Update llvm/test/Transforms/InstCombine/AMDGPU/addrspacecast.ll

Co-authored-by: Nikita Popov <[email protected]>

Author: wenju-he

llvm/test/Transforms/InstCombine/AMDGPU/addrspacecast.ll

@@ -1,7 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt -S -mtriple=amdgcn-amd-amdhsa -passes=instcombine %s | FileCheck %s
 
-; Check that `select B, true, C` isn't optimized to `or B, C`.
+; Check that `select B, true, C` isn't optimized to `or B, C`,
+; because the invalid addrspacecast %asc.shared may introduce poison.
 define i1 @not_fold_select(ptr addrspace(1) noundef %x) {
 ; CHECK-LABEL: define i1 @not_fold_select(
 ; CHECK-SAME: ptr addrspace(1) noundef [[X:%.*]]) {