Changes in directory llvm/lib/CodeGen/SelectionDAG:
SelectionDAGISel.cpp updated: 1.280 -> 1.281 --- Log message: refactor critical edge breaking out into the SplitCritEdgesForPHIConstants method. This is a baby step towards fixing PR925: http://llvm.org/PR925 . --- Diffs of the changes: (+20 -9) SelectionDAGISel.cpp | 29 ++++++++++++++++++++--------- 1 files changed, 20 insertions(+), 9 deletions(-) Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.280 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.281 --- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.280 Tue Sep 26 15:02:30 2006 +++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Thu Sep 28 01:17:10 2006 @@ -845,8 +845,6 @@ CurMBB->addSuccessor(CB.RHSBB); } -/// visitSwitchCase - Emits the necessary code to represent a single node in -/// the binary search tree resulting from lowering a switch instruction. void SelectionDAGLowering::visitJumpTable(SelectionDAGISel::JumpTable &JT) { // FIXME: Need to emit different code for PIC vs. Non-PIC, specifically, // we need to add the address of the jump table to the value loaded, since @@ -3207,6 +3205,21 @@ return true; } +/// SplitCritEdgesForPHIConstants - If this block has any PHI nodes with +/// constant operands, and if any of the edges feeding the PHI node are +/// critical, split them so that the assignments of a constant to a register +/// will not be executed on a path that isn't relevant. +void SelectionDAGISel::SplitCritEdgesForPHIConstants(BasicBlock *BB) { + PHINode *PN; + BasicBlock::iterator BBI = BB->begin(); + while ((PN = dyn_cast<PHINode>(BBI++))) { + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (isa<Constant>(PN->getIncomingValue(i))) + SplitCriticalEdge(PN->getIncomingBlock(i), BB); + } +} + + bool SelectionDAGISel::runOnFunction(Function &Fn) { MachineFunction &MF = MachineFunction::construct(&Fn, TLI.getTargetMachine()); RegMap = MF.getSSARegMap(); @@ -3225,14 +3238,12 @@ while (MadeChange) { MadeChange = false; for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) { - PHINode *PN; - BasicBlock::iterator BBI; - for (BBI = BB->begin(); (PN = dyn_cast<PHINode>(BBI)); ++BBI) - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) - if (isa<Constant>(PN->getIncomingValue(i))) - SplitCriticalEdge(PN->getIncomingBlock(i), BB); + // If this block has any PHI nodes with constant operands, and if any of the + // edges feeding the PHI node are critical, split them. + if (isa<PHINode>(BB->begin())) + SplitCritEdgesForPHIConstants(BB); - for (BasicBlock::iterator E = BB->end(); BBI != E; ) { + for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { Instruction *I = BBI++; if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) { MadeChange |= OptimizeGEPExpression(GEPI, TLI.getTargetData()); _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
