[llvm] [RISCV] Add SRAW to ComputeNumSignBitsForTargetNode. (PR #155564)

[Craig Topper via llvm-commits]

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@@ -220,3 +220,18 @@ define signext i32 @test14(ptr %0, ptr %1, i64 %2) {
   %12 = add i32 %9, %11
   ret i32 %12
 }
+
+; Test that we can propage sign bits through sraw. We should use an slli
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topperc wrote:

```suggestion
; Test that we can propagate sign bits through sraw. We should use an slli
```

https://github.com/llvm/llvm-project/pull/155564