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-rw-r--r--lib/VMCore/BasicBlock.cpp371
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diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp
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--- a/lib/VMCore/BasicBlock.cpp
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-//===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file 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 "SymbolTableListTraitsImpl.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Constants.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Support/LeakDetector.h"
-#include "llvm/Type.h"
-#include <algorithm>
-using namespace llvm;
-
-ValueSymbolTable *BasicBlock::getValueSymbolTable() {
- if (Function *F = getParent())
- return &F->getValueSymbolTable();
- return 0;
-}
-
-LLVMContext &BasicBlock::getContext() const {
- return getType()->getContext();
-}
-
-// Explicit instantiation of SymbolTableListTraits since some of the methods
-// are not in the public header file...
-template class llvm::SymbolTableListTraits<Instruction, BasicBlock>;
-
-
-BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent,
- BasicBlock *InsertBefore)
- : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(0) {
-
- // Make sure that we get added to a function
- LeakDetector::addGarbageObject(this);
-
- if (InsertBefore) {
- assert(NewParent &&
- "Cannot insert block before another block with no function!");
- NewParent->getBasicBlockList().insert(InsertBefore, this);
- } else if (NewParent) {
- NewParent->getBasicBlockList().push_back(this);
- }
-
- setName(Name);
-}
-
-
-BasicBlock::~BasicBlock() {
- // If the address of the block is taken and it is being deleted (e.g. because
- // it is dead), this means that there is either a dangling constant expr
- // hanging off the block, or an undefined use of the block (source code
- // expecting the address of a label to keep the block alive even though there
- // is no indirect branch). Handle these cases by zapping the BlockAddress
- // nodes. There are no other possible uses at this point.
- if (hasAddressTaken()) {
- assert(!use_empty() && "There should be at least one blockaddress!");
- Constant *Replacement =
- ConstantInt::get(llvm::Type::getInt32Ty(getContext()), 1);
- while (!use_empty()) {
- BlockAddress *BA = cast<BlockAddress>(use_back());
- BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
- BA->getType()));
- BA->destroyConstant();
- }
- }
-
- assert(getParent() == 0 && "BasicBlock still linked into the program!");
- dropAllReferences();
- InstList.clear();
-}
-
-void BasicBlock::setParent(Function *parent) {
- if (getParent())
- LeakDetector::addGarbageObject(this);
-
- // Set Parent=parent, updating instruction symtab entries as appropriate.
- InstList.setSymTabObject(&Parent, parent);
-
- if (getParent())
- LeakDetector::removeGarbageObject(this);
-}
-
-void BasicBlock::removeFromParent() {
- getParent()->getBasicBlockList().remove(this);
-}
-
-void BasicBlock::eraseFromParent() {
- getParent()->getBasicBlockList().erase(this);
-}
-
-/// moveBefore - Unlink this basic block 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);
-}
-
-/// moveAfter - Unlink this basic block from its current function and
-/// insert it into the function that MovePos lives in, right after MovePos.
-void BasicBlock::moveAfter(BasicBlock *MovePos) {
- Function::iterator I = MovePos;
- MovePos->getParent()->getBasicBlockList().splice(++I,
- getParent()->getBasicBlockList(), this);
-}
-
-
-TerminatorInst *BasicBlock::getTerminator() {
- if (InstList.empty()) return 0;
- return dyn_cast<TerminatorInst>(&InstList.back());
-}
-
-const TerminatorInst *BasicBlock::getTerminator() const {
- if (InstList.empty()) return 0;
- return dyn_cast<TerminatorInst>(&InstList.back());
-}
-
-Instruction* BasicBlock::getFirstNonPHI() {
- BasicBlock::iterator i = begin();
- // All valid basic blocks should have a terminator,
- // which is not a PHINode. If we have an invalid basic
- // block we'll get an assertion failure when dereferencing
- // a past-the-end iterator.
- while (isa<PHINode>(i)) ++i;
- return &*i;
-}
-
-Instruction* BasicBlock::getFirstNonPHIOrDbg() {
- BasicBlock::iterator i = begin();
- // All valid basic blocks should have a terminator,
- // which is not a PHINode. If we have an invalid basic
- // block we'll get an assertion failure when dereferencing
- // a past-the-end iterator.
- while (isa<PHINode>(i) || isa<DbgInfoIntrinsic>(i)) ++i;
- return &*i;
-}
-
-Instruction* BasicBlock::getFirstNonPHIOrDbgOrLifetime() {
- // All valid basic blocks should have a terminator,
- // which is not a PHINode. If we have an invalid basic
- // block we'll get an assertion failure when dereferencing
- // a past-the-end iterator.
