mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-26 07:29:55 +00:00
into their new header subdirectory: include/llvm/IR. This matches the directory structure of lib, and begins to correct a long standing point of file layout clutter in LLVM. There are still more header files to move here, but I wanted to handle them in separate commits to make tracking what files make sense at each layer easier. The only really questionable files here are the target intrinsic tablegen files. But that's a battle I'd rather not fight today. I've updated both CMake and Makefile build systems (I think, and my tests think, but I may have missed something). I've also re-sorted the includes throughout the project. I'll be committing updates to Clang, DragonEgg, and Polly momentarily. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171366 91177308-0d34-0410-b5e6-96231b3b80d8
123 lines
4.5 KiB
C++
123 lines
4.5 KiB
C++
//===- UnifyFunctionExitNodes.cpp - Make all functions have a single exit -===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This pass is used to ensure that functions have at most one return
|
|
// instruction in them. Additionally, it keeps track of which node is the new
|
|
// exit node of the CFG. If there are no exit nodes in the CFG, the getExitNode
|
|
// method will return a null pointer.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
|
|
#include "llvm/ADT/StringExtras.h"
|
|
#include "llvm/IR/BasicBlock.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/IR/Instructions.h"
|
|
#include "llvm/IR/Type.h"
|
|
#include "llvm/Transforms/Scalar.h"
|
|
using namespace llvm;
|
|
|
|
char UnifyFunctionExitNodes::ID = 0;
|
|
INITIALIZE_PASS(UnifyFunctionExitNodes, "mergereturn",
|
|
"Unify function exit nodes", false, false)
|
|
|
|
Pass *llvm::createUnifyFunctionExitNodesPass() {
|
|
return new UnifyFunctionExitNodes();
|
|
}
|
|
|
|
void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
|
|
// We preserve the non-critical-edgeness property
|
|
AU.addPreservedID(BreakCriticalEdgesID);
|
|
// This is a cluster of orthogonal Transforms
|
|
AU.addPreserved("mem2reg");
|
|
AU.addPreservedID(LowerSwitchID);
|
|
}
|
|
|
|
// 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 Function, a null pointer is returned.
|
|
//
|
|
bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
|
|
// Loop over all of the blocks in a function, tracking all of the blocks that
|
|
// return.
|
|
//
|
|
std::vector<BasicBlock*> ReturningBlocks;
|
|
std::vector<BasicBlock*> UnreachableBlocks;
|
|
for(Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
|
|
if (isa<ReturnInst>(I->getTerminator()))
|
|
ReturningBlocks.push_back(I);
|
|
else if (isa<UnreachableInst>(I->getTerminator()))
|
|
UnreachableBlocks.push_back(I);
|
|
|
|
// Then unreachable blocks.
|
|
if (UnreachableBlocks.empty()) {
|
|
UnreachableBlock = 0;
|
|
} else if (UnreachableBlocks.size() == 1) {
|
|
UnreachableBlock = UnreachableBlocks.front();
|
|
} else {
|
|
UnreachableBlock = BasicBlock::Create(F.getContext(),
|
|
"UnifiedUnreachableBlock", &F);
|
|
new UnreachableInst(F.getContext(), UnreachableBlock);
|
|
|
|
for (std::vector<BasicBlock*>::iterator I = UnreachableBlocks.begin(),
|
|
E = UnreachableBlocks.end(); I != E; ++I) {
|
|
BasicBlock *BB = *I;
|
|
BB->getInstList().pop_back(); // Remove the unreachable inst.
|
|
BranchInst::Create(UnreachableBlock, BB);
|
|
}
|
|
}
|
|
|
|
// Now handle return blocks.
|
|
if (ReturningBlocks.empty()) {
|
|
ReturnBlock = 0;
|
|
return false; // No blocks return
|
|
} else if (ReturningBlocks.size() == 1) {
|
|
ReturnBlock = ReturningBlocks.front(); // Already has a single return block
|
|
return false;
|
|
}
|
|
|
|
// Otherwise, we need to insert a new basic block into the function, add a PHI
|
|
// nodes (if the function returns values), and convert all of the return
|
|
// instructions into unconditional branches.
|
|
//
|
|
BasicBlock *NewRetBlock = BasicBlock::Create(F.getContext(),
|
|
"UnifiedReturnBlock", &F);
|
|
|
|
PHINode *PN = 0;
|
|
if (F.getReturnType()->isVoidTy()) {
|
|
ReturnInst::Create(F.getContext(), NULL, NewRetBlock);
|
|
} else {
|
|
// If the function doesn't return void... add a PHI node to the block...
|
|
PN = PHINode::Create(F.getReturnType(), ReturningBlocks.size(),
|
|
"UnifiedRetVal");
|
|
NewRetBlock->getInstList().push_back(PN);
|
|
ReturnInst::Create(F.getContext(), PN, NewRetBlock);
|
|
}
|
|
|
|
// Loop over all of the blocks, replacing the return instruction with an
|
|
// unconditional branch.
|
|
//
|
|
for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
|
|
E = ReturningBlocks.end(); I != E; ++I) {
|
|
BasicBlock *BB = *I;
|
|
|
|
// Add an incoming element to the PHI node for every return instruction that
|
|
// is merging into this new block...
|
|
if (PN)
|
|
PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
|
|
|
|
BB->getInstList().pop_back(); // Remove the return insn
|
|
BranchInst::Create(NewRetBlock, BB);
|
|
}
|
|
ReturnBlock = NewRetBlock;
|
|
return true;
|
|
}
|