Index: llvm/lib/Analysis/LoopAccessAnalysis.cpp =================================================================== --- llvm/lib/Analysis/LoopAccessAnalysis.cpp +++ llvm/lib/Analysis/LoopAccessAnalysis.cpp @@ -2505,12 +2505,24 @@ LLVM_DEBUG(dbgs() << "LAA: unsafe dependent memory operations in loop\n"); // Emit remark for first unsafe dependence + bool HasForcedDistribution = false; + std::optional Value = + findStringMetadataForLoop(TheLoop, "llvm.loop.distribute.enable"); + if (Value) { + const MDOperand *Op = *Value; + assert(Op && mdconst::hasa(*Op) && "invalid metadata"); + HasForcedDistribution = mdconst::extract(*Op)->getZExtValue(); + } + + const std::string Info = + HasForcedDistribution + ? "unsafe dependent memory operations in loop." + : "unsafe dependent memory operations in loop. Use " + "#pragma loop distribute(enable) to allow loop distribution " + "to attempt to isolate the offending operations into a separate " + "loop"; OptimizationRemarkAnalysis &R = - recordAnalysis("UnsafeDep", Dep.getDestination(*this)) - << "unsafe dependent memory operations in loop. Use " - "#pragma loop distribute(enable) to allow loop distribution " - "to attempt to isolate the offending operations into a separate " - "loop"; + recordAnalysis("UnsafeDep", Dep.getDestination(*this)) << Info; switch (Dep.Type) { case MemoryDepChecker::Dependence::NoDep: Index: llvm/test/Analysis/LoopAccessAnalysis/pr64637.ll =================================================================== --- /dev/null +++ llvm/test/Analysis/LoopAccessAnalysis/pr64637.ll @@ -0,0 +1,55 @@ +; RUN: opt -S -passes='print' -pass-remarks-analysis=loop-vectorize -disable-output < %s 2>&1 | FileCheck %s --check-prefix=ANALYSIS + +; Test that LoopVectorize don't report 'Use #pragma loop distribute(enable) to allow loop distribution' +; when we already add #pragma clang loop distribute(enable). +; +; Testcase derived from the following C: +; +; #define M 100 +; void foo (int *restrict y, int *restrict x, int *restrict indices, int n) +; { +; int k = 3; +; #pragma clang loop distribute(enable) +; for (int i = 0; i < n; i++) { +; y[i + k * M] = y[i + k* M] + 1; +; y[i + k * (M+1)] = indices[i] + 2; +; } +; } + +define void @foo(ptr noalias nocapture noundef %y, ptr noalias nocapture noundef readnone %x, ptr noalias nocapture noundef readonly %indices, i32 noundef %n) { +; ANALYSIS: Report: unsafe dependent memory operations in loop. +; ANALYSIS: Backward loop carried data dependence that prevents store-to-load forwarding. +entry: + %cmp22 = icmp sgt i32 %n, 0 + br i1 %cmp22, label %for.body.preheader, label %for.cond.cleanup + +for.body.preheader: ; preds = %entry + %wide.trip.count = zext i32 %n to i64 + br label %for.body + +for.cond.cleanup.loopexit: ; preds = %for.body + br label %for.cond.cleanup + +for.cond.cleanup: ; preds = %for.cond.cleanup.loopexit, %entry + ret void + +for.body: ; preds = %for.body, %for.body.preheader + %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.body ] + %0 = add nuw nsw i64 %indvars.iv, 300 + %arrayidx = getelementptr inbounds i32, ptr %y, i64 %0 + %1 = load i32, ptr %arrayidx, align 4 + %add1 = add nsw i32 %1, 1 + store i32 %add1, ptr %arrayidx, align 4 + %arrayidx7 = getelementptr inbounds i32, ptr %indices, i64 %indvars.iv + %2 = load i32, ptr %arrayidx7, align 4 + %add8 = add nsw i32 %2, 2 + %3 = add nuw nsw i64 %indvars.iv, 303 + %arrayidx12 = getelementptr inbounds i32, ptr %y, i64 %3 + store i32 %add8, ptr %arrayidx12, align 4 + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 + %exitcond.not = icmp eq i64 %indvars.iv.next, %wide.trip.count + br i1 %exitcond.not, label %for.cond.cleanup.loopexit, label %for.body, !llvm.loop !0 +} + +!0 = distinct !{!0, !1} +!1 = !{!"llvm.loop.distribute.enable", i1 true}