diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/IndVarSimplify.cpp | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp index 8b3707db8cb..0f70384e904 100644 --- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -2027,16 +2027,9 @@ static PHINode *getLoopPhiForCounter(Value *IncV, Loop *L) { return nullptr; } -/// Given a loop with one backedge and one exit, return the ICmpInst -/// controlling the sole loop exit. There is no guarantee that the exiting -/// block is also the latch. -static ICmpInst *getLoopTest(Loop *L, BasicBlock *ExitingBB) { - - BasicBlock *LatchBlock = L->getLoopLatch(); - // Don't bother with LFTR if the loop is not properly simplified. - if (!LatchBlock) - return nullptr; - +/// Return the ICmpInst controlling the given loop exit. There is no guarantee +/// that the exiting block is also the latch. +static ICmpInst *getLoopTest(BasicBlock *ExitingBB) { BranchInst *BI = cast<BranchInst>(ExitingBB->getTerminator()); return dyn_cast<ICmpInst>(BI->getCondition()); } @@ -2044,6 +2037,8 @@ static ICmpInst *getLoopTest(Loop *L, BasicBlock *ExitingBB) { /// linearFunctionTestReplace policy. Return true unless we can show that the /// current exit test is already sufficiently canonical. static bool needsLFTR(Loop *L, BasicBlock *ExitingBB) { + assert(L->getLoopLatch() && "Must be in simplified form"); + // Avoid converting a constant or loop invariant test back to a runtime // test. This is critical for when SCEV's cached ExitCount is less precise // than the current IR (such as after we've proven a particular exit is @@ -2053,7 +2048,7 @@ static bool needsLFTR(Loop *L, BasicBlock *ExitingBB) { return false; // Do LFTR to simplify the exit condition to an ICMP. - ICmpInst *Cond = getLoopTest(L, ExitingBB); + ICmpInst *Cond = getLoopTest(ExitingBB); if (!Cond) return true; @@ -2228,7 +2223,7 @@ static PHINode *FindLoopCounter(Loop *L, BasicBlock *ExitingBB, PHINode *BestPhi = nullptr; const SCEV *BestInit = nullptr; BasicBlock *LatchBlock = L->getLoopLatch(); - assert(LatchBlock && "needsLFTR should guarantee a loop latch"); + assert(LatchBlock && "Must be in simplified form"); const DataLayout &DL = L->getHeader()->getModule()->getDataLayout(); for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) { @@ -2255,7 +2250,7 @@ static PHINode *FindLoopCounter(Loop *L, BasicBlock *ExitingBB, // We explicitly allow unknown phis as long as they are already used by // the loop exit test. This is legal since performing LFTR could not // increase the number of undef users. - if (ICmpInst *Cond = getLoopTest(L, ExitingBB)) + if (ICmpInst *Cond = getLoopTest(ExitingBB)) if (Phi != getLoopPhiForCounter(Cond->getOperand(0), L) && Phi != getLoopPhiForCounter(Cond->getOperand(1), L)) continue; @@ -2412,7 +2407,7 @@ linearFunctionTestReplace(Loop *L, BasicBlock *ExitingBB, // to add a potentially UB introducing use. We need to either a) show // the loop test we're modifying is already in post-inc form, or b) show // that adding a use must not introduce UB. - if (ICmpInst *LoopTest = getLoopTest(L, ExitingBB)) + if (ICmpInst *LoopTest = getLoopTest(ExitingBB)) SafeToPostInc = LoopTest->getOperand(0) == IncVar || LoopTest->getOperand(1) == IncVar; if (!SafeToPostInc) |
