mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-22 10:29:35 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52907 91177308-0d34-0410-b5e6-96231b3b80d8
290 lines
10 KiB
C++
290 lines
10 KiB
C++
//===- Dominators.cpp - Dominator Calculation -----------------------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements simple dominator construction algorithms for finding
|
|
// forward dominators. Postdominators are available in libanalysis, but are not
|
|
// included in libvmcore, because it's not needed. Forward dominators are
|
|
// needed to support the Verifier pass.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/Dominators.h"
|
|
#include "llvm/Support/CFG.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include "llvm/ADT/DepthFirstIterator.h"
|
|
#include "llvm/ADT/SetOperations.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
#include "llvm/Analysis/DominatorInternals.h"
|
|
#include "llvm/Instructions.h"
|
|
#include "llvm/Support/Streams.h"
|
|
#include <algorithm>
|
|
using namespace llvm;
|
|
|
|
namespace llvm {
|
|
static std::ostream &operator<<(std::ostream &o,
|
|
const std::set<BasicBlock*> &BBs) {
|
|
for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
|
|
I != E; ++I)
|
|
if (*I)
|
|
WriteAsOperand(o, *I, false);
|
|
else
|
|
o << " <<exit node>>";
|
|
return o;
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// DominatorTree Implementation
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// Provide public access to DominatorTree information. Implementation details
|
|
// can be found in DominatorCalculation.h.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
|
|
TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
|
|
|
|
char DominatorTree::ID = 0;
|
|
static RegisterPass<DominatorTree>
|
|
E("domtree", "Dominator Tree Construction", true, true);
|
|
|
|
bool DominatorTree::runOnFunction(Function &F) {
|
|
DT->recalculate(F);
|
|
return false;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// DominanceFrontier Implementation
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
char DominanceFrontier::ID = 0;
|
|
static RegisterPass<DominanceFrontier>
|
|
G("domfrontier", "Dominance Frontier Construction", true, true);
|
|
|
|
// NewBB is split and now it has one successor. Update dominace frontier to
|
|
// reflect this change.
|
|
void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
|
|
assert(NewBB->getTerminator()->getNumSuccessors() == 1
|
|
&& "NewBB should have a single successor!");
|
|
BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
|
|
|
|
std::vector<BasicBlock*> PredBlocks;
|
|
for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
|
|
PI != PE; ++PI)
|
|
PredBlocks.push_back(*PI);
|
|
|
|
if (PredBlocks.empty())
|
|
// If NewBB does not have any predecessors then it is a entry block.
|
|
// In this case, NewBB and its successor NewBBSucc dominates all
|
|
// other blocks.
|
|
return;
|
|
|
|
// NewBBSucc inherits original NewBB frontier.
|
|
DominanceFrontier::iterator NewBBI = find(NewBB);
|
|
if (NewBBI != end()) {
|
|
DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
|
|
DominanceFrontier::DomSetType NewBBSuccSet;
|
|
NewBBSuccSet.insert(NewBBSet.begin(), NewBBSet.end());
|
|
addBasicBlock(NewBBSucc, NewBBSuccSet);
|
|
}
|
|
|
|
// If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
|
|
// DF(PredBlocks[0]) without the stuff that the new block does not dominate
|
|
// a predecessor of.
|
|
DominatorTree &DT = getAnalysis<DominatorTree>();
|
|
if (DT.dominates(NewBB, NewBBSucc)) {
|
|
DominanceFrontier::iterator DFI = find(PredBlocks[0]);
|
|
if (DFI != end()) {
|
|
DominanceFrontier::DomSetType Set = DFI->second;
|
|
// Filter out stuff in Set that we do not dominate a predecessor of.
|
|
for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
|
|
E = Set.end(); SetI != E;) {
|
|
bool DominatesPred = false;
|
|
for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
|
|
PI != E; ++PI)
|
|
if (DT.dominates(NewBB, *PI))
|
|
DominatesPred = true;
|
|
if (!DominatesPred)
|
|
Set.erase(SetI++);
|
|
else
|
|
++SetI;
|
|
}
|
|
|
|
if (NewBBI != end()) {
|
|
for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
|
|
E = Set.end(); SetI != E; ++SetI) {
|
|
BasicBlock *SB = *SetI;
|
|
addToFrontier(NewBBI, SB);
|
|
}
|
|
} else
|
|
addBasicBlock(NewBB, Set);
|
|
}
|
|
|
|
} else {
|
|
// DF(NewBB) is {NewBBSucc} because NewBB does not strictly dominate
|
|
// NewBBSucc, but it does dominate itself (and there is an edge (NewBB ->
|
|
// NewBBSucc)). NewBBSucc is the single successor of NewBB.
|
|
DominanceFrontier::DomSetType NewDFSet;
|
|
NewDFSet.insert(NewBBSucc);
|
|
addBasicBlock(NewBB, NewDFSet);
|
|
}
|
|
|
|
// Now we must loop over all of the dominance frontiers in the function,
|
|
// replacing occurrences of NewBBSucc with NewBB in some cases. All
|
|
// blocks that dominate a block in PredBlocks and contained NewBBSucc in
|
|
// their dominance frontier must be updated to contain NewBB instead.
|
|
//
|
|
for (Function::iterator FI = NewBB->getParent()->begin(),
|
|
FE = NewBB->getParent()->end(); FI != FE; ++FI) {
|
|
DominanceFrontier::iterator DFI = find(FI);
|
|
if (DFI == end()) continue; // unreachable block.
|
|
|
|
// Only consider nodes that have NewBBSucc in their dominator frontier.
|
|
if (!DFI->second.count(NewBBSucc)) continue;
|
|
|
|
// Verify whether this block dominates a block in predblocks. If not, do
|
|
// not update it.
