[llvm] [InstCombine] Handle isnormal idiom (PR #125454)

[Matt Arsenault via llvm-commits]

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@@ -3500,6 +3500,22 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
     }
   }
 
+  // (X & ExpMask) != 0 && (X & ExpMask) != ExpMask -> isnormal(X)
+  // (X & ExpMask) == 0 || (X & ExpMask) == ExpMask -> !isnormal(X)
+  Value *X;
+  const APInt *MaskC;
+  if (LHS0 == RHS0 && PredL == PredR &&
+      PredL == (IsAnd ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ) &&
+      !I.getFunction()->hasFnAttribute(Attribute::NoImplicitFloat) &&
+      match(LHS0, m_And(m_ElementWiseBitCast(m_Value(X)), m_APInt(MaskC))) &&
+      X->getType()->getScalarType()->isIEEELikeFPTy() &&
+      APFloat(X->getType()->getScalarType()->getFltSemantics(), *MaskC)
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arsenm wrote:

Needs hasOneUse checks? 

https://github.com/llvm/llvm-project/pull/125454