Allow PRE to insert no-cost phi nodes

[oota-llvm.git] / lib / Transforms / Utils / AddDiscriminators.cpp

diff --git a/lib/Transforms/Utils/AddDiscriminators.cpp b/lib/Transforms/Utils/AddDiscriminators.cpp
index e76a4115655d93643950acb494ad2d4c071dd6db..820544bcebf0c1f7e3fc92c46ed31d558d50a25e 100644 (file)
--- a/lib/Transforms/Utils/AddDiscriminators.cpp
+++ b/lib/Transforms/Utils/AddDiscriminators.cpp
@@ -52,13 +52,11 @@
 // http://wiki.dwarfstd.org/index.php?title=Path_Discriminators
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "add-discriminators"
-
 #include "llvm/Transforms/Scalar.h"
-#include "llvm/DIBuilder.h"
-#include "llvm/DebugInfo.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DIBuilder.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
@@ -69,6 +67,8 @@
 
 using namespace llvm;
 
+#define DEBUG_TYPE "add-discriminators"
+
 namespace {
   struct AddDiscriminators : public FunctionPass {
     static char ID; // Pass identification, replacement for typeid
@@ -99,7 +99,7 @@ FunctionPass *llvm::createAddDiscriminatorsPass() {
 
 static bool hasDebugInfo(const Function &F) {
   NamedMDNode *CUNodes = F.getParent()->getNamedMetadata("llvm.dbg.cu");
-  return CUNodes != 0;
+  return CUNodes != nullptr;
 }
 
 /// \brief Assign DWARF discriminators.
@@ -154,15 +154,20 @@ static bool hasDebugInfo(const Function &F) {
 /// file and line location as I2. This new lexical block will have a
 /// different discriminator number than I1.
 bool AddDiscriminators::runOnFunction(Function &F) {
-  // No need to do anything if there is no debug info for this function.
   // If the function has debug information, but the user has disabled
   // discriminators, do nothing.
-  if (!hasDebugInfo(F) || NoDiscriminators) return false;
+  // Simlarly, if the function has no debug info, do nothing.
+  // Finally, if this module is built with dwarf versions earlier than 4,
+  // do nothing (discriminator support is a DWARF 4 feature).
+  if (NoDiscriminators ||
+      !hasDebugInfo(F) ||
+      F.getParent()->getDwarfVersion() < 4)
+    return false;
 
   bool Changed = false;
   Module *M = F.getParent();
   LLVMContext &Ctx = M->getContext();
-  DIBuilder Builder(*M);
+  DIBuilder Builder(*M, /*AllowUnresolved*/ false);
 
   // Traverse all the blocks looking for instructions in different
   // blocks that are at the same file:line location.
@@ -188,13 +193,11 @@ bool AddDiscriminators::runOnFunction(Function &F) {
         // Create a new lexical scope and compute a new discriminator
         // number for it.
         StringRef Filename = FirstDIL.getFilename();
-        unsigned LineNumber = FirstDIL.getLineNumber();
-        unsigned ColumnNumber = FirstDIL.getColumnNumber();
         DIScope Scope = FirstDIL.getScope();
         DIFile File = Builder.createFile(Filename, Scope.getDirectory());
         unsigned Discriminator = FirstDIL.computeNewDiscriminator(Ctx);
-        DILexicalBlock NewScope = Builder.createLexicalBlock(
-            Scope, File, LineNumber, ColumnNumber, Discriminator);
+        DILexicalBlockFile NewScope =
+            Builder.createLexicalBlockFile(Scope, File, Discriminator);
         DILocation NewDIL = FirstDIL.copyWithNewScope(Ctx, NewScope);
         DebugLoc newDebugLoc = DebugLoc::getFromDILocation(NewDIL);