[llvm] [SelectionDAG] Let ComputeKnownSignBits handle (shl (ext X), C) (PR #97695)

[Simon Pilgrim via llvm-commits]

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@@ -0,0 +1,158 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s --check-prefix=X64
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RKSimon wrote:

(pedantic) rename to `known-signtbits-shl.ll` to

https://github.com/llvm/llvm-project/pull/97695