X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FBasicBlock.cpp;h=ab7798c3866e91a82b673516ce7ea2af587114d6;hb=d659360e58fc6da08132f3d263a5aafead0d2999;hp=87b9ddd3808ca5d826239521edd3237d79011601;hpb=bca81448ac8e19c588c9a4ad16fc70732b76327c;p=oota-llvm.git diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp index 87b9ddd3808..ab7798c3866 100644 --- a/lib/VMCore/BasicBlock.cpp +++ b/lib/VMCore/BasicBlock.cpp @@ -1,10 +1,10 @@ //===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===// -// +// // The LLVM Compiler Infrastructure // // This file was developed by the LLVM research group and is distributed under // the University of Illinois Open Source License. See LICENSE.TXT for details. -// +// //===----------------------------------------------------------------------===// // // This file implements the BasicBlock class for the VMCore library. @@ -12,11 +12,10 @@ //===----------------------------------------------------------------------===// #include "llvm/BasicBlock.h" -#include "llvm/Constant.h" +#include "llvm/Constants.h" #include "llvm/Instructions.h" #include "llvm/Type.h" #include "llvm/Support/CFG.h" -#include "llvm/SymbolTable.h" #include "llvm/Support/LeakDetector.h" #include "SymbolTableListTraitsImpl.h" #include @@ -95,16 +94,6 @@ void BasicBlock::setParent(Function *parent) { LeakDetector::removeGarbageObject(this); } -// Specialize setName to take care of symbol table majik -void BasicBlock::setName(const std::string &name, SymbolTable *ST) { - Function *P; - assert((ST == 0 || (!getParent() || ST == &getParent()->getSymbolTable())) && - "Invalid symtab argument!"); - if ((P = getParent()) && hasName()) P->getSymbolTable().remove(this); - Value::setName(name); - if (P && hasName()) P->getSymbolTable().insert(this); -} - void BasicBlock::removeFromParent() { getParent()->getBasicBlockList().remove(this); } @@ -113,6 +102,14 @@ void BasicBlock::eraseFromParent() { getParent()->getBasicBlockList().erase(this); } +/// moveBefore - Unlink this instruction from its current function and +/// insert it into the function that MovePos lives in, right before +/// MovePos. +void BasicBlock::moveBefore(BasicBlock *MovePos) { + MovePos->getParent()->getBasicBlockList().splice(MovePos, + getParent()->getBasicBlockList(), this); +} + TerminatorInst *BasicBlock::getTerminator() { if (InstList.empty()) return 0; @@ -129,15 +126,28 @@ void BasicBlock::dropAllReferences() { I->dropAllReferences(); } -// removePredecessor - This method is used to notify a BasicBlock that the -// specified Predecessor of the block is no longer able to reach it. This is -// actually not used to update the Predecessor list, but is actually used to -// update the PHI nodes that reside in the block. Note that this should be -// called while the predecessor still refers to this block. -// -void BasicBlock::removePredecessor(BasicBlock *Pred) { - assert(find(pred_begin(this), pred_end(this), Pred) != pred_end(this) && - "removePredecessor: BB is not a predecessor!"); +/// getSinglePredecessor - If this basic block has a single predecessor block, +/// return the block, otherwise return a null pointer. +BasicBlock *BasicBlock::getSinglePredecessor() { + pred_iterator PI = pred_begin(this), E = pred_end(this); + if (PI == E) return 0; // No preds. + BasicBlock *ThePred = *PI; + ++PI; + return (PI == E) ? ThePred : 0 /*multiple preds*/; +} + +/// removePredecessor - This method is used to notify a BasicBlock that the +/// specified Predecessor of the block is no longer able to reach it. This is +/// actually not used to update the Predecessor list, but is actually used to +/// update the PHI nodes that reside in the block. Note that this should be +/// called while the predecessor still refers to this block. +/// +void BasicBlock::removePredecessor(BasicBlock *Pred, + bool DontDeleteUselessPHIs) { + assert((hasNUsesOrMore(16)||// Reduce cost of this assertion for complex