[llvm] [AArch64][InstCombine] Eliminate redundant barrier intrinsics (PR #112023)
Paul Walker via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 14 10:59:45 PDT 2024
================
@@ -2150,13 +2150,42 @@ static std::optional<Instruction *> instCombineSVEInsr(InstCombiner &IC,
return std::nullopt;
}
+static std::optional<Instruction *> instCombineDMB(InstCombiner &IC,
+ IntrinsicInst &II) {
+ // If this barrier is post-dominated by identical one we can remove it
+ auto *NI = II.getNextNonDebugInstruction();
+ int LookaheadThreshold = 10;
+ auto CanSkipOver = [](Instruction *I) {
+ return !I->mayReadOrWriteMemory() && !I->mayHaveSideEffects();
+ };
+ while (--LookaheadThreshold && !isa<IntrinsicInst>(NI)) {
----------------
paulwalker-arm wrote:
Not knowing the exact use case I'm just wondering if there are any concerns over the looseness of bailing for any intrinsic, even something like `llvm.ctlz` which can be safely skipped over?
https://github.com/llvm/llvm-project/pull/112023
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