[llvm] [Codegen][LegalizeIntegerTypes] Improve shift through stack (PR #96151)
Matt Arsenault via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 21 01:43:02 PDT 2024
================
@@ -4530,14 +4530,25 @@ void DAGTypeLegalizer::ExpandIntRes_ShiftThroughStack(SDNode *N, SDValue &Lo,
SDValue ShAmt = N->getOperand(1);
EVT ShAmtVT = ShAmt.getValueType();
- // This legalization is optimal when the shift is by a multiple of byte width,
- // %x * 8 <-> %x << 3 so 3 low bits should be be known zero.
- bool ShiftByByteMultiple =
- DAG.computeKnownBits(ShAmt).countMinTrailingZeros() >= 3;
+ EVT LoadStoreVT = VT;
+ do {
+ LoadStoreVT = TLI.getTypeToTransformTo(*DAG.getContext(), LoadStoreVT);
+ }while (!TLI.isTypeLegal(LoadStoreVT));
+
+ const Align LoadStoreAlign = [&]() -> Align {
+ if (TLI.allowsMisalignedMemoryAccesses(LoadStoreVT))
+ return Align(1);
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arsenm wrote:
Don't understand this. Just because it's allowed doesn't mean it's a good idea to use Align 1
https://github.com/llvm/llvm-project/pull/96151
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