[llvm] [InstCombine] Optimise x / sqrt(y / z) with fast-math pattern. (PR #76737)
Zain Jaffal via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 2 10:34:13 PST 2024
================
@@ -1701,6 +1701,31 @@ static Instruction *foldFDivPowDivisor(BinaryOperator &I,
return BinaryOperator::CreateFMulFMF(Op0, Pow, &I);
}
+/// Convert div to mul if we have an sqrt divisor iff sqrt's operand is a fdiv
+/// instruction.
+static Instruction *foldFDivSqrtDivisor(BinaryOperator &I,
+ InstCombiner::BuilderTy &Builder) {
+ // X / sqrt(Y / Z) --> X * sqrt(Z / Y)
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+ auto *II = dyn_cast<IntrinsicInst>(Op1);
+ if (!II || II->getIntrinsicID() != Intrinsic::sqrt || !II->hasOneUse() ||
+ !I.hasAllowReassoc() || !I.hasAllowReciprocal())
----------------
zjaffal wrote:
my assumption was following the implementation of `foldFDivPowDivisor` or at least the div inside the sqrt should have that flag enabled?
https://github.com/llvm/llvm-project/pull/76737
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