[X86] Add test for PR64589 (NFC)

llvm/test/CodeGen/X86/pr64589.ll

@@ -0,0 +1,25 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc -mtriple=x86_64-- < %s | FileCheck %s
+
+; FIXME: This is a miscompile.
+; It's not possible to directly or the two loads together, because this might
+; propagate a poison value from the second load (which has !range but not
+; !noundef).
+define i8 @test(ptr %p) {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movzbl (%rdi), %eax
+; CHECK-NEXT:    orb 1(%rdi), %al
+; CHECK-NEXT:    addb %al, %al
+; CHECK-NEXT:    retq
+  %v1 = load i8, ptr %p, align 4, !range !0, !noundef !{}
+  %cmp1 = icmp ne i8 %v1, 0
+  %p2 = getelementptr inbounds i8, ptr %p, i64 1
+  %v2 = load i8, ptr %p2, align 1, !range !0
+  %cmp2 = icmp ne i8 %v2, 0
+  %or = select i1 %cmp1, i1 true, i1 %cmp2
+  %res = select i1 %or, i8 2, i8 0
+  ret i8 %res
+}
+
+!0 = !{i8 0, i8 2}