[BasicAA] Add test for decomposition limit (NFC)

Test behavior before/at/after the GEP decomposition limit.

diff --git a/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll b/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
new file mode 100644 (file)
index 0000000..a375c4e
--- /dev/null
+++ b/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
@@ -0,0 +1,31 @@
+; RUN: opt -S -basic-aa -aa-eval -print-all-alias-modref-info -disable-output < %s 2>&1 | FileCheck %s
+
+; CHECK-LABEL: Function: test
+;; Before limit:
+; CHECK-DAG: MustAlias: i8* %gep.add5, i8* %gep.inc5
+; CHECK-DAG: NoAlias: i8* %gep.inc3, i8* %gep.inc5
+; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc5
+;; At limit:
+; CHECK-DAG: MayAlias: i8* %gep.add6, i8* %gep.inc6
+; CHECK-DAG: MayAlias: i8* %gep.inc4, i8* %gep.inc6
+; CHECK-DAG: MayAlias: i8* %gep.inc5, i8* %gep.inc6
+;; After limit:
+; CHECK-DAG: MayAlias: i8* %gep.add7, i8* %gep.inc7
+; CHECK-DAG: MayAlias: i8* %gep.inc5, i8* %gep.inc7
+; CHECK-DAG: MayAlias: i8* %gep.inc6, i8* %gep.inc7
+
+define void @test(i8* %base) {
+  %gep.add5 = getelementptr i8, i8* %base, i64 5
+  %gep.add6 = getelementptr i8, i8* %base, i64 6
+  %gep.add7 = getelementptr i8, i8* %base, i64 7
+
+  %gep.inc1 = getelementptr i8, i8* %base, i64 1
+  %gep.inc2 = getelementptr i8, i8* %gep.inc1, i64 1
+  %gep.inc3 = getelementptr i8, i8* %gep.inc2, i64 1
+  %gep.inc4 = getelementptr i8, i8* %gep.inc3, i64 1
+  %gep.inc5 = getelementptr i8, i8* %gep.inc4, i64 1
+  %gep.inc6 = getelementptr i8, i8* %gep.inc5, i64 1
+  %gep.inc7 = getelementptr i8, i8* %gep.inc6, i64 1
+
+  ret void
+}