Index: lib/Transforms/Scalar/LoopStrengthReduce.cpp =================================================================== --- lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -325,7 +325,7 @@ // Look at addrec operands. if (const SCEVAddRecExpr *AR = dyn_cast(S)) - if (!AR->getStart()->isZero()) { + if (!AR->getStart()->isZero() && AR->isAffine()) { DoInitialMatch(AR->getStart(), L, Good, Bad, SE); DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0), AR->getStepRecurrence(SE), @@ -578,7 +578,8 @@ // FlagNW is independent of the start value, step direction, and is // preserved with smaller magnitude steps. // FIXME: AR->getNoWrapFlags(SCEV::FlagNW) - return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap); + if (AR->isAffine()) + return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap); } return nullptr; } @@ -3202,7 +3203,7 @@ Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder); Remainder = nullptr; } - if (Remainder != AR->getStart()) { + if (Remainder != AR->getStart() && AR->isAffine()) { if (!Remainder) Remainder = SE.getConstant(AR->getType(), 0); return SE.getAddRecExpr(Remainder, Index: test/Transforms/LoopStrengthReduce/ARM/addrec-is-loop-invariant.ll =================================================================== --- /dev/null +++ test/Transforms/LoopStrengthReduce/ARM/addrec-is-loop-invariant.ll @@ -0,0 +1,35 @@ +; RUN: llc -mtriple=armv8-eabi -verify-machineinstrs %s -o /dev/null + +; This test checks that when the IR is not under LCSSA form, +; Loop Strength Reduction will not create an Add Reccurence +; Expression if not all its operands are loop invariants. + +define void @add_rec_expr() { +entry: + br label %loop0 + +loop0: + %c.0 = phi i32 [ 0, %entry ], [ %inc.0, %loop0 ] + %inc.0 = add nuw i32 %c.0, 1 + br i1 undef, label %loop0, label %bb1 + +bb1: + %mul.0 = mul i32 %c.0, %c.0 + %gelptr.0 = getelementptr inbounds i16, i16* undef, i32 %mul.0 + br label %loop1 + +loop1: + %inc.1 = phi i32 [ %inc.2, %bb4 ], [ 0, %bb1 ] + %mul.1 = mul i32 %inc.1, %c.0 + br label %bb3 + +bb3: + %add.0 = add i32 undef, %mul.1 + %gelptr.1 = getelementptr inbounds i16, i16* %gelptr.0, i32 %add.0 + store i16 undef, i16* %gelptr.1, align 2 + br label %bb4 + +bb4: + %inc.2 = add nuw i32 %inc.1, 1 + br label %loop1 +}