[llvm] [RISCV] Pass sign-extended value to isInt check in expandMul (PR #150211)

[Sam Elliott via llvm-commits]

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@@ -16079,7 +16079,7 @@ static SDValue expandMul(SDNode *N, SelectionDAG &DAG,
   uint64_t MulAmt = CNode->getZExtValue();
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lenary wrote:

My instincts are wrong, nvm. 

https://github.com/llvm/llvm-project/pull/150211