[llvm] [RISCV][TTI] Cost non-power-of-two size changing casts (PR #101047)

[Shih-Po Hung via llvm-commits]

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@@ -1030,17 +1030,28 @@ InstructionCost RISCVTTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst,
   if (!IsVectorType)
     return BaseT::getCastInstrCost(Opcode, Dst, Src, CCH, CostKind, I);
 
-  bool IsTypeLegal = isTypeLegal(Src) && isTypeLegal(Dst) &&
-                     (Src->getScalarSizeInBits() <= ST->getELen()) &&
-                     (Dst->getScalarSizeInBits() <= ST->getELen());
-
-  // FIXME: Need to compute legalizing cost for illegal types.
-  if (!IsTypeLegal)
+  // FIXME: Need to compute legalizing cost for illegal types.  The current
+  // code handles only legal types and those which can be trivially
+  // promoted to legal.
+  if (Src->getScalarSizeInBits() > ST->getELen() ||
+      Dst->getScalarSizeInBits() > ST->getELen())
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arcbbb wrote:

need `ST->hasVInstructions()` before calling `ST->getELen`

https://github.com/llvm/llvm-project/pull/101047