1 files changed, 8 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index cc4af1efba6..62bc755ebab 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -4270,6 +4270,14 @@ bool CodeGenPrepare::moveExtToFormExtLoad(Instruction *&I) {
   TPT.commit();
   I->removeFromParent();
   I->insertAfter(LI);
+  // CGP does not check if the zext would be speculatively executed when moved
+  // to the same basic block as the load. Preserving its original location would
+  // pessimize the debugging experience, as well as negatively impact the 
+  // quality of sample pgo. We don't want to use "line 0" as that has a
+  // size cost in the line-table section and logically the zext can be seen as
+  // part of the load. Therefore we conservatively reuse the same debug location
+  // for the load and the zext.
+  I->setDebugLoc(LI->getDebugLoc());
   ++NumExtsMoved;
   return true;
 }