|
|
bool BlockDominatesAny = false;
|
|
for (std::vector<BasicBlock*>::const_iterator BI = PredBlocks.begin(),
|
|
BE = PredBlocks.end(); BI != BE; ++BI) {
|
|
if (DT.dominates(FI, *BI)) {
|
|
BlockDominatesAny = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!BlockDominatesAny)
|
|
continue;
|
|
|
|
// If NewBBSucc should not stay in our dominator frontier, remove it.
|
|
// We remove it unless there is a predecessor of NewBBSucc that we
|
|
// dominate, but we don't strictly dominate NewBBSucc.
|
|
bool ShouldRemove = true;
|
|
if ((BasicBlock*)FI == NewBBSucc || !DT.dominates(FI, NewBBSucc)) {
|
|
// Okay, we know that PredDom does not strictly dominate NewBBSucc.
|
|
// Check to see if it dominates any predecessors of NewBBSucc.
|
|
for (pred_iterator PI = pred_begin(NewBBSucc),
|
|
E = pred_end(NewBBSucc); PI != E; ++PI)
|
|
if (DT.dominates(FI, *PI)) {
|
|
ShouldRemove = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (ShouldRemove)
|
|
removeFromFrontier(DFI, NewBBSucc);
|
|
addToFrontier(DFI, NewBB);
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
class DFCalculateWorkObject {
|
|
public:
|
|
DFCalculateWorkObject(BasicBlock *B, BasicBlock *P,
|
|
const DomTreeNode *N,
|
|
const DomTreeNode *PN)
|
|
: currentBB(B), parentBB(P), Node(N), parentNode(PN) {}
|
|
BasicBlock *currentBB;
|
|
BasicBlock *parentBB;
|
|
const DomTreeNode *Node;
|
|
const DomTreeNode *parentNode;
|
|
};
|
|
}
|
|
|
|
const DominanceFrontier::DomSetType &
|
|
DominanceFrontier::calculate(const DominatorTree &DT,
|
|
const DomTreeNode *Node) {
|
|
BasicBlock *BB = Node->getBlock();
|
|
DomSetType *Result = NULL;
|
|
|
|
std::vector<DFCalculateWorkObject> workList;
|
|
SmallPtrSet<BasicBlock *, 32> visited;
|
|
|
|
workList.push_back(DFCalculateWorkObject(BB, NULL, Node, NULL));
|
|
do {
|
|
DFCalculateWorkObject *currentW = &workList.back();
|
|
assert (currentW && "Missing work object.");
|
|
|
|
BasicBlock *currentBB = currentW->currentBB;
|
|
BasicBlock *parentBB = currentW->parentBB;
|
|
const DomTreeNode *currentNode = currentW->Node;
|
|
const DomTreeNode *parentNode = currentW->parentNode;
|
|
assert (currentBB && "Invalid work object. Missing current Basic Block");
|
|
assert (currentNode && "Invalid work object. Missing current Node");
|
|
DomSetType &S = Frontiers[currentBB];
|
|
|
|
// Visit each block only once.
|
|
if (visited.count(currentBB) == 0) {
|
|
visited.insert(currentBB);
|
|
|
|
// Loop over CFG successors to calculate DFlocal[currentNode]
|
|
for (succ_iterator SI = succ_begin(currentBB), SE = succ_end(currentBB);
|
|
SI != SE; ++SI) {
|
|
// Does Node immediately dominate this successor?
|
|
if (DT[*SI]->getIDom() != currentNode)
|
|
S.insert(*SI);
|
|
}
|
|
}
|
|
|
|
// At this point, S is DFlocal. Now we union in DFup's of our children...
|
|
// Loop through and visit the nodes that Node immediately dominates (Node's
|
|
// children in the IDomTree)
|
|
bool visitChild = false;
|
|
for (DomTreeNode::const_iterator NI = currentNode->begin(),
|
|
NE = currentNode->end(); NI != NE; ++NI) {
|
|
DomTreeNode *IDominee = *NI;
|
|
BasicBlock *childBB = IDominee->getBlock();
|
|
if (visited.count(childBB) == 0) {
|
|
workList.push_back(DFCalculateWorkObject(childBB, currentBB,
|
|
IDominee, currentNode));
|
|
visitChild = true;
|
|
}
|
|
}
|
|
|
|
// If all children are visited or there is any child then pop this block
|
|
// from the workList.
|
|
if (!visitChild) {
|
|
|
|
if (!parentBB) {
|
|
Result = &S;
|
|
break;
|
|
}
|
|
|
|
DomSetType::const_iterator CDFI = S.begin(), CDFE = S.end();
|
|
DomSetType &parentSet = Frontiers[parentBB];
|
|
for (; CDFI != CDFE; ++CDFI) {
|
|
if (!DT.properlyDominates(parentNode, DT[*CDFI]))
|
|
parentSet.insert(*CDFI);
|
|
}
|
|
workList.pop_back();
|
|
}
|
|
|
|
} while (!workList.empty());
|
|
|
|
return *Result;
|
|
}
|
|
|
|
void DominanceFrontierBase::print(std::ostream &o, const Module* ) const {
|
|
for (const_iterator I = begin(), E = end(); I != E; ++I) {
|
|
o << " DomFrontier for BB";
|
|
if (I->first)
|
|
WriteAsOperand(o, I->first, false);
|
|
else
|
|
o << " <<exit node>>";
|
|
o << " is:\t" << I->second << "\n";
|
|
}
|
|
}
|
|
|
|
void DominanceFrontierBase::dump() {
|
|
print (llvm::cerr);
|
|
}
|
|
|