[llvm] [ValueTracking] use KnownBits to compute fpclass from bitcast (PR #97762)

[Yingwei Zheng via llvm-commits]

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@@ -5805,6 +5805,36 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
 
     break;
   }
+  case Instruction::BitCast: {
+    const Type *Ty = Op->getType();
+    const Value *Casted = Op->getOperand(0);
+    if (Ty->isVectorTy() || !Casted->getType()->isIntOrIntVectorTy())
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dtcxzyw wrote:

Why not handle `vector -> vector` casts? You can use `m_ElementWiseBitCast` to rule out `vector <-> scalar` casts.


https://github.com/llvm/llvm-project/pull/97762