Changes in directory llvm/lib/CodeGen/SelectionDAG:
SelectionDAGISel.cpp updated: 1.303 -> 1.304 --- Log message: Split *all* critical edges before isel. This resolves issues with spill code being inserted on unsplit critical edges, which introduces (sometimes large amounts of) partially dead spill code. This also fixes PR925: http://llvm.org/PR925 + CodeGen/Generic/switch-crit-edge-constant.ll --- Diffs of the changes: (+8 -44) SelectionDAGISel.cpp | 52 +++++++-------------------------------------------- 1 files changed, 8 insertions(+), 44 deletions(-) Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.303 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.304 --- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.303 Fri Oct 27 18:50:33 2006 +++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Sat Oct 28 12:04:37 2006 @@ -3490,64 +3490,28 @@ 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) { - // The most common case is that this is a PHI node with two incoming - // successors handle this case efficiently, because it is simple. - PHINode *PN = cast<PHINode>(BB->begin()); - if (PN->getNumIncomingValues() == 2) { - // If neither edge is critical, we never need to split. - if (PN->getIncomingBlock(0)->getTerminator()->getNumSuccessors() == 1 && - PN->getIncomingBlock(1)->getTerminator()->getNumSuccessors() == 1) - return; - - 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); - } - return; - } - - // Otherwise, things are a bit trickier. - - // BE SMART HERE. - - 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(); DEBUG(std::cerr << "\n\n\n=== " << Fn.getName() << "\n"); - // First, split all critical edges for PHI nodes with incoming values that are - // constants, this way the load of the constant into a vreg will not be placed - // into MBBs that are used some other way. + // First, split all critical edges. // // In this pass we also look for GEP and cast instructions that are used // across basic blocks and rewrite them to improve basic-block-at-a-time // selection. // - // bool MadeChange = true; while (MadeChange) { MadeChange = false; for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++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); + // Split all critical edges. + TerminatorInst *BBTI = BB->getTerminator(); + if (BBTI->getNumSuccessors() > 1) { + for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i) + SplitCriticalEdge(BBTI, i, this, true); + } + for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { Instruction *I = BBI++; _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
