -2027,14 +2034,14 @@
     // Second, emit each global that is in a comdat into its own .debug$S
     // section along with its own symbol substream.
     for (const DIGlobalVariable *G : CU->getGlobalVariables()) {
-      if (const auto *GV = dyn_cast_or_null<GlobalVariable>(G->getVariable())) {
+      if (const auto *GV = GlobalMap.lookup(G)) {
         if (GV->hasComdat()) {
           MCSymbol *GVSym = Asm->getSymbol(GV);
           OS.AddComment("Symbol subsection for " +
                         Twine(GlobalValue::getRealLinkageName(GV->getName())));
           switchToDebugSectionForSymbol(GVSym);
           EndLabel = beginCVSubsection(ModuleSubstreamKind::Symbols);
-          emitDebugInfoForGlobal(G, GVSym);
+          emitDebugInfoForGlobal(G, GV, GVSym);
           endCVSubsection(EndLabel);
         }
       }
@@ -2055,6 +2062,7 @@
 }
 
 void CodeViewDebug::emitDebugInfoForGlobal(const DIGlobalVariable *DIGV,
+                                           const GlobalVariable *GV,
                                            MCSymbol *GVSym) {
   // DataSym record, see SymbolRecord.h for more info.
   // FIXME: Thread local data, etc
@@ -2063,7 +2071,6 @@
   OS.AddComment("Record length");
   OS.emitAbsoluteSymbolDiff(DataEnd, DataBegin, 2);
   OS.EmitLabel(DataBegin);
-  const auto *GV = cast<GlobalVariable>(DIGV->getVariable());
   if (DIGV->isLocalToUnit()) {
     if (GV->isThreadLocal()) {
       OS.AddComment("Record kind: S_LTHREAD32");