diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -11470,7 +11470,7 @@ // A[i] = i; // if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) || - !loopHasNoSideEffects(L)) + !loopIsFiniteByAssumption(L)) return getCouldNotCompute(); } else if (!Stride->isOne() && !NoWrap) { auto isUBOnWrap = [&]() { diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-unknown-stride.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-unknown-stride.ll --- a/llvm/test/Analysis/ScalarEvolution/trip-count-unknown-stride.ll +++ b/llvm/test/Analysis/ScalarEvolution/trip-count-unknown-stride.ll @@ -13,8 +13,7 @@ target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128" -; Function Attrs: norecurse nounwind -define void @foo1(i32* nocapture %A, i32 %n, i32 %s) #0 { +define void @foo1(i32* nocapture %A, i32 %n, i32 %s) mustprogress { entry: %cmp4 = icmp sgt i32 %n, 0 br i1 %cmp4, label %for.body, label %for.end @@ -42,8 +41,7 @@ ; loops with unknown stride. ; CHECK: max backedge-taken count is -1 -; Function Attrs: norecurse nounwind -define void @foo2(i32* nocapture %A, i32 %n, i32 %s) #0 { +define void @foo2(i32* nocapture %A, i32 %n, i32 %s) mustprogress { entry: br label %for.body @@ -61,3 +59,26 @@ ret void } +; Check that without mustprogress we don't make assumptions about infinite +; loops being UB. +; CHECK: Determining loop execution counts for: @foo3 +; CHECK: Loop %for.body: Unpredictable backedge-taken count. +; CHECK: Loop %for.body: Unpredictable max backedge-taken count. + +define void @foo3(i32* nocapture %A, i32 %n, i32 %s) { +entry: + br label %for.body + +for.body: ; preds = %entry, %for.body + %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ] + %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05 + %0 = load i32, i32* %arrayidx, align 4 + %inc = add nsw i32 %0, 1 + store i32 %inc, i32* %arrayidx, align 4 + %add = add nsw i32 %i.05, %s + %cmp = icmp slt i32 %add, %n + br i1 %cmp, label %for.body, label %for.end + +for.end: ; preds = %for.body, %entry + ret void +} diff --git a/llvm/test/Transforms/LoopVectorize/pr38697.ll b/llvm/test/Transforms/LoopVectorize/pr38697.ll --- a/llvm/test/Transforms/LoopVectorize/pr38697.ll +++ b/llvm/test/Transforms/LoopVectorize/pr38697.ll @@ -30,7 +30,7 @@ ; Verify that a 'udiv' does not appear in the 'loop1.preheader' block, and that ; a 'udiv' has been inserted at the top of the 'while.body.preheader' block. -define void @testCountIncrLoop(i8* %ptr, i32 %lim, i32 %count, i32 %val) { +define void @testCountIncrLoop(i8* %ptr, i32 %lim, i32 %count, i32 %val) mustprogress { ; CHECK-LABEL: @testCountIncrLoop( ; CHECK-NEXT: entry: ; CHECK: loop1.preheader: