[llvm] [RISCV][TTI] Add checks for invalid cast operations (PR #88854)

[Craig Topper via llvm-commits]

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@@ -956,6 +956,9 @@ InstructionCost RISCVTTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst,
     return getRISCVInstructionCost(Op, DstLT.second, CostKind);
   }
   case ISD::TRUNCATE:
+    // Early return for invalid operation
+    if (Dst->getScalarSizeInBits() >= Src->getScalarSizeInBits())
+      break;
     if (Dst->getScalarSizeInBits() == 1) {
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topperc wrote:

Don't repeatedly call getScalarSizeInBits on the same object. Use a variable.

https://github.com/llvm/llvm-project/pull/88854