[llvm-branch-commits] [llvm] [DAGCombiner] Relax nsz constraint with fp->int->fp optimizations (PR #164503)

[Yingwei Zheng via llvm-branch-commits]

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@@ -18871,6 +18871,37 @@ SDValue DAGCombiner::visitFPOW(SDNode *N) {
 
   return SDValue();
 }
+/// Check if a use of a floating-point operation doesn't care about the sign of
+/// zero. This allows us to optimize (sitofp (fptosi x)) -> ftrunc(x) even
+/// without NoSignedZerosFPMath, as long as all uses are sign-insensitive.
+static bool isSignInsensitiveUse(SDNode *Use, unsigned OperandNo,
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dtcxzyw wrote:

Yeah. In ValueTracking we have `canIgnoreSignBitOfZero` and `canIgnoreSignBitOfNaN`.

https://github.com/llvm/llvm-project/pull/164503