[llvm] [DAG] Lower frem of power-2 using div/trunc/mul+sub (PR #91148)

[Jay Foad via llvm-commits]

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@@ -5555,6 +5565,13 @@ bool SelectionDAG::isKnownNeverZero(SDValue Op, unsigned Depth) const {
   return computeKnownBits(Op, Depth).isNonZero();
 }
 
+bool SelectionDAG::isKnownNonNegativeFP(SDValue Op) const {
+  if (ConstantFPSDNode *C1 = isConstOrConstSplatFP(Op, true))
+    return !C1->isNegative();
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jayfoad wrote:

Since nans are allowed I would suggest being explicit and renaming to `isKnownPositiveOrNaNFP`

https://github.com/llvm/llvm-project/pull/91148