- BasicBlock::iterator i = begin();
- for (;; ++i) {
- if (isa<PHINode>(i) || isa<DbgInfoIntrinsic>(i))
- continue;
-
- const IntrinsicInst *II = dyn_cast<IntrinsicInst>(i);
- if (!II)
- break;
- if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
- II->getIntrinsicID() != Intrinsic::lifetime_end)
- break;
- }
- return &*i;
-}
-
-BasicBlock::iterator BasicBlock::getFirstInsertionPt() {
- iterator InsertPt = getFirstNonPHI();
- if (isa<LandingPadInst>(InsertPt)) ++InsertPt;
- return InsertPt;
-}
-
-void BasicBlock::dropAllReferences() {
- for(iterator I = begin(), E = end(); I != E; ++I)
- I->dropAllReferences();
-}
-
-/// 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*/;
-}
-
-/// getUniquePredecessor - If this basic block has a unique predecessor block,
-/// return the block, otherwise return a null pointer.
-/// Note that unique predecessor doesn't mean single edge, there can be
-/// multiple edges from the unique predecessor to this block (for example
-/// a switch statement with multiple cases having the same destination).
-BasicBlock *BasicBlock::getUniquePredecessor() {
- pred_iterator PI = pred_begin(this), E = pred_end(this);
- if (PI == E) return 0; // No preds.
- BasicBlock *PredBB = *PI;
- ++PI;
- for (;PI != E; ++PI) {
- if (*PI != PredBB)
- return 0;
- // The same predecessor appears multiple times in the predecessor list.
- // This is OK.
- }
- return PredBB;
-}
-
-/// 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. However, we cannot do this, if this in this case:
- //
- // Loop:
- // %x = phi [X, Loop]
- // %x2 = add %x, 1 ;; This would become %x2 = add %x2, 1
- // 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
- // 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) {
- BasicBlock *Other = APN->getIncomingBlock(APN->getIncomingBlock(0) == Pred);
-
- // Disable PHI elimination!
- if (this == Other) max_idx = 3;
- }
-
- // <= 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())) {
- // 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) {
- if (PN->getIncomingValue(0) != PN)
- PN->replaceAllUsesWith(PN->getIncomingValue(0));
- else
- // We are left with an infinite loop with no entries: kill the PHI.
- PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
- getInstList().pop_front(); // Remove the PHI node
- }
-
- // If the PHI node already only had one entry, it got deleted by
- // removeIncomingValue.
- }
- } 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
- 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.
- Value* PNV = 0;
- if (!DontDeleteUselessPHIs && (PNV = PN->hasConstantValue()))
- if (PNV != PN) {
- 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).
-///
-BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
- assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!");
- assert(I != InstList.end() &&
- "Trying to get me to create degenerate basic block!");
-
- BasicBlock *InsertBefore = llvm::next(Function::iterator(this))
- .getNodePtrUnchecked();
- BasicBlock *New = BasicBlock::Create(getContext(), BBName,
- getParent(), InsertBefore);
-
- // Move all of the specified instructions from the original basic block into
- // the new basic block.
- New->getInstList().splice(New->end(), this->getInstList(), I, end());
-
- // Add a branch instruction to the newly formed basic block.
- BranchInst::Create(New, this);
-
- // Now we must loop through all of the successors of the New block (which
- // _were_ the successors of the 'this' block), and update any PHI nodes in
- // successors. If there were PHI nodes in the successors, then they need to
- // know that incoming branches will be from New, not from Old.
- //
- for (succ_iterator I = succ_begin(New), E = succ_end(New); I != E; ++I) {
- // 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();
- (PN = dyn_cast<PHINode>(II)); ++II) {
- int IDX = PN->getBasicBlockIndex(this);
- while (IDX != -1) {
- PN->setIncomingBlock((unsigned)IDX, New);
- IDX = PN->getBasicBlockIndex(this);
- }
- }
- }
- return New;
-}
-
-void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
- TerminatorInst *TI = getTerminator();
- if (!TI)
- // Cope with being called on a BasicBlock that doesn't have a terminator
- // yet. Clang's CodeGenFunction::EmitReturnBlock() likes to do this.
- return;
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
- BasicBlock *Succ = TI->getSuccessor(i);
- // N.B. Succ might not be a complete BasicBlock, so don't assume
- // that it ends with a non-phi instruction.
- for (iterator II = Succ->begin(), IE = Succ->end(); II != IE; ++II) {
- PHINode *PN = dyn_cast<PHINode>(II);
- if (!PN)
- break;
- int i;
- while ((i = PN->getBasicBlockIndex(this)) >= 0)
- PN->setIncomingBlock(i, New);
- }
- }
-}
-
-/// isLandingPad - Return true if this basic block is a landing pad. I.e., it's
-/// the destination of the 'unwind' edge of an invoke instruction.
-bool BasicBlock::isLandingPad() const {
- return isa<LandingPadInst>(getFirstNonPHI());
-}
-
-/// getLandingPadInst() - Return the landingpad instruction associated with
-/// the landing pad.
-LandingPadInst *BasicBlock::getLandingPadInst() {
- return dyn_cast<LandingPadInst>(getFirstNonPHI());
-}
-const LandingPadInst *BasicBlock::getLandingPadInst() const {
- return dyn_cast<LandingPadInst>(getFirstNonPHI());
-}
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