Implement PartialAlias checking in BasicAA.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121520 91177308-0d34-0410-b5e6-96231b3b80d8

test/Analysis/TypeBasedAliasAnalysis/precedence.ll

@@ -1,5 +1,5 @@
-; RUN: opt -enable-tbaa -basicaa -tbaa -gvn -instcombine -S < %s | grep {ret i32 0}
-; RUN: opt -enable-tbaa -tbaa -basicaa -gvn -instcombine -S < %s | grep {ret i32 1075000115}
+; RUN: opt -enable-tbaa -basicaa -tbaa -gvn -instcombine -S < %s | FileCheck %s --check-prefix=TBAA
+; RUN: opt -enable-tbaa -tbaa -basicaa -gvn -instcombine -S < %s | FileCheck %s --check-prefix=BASICAA
 
 ; According to the TBAA metadata the load and store don't alias. However,
 ; according to the actual code, they do. The order of the alias analysis
@@ -7,6 +7,12 @@
 
 target datalayout = "e-p:64:64:64"
 
+; Test for simple MustAlias aliasing.
+
+; TBAA:    @trouble
+; TBAA:      ret i32 0
+; BASICAA: @trouble
+; BASICAA:   ret i32 1075000115
 define i32 @trouble(i32* %x) nounwind {
 entry:
   store i32 0, i32* %x, !tbaa !0
@@ -16,6 +22,25 @@ entry:
   ret i32 %tmp3
 }
 
+; Test for PartialAlias aliasing. GVN doesn't yet eliminate the load
+; in the BasicAA case.
+
+; TBAA:    @offset
+; TBAA:      ret i64 0
+; BASICAA: @offset
+; BASICAA:   ret i64 %tmp3
+define i64 @offset(i64* %x) nounwind {
+entry:
+  store i64 0, i64* %x, !tbaa !4
+  %0 = bitcast i64* %x to i8*
+  %1 = getelementptr i8* %0, i64 1
+  store i8 1, i8* %1, !tbaa !5
+  %tmp3 = load i64* %x, !tbaa !4
+  ret i64 %tmp3
+}
+
 !0 = metadata !{metadata !"int", metadata !1}
 !1 = metadata !{metadata !"simple"}
 !3 = metadata !{metadata !"float", metadata !1}
+!4 = metadata !{metadata !"long", metadata !1}
+!5 = metadata !{metadata !"small", metadata !1}