[llvm] [GlobalIsel][AArch64] Replace N bit G_ADD with N/2 bit G_ADD if the lower bits are known to be zeros (PR #101327)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,114 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 2
+# RUN: llc -mtriple aarch64 -global-isel -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s -o - | FileCheck %s
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arsenm wrote:

Don't need -global-isel 

https://github.com/llvm/llvm-project/pull/101327