replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Revert "Use const DebugLoc&" 

This reverts r358910 (git commit 2b74466530)

While this patch *seems* trivial and safe and correct, it is not. The
copies are actually load bearing copies. You can observe this with MSan
or other ways of checking for use-after-destroy, but otherwise this may
result in ... difficult to debug inexplicable behavior.

I suspect the issue is that the debug location is used after the
original reference to it is removed. The metadata backing it gets
destroyed as its last references goes away, and then we reference it
later through these const references.

llvm-svn: 358940
This commit is contained in:
Chandler Carruth 2019-04-23 01:42:07 +00:00
parent 759805fd8a
commit bbddf21f90
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
llvm/lib/CodeGen/BranchRelaxation.cpp
View File

@ -300,7 +300,7 @@ bool BranchRelaxation::isBlockInRange(
/// too far away to fit in its displacement field. It is converted to an inverse
/// conditional branch + an unconditional branch to the destination.
bool BranchRelaxation::fixupConditionalBranch(MachineInstr &MI) {
const DebugLoc &DL = MI.getDebugLoc();
DebugLoc DL = MI.getDebugLoc();
MachineBasicBlock *MBB = MI.getParent();
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
MachineBasicBlock *NewBB = nullptr;
@ -468,7 +468,7 @@ bool BranchRelaxation::fixupUnconditionalBranch(MachineInstr &MI) {
MBB->replaceSuccessor(DestBB, BranchBB);
}
const DebugLoc &DL = MI.getDebugLoc();
DebugLoc DL = MI.getDebugLoc();
MI.eraseFromParent();
BlockInfo[BranchBB->getNumber()].Size += TII->insertIndirectBranch(
*BranchBB, *DestBB, DL, DestOffset - SrcOffset, RS.get());