Index: lib/Analysis/IVUsers.cpp =================================================================== --- lib/Analysis/IVUsers.cpp +++ lib/Analysis/IVUsers.cpp @@ -253,18 +253,8 @@ const SCEV *OriginalISE = ISE; auto NormalizePred = [&](const SCEVAddRecExpr *AR) { - // We only allow affine AddRecs to be normalized, otherwise we would not - // be able to correctly denormalize. - // e.g. {1,+,3,+,2} == {-2,+,1,+,2} + {3,+,2} - // Normalized form: {-2,+,1,+,2} - // Denormalized form: {1,+,3,+,2} - // - // However, denormalization would use a different step expression than - // normalization (see getPostIncExpr), generating the wrong final - // expression: {-2,+,1,+,2} + {1,+,2} => {-1,+,3,+,2} auto *L = AR->getLoop(); - bool Result = - AR->isAffine() && IVUseShouldUsePostIncValue(User, I, L, DT); + bool Result = IVUseShouldUsePostIncValue(User, I, L, DT); if (Result) NewUse.PostIncLoops.insert(L); return Result; Index: test/Analysis/IVUsers/quadradic-exit-value.ll =================================================================== --- test/Analysis/IVUsers/quadradic-exit-value.ll +++ test/Analysis/IVUsers/quadradic-exit-value.ll @@ -29,33 +29,3 @@ %r = mul i64 %indvar.next, %indvar.next ret i64 %r } - -; PR15470: LSR miscompile. The test2 function should return '1'. -; -; SCEV does not know how to denormalize chained recurrences, so make -; sure they aren't marked as post-inc users. -; -; CHECK-LABEL: IV Users for loop %test2.loop -; CHECK-NO-LCSSA: %sext.us = {0,+,(16777216 + (-16777216 * %sub.us)),+,33554432}<%test2.loop> in %f = ashr i32 %sext.us, 24 -define i32 @test2() { -entry: - br label %test2.loop - -test2.loop: - %inc1115.us = phi i32 [ 0, %entry ], [ %inc11.us, %test2.loop ] - %inc11.us = add nsw i32 %inc1115.us, 1 - %cmp.us = icmp slt i32 %inc11.us, 2 - br i1 %cmp.us, label %test2.loop, label %for.end - -for.end: - %tobool.us = icmp eq i32 %inc1115.us, 0 - %sub.us = select i1 %tobool.us, i32 0, i32 0 - %mul.us = shl i32 %inc1115.us, 24 - %sub.cond.us = sub nsw i32 %inc1115.us, %sub.us - %sext.us = mul i32 %mul.us, %sub.cond.us - %f = ashr i32 %sext.us, 24 - br label %exit - -exit: - ret i32 %f -}