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//===- CallGraphSCCPass.h - Pass that operates BU on call graph -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the CallGraphSCCPass class, which is used for passes which
// are implemented as bottom-up traversals on the call graph. Because there may
// be cycles in the call graph, passes of this type operate on the call-graph in
// SCC order: that is, they process function bottom-up, except for recursive
// functions, which they process all at once.
//
// These passes are inherently interprocedural, and are required to keep the
// call graph up-to-date if they do anything which could modify it.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
#define LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Pass.h"
#include <vector>
namespace llvm {
class CallGraph;
class CallGraphNode;
class CallGraphSCC;
class PMStack;
class CallGraphSCCPass : public Pass {
public:
explicit CallGraphSCCPass(char &pid) : Pass(PT_CallGraphSCC, pid) {}
/// createPrinterPass - Get a pass that prints the Module
/// corresponding to a CallGraph.
Pass *createPrinterPass(raw_ostream &OS,
const std::string &Banner) const override;
using llvm::Pass::doInitialization;
using llvm::Pass::doFinalization;
/// doInitialization - This method is called before the SCC's of the program
/// has been processed, allowing the pass to do initialization as necessary.
virtual bool doInitialization(CallGraph &CG) {
return false;
}
/// runOnSCC - This method should be implemented by the subclass to perform
/// whatever action is necessary for the specified SCC. Note that
/// non-recursive (or only self-recursive) functions will have an SCC size of
/// 1, where recursive portions of the call graph will have SCC size > 1.
///
/// SCC passes that add or delete functions to the SCC are required to update
/// the SCC list, otherwise stale pointers may be dereferenced.
virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
/// doFinalization - This method is called after the SCC's of the program has
/// been processed, allowing the pass to do final cleanup as necessary.
virtual bool doFinalization(CallGraph &CG) {
return false;
}
/// Assign pass manager to manager this pass
void assignPassManager(PMStack &PMS, PassManagerType PMT) override;
/// Return what kind of Pass Manager can manage this pass.
PassManagerType getPotentialPassManagerType() const override {
return PMT_CallGraphPassManager;
}
/// getAnalysisUsage - For this class, we declare that we require and preserve
/// the call graph. If the derived class implements this method, it should
/// always explicitly call the implementation here.
void getAnalysisUsage(AnalysisUsage &Info) const override;
protected:
/// Optional passes call this function to check whether the pass should be
/// skipped. This is the case when optimization bisect is over the limit.
bool skipSCC(CallGraphSCC &SCC) const;
};
/// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
class CallGraphSCC {
const CallGraph &CG; // The call graph for this SCC.
void *Context; // The CGPassManager object that is vending this.
std::vector<CallGraphNode *> Nodes;
public:
CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {}
void initialize(ArrayRef<CallGraphNode *> NewNodes) {
Nodes.assign(NewNodes.begin(), NewNodes.end());
}
bool isSingular() const { return Nodes.size() == 1; }
unsigned size() const { return Nodes.size(); }
/// ReplaceNode - This informs the SCC and the pass manager that the specified
/// Old node has been deleted, and New is to be used in its place.
void ReplaceNode(CallGraphNode *Old, CallGraphNode *New);
using iterator = std::vector<CallGraphNode *>::const_iterator;
iterator begin() const { return Nodes.begin(); }
iterator end() const { return Nodes.end(); }
const CallGraph &getCallGraph() { return CG; }
};
void initializeDummyCGSCCPassPass(PassRegistry &);
/// This pass is required by interprocedural register allocation. It forces
/// codegen to follow bottom up order on call graph.
class DummyCGSCCPass : public CallGraphSCCPass {
public:
static char ID;
DummyCGSCCPass() : CallGraphSCCPass(ID) {
PassRegistry &Registry = *PassRegistry::getPassRegistry();
initializeDummyCGSCCPassPass(Registry);
}
bool runOnSCC(CallGraphSCC &SCC) override { return false; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
}
};
} // end namespace llvm
#endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
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