Index: lib/Analysis/LoopAccessAnalysis.cpp =================================================================== --- lib/Analysis/LoopAccessAnalysis.cpp +++ lib/Analysis/LoopAccessAnalysis.cpp @@ -900,19 +900,7 @@ } bool MemoryDepChecker::Dependence::isInterestingDependence(DepType Type) { - switch (Type) { - case NoDep: - case Forward: - return false; - - case BackwardVectorizable: - case Unknown: - case ForwardButPreventsForwarding: - case Backward: - case BackwardVectorizableButPreventsForwarding: - return true; - } - llvm_unreachable("unexpected DepType!"); + return Type != NoDep; } bool MemoryDepChecker::Dependence::isPossiblyBackward() const { Index: test/Analysis/LoopAccessAnalysis/forward-loop-carried.ll =================================================================== --- /dev/null +++ test/Analysis/LoopAccessAnalysis/forward-loop-carried.ll @@ -0,0 +1,44 @@ +; RUN: opt -loop-accesses -analyze < %s | FileCheck %s + +; for (unsigned i = 0; i < 100; i++) { +; A[i+8] = B[i] + 2; +; C[i] = A[i] * 2; +; } + +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" + +define void @f(i32* %A, i32* %B, i32* %C, i64 %N) { + +; CHECK: Interesting Dependences: +; CHECK-NEXT: Forward: +; CHECK-NEXT: store i32 %a_p1, i32* %Aidx_ahead, align 4 -> +; CHECK-NEXT: %a = load i32, i32* %Aidx, align 4 + +entry: + br label %for.body + +for.body: ; preds = %for.body, %entry + %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ] + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 + + %idx = add nuw nsw i64 %indvars.iv, 8 + + %Aidx_ahead = getelementptr inbounds i32, i32* %A, i64 %idx + %Bidx = getelementptr inbounds i32, i32* %B, i64 %indvars.iv + %Cidx = getelementptr inbounds i32, i32* %C, i64 %indvars.iv + %Aidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv + + %b = load i32, i32* %Bidx, align 4 + %a_p1 = add i32 %b, 2 + store i32 %a_p1, i32* %Aidx_ahead, align 4 + + %a = load i32, i32* %Aidx, align 4 + %c = mul i32 %a, 2 + store i32 %c, i32* %Cidx, align 4 + + %exitcond = icmp eq i64 %indvars.iv.next, %N + br i1 %exitcond, label %for.end, label %for.body + +for.end: ; preds = %for.body + ret void +} Index: test/Analysis/LoopAccessAnalysis/safe-no-checks.ll =================================================================== --- test/Analysis/LoopAccessAnalysis/safe-no-checks.ll +++ test/Analysis/LoopAccessAnalysis/safe-no-checks.ll @@ -7,7 +7,15 @@ target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-apple-macosx10.10.0" +; Check the loop-carried forward anti-dep between the load of A[i+1] and the +; store of A[i]; + ; CHECK: Memory dependences are safe{{$}} +; CHECK-NEXT: Interesting Dependences: +; CHECK-NEXT: Forward: +; CHECK-NEXT: %loadA_plus_2 = load i16, i16* %arrayidxA_plus_2, align 2 -> +; CHECK-NEXT: store i16 %mul1, i16* %arrayidxA, align 2 + define void @f(i16* noalias %a, i16* noalias %b,