================
@@ -1877,3 +1877,139 @@ Value
*InstCombinerImpl::SimplifyDemandedVectorElts(Value *V,
return MadeChange ? I : nullptr;
}
+
+/// For floating-point classes that resolve to a single bit pattern, return
that
+/// value.
+static Constant *getFPClassConstant(Type *Ty, FPClassTest Mask) {
+ switch (Mask) {
+ case fcPosZero:
+ return ConstantFP::getZero(Ty);
+ case fcNegZero:
+ return ConstantFP::getZero(Ty, true);
+ case fcPosInf:
+ return ConstantFP::getInfinity(Ty);
+ case fcNegInf:
+ return ConstantFP::getInfinity(Ty, true);
+ case fcNone:
+ return PoisonValue::get(Ty);
+ default:
+ return nullptr;
+ }
+}
+
+Value *InstCombinerImpl::SimplifyDemandedUseFPClass(
+ Value *V, const FPClassTest DemandedMask, KnownFPClass &Known,
+ unsigned Depth, Instruction *CxtI) {
+ assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");
+ Type *VTy = V->getType();
+
+ assert(Known == KnownFPClass() && "expected uninitialized state");
+
+ if (DemandedMask == fcNone)
+ return isa<UndefValue>(V) ? nullptr : PoisonValue::get(VTy);
+
+ if (Depth == MaxAnalysisRecursionDepth)
+ return nullptr;
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) {
+ // Handle constants and arguments
+ Known = computeKnownFPClass(V, fcAllFlags, CxtI, Depth + 1);
+ Value *FoldedToConst =
+ getFPClassConstant(VTy, DemandedMask & Known.KnownFPClasses);
+ return FoldedToConst == V ? nullptr : FoldedToConst;
----------------
arsenm wrote:
This isn't true, this guards against infinite loops from returning the same
value when no change was made
https://github.com/llvm/llvm-project/pull/74056
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