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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1503 91177308-0d34-0410-b5e6-96231b3b80d8
161 lines
5.9 KiB
C++
161 lines
5.9 KiB
C++
//===-- BasicBlock.cpp - Implement BasicBlock related functions --*- C++ -*--=//
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//
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// This file implements the Method class for the VMCore library.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ValueHolderImpl.h"
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#include "llvm/BasicBlock.h"
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#include "llvm/iTerminators.h"
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#include "llvm/Method.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/Type.h"
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#include "llvm/iPHINode.h"
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#include "llvm/CodeGen/MachineInstr.h"
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// Instantiate Templates - This ugliness is the price we have to pay
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// for having a ValueHolderImpl.h file seperate from ValueHolder.h! :(
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//
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template class ValueHolder<Instruction, BasicBlock, Method>;
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BasicBlock::BasicBlock(const std::string &name, Method *Parent)
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: Value(Type::LabelTy, Value::BasicBlockVal, name), InstList(this, 0),
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machineInstrVec(new MachineCodeForBasicBlock) {
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if (Parent)
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Parent->getBasicBlocks().push_back(this);
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}
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BasicBlock::~BasicBlock() {
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dropAllReferences();
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InstList.delete_all();
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delete machineInstrVec;
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}
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// Specialize setName to take care of symbol table majik
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void BasicBlock::setName(const std::string &name, SymbolTable *ST) {
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Method *P;
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assert((ST == 0 || (!getParent() || ST == getParent()->getSymbolTable())) &&
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"Invalid symtab argument!");
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if ((P = getParent()) && hasName()) P->getSymbolTable()->remove(this);
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Value::setName(name);
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if (P && hasName()) P->getSymbolTable()->insert(this);
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}
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void BasicBlock::setParent(Method *parent) {
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if (getParent() && hasName())
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getParent()->getSymbolTable()->remove(this);
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InstList.setParent(parent);
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if (getParent() && hasName())
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getParent()->getSymbolTableSure()->insert(this);
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}
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TerminatorInst *BasicBlock::getTerminator() {
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if (InstList.empty()) return 0;
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Instruction *T = InstList.back();
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if (isa<TerminatorInst>(T)) return cast<TerminatorInst>(T);
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return 0;
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}
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const TerminatorInst *const BasicBlock::getTerminator() const {
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if (InstList.empty()) return 0;
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if (const TerminatorInst *TI = dyn_cast<TerminatorInst>(InstList.back()))
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return TI;
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return 0;
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}
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void BasicBlock::dropAllReferences() {
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for_each(InstList.begin(), InstList.end(),
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std::mem_fun(&Instruction::dropAllReferences));
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}
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// hasConstantReferences() - This predicate is true if there is a
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// reference to this basic block in the constant pool for this method. For
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// example, if a block is reached through a switch table, that table resides
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// in the constant pool, and the basic block is reference from it.
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//
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bool BasicBlock::hasConstantReferences() const {
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for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I)
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if (::isa<Constant>(*I))
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return true;
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return false;
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}
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// removePredecessor - This method is used to notify a BasicBlock that the
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// specified Predecessor of the block is no longer able to reach it. This is
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// actually not used to update the Predecessor list, but is actually used to
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// update the PHI nodes that reside in the block. Note that this should be
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// called while the predecessor still refers to this block.
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//
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void BasicBlock::removePredecessor(BasicBlock *Pred) {
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assert(find(pred_begin(), pred_end(), Pred) != pred_end() &&
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"removePredecessor: BB is not a predecessor!");
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if (!isa<PHINode>(front())) return; // Quick exit.
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pred_iterator PI(pred_begin()), EI(pred_end());
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unsigned max_idx;
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// Loop over the rest of the predecessors until we run out, or until we find
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// out that there are more than 2 predecessors.
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for (max_idx = 0; PI != EI && max_idx < 3; ++PI, ++max_idx) /*empty*/;
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// If there are exactly two predecessors, then we want to nuke the PHI nodes
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// altogether.
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assert(max_idx != 0 && "PHI Node in block with 0 predecessors!?!?!");
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if (max_idx <= 2) { // <= Two predecessors BEFORE I remove one?
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// Yup, loop through and nuke the PHI nodes
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while (PHINode *PN = dyn_cast<PHINode>(front())) {
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PN->removeIncomingValue(Pred); // Remove the predecessor first...
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assert(PN->getNumIncomingValues() == max_idx-1 &&
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"PHI node shouldn't have this many values!!!");
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// If the PHI _HAD_ two uses, replace PHI node with its now *single* value
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if (max_idx == 2)
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PN->replaceAllUsesWith(PN->getOperand(0));
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delete getInstList().remove(begin()); // Remove the PHI node
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}
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} else {
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// Okay, now we know that we need to remove predecessor #pred_idx from all
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// PHI nodes. Iterate over each PHI node fixing them up
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iterator II(begin());
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for (; isa<PHINode>(*II); ++II)
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cast<PHINode>(*II)->removeIncomingValue(Pred);
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}
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}
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// splitBasicBlock - This splits a basic block into two at the specified
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// instruction. Note that all instructions BEFORE the specified iterator stay
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// as part of the original basic block, an unconditional branch is added to
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// the new BB, and the rest of the instructions in the BB are moved to the new
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// BB, including the old terminator. This invalidates the iterator.
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//
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// Note that this only works on well formed basic blocks (must have a
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// terminator), and 'I' must not be the end of instruction list (which would
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// cause a degenerate basic block to be formed, having a terminator inside of
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// the basic block).
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//
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BasicBlock *BasicBlock::splitBasicBlock(iterator I) {
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assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!");
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assert(I != InstList.end() &&
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"Trying to get me to create degenerate basic block!");
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BasicBlock *New = new BasicBlock("", getParent());
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// Go from the end of the basic block through to the iterator pointer, moving
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// to the new basic block...
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Instruction *Inst = 0;
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do {
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iterator EndIt = end();
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Inst = InstList.remove(--EndIt); // Remove from end
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New->InstList.push_front(Inst); // Add to front
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} while (Inst != *I); // Loop until we move the specified instruction.
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// Add a branch instruction to the newly formed basic block.
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InstList.push_back(new BranchInst(New));
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return New;
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}
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