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//===- PostOrderCFGView.cpp - Post order view of CFG blocks -------*- C++ --*-//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements post order views of the blocks in a CFG.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/Analyses/PostOrderCFGView.h"
using namespace clang;
void PostOrderCFGView::anchor() { }
ReversePostOrderCFGView::ReversePostOrderCFGView(const CFG *cfg) {
Blocks.reserve(cfg->getNumBlockIDs());
CFGBlockSet BSet(cfg);
typedef llvm::po_iterator<const CFG*, CFGBlockSet, true> po_iterator;
for (po_iterator I = po_iterator::begin(cfg, BSet),
E = po_iterator::end(cfg, BSet); I != E; ++I) {
Blocks.push_back(*I);
BlockOrder[*I] = Blocks.size();
}
}
PostOrderCFGView *PostOrderCFGView::create(AnalysisDeclContext &ctx) {
const CFG *cfg = ctx.getCFG();
if (!cfg)
return nullptr;
return new PostOrderCFGView(cfg);
}
const void *PostOrderCFGView::getTag() { static int x; return &x; }
bool PostOrderCFGView::BlockOrderCompare::operator()(const CFGBlock *b1,
const CFGBlock *b2) const {
PostOrderCFGView::BlockOrderTy::const_iterator b1It = POV.BlockOrder.find(b1);
PostOrderCFGView::BlockOrderTy::const_iterator b2It = POV.BlockOrder.find(b2);
unsigned b1V = (b1It == POV.BlockOrder.end()) ? 0 : b1It->second;
unsigned b2V = (b2It == POV.BlockOrder.end()) ? 0 : b2It->second;
return b1V > b2V;
}
PostOrderCFGView::PostOrderCFGView(const CFG *cfg) {
unsigned size = cfg->getNumBlockIDs();
Blocks.reserve(size);
CFGBlockSet BSet(cfg);
typedef llvm::po_iterator<const CFG*, CFGBlockSet, true,
llvm::GraphTraits<llvm::Inverse<const CFG*> >
> po_iterator;
for (po_iterator I = po_iterator::begin(cfg, BSet),
E = po_iterator::end(cfg, BSet); I != E; ++I) {
Blocks.push_back(*I);
BlockOrder[*I] = Blocks.size();
}
// It may be that some blocks are inaccessible going from the CFG exit upwards
// (e.g. infinite loops); we still need to add them.
for (CFG::const_iterator I = cfg->begin(), E = cfg->end();
(Blocks.size() < size) && (I != E); ++I) {
const CFGBlock* block = *I;
// Add a chain going upwards.
while (!BlockOrder.count(block)) {
Blocks.push_back(block);
BlockOrder[block] = Blocks.size();
CFGBlock::const_pred_iterator PI = block->pred_begin(),
PE = block->pred_end();
for (; PI != PE; ++PI) {
const CFGBlock* pred = *PI;
if (pred && !BlockOrder.count(pred)) {
block = pred;
break;
}
}
// Chain ends when we couldn't find an unmapped pred.
if (PI == PE) break;
}
}
}
ReversePostOrderCFGView *
ReversePostOrderCFGView::create(AnalysisDeclContext &ctx) {
const CFG *cfg = ctx.getCFG();
if (!cfg)
return nullptr;
return new ReversePostOrderCFGView(cfg);
}
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