[Test] Add failing test for PR49087

Author: xortator

llvm/test/CodeGen/X86/pr49087.ll

@@ -0,0 +1,30 @@
+; RUN: llc -o - -global-isel < %s 2>&1 | FileCheck %s
+; REQUIRES: asserts
+; XFAIL: *
+
+define i32 @test_01(i32* %p, i64 %len, i32 %x) {
+; CHECK-LABEL: test_01
+
+entry:
+  %scevgep = getelementptr i32, i32* %p, i64 -1
+  br label %loop
+
+loop:                                             ; preds = %backedge, %entry
+  %iv = phi i64 [ %iv.next, %backedge ], [ %len, %entry ]
+  %iv.next = add i64 %iv, -1
+  %cond_1 = icmp eq i64 %iv, 0
+  br i1 %cond_1, label %exit, label %backedge
+
+backedge:                                         ; preds = %loop
+  %scevgep1 = getelementptr i32, i32* %scevgep, i64 %iv
+  %loaded = load atomic i32, i32* %scevgep1 unordered, align 4
+  %cond_2 = icmp eq i32 %loaded, %x
+  br i1 %cond_2, label %failure, label %loop
+
+exit:                                             ; preds = %loop
+  ret i32 -1
+
+failure:
+  unreachable
+}
+