Let llvm::ReplaceInstWithInst copy debug location from old to new instruction.

Currently some users of this function do this explicitly, and all the
rest forget to do this.

ThreadSanitizer was one of such users, and had missing debug
locations for calls into TSan runtime handling atomic operations,
eventually leading to poorly symbolized stack traces and malfunctioning
suppressions.

This is another change relevant to PR23837.

llvm-svn: 240460

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 798376e9554..53471de6154 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -211,6 +211,11 @@ void llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL,
   assert(I->getParent() == nullptr &&
          "ReplaceInstWithInst: Instruction already inserted into basic block!");
 
+  // Copy debug location to newly added instruction, if it wasn't already set
+  // by the caller.
+  if (!I->getDebugLoc())
+    I->setDebugLoc(BI->getDebugLoc());
+
   // Insert the new instruction into the basic block...
   BasicBlock::iterator New = BIL.insert(BI, I);
 
@@ -716,7 +721,6 @@ TerminatorInst *llvm::SplitBlockAndInsertIfThen(Value *Cond,
   CheckTerm->setDebugLoc(SplitBefore->getDebugLoc());
   BranchInst *HeadNewTerm =
     BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cond);
-  HeadNewTerm->setDebugLoc(SplitBefore->getDebugLoc());
   HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
   ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
 
@@ -766,7 +770,6 @@ void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
   (*ElseTerm)->setDebugLoc(SplitBefore->getDebugLoc());
   BranchInst *HeadNewTerm =
     BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/ElseBlock, Cond);
-  HeadNewTerm->setDebugLoc(SplitBefore->getDebugLoc());
   HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
   ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
 }