[llvm] [DAGCombiner] Preserve nsw when folding (mul x, 2^c) to (shl x, c) (PR #192366)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,38 @@
+; REQUIRES: asserts
+; RUN: llc -mtriple=riscv64 -debug-only=isel -o /dev/null %s 2>&1 | FileCheck %s
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arsenm wrote:

Use -filetype=null instead of -o /dev/null. However in this case it would be better to check the resulting mir instead of relying on asserts + debug output 

https://github.com/llvm/llvm-project/pull/192366