[llvm] [AMDGPU][GlobalISel] Look through readfirstlane/readlane in computeKnownBitsForTargetInstr. (PR #224275)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,89 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=amdgpu9.00 < %s | FileCheck -check-prefixes=SDAG,CHECK %s
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arsenm wrote:

explicit -global-isel=0 if mixing the two 

https://github.com/llvm/llvm-project/pull/224275