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by other passes. Make BCE pass be in anonymous namespace now. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3907 91177308-0d34-0410-b5e6-96231b3b80d8
56 lines
1.9 KiB
C++
56 lines
1.9 KiB
C++
//===- BreakCriticalEdges.cpp - Critical Edge Elimination Pass ------------===//
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//
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// BreakCriticalEdges pass - Break all of the critical edges in the CFG by
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// inserting a dummy basic block. This pass may be "required" by passes that
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// cannot deal with critical edges. For this usage, the structure type is
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// forward declared. This pass obviously invalidates the CFG, but can update
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// forward dominator (set, immediate dominators, and tree) information.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Function.h"
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#include "llvm/InstrTypes.h"
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#include "Support/StatisticReporter.h"
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namespace {
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Statistic<> NumBroken("break-crit-edges\t- Number of blocks inserted");
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struct BreakCriticalEdges : public FunctionPass {
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virtual bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addPreserved<DominatorSet>();
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AU.addPreserved<ImmediateDominators>();
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AU.addPreserved<DominatorTree>();
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}
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};
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RegisterOpt<BreakCriticalEdges> X("break-crit-edges",
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"Break critical edges in CFG");
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}
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const PassInfo *BreakCriticalEdgesID = X.getPassInfo();
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Pass *createBreakCriticalEdgesPass() { return new BreakCriticalEdges(); }
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// runOnFunction - Loop over all of the edges in the CFG, breaking critical
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// edges as they are found.
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//
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bool BreakCriticalEdges::runOnFunction(Function &F) {
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bool Changed = false;
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for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
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TerminatorInst *TI = I->getTerminator();
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for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
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if (isCriticalEdge(TI, i)) {
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SplitCriticalEdge(TI, i, this);
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++NumBroken;
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Changed = true;
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}
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}
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return Changed;
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}
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