//===-- 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.
//===----------------------------------------------------------------------===//
#include "llvm/BasicBlock.h"
-#include "llvm/iTerminators.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Support/CFG.h"
-#include "llvm/Constant.h"
-#include "llvm/iPHINode.h"
-#include "llvm/SymbolTable.h"
-#include "Support/LeakDetector.h"
+#include "llvm/Support/LeakDetector.h"
#include "SymbolTableListTraitsImpl.h"
#include <algorithm>
using namespace llvm;
/// DummyInst - An instance of this class is used to mark the end of the
/// instruction list. This is not a real instruction.
struct DummyInst : public Instruction {
- DummyInst() : Instruction(Type::VoidTy, OtherOpsEnd) {
+ DummyInst() : Instruction(Type::VoidTy, OtherOpsEnd, 0, 0) {
// This should not be garbage monitored.
LeakDetector::removeGarbageObject(this);
}
};
}
-Instruction *ilist_traits<Instruction>::createNode() {
+Instruction *ilist_traits<Instruction>::createSentinel() {
return new DummyInst();
}
iplist<Instruction> &ilist_traits<Instruction>::getList(BasicBlock *BB) {
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);
+}
+
+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;
return dyn_cast<TerminatorInst>(&InstList.back());
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!");
- if (!isa<PHINode>(front())) return; // Quick exit.
-
- pred_iterator PI(pred_begin(this)), EI(pred_end(this));
- unsigned max_idx;
+/// 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*/;
+}
- // Loop over the rest of the predecessors until we run out, or until we find
- // out that there are more than 2 predecessors.
- for (max_idx = 0; PI != EI && max_idx < 3; ++PI, ++max_idx) /*empty*/;
+/// 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<PHINode>(&front());
+ if (!APN) return; // Quick exit.
// If there are exactly two predecessors, then we want to nuke the PHI nodes
- // altogether. We cannot do this, however if this in this case however:
+ // altogether. However, we cannot do this, if this in this case:
//
// Loop:
// %x = phi [X, Loop]
// 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) {
- PI = pred_begin(this);
- BasicBlock *Other = *PI == Pred ? *++PI : *PI;
+ BasicBlock *Other = APN->getIncomingBlock(APN->getIncomingBlock(0) == Pred);
// Disable PHI elimination!
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<PHINode>(&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) {
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
}
} else {
// Okay, now we know that we need to remove predecessor #pred_idx from all
// PHI nodes. Iterate over each PHI node fixing them up
- for (iterator II = begin(); PHINode *PN = dyn_cast<PHINode>(II); ++II)
- PN->removeIncomingValue(Pred);
+ PHINode *PN;
+ for (iterator II = begin(); (PN = dyn_cast<PHINode>(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());
// Loop over any phi nodes in the basic block, updating the BB field of
// incoming values...
BasicBlock *Successor = *I;
+ PHINode *PN;
for (BasicBlock::iterator II = Successor->begin();
- PHINode *PN = dyn_cast<PHINode>(II); ++II) {
+ (PN = dyn_cast<PHINode>(II)); ++II) {
int IDX = PN->getBasicBlockIndex(this);
while (IDX != -1) {
PN->setIncomingBlock((unsigned)IDX, New);
projects / oota-llvm.git / blobdiff