CFGs. + find(pred_begin(this), pred_end(this), Pred) != pred_end(this)) && + "removePredecessor: BB is not a predecessor!"); + if (InstList.empty()) return; PHINode *APN = dyn_cast(&front()); if (!APN) return; // Quick exit. @@ -151,9 +161,9 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { // br Loop ;; %x2 does not dominate all uses // // This is because the PHI node input is actually taken from the predecessor - // basic block. The only case this can happen is with a self loop, so we + // basic block. The only case this can happen is with a self loop, so we // check for this case explicitly now. - // + // unsigned max_idx = APN->getNumIncomingValues(); assert(max_idx != 0 && "PHI Node in block with 0 predecessors!?!?!"); if (max_idx == 2) { @@ -163,10 +173,12 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { if (this == Other) max_idx = 3; } - if (max_idx <= 2) { // <= Two predecessors BEFORE I remove one? + // <= Two predecessors BEFORE I remove one? + if (max_idx <= 2 && !DontDeleteUselessPHIs) { // Yup, loop through and nuke the PHI nodes while (PHINode *PN = dyn_cast(&front())) { - PN->removeIncomingValue(Pred); // Remove the predecessor first... + // Remove the predecessor first. + PN->removeIncomingValue(Pred, !DontDeleteUselessPHIs); // If the PHI _HAD_ two uses, replace PHI node with its now *single* value if (max_idx == 2) { @@ -174,7 +186,7 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { PN->replaceAllUsesWith(PN->getOperand(0)); else // We are left with an infinite loop with no entries: kill the PHI. - PN->replaceAllUsesWith(Constant::getNullValue(PN->getType())); + PN->replaceAllUsesWith(UndefValue::get(PN->getType())); getInstList().pop_front(); // Remove the PHI node } @@ -185,27 +197,35 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { // Okay, now we know that we need to remove predecessor #pred_idx from all // PHI nodes. Iterate over each PHI node fixing them up PHINode *PN; - for (iterator II = begin(); (PN = dyn_cast(II)); ++II) - PN->removeIncomingValue(Pred); + for (iterator II = begin(); (PN = dyn_cast(II)); ) { + ++II; + PN->removeIncomingValue(Pred, false); + // If all incoming values to the Phi are the same, we can replace the Phi + // with that value. + if (Value *PNV = PN->hasConstantValue()) { + PN->replaceAllUsesWith(PNV); + PN->eraseFromParent(); + } + } } } -// splitBasicBlock - This splits a basic block into two at the specified -// instruction. Note that all instructions BEFORE the specified iterator stay -// as part of the original basic block, an unconditional branch is added to -// the new BB, and the rest of the instructions in the BB are moved to the new -// BB, including the old terminator. This invalidates the iterator. -// -// Note that this only works on well formed basic blocks (must have a -// terminator), and 'I' must not be the end of instruction list (which would -// cause a degenerate basic block to be formed, having a terminator inside of -// the basic block). -// +/// splitBasicBlock - This splits a basic block into two at the specified +/// instruction. Note that all instructions BEFORE the specified iterator stay +/// as part of the original basic block, an unconditional branch is added to +/// the new BB, and the rest of the instructions in the BB are moved to the new +/// BB, including the old terminator. This invalidates the iterator. +/// +/// Note that this only works on well formed basic blocks (must have a +/// terminator), and 'I' must not be the end of instruction list (which would +/// cause a degenerate basic block to be formed, having a terminator inside of +/// the basic block). +/// BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!"); - assert(I != InstList.end() && - "Trying to get me to create degenerate basic block!"); + assert(I != InstList.end() && + "Trying to get me to create degenerate basic block!"); BasicBlock *New = new BasicBlock(BBName, getParent(), getNext());