llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-llvm-regalloc Author: Peter Collingbourne (pcc) <details> <summary>Changes</summary> Without this, we end up with quadratic behavior affecting functions with large numbers of code motion barriers, such as CFI jump tables. --- Full diff: https://github.com/llvm/llvm-project/pull/136806.diff 1 Files Affected: - (modified) llvm/lib/CodeGen/LiveRangeShrink.cpp (+12-3) ``````````diff diff --git a/llvm/lib/CodeGen/LiveRangeShrink.cpp b/llvm/lib/CodeGen/LiveRangeShrink.cpp index dae7e14e54aae..46e837c086c5d 100644 --- a/llvm/lib/CodeGen/LiveRangeShrink.cpp +++ b/llvm/lib/CodeGen/LiveRangeShrink.cpp @@ -95,14 +95,24 @@ static MachineInstr *FindDominatedInstruction(MachineInstr &New, return Old; } +static bool isCodeMotionBarrier(MachineInstr &MI) { + return MI.hasUnmodeledSideEffects() && !MI.isPseudoProbe(); +} + /// Builds Instruction to its dominating order number map \p M by traversing /// from instruction \p Start. static void BuildInstOrderMap(MachineBasicBlock::iterator Start, InstOrderMap &M) { M.clear(); unsigned i = 0; - for (MachineInstr &I : make_range(Start, Start->getParent()->end())) + bool SawStore = false; + for (MachineInstr &I : make_range(Start, Start->getParent()->end())) { + if (I.mayStore()) + SawStore = true; + if (!I.isSafeToMove(SawStore) && isCodeMotionBarrier(I)) + break; M[&I] = i++; + } } bool LiveRangeShrink::runOnMachineFunction(MachineFunction &MF) { @@ -166,8 +176,7 @@ bool LiveRangeShrink::runOnMachineFunction(MachineFunction &MF) { // If MI has side effects, it should become a barrier for code motion. // IOM is rebuild from the next instruction to prevent later // instructions from being moved before this MI. - if (MI.hasUnmodeledSideEffects() && !MI.isPseudoProbe() && - Next != MBB.end()) { + if (isCodeMotionBarrier(MI) && Next != MBB.end()) { BuildInstOrderMap(Next, IOM); SawStore = false; } `````````` </details> https://github.com/llvm/llvm-project/pull/136806 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
