Pass to emit DWARF path discriminators.

DWARF discriminators are used to distinguish multiple control flow paths
on the same source location. When this happens, instructions across
basic block boundaries will share the same debug location.

This pass detects this situation and creates a new lexical scope to one
of the two instructions. This lexical scope is a child scope of the
original and contains a new discriminator value. This discriminator is
then picked up from MCObjectStreamer::EmitDwarfLocDirective to be
written on the object file.

This fixes http://llvm.org/bugs/show_bug.cgi?id=18270.

llvm-svn: 202752

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/Utils.cpp b/llvm/lib/Transforms/Utils/Utils.cpp
index 3fb5463..ed4f45c6 100644
--- a/llvm/lib/Transforms/Utils/Utils.cpp
+++ b/llvm/lib/Transforms/Utils/Utils.cpp
@@ -21,6 +21,7 @@ using namespace llvm;
 /// initializeTransformUtils - Initialize all passes in the TransformUtils
 /// library.
 void llvm::initializeTransformUtils(PassRegistry &Registry) {
+  initializeAddDiscriminatorsPass(Registry);
   initializeBreakCriticalEdgesPass(Registry);
   initializeInstNamerPass(Registry);
   initializeLCSSAPass(Registry);