mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-11-03 14:21:30 +00:00
b0f0ef8f26
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3131 91177308-0d34-0410-b5e6-96231b3b80d8
108 lines
3.9 KiB
C++
108 lines
3.9 KiB
C++
//===-- BasicBlockUtils.cpp - BasicBlock Utilities -------------------------==//
|
|
//
|
|
// This family of functions perform manipulations on basic blocks, and
|
|
// instructions contained within basic blocks.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/iTerminators.h"
|
|
#include "llvm/Constant.h"
|
|
#include "llvm/Type.h"
|
|
#include <algorithm>
|
|
|
|
// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)
|
|
// with a value, then remove and delete the original instruction.
|
|
//
|
|
void ReplaceInstWithValue(BasicBlock::InstListType &BIL,
|
|
BasicBlock::iterator &BI, Value *V) {
|
|
Instruction &I = *BI;
|
|
// Replaces all of the uses of the instruction with uses of the value
|
|
I.replaceAllUsesWith(V);
|
|
|
|
std::string OldName = I.getName();
|
|
|
|
// Delete the unneccesary instruction now...
|
|
BI = BIL.erase(BI);
|
|
|
|
// Make sure to propogate a name if there is one already...
|
|
if (OldName.size() && !V->hasName())
|
|
V->setName(OldName, BIL.getParent()->getSymbolTable());
|
|
}
|
|
|
|
|
|
// ReplaceInstWithInst - Replace the instruction specified by BI with the
|
|
// instruction specified by I. The original instruction is deleted and BI is
|
|
// updated to point to the new instruction.
|
|
//
|
|
void ReplaceInstWithInst(BasicBlock::InstListType &BIL,
|
|
BasicBlock::iterator &BI, Instruction *I) {
|
|
assert(I->getParent() == 0 &&
|
|
"ReplaceInstWithInst: Instruction already inserted into basic block!");
|
|
|
|
// Insert the new instruction into the basic block...
|
|
BasicBlock::iterator New = BIL.insert(BI, I);
|
|
|
|
// Replace all uses of the old instruction, and delete it.
|
|
ReplaceInstWithValue(BIL, BI, I);
|
|
|
|
// Move BI back to point to the newly inserted instruction
|
|
BI = New;
|
|
}
|
|
|
|
// ReplaceInstWithInst - Replace the instruction specified by From with the
|
|
// instruction specified by To.
|
|
//
|
|
void ReplaceInstWithInst(Instruction *From, Instruction *To) {
|
|
BasicBlock::iterator BI(From);
|
|
ReplaceInstWithInst(From->getParent()->getInstList(), BI, To);
|
|
}
|
|
|
|
// RemoveSuccessor - Change the specified terminator instruction such that its
|
|
// successor #SuccNum no longer exists. Because this reduces the outgoing
|
|
// degree of the current basic block, the actual terminator instruction itself
|
|
// may have to be changed. In the case where the last successor of the block is
|
|
// deleted, a return instruction is inserted in its place which can cause a
|
|
// suprising change in program behavior if it is not expected.
|
|
//
|
|
void RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) {
|
|
assert(SuccNum < TI->getNumSuccessors() &&
|
|
"Trying to remove a nonexistant successor!");
|
|
|
|
// If our old successor block contains any PHI nodes, remove the entry in the
|
|
// PHI nodes that comes from this branch...
|
|
//
|
|
BasicBlock *BB = TI->getParent();
|
|
TI->getSuccessor(SuccNum)->removePredecessor(BB);
|
|
|
|
TerminatorInst *NewTI = 0;
|
|
switch (TI->getOpcode()) {
|
|
case Instruction::Br:
|
|
// If this is a conditional branch... convert to unconditional branch.
|
|
if (TI->getNumSuccessors() == 2) {
|
|
cast<BranchInst>(TI)->setUnconditionalDest(TI->getSuccessor(1-SuccNum));
|
|
} else { // Otherwise convert to a return instruction...
|
|
Value *RetVal = 0;
|
|
|
|
// Create a value to return... if the function doesn't return null...
|
|
if (BB->getParent()->getReturnType() != Type::VoidTy)
|
|
RetVal = Constant::getNullValue(BB->getParent()->getReturnType());
|
|
|
|
// Create the return...
|
|
NewTI = new ReturnInst(RetVal);
|
|
}
|
|
break;
|
|
|
|
case Instruction::Invoke: // Should convert to call
|
|
case Instruction::Switch: // Should remove entry
|
|
default:
|
|
case Instruction::Ret: // Cannot happen, has no successors!
|
|
assert(0 && "Unhandled terminator instruction type in RemoveSuccessor!");
|
|
abort();
|
|
}
|
|
|
|
if (NewTI) // If it's a different instruction, replace.
|
|
ReplaceInstWithInst(TI, NewTI);
|
|
}
|