[llvm] [RISCV] Combine (ADDI (ADDI X, C1), C2) -> (ADDI X, C1+C2) (PR #157416)

[Piotr Fusik via llvm-commits]

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@@ -4019,7 +4019,7 @@ void SelectionDAGBuilder::visitBitCast(const User &I) {
   // constant integer as an opaque constant.
   else if(ConstantInt *C = dyn_cast<ConstantInt>(I.getOperand(0)))
     setValue(&I, DAG.getConstant(C->getValue(), dl, DestVT, /*isTarget=*/false,
-                                 /*isOpaque*/true));
+                                 /*isOpaque*/false));
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pfusik wrote:

Why did we have an opaque constant here?

https://github.com/llvm/llvm-project/pull/157416