From 6eb1a087aac0fec5ef49224c17d07ce3a1bad2f9 Mon Sep 17 00:00:00 2001
From: Philip Reames <listmail@philipreames.com>
Date: Wed, 3 Mar 2021 08:30:36 -0800
Subject: [PATCH] [tests] Add tests for cases brought up during review of
 D97520

---
 llvm/test/Analysis/BasicAA/negoffset.ll | 35 +++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/llvm/test/Analysis/BasicAA/negoffset.ll b/llvm/test/Analysis/BasicAA/negoffset.ll
index cc0d68a..1fe69a1 100644
--- a/llvm/test/Analysis/BasicAA/negoffset.ll
+++ b/llvm/test/Analysis/BasicAA/negoffset.ll
@@ -4,6 +4,7 @@ target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
 target triple = "i386-unknown-linux-gnu"
 
 declare i32* @random.i32(i32* %ptr)
+declare i8* @random.i8(i32* %ptr)
 
 ; CHECK-LABEL: Function: arr:
 ; CHECK-DAG: MayAlias: i32* %alloca, i32* %p0
@@ -126,4 +127,38 @@ define void @one_size_unknown(i8* %p, i32 %size) {
   ret void
 }
 
+
+; If part of the addressing is done with non-inbounds GEPs, we can't use
+; properties implied by the last gep w/the whole offset. In this case,
+; %random = %alloc - 4 bytes is well defined, and results in %p1 == %alloca.
+; CHECK-LABEL: Function: all_inbounds:
+; CHECK: MayAlias: i32* %alloca, i8* %p0
+; CHECK: NoAlias:  i32* %alloca, i8* %p1
+; FIXME: Result produced is currently wrong.
+define void @all_inbounds() {
+  %alloca = alloca i32, i32 4
+  %random = call i8* @random.i8(i32* %alloca)
+  %p0 = getelementptr inbounds i8, i8* %random, i8 0
+  %step = getelementptr i8, i8* %random, i8 4
+  %p1 = getelementptr inbounds i8, i8* %step, i8 2
+  ret void
+}
+
+
+; For all values of %x, %p0 and %p1 can't alias because %random would
+; have to be out of bounds (and thus a contradiction) for them to be equal.
+; CHECK-LABEL: Function: common_factor:
+; CHECK: MayAlias:  i32* %p0, i32* %p1
+; TODO: Missing oppurtunity
+define void @common_factor(i32 %x) {
+  %alloca = alloca i32, i32 4
+  %random = call i8* @random.i8(i32* %alloca)
+  %p0 = getelementptr inbounds i32, i32* %alloca, i32 %x
+  %step = getelementptr inbounds i8, i8* %random, i8 4
+  %step.bitcast = bitcast i8* %step to i32*
+  %p1 = getelementptr inbounds i32, i32* %step.bitcast, i32 %x
+  ret void
+}
+
+
 declare void @llvm.memset.p0i8.i32(i8*, i8, i32, i1)
-- 
2.7.4