-//===-- BasicBlock.cpp - Implement BasicBlock related functions --*- C++ -*--=//
+//===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===//
//
-// This file implements the Method class for the VMCore library.
+// This file implements the BasicBlock class for the VMCore library.
//
//===----------------------------------------------------------------------===//
-#include "llvm/ValueHolderImpl.h"
#include "llvm/BasicBlock.h"
#include "llvm/iTerminators.h"
-#include "llvm/Module.h"
-#include "llvm/Method.h"
-#include "llvm/SymbolTable.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 "SymbolTableListTraitsImpl.h"
+#include <algorithm>
+
+// 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) {
+ // This should not be garbage monitored.
+ LeakDetector::removeGarbageObject(this);
+ }
+
+ virtual Instruction *clone() const {
+ assert(0 && "Cannot clone EOL");abort();
+ return 0;
+ }
+ virtual const char *getOpcodeName() const { return "*end-of-list-inst*"; }
+
+ // Methods for support type inquiry through isa, cast, and dyn_cast...
+ static inline bool classof(const DummyInst *) { return true; }
+ static inline bool classof(const Instruction *I) {
+ return I->getOpcode() == OtherOpsEnd;
+ }
+ static inline bool classof(const Value *V) {
+ return isa<Instruction>(V) && classof(cast<Instruction>(V));
+ }
+};
+
+Instruction *ilist_traits<Instruction>::createNode() {
+ return new DummyInst();
+}
+iplist<Instruction> &ilist_traits<Instruction>::getList(BasicBlock *BB) {
+ return BB->getInstList();
+}
-// Instantiate Templates - This ugliness is the price we have to pay
-// for having a ValueHolderImpl.h file seperate from ValueHolder.h! :(
+// Explicit instantiation of SymbolTableListTraits since some of the methods
+// are not in the public header file...
+template SymbolTableListTraits<Instruction, BasicBlock, Function>;
+
+
+// BasicBlock ctor - If the function parameter is specified, the basic block is
+// automatically inserted at the end of the function.
//
-template class ValueHolder<Instruction, BasicBlock>;
+BasicBlock::BasicBlock(const std::string &name, Function *Parent)
+ : Value(Type::LabelTy, Value::BasicBlockVal, name) {
+ // Initialize the instlist...
+ InstList.setItemParent(this);
-BasicBlock::BasicBlock(const string &name, Method *parent)
- : Value(Type::LabelTy, Value::BasicBlockVal, name), InstList(this, 0) {
+ // Make sure that we get added to a function
+ LeakDetector::addGarbageObject(this);
- if (parent)
- parent->getBasicBlocks().push_back(this);
+ if (Parent)
+ Parent->getBasicBlockList().push_back(this);
}
-BasicBlock::~BasicBlock() {
- dropAllReferences();
- InstList.delete_all();
+/// BasicBlock ctor - If the InsertBefore parameter is specified, the basic
+/// block is automatically inserted right before the specified block.
+///
+BasicBlock::BasicBlock(const std::string &Name, BasicBlock *InsertBefore)
+ : Value(Type::LabelTy, Value::BasicBlockVal, Name) {
+ // Initialize the instlist...
+ InstList.setItemParent(this);
+
+ // Make sure that we get added to a function
+ LeakDetector::addGarbageObject(this);
+
+ if (InsertBefore) {
+ assert(InsertBefore->getParent() &&
+ "Cannot insert block before another block that is not embedded into"
+ " a function yet!");
+ InsertBefore->getParent()->getBasicBlockList().insert(InsertBefore, this);
+ }
}
-// Specialize setName to take care of symbol table majik
-void BasicBlock::setName(const string &name) {
- Method *P;
- if ((P = getParent()) && hasName()) P->getSymbolTable()->remove(this);
- Value::setName(name);
- if (P && hasName()) P->getSymbolTable()->insert(this);
+
+BasicBlock::~BasicBlock() {
+ dropAllReferences();
+ InstList.clear();
}
-void BasicBlock::setParent(Method *parent) {
- if (getParent() && hasName())
- getParent()->getSymbolTable()->remove(this);
+void BasicBlock::setParent(Function *parent) {
+ if (getParent())
+ LeakDetector::addGarbageObject(this);
InstList.setParent(parent);
- if (getParent() && hasName())
- getParent()->getSymbolTableSure()->insert(this);
+ if (getParent())
+ 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);
}
TerminatorInst *BasicBlock::getTerminator() {
if (InstList.empty()) return 0;
- Instruction *T = InstList.back();
- if (T->isTerminator()) return (TerminatorInst*)T;
- return 0;
+ return dyn_cast<TerminatorInst>(&InstList.back());
}
const TerminatorInst *const BasicBlock::getTerminator() const {
if (InstList.empty()) return 0;
- const Instruction *T = InstList.back();
- if (T->isTerminator()) return (TerminatorInst*)T;
- return 0;
+ return dyn_cast<TerminatorInst>(&InstList.back());
}
void BasicBlock::dropAllReferences() {
- for_each(InstList.begin(), InstList.end(),
- std::mem_fun(&Instruction::dropAllReferences));
+ for(iterator I = begin(), E = end(); I != E; ++I)
+ I->dropAllReferences();
}
-// hasConstantPoolReferences() - This predicate is true if there is a
+// hasConstantReferences() - This predicate is true if there is a
// reference to this basic block in the constant pool for this method. For
// example, if a block is reached through a switch table, that table resides
// in the constant pool, and the basic block is reference from it.
//
-bool BasicBlock::hasConstantPoolReferences() const {
+bool BasicBlock::hasConstantReferences() const {
for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I)
- if ((*I)->isConstant())
+ if (::isa<Constant>((Value*)*I))
return true;
return false;
}
+// 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;
+
+ // 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*/;
+
+ // 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:
+ //
+ // 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.
+ //
+ 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;
+
+ // Disable PHI elimination!
+ if (this == Other) max_idx = 3;
+ }
+
+ if (max_idx <= 2) { // <= Two predecessors BEFORE I remove one?
+ // Yup, loop through and nuke the PHI nodes
+ while (PHINode *PN = dyn_cast<PHINode>(&front())) {
+ PN->removeIncomingValue(Pred); // Remove the predecessor first...
+
+ // If the PHI _HAD_ two uses, replace PHI node with its now *single* value
+ if (max_idx == 2) {
+ PN->replaceAllUsesWith(PN->getOperand(0));
+ 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
+ for (iterator II = begin(); PHINode *PN = dyn_cast<PHINode>(&*II); ++II)
+ PN->removeIncomingValue(Pred);
+ }
+}
+
// splitBasicBlock - This splits a basic block into two at the specified
// instruction. Note that all instructions BEFORE the specified iterator stay
iterator EndIt = end();
Inst = InstList.remove(--EndIt); // Remove from end
New->InstList.push_front(Inst); // Add to front
- } while (Inst != *I); // Loop until we move the specified instruction.
+ } while (Inst != &*I); // Loop until we move the specified instruction.
// Add a branch instruction to the newly formed basic block.
InstList.push_back(new BranchInst(New));
+
+ // 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 (BasicBlock::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;
+ for (BasicBlock::iterator II = Successor->begin();
+ PHINode *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;
}
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