diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp | 69 |
1 files changed, 18 insertions, 51 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp index eda01c0e656..33633ae073f 100644 --- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp +++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp @@ -69,22 +69,6 @@ namespace { class LoopIdiomRecognize; -/// This class defines some utility functions for loop idiom recognization. -class LIRUtil { -public: - /// Return true iff the block contains nothing but an uncondition branch - /// (aka goto instruction). - static bool isAlmostEmpty(BasicBlock *); - - static BranchInst *getBranch(BasicBlock *BB) { - return dyn_cast<BranchInst>(BB->getTerminator()); - } - - /// Derive the precondition block (i.e the block that guards the loop - /// preheader) from the given preheader. - static BasicBlock *getPrecondBb(BasicBlock *PreHead); -}; - /// This class is to recoginize idioms of population-count conducted in /// a noncountable loop. Currently it only recognizes this pattern: /// \code @@ -242,32 +226,6 @@ static void deleteDeadInstruction(Instruction *I, //===----------------------------------------------------------------------===// // -// Implementation of LIRUtil -// -//===----------------------------------------------------------------------===// - -// This function will return true iff the given block contains nothing but goto. -// A typical usage of this function is to check if the preheader function is -// "almost" empty such that generated intrinsic functions can be moved across -// the preheader and be placed at the end of the precondition block without -// the concern of breaking data dependence. -bool LIRUtil::isAlmostEmpty(BasicBlock *BB) { - if (BranchInst *Br = getBranch(BB)) { - return Br->isUnconditional() && Br == BB->begin(); - } - return false; -} - -BasicBlock *LIRUtil::getPrecondBb(BasicBlock *PreHead) { - if (BasicBlock *BB = PreHead->getSinglePredecessor()) { - BranchInst *Br = getBranch(BB); - return Br && Br->isConditional() ? BB : nullptr; - } - return nullptr; -} - -//===----------------------------------------------------------------------===// -// // Implementation of NclPopcountRecognize // //===----------------------------------------------------------------------===// @@ -295,16 +253,24 @@ bool NclPopcountRecognize::preliminaryScreen() { return false; } - // It should have a preheader containing nothing but a goto instruction. - BasicBlock *PreHead = CurLoop->getLoopPreheader(); - if (!PreHead || !LIRUtil::isAlmostEmpty(PreHead)) + // It should have a preheader containing nothing but an unconditional branch. + BasicBlock *PH = CurLoop->getLoopPreheader(); + if (!PH) + return false; + if (&PH->front() != PH->getTerminator()) + return false; + auto *EntryBI = dyn_cast<BranchInst>(PH->getTerminator()); + if (!EntryBI || EntryBI->isConditional()) return false; // It should have a precondition block where the generated popcount instrinsic - // function will be inserted. - PreCondBB = LIRUtil::getPrecondBb(PreHead); + // function can be inserted. + PreCondBB = PH->getSinglePredecessor(); if (!PreCondBB) return false; + auto *PreCondBI = dyn_cast<BranchInst>(PreCondBB->getTerminator()); + if (!PreCondBI || PreCondBI->isUnconditional()) + return false; return true; } @@ -364,7 +330,8 @@ bool NclPopcountRecognize::detectIdiom(Instruction *&CntInst, PHINode *&CntPhi, // step 1: Check if the loop-back branch is in desirable form. { - if (Value *T = matchCondition(LIRUtil::getBranch(LoopEntry), LoopEntry)) + if (Value *T = matchCondition( + dyn_cast<BranchInst>(LoopEntry->getTerminator()), LoopEntry)) DefX2 = dyn_cast<Instruction>(T); else return false; @@ -446,7 +413,7 @@ bool NclPopcountRecognize::detectIdiom(Instruction *&CntInst, PHINode *&CntPhi, // step 5: check if the precondition is in this form: // "if (x != 0) goto loop-head ; else goto somewhere-we-don't-care;" { - BranchInst *PreCondBr = LIRUtil::getBranch(PreCondBB); + auto *PreCondBr = dyn_cast<BranchInst>(PreCondBB->getTerminator()); Value *T = matchCondition(PreCondBr, CurLoop->getLoopPreheader()); if (T != PhiX->getOperand(0) && T != PhiX->getOperand(1)) return false; @@ -465,7 +432,7 @@ void NclPopcountRecognize::transform(Instruction *CntInst, PHINode *CntPhi, ScalarEvolution *SE = LIR.getScalarEvolution(); TargetLibraryInfo *TLI = LIR.getTargetLibraryInfo(); BasicBlock *PreHead = CurLoop->getLoopPreheader(); - BranchInst *PreCondBr = LIRUtil::getBranch(PreCondBB); + auto *PreCondBr = dyn_cast<BranchInst>(PreCondBB->getTerminator()); const DebugLoc DL = CntInst->getDebugLoc(); // Assuming before transformation, the loop is following: @@ -536,7 +503,7 @@ void NclPopcountRecognize::transform(Instruction *CntInst, PHINode *CntPhi, // do { cnt++; x &= x-1; t--) } while (t > 0); BasicBlock *Body = *(CurLoop->block_begin()); { - BranchInst *LbBr = LIRUtil::getBranch(Body); + auto *LbBr = dyn_cast<BranchInst>(Body->getTerminator()); ICmpInst *LbCond = cast<ICmpInst>(LbBr->getCondition()); Type *Ty = TripCnt->getType(); |
