diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp | 27 | ||||
| -rw-r--r-- | llvm/test/Transforms/LoopIdiom/basic.ll | 43 |
2 files changed, 53 insertions, 17 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp index 318c4c06f0f7..aa9b1a5010da 100644 --- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp +++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp @@ -1420,26 +1420,19 @@ bool LoopIdiomRecognize::processLoopStoreOfLoopLoad( // If the store is a memcpy instruction, we must check if it will write to // the load memory locations. So remove it from the ignored stores. - if (IsMemCpy) - IgnoredInsts.erase(TheStore); MemmoveVerifier Verifier(*LoadBasePtr, *StoreBasePtr, *DL); + if (IsMemCpy && !Verifier.IsSameObject) + IgnoredInsts.erase(TheStore); if (mayLoopAccessLocation(LoadBasePtr, ModRefInfo::Mod, CurLoop, BECount, StoreSizeSCEV, *AA, IgnoredInsts)) { - if (!IsMemCpy) { - ORE.emit([&]() { - return OptimizationRemarkMissed(DEBUG_TYPE, "LoopMayAccessLoad", - TheLoad) - << ore::NV("Inst", InstRemark) << " in " - << ore::NV("Function", TheStore->getFunction()) - << " function will not be hoisted: " - << ore::NV("Reason", "The loop may access load location"); - }); - return Changed; - } - // At this point loop may access load only for memcpy in same underlying - // object. If that's not the case bail out. - if (!Verifier.IsSameObject) - return Changed; + ORE.emit([&]() { + return OptimizationRemarkMissed(DEBUG_TYPE, "LoopMayAccessLoad", TheLoad) + << ore::NV("Inst", InstRemark) << " in " + << ore::NV("Function", TheStore->getFunction()) + << " function will not be hoisted: " + << ore::NV("Reason", "The loop may access load location"); + }); + return Changed; } bool UseMemMove = IsMemCpy ? Verifier.IsSameObject : LoopAccessStore; diff --git a/llvm/test/Transforms/LoopIdiom/basic.ll b/llvm/test/Transforms/LoopIdiom/basic.ll index 0bf4ad4f6495..e30d20a22299 100644 --- a/llvm/test/Transforms/LoopIdiom/basic.ll +++ b/llvm/test/Transforms/LoopIdiom/basic.ll @@ -1530,6 +1530,49 @@ for.body: ; preds = %entry, %for.body br i1 %cmp, label %for.body, label %for.cond.cleanup } +; Do not form memmove when there's an aliasing operation, even +; if the memcpy source and destination are in the same object. +define void @do_not_form_memmove8(i64* %p) { +; CHECK-LABEL: @do_not_form_memmove8( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[P2:%.*]] = getelementptr inbounds i64, i64* [[P:%.*]], i64 1000 +; CHECK-NEXT: br label [[LOOP:%.*]] +; CHECK: exit: +; CHECK-NEXT: ret void +; CHECK: loop: +; CHECK-NEXT: [[X4:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[X13:%.*]], [[LOOP]] ] +; CHECK-NEXT: [[X5:%.*]] = zext i32 [[X4]] to i64 +; CHECK-NEXT: [[X7:%.*]] = getelementptr inbounds i64, i64* [[P2]], i64 [[X5]] +; CHECK-NEXT: [[X8:%.*]] = bitcast i64* [[X7]] to i8* +; CHECK-NEXT: store i64 1, i64* [[X7]], align 4 +; CHECK-NEXT: [[X11:%.*]] = getelementptr inbounds i64, i64* [[P]], i64 [[X5]] +; CHECK-NEXT: [[X12:%.*]] = bitcast i64* [[X11]] to i8* +; CHECK-NEXT: tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[X12]], i8* [[X8]], i64 8, i1 false) +; CHECK-NEXT: [[X13]] = add i32 [[X4]], 1 +; CHECK-NEXT: [[X14:%.*]] = icmp eq i32 [[X13]], 44 +; CHECK-NEXT: br i1 [[X14]], label [[EXIT:%.*]], label [[LOOP]] +; +entry: + %p2 = getelementptr inbounds i64, i64* %p, i64 1000 + br label %loop + +exit: + ret void + +loop: + %x4 = phi i32 [ 0, %entry ], [ %x13, %loop ] + %x5 = zext i32 %x4 to i64 + %x7 = getelementptr inbounds i64, i64* %p2, i64 %x5 + %x8 = bitcast i64* %x7 to i8* + store i64 1, i64* %x7, align 4 + %x11 = getelementptr inbounds i64, i64* %p, i64 %x5 + %x12 = bitcast i64* %x11 to i8* + tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %x12, i8* %x8, i64 8, i1 false) + %x13 = add i32 %x4, 1 + %x14 = icmp eq i32 %x13, 44 + br i1 %x14, label %exit, label %loop +} + ;; Memcpy formation is still preferred over memmove. define void @prefer_memcpy_over_memmove(i8* noalias %Src, i8* noalias %Dest, i64 %Size) { ; CHECK-LABEL: @prefer_memcpy_over_memmove( |