Reapply "[SimplifyCFG] In sinkLastInstruction correctly set debugloc of common inst"

This reapplies r289828 (reverted in r289833 as it broke the address sanitizer).  The
debugloc is now only set when the instruction is not a call, as this causes the
verifier to assert (the inliner requires an inlinable callsite to have a debug loc
if the caller and callee have debug info).

Original commit message:

Simplify CFG will try to sink the last instruction in a series of basic blocks,
creating a "common" instruction in the successor block (sinkLastInstruction).
When it does this, the debug location of the single instruction should be the
merged debug locations of the commoned instructions.

Original review: https://reviews.llvm.org/D27590

llvm-svn: 290973

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 3846b21c502..54390e77bb1 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1574,12 +1574,20 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
     I0->getOperandUse(O).set(NewOperands[O]);
   I0->moveBefore(&*BBEnd->getFirstInsertionPt());
 
-  // Update metadata and IR flags.
+  // The debug location for the "common" instruction is the merged locations of
+  // all the commoned instructions.  We start with the original location of the
+  // "common" instruction and iteratively merge each location in the loop below.
+  DILocation *Loc = I0->getDebugLoc();
+
+  // Update metadata and IR flags, and merge debug locations.
   for (auto *I : Insts)
     if (I != I0) {
+      Loc = DILocation::getMergedLocation(Loc, I->getDebugLoc());
       combineMetadataForCSE(I0, I);
       I0->andIRFlags(I);
     }
+  if (!isa<CallInst>(I0))
+    I0->setDebugLoc(Loc);
 
   if (!isa<StoreInst>(I0)) {
     // canSinkLastInstruction checked that all instructions were used by