mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-11-04 22:07:27 +00:00
a298d27808
const BasicBlocks git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2337 91177308-0d34-0410-b5e6-96231b3b80d8
112 lines
3.6 KiB
C++
112 lines
3.6 KiB
C++
//===- LoopInfo.cpp - Natural Loop Calculator -------------------------------=//
|
|
//
|
|
// This file defines the LoopInfo class that is used to identify natural loops
|
|
// and determine the loop depth of various nodes of the CFG. Note that the
|
|
// loops identified may actually be several natural loops that share the same
|
|
// header node... not just a single natural loop.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/LoopInfo.h"
|
|
#include "llvm/Analysis/Dominators.h"
|
|
#include "llvm/Support/CFG.h"
|
|
#include "Support/DepthFirstIterator.h"
|
|
#include <algorithm>
|
|
|
|
AnalysisID cfg::LoopInfo::ID(AnalysisID::create<cfg::LoopInfo>());
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// cfg::Loop implementation
|
|
//
|
|
bool cfg::Loop::contains(BasicBlock *BB) const {
|
|
return find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
|
|
}
|
|
|
|
void cfg::LoopInfo::releaseMemory() {
|
|
for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(),
|
|
E = TopLevelLoops.end(); I != E; ++I)
|
|
delete *I; // Delete all of the loops...
|
|
|
|
BBMap.clear(); // Reset internal state of analysis
|
|
TopLevelLoops.clear();
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// cfg::LoopInfo implementation
|
|
//
|
|
bool cfg::LoopInfo::runOnFunction(Function *F) {
|
|
releaseMemory();
|
|
Calculate(getAnalysis<DominatorSet>()); // Update
|
|
return false;
|
|
}
|
|
|
|
void cfg::LoopInfo::Calculate(const DominatorSet &DS) {
|
|
BasicBlock *RootNode = DS.getRoot();
|
|
|
|
for (df_iterator<BasicBlock*> NI = df_begin(RootNode),
|
|
NE = df_end(RootNode); NI != NE; ++NI)
|
|
if (Loop *L = ConsiderForLoop(*NI, DS))
|
|
TopLevelLoops.push_back(L);
|
|
|
|
for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
|
|
TopLevelLoops[i]->setLoopDepth(1);
|
|
}
|
|
|
|
void cfg::LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesAll();
|
|
AU.addRequired(DominatorSet::ID);
|
|
AU.addProvided(ID);
|
|
}
|
|
|
|
|
|
cfg::Loop *cfg::LoopInfo::ConsiderForLoop(BasicBlock *BB,
|
|
const DominatorSet &DS) {
|
|
if (BBMap.find(BB) != BBMap.end()) return 0; // Havn't processed this node?
|
|
|
|
std::vector<BasicBlock *> TodoStack;
|
|
|
|
// Scan the predecessors of BB, checking to see if BB dominates any of
|
|
// them.
|
|
for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I)
|
|
if (DS.dominates(BB, *I)) // If BB dominates it's predecessor...
|
|
TodoStack.push_back(*I);
|
|
|
|
if (TodoStack.empty()) return 0; // Doesn't dominate any predecessors...
|
|
|
|
// Create a new loop to represent this basic block...
|
|
Loop *L = new Loop(BB);
|
|
BBMap[BB] = L;
|
|
|
|
while (!TodoStack.empty()) { // Process all the nodes in the loop
|
|
BasicBlock *X = TodoStack.back();
|
|
TodoStack.pop_back();
|
|
|
|
if (!L->contains(X)) { // As of yet unprocessed??
|
|
L->Blocks.push_back(X);
|
|
|
|
// Add all of the predecessors of X to the end of the work stack...
|
|
TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X));
|
|
}
|
|
}
|
|
|
|
// Add the basic blocks that comprise this loop to the BBMap so that this
|
|
// loop can be found for them. Also check subsidary basic blocks to see if
|
|
// they start subloops of their own.
|
|
//
|
|
for (std::vector<BasicBlock*>::reverse_iterator I = L->Blocks.rbegin(),
|
|
E = L->Blocks.rend(); I != E; ++I) {
|
|
|
|
// Check to see if this block starts a new loop
|
|
if (Loop *NewLoop = ConsiderForLoop(*I, DS)) {
|
|
L->SubLoops.push_back(NewLoop);
|
|
NewLoop->ParentLoop = L;
|
|
}
|
|
|
|
if (BBMap.find(*I) == BBMap.end())
|
|
BBMap.insert(std::make_pair(*I, L));
|
|
}
|
|
|
|
return L;
|
|
}
|