diff options
Diffstat (limited to 'lib/Transforms/Scalar/GVN.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index 9485bfd7c296..0137378b828b 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -1572,6 +1572,13 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock, // Assign value numbers to the new instructions. for (Instruction *I : NewInsts) { + // Instructions that have been inserted in predecessor(s) to materialize + // the load address do not retain their original debug locations. Doing + // so could lead to confusing (but correct) source attributions. + // FIXME: How do we retain source locations without causing poor debugging + // behavior? + I->setDebugLoc(DebugLoc()); + // FIXME: We really _ought_ to insert these value numbers into their // parent's availability map. However, in doing so, we risk getting into // ordering issues. If a block hasn't been processed yet, we would be @@ -1601,8 +1608,11 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock, if (auto *RangeMD = LI->getMetadata(LLVMContext::MD_range)) NewLoad->setMetadata(LLVMContext::MD_range, RangeMD); - // Transfer DebugLoc. - NewLoad->setDebugLoc(LI->getDebugLoc()); + // We do not propagate the old load's debug location, because the new + // load now lives in a different BB, and we want to avoid a jumpy line + // table. + // FIXME: How do we retain source locations without causing poor debugging + // behavior? // Add the newly created load. ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred, |