mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-21 00:32:23 +00:00
a41f50dea8
* Renamed getOpcode to getOpcodeName * Changed getOpcodeName to return a const char * instead of string * Added a getOpcode method to replace getInstType * Changed code to use getOpcode instead of getInstType git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152 91177308-0d34-0410-b5e6-96231b3b80d8
70 lines
2.7 KiB
C++
70 lines
2.7 KiB
C++
//===- SimplifyCFG.cpp - CFG Simplification Routines -------------*- C++ -*--=//
|
|
//
|
|
// This file provides several routines that are useful for simplifying CFGs in
|
|
// various ways...
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/SimplifyCFG.h"
|
|
#include "llvm/BasicBlock.h"
|
|
#include "llvm/Method.h"
|
|
#include "llvm/iTerminators.h"
|
|
#include "llvm/iOther.h"
|
|
#include "llvm/Type.h"
|
|
|
|
// UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
|
|
// BasicBlock, and converting all returns to unconditional branches to this
|
|
// new basic block. The singular exit node is returned.
|
|
//
|
|
// If there are no return stmts in the Method, a null pointer is returned.
|
|
//
|
|
BasicBlock *cfg::UnifyAllExitNodes(Method *M) {
|
|
vector<BasicBlock*> ReturningBlocks;
|
|
|
|
// Loop over all of the blocks in a method, tracking all of the blocks that
|
|
// return.
|
|
//
|
|
for(Method::iterator I = M->begin(), E = M->end(); I != E; ++I)
|
|
if ((*I)->getTerminator()->getOpcode() == Instruction::Ret)
|
|
ReturningBlocks.push_back(*I);
|
|
|
|
if (ReturningBlocks.size() == 0)
|
|
return 0; // No blocks return
|
|
else if (ReturningBlocks.size() == 1)
|
|
return ReturningBlocks.front(); // Already has a single return block
|
|
|
|
// Otherwise, we need to insert a new basic block into the method, add a PHI
|
|
// node (if the function returns a value), and convert all of the return
|
|
// instructions into unconditional branches.
|
|
//
|
|
BasicBlock *NewRetBlock = new BasicBlock("", M);
|
|
|
|
if (M->getReturnType() != Type::VoidTy) {
|
|
// If the method doesn't return void... add a PHI node to the block...
|
|
PHINode *PN = new PHINode(M->getReturnType());
|
|
NewRetBlock->getInstList().push_back(PN);
|
|
|
|
// Add an incoming element to the PHI node for every return instruction that
|
|
// is merging into this new block...
|
|
for (vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
|
|
E = ReturningBlocks.end(); I != E; ++I)
|
|
PN->addIncoming((*I)->getTerminator()->getOperand(0), *I);
|
|
|
|
// Add a return instruction to return the result of the PHI node...
|
|
NewRetBlock->getInstList().push_back(new ReturnInst(PN));
|
|
} else {
|
|
// If it returns void, just add a return void instruction to the block
|
|
NewRetBlock->getInstList().push_back(new ReturnInst());
|
|
}
|
|
|
|
// Loop over all of the blocks, replacing the return instruction with an
|
|
// unconditional branch.
|
|
//
|
|
for (vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
|
|
E = ReturningBlocks.end(); I != E; ++I) {
|
|
delete (*I)->getInstList().pop_back(); // Remove the return insn
|
|
(*I)->getInstList().push_back(new BranchInst(NewRetBlock));
|
|
}
|
|
return NewRetBlock;
|
|
}
|