diff --git a/include/llvm/Analysis/LoopAccessAnalysis.h b/include/llvm/Analysis/LoopAccessAnalysis.h index 0bd17c570ea..c14e1451f33 100644 --- a/include/llvm/Analysis/LoopAccessAnalysis.h +++ b/include/llvm/Analysis/LoopAccessAnalysis.h @@ -225,6 +225,8 @@ public: return RecordInterestingDependences ? &InterestingDependences : nullptr; } + void clearInterestingDependences() { InterestingDependences.clear(); } + /// \brief The vector of memory access instructions. The indices are used as /// instruction identifiers in the Dependence class. const SmallVectorImpl &getMemoryInstructions() const { diff --git a/lib/Analysis/LoopAccessAnalysis.cpp b/lib/Analysis/LoopAccessAnalysis.cpp index 580491ff536..b70de00db04 100644 --- a/lib/Analysis/LoopAccessAnalysis.cpp +++ b/lib/Analysis/LoopAccessAnalysis.cpp @@ -235,7 +235,12 @@ public: bool isRTCheckNeeded() { return IsRTCheckNeeded; } bool isDependencyCheckNeeded() { return !CheckDeps.empty(); } - void resetDepChecks() { CheckDeps.clear(); } + + /// We decided that no dependence analysis would be used. Reset the state. + void resetDepChecks(MemoryDepChecker &DepChecker) { + CheckDeps.clear(); + DepChecker.clearInterestingDependences(); + } MemAccessInfoSet &getDependenciesToCheck() { return CheckDeps; } @@ -1161,7 +1166,7 @@ void LoopAccessInfo::analyzeLoop(const ValueToValueMap &Strides) { NeedRTCheck = true; // Clear the dependency checks. We assume they are not needed. - Accesses.resetDepChecks(); + Accesses.resetDepChecks(DepChecker); PtrRtCheck.reset(); PtrRtCheck.Need = true; diff --git a/test/Analysis/LoopAccessAnalysis/resort-to-memchecks-only.ll b/test/Analysis/LoopAccessAnalysis/resort-to-memchecks-only.ll new file mode 100644 index 00000000000..64f7729fa18 --- /dev/null +++ b/test/Analysis/LoopAccessAnalysis/resort-to-memchecks-only.ll @@ -0,0 +1,57 @@ +; RUN: opt -loop-accesses -analyze < %s | FileCheck %s + +; We give up analyzing the dependences in this loop due to non-constant +; distance between A[i+offset] and A[i] and add memchecks to prove +; independence. Make sure that no interesting dependences are reported in +; this case. +; +; for (i = 0; i < n; i++) +; A[i + offset] = A[i] * B[i] * C[i]; + +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.10.0" + +; CHECK: Memory dependences are safe with run-time checks +; CHECK-NEXT: Interesting Dependences: +; CHECK-NEXT: Run-time memory checks: +; CHECK-NEXT: 0: +; CHECK-NEXT: %arrayidxA2 = getelementptr inbounds i16, i16* %a, i64 %idx +; CHECK-NEXT: %arrayidxA = getelementptr inbounds i16, i16* %a, i64 %indvar + +@B = common global i16* null, align 8 +@A = common global i16* null, align 8 +@C = common global i16* null, align 8 + +define void @f(i64 %offset) { +entry: + %a = load i16*, i16** @A, align 8 + %b = load i16*, i16** @B, align 8 + %c = load i16*, i16** @C, align 8 + br label %for.body + +for.body: ; preds = %for.body, %entry + %indvar = phi i64 [ 0, %entry ], [ %add, %for.body ] + + %arrayidxA = getelementptr inbounds i16, i16* %a, i64 %indvar + %loadA = load i16, i16* %arrayidxA, align 2 + + %arrayidxB = getelementptr inbounds i16, i16* %b, i64 %indvar + %loadB = load i16, i16* %arrayidxB, align 2 + + %arrayidxC = getelementptr inbounds i16, i16* %c, i64 %indvar + %loadC = load i16, i16* %arrayidxC, align 2 + + %mul = mul i16 %loadB, %loadA + %mul1 = mul i16 %mul, %loadC + + %idx = add i64 %indvar, %offset + %arrayidxA2 = getelementptr inbounds i16, i16* %a, i64 %idx + store i16 %mul1, i16* %arrayidxA2, align 2 + + %add = add nuw nsw i64 %indvar, 1 + %exitcond = icmp eq i64 %add, 20 + br i1 %exitcond, label %for.end, label %for.body + +for.end: ; preds = %for.body + ret void +}