[llvm] [licm] clone metadata when hoisting conditional branch (PR #152232)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 6 13:41:59 PDT 2025
================
@@ -857,9 +859,18 @@ class ControlFlowHoister {
}
// Now finally clone BI.
- ReplaceInstWithInst(
- HoistTarget->getTerminator(),
- BranchInst::Create(HoistTrueDest, HoistFalseDest, BI->getCondition()));
+ auto *NewBI =
+ BranchInst::Create(HoistTrueDest, HoistFalseDest, BI->getCondition(),
+ HoistTarget->getTerminator()->getIterator());
+ HoistTarget->getTerminator()->eraseFromParent();
+ // Copy all the metadata. In particular:
+ // - debug info (critical to Sample-based profiling) should be the same
+ // as the original branch, not that of HoistTarget->getTerminator(),
+ // which is what ReplaceInstWithInst would use.
----------------
nikic wrote:
Hm, looking at https://llvm.org/docs/HowToUpdateDebugInfo.html#when-to-preserve-an-instruction-location again, it specifically calls out LICM as a case where the debug location should be dropped, not preserved.
https://github.com/llvm/llvm-project/pull/152232
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