diff options
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 11 | ||||
| -rw-r--r-- | test/Analysis/TypeBasedAliasAnalysis/precedence.ll | 29 |
2 files changed, 38 insertions, 2 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index 3ab18fd3c0..17a502e1f7 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -857,6 +857,17 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, if (GEP1BaseOffset == 0 && GEP1VariableIndices.empty()) return MustAlias; + // If there is a difference betwen the pointers, but the difference is + // less than the size of the associated memory object, then we know + // that the objects are partially overlapping. + if (GEP1BaseOffset != 0 && GEP1VariableIndices.empty()) { + if (GEP1BaseOffset >= 0 ? + (V2Size != UnknownSize && (uint64_t)GEP1BaseOffset < V2Size) : + (V1Size != UnknownSize && -(uint64_t)GEP1BaseOffset < V1Size && + GEP1BaseOffset != INT64_MIN)) + return PartialAlias; + } + // If we have a known constant offset, see if this offset is larger than the // access size being queried. If so, and if no variable indices can remove // pieces of this constant, then we know we have a no-alias. For example, diff --git a/test/Analysis/TypeBasedAliasAnalysis/precedence.ll b/test/Analysis/TypeBasedAliasAnalysis/precedence.ll index 9fa859eaab..ade39f7c8e 100644 --- a/test/Analysis/TypeBasedAliasAnalysis/precedence.ll +++ b/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} |