Index: lib/Analysis/DependenceAnalysis.cpp =================================================================== --- lib/Analysis/DependenceAnalysis.cpp +++ lib/Analysis/DependenceAnalysis.cpp @@ -3342,7 +3342,8 @@ UsefulGEP = isLoopInvariant(SrcPtrSCEV, LI->getLoopFor(Src->getParent())) && isLoopInvariant(DstPtrSCEV, LI->getLoopFor(Dst->getParent())) && - (SrcGEP->getNumOperands() == DstGEP->getNumOperands()); + (SrcGEP->getNumOperands() == DstGEP->getNumOperands()) && + isKnownPredicate(CmpInst::ICMP_EQ, SrcPtrSCEV, DstPtrSCEV); } unsigned Pairs = UsefulGEP ? SrcGEP->idx_end() - SrcGEP->idx_begin() : 1; SmallVector Pair(Pairs); Index: test/Analysis/DependenceAnalysis/BasePtrBug.ll =================================================================== --- test/Analysis/DependenceAnalysis/BasePtrBug.ll +++ test/Analysis/DependenceAnalysis/BasePtrBug.ll @@ -0,0 +1,80 @@ +; RUN: opt < %s -analyze -basicaa -da | FileCheck %s + +; Test that the dependence analysis generates the correct results when using +; an aliased object that points to a different element in the same array. +; PR33567 - https://bugs.llvm.org/show_bug.cgi?id=33567 + +; void test1(int *A, int *B, int N) { +; int *top = A; +; int *bot = A + N/2; +; for (int i = 0; i < N; i++) +; B[i] = top[i] + bot[i]; +; } + +; CHECK-LABEL: test1 +; CHECK: da analyze - input [*|<]! + +define void @test1(i32* nocapture %A, i32* nocapture %B, i32 %N) #0 { +entry: + %cmp9 = icmp sgt i32 %N, 0 + br i1 %cmp9, label %for.body.lr.ph, label %for.end + +for.body.lr.ph: + %div = sdiv i32 %N, 2 + %bot.gep = getelementptr i32, i32* %A, i32 %div + br label %for.body + +for.body: + %i = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ] + %gep.0 = getelementptr i32, i32* %A, i32 %i + %gep.1 = getelementptr i32, i32* %bot.gep, i32 %i + %gep.B = getelementptr i32, i32* %B, i32 %i + %0 = load i32, i32* %gep.0, align 4 + %1 = load i32, i32* %gep.1, align 4 + %add = add nsw i32 %1, %0 + store i32 %add, i32* %gep.B, align 4 + %inc = add nsw i32 %i, 1 + %exitcond = icmp eq i32 %inc, %N + br i1 %exitcond, label %for.end, label %for.body + +for.end: + ret void +} + + +; void test2(int *A, unsigned n) { +; int *B = A + 1; +; for (unsigned i = 0; i < n; ++i) { +; A[i] = B[i]; +; } +; } + +; CHECK-LABEL: test2 +; CHECK: da analyze - consistent anti [1]! + +define void @test2(i32*, i32) #3 { + %3 = getelementptr inbounds i32, i32* %0, i64 1 + br label %4 + +;