llvm-6502/lib/Analysis/IPA/CallGraphSCCPass.cpp
David Greene 5c8aa950fe Ok, third time's the charm. No changes from last time except the CMake
source addition.  Apparently the buildbots were wrong about failures.

---

Add some switches helpful for debugging:

-print-before=<Pass Name>

Dump IR before running pass <Pass Name>.

-print-before-all

Dump IR before running each pass.

-print-after-all

Dump IR after running each pass.

These are helpful when tracking down a miscompilation.  It is easy to
get IR dumps and do diffs on them, etc.

To make this work well, add a new getPrinterPass API to Pass so that
each kind of pass (ModulePass, FunctionPass, etc.) can create a Pass
suitable for dumping out the kind of object the Pass works on.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100249 91177308-0d34-0410-b5e6-96231b3b80d8
2010-04-02 23:17:14 +00:00

478 lines
17 KiB
C++

//===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements 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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "cgscc-passmgr"
#include "llvm/CallGraphSCCPass.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Function.h"
#include "llvm/PassManagers.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// CGPassManager
//
/// CGPassManager manages FPPassManagers and CallGraphSCCPasses.
namespace {
class CGPassManager : public ModulePass, public PMDataManager {
public:
static char ID;
explicit CGPassManager(int Depth)
: ModulePass(&ID), PMDataManager(Depth) { }
/// run - Execute all of the passes scheduled for execution. Keep track of
/// whether any of the passes modifies the module, and if so, return true.
bool runOnModule(Module &M);
bool doInitialization(CallGraph &CG);
bool doFinalization(CallGraph &CG);
/// Pass Manager itself does not invalidate any analysis info.
void getAnalysisUsage(AnalysisUsage &Info) const {
// CGPassManager walks SCC and it needs CallGraph.
Info.addRequired<CallGraph>();
Info.setPreservesAll();
}
virtual const char *getPassName() const {
return "CallGraph Pass Manager";
}
virtual PMDataManager *getAsPMDataManager() { return this; }
virtual Pass *getAsPass() { return this; }
// Print passes managed by this manager
void dumpPassStructure(unsigned Offset) {
errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";
for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
Pass *P = getContainedPass(Index);
P->dumpPassStructure(Offset + 1);
dumpLastUses(P, Offset+1);
}
}
Pass *getContainedPass(unsigned N) {
assert(N < PassVector.size() && "Pass number out of range!");
return static_cast<Pass *>(PassVector[N]);
}
virtual PassManagerType getPassManagerType() const {
return PMT_CallGraphPassManager;
}
private:
bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
CallGraph &CG, bool &CallGraphUpToDate);
void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
bool IsCheckingMode);
};
/// PrintCallGraphPass - Print a Module corresponding to a call graph.
///
class PrintCallGraphPass : public CallGraphSCCPass {
private:
std::string Banner;
raw_ostream &Out; // raw_ostream to print on.
public:
static char ID;
PrintCallGraphPass() : CallGraphSCCPass(&ID), Out(dbgs()) {}
PrintCallGraphPass(const std::string &B, raw_ostream &o)
: CallGraphSCCPass(&ID), Banner(B), Out(o) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
bool runOnSCC(std::vector<CallGraphNode *> &SCC) {
Out << Banner;
for (std::vector<CallGraphNode *>::iterator n = SCC.begin(), ne = SCC.end();
n != ne;
++n) {
(*n)->getFunction()->print(Out);
}
return false;
}
};
} // end anonymous namespace.
char CGPassManager::ID = 0;
char PrintCallGraphPass::ID = 0;
bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
CallGraph &CG, bool &CallGraphUpToDate) {
bool Changed = false;
PMDataManager *PM = P->getAsPMDataManager();
if (PM == 0) {
CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P;
if (!CallGraphUpToDate) {
RefreshCallGraph(CurSCC, CG, false);
CallGraphUpToDate = true;
}
{
TimeRegion PassTimer(getPassTimer(CGSP));
Changed = CGSP->runOnSCC(CurSCC);
}
// After the CGSCCPass is done, when assertions are enabled, use
// RefreshCallGraph to verify that the callgraph was correctly updated.
#ifndef NDEBUG
if (Changed)
RefreshCallGraph(CurSCC, CG, true);
#endif
return Changed;
}
assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
"Invalid CGPassManager member");
FPPassManager *FPP = (FPPassManager*)P;
// Run pass P on all functions in the current SCC.
for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
if (Function *F = CurSCC[i]->getFunction()) {
dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
TimeRegion PassTimer(getPassTimer(FPP));
Changed |= FPP->runOnFunction(*F);
}
}
// The function pass(es) modified the IR, they may have clobbered the
// callgraph.
if (Changed && CallGraphUpToDate) {
DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
<< P->getPassName() << '\n');
CallGraphUpToDate = false;
}
return Changed;
}
/// RefreshCallGraph - Scan the functions in the specified CFG and resync the
/// callgraph with the call sites found in it. This is used after
/// FunctionPasses have potentially munged the callgraph, and can be used after
/// CallGraphSCC passes to verify that they correctly updated the callgraph.
///
void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
CallGraph &CG, bool CheckingMode) {
DenseMap<Value*, CallGraphNode*> CallSites;
DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
<< " nodes:\n";
for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
CurSCC[i]->dump();
);
bool MadeChange = false;
// Scan all functions in the SCC.
for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
CallGraphNode *CGN = CurSCC[sccidx];
Function *F = CGN->getFunction();
if (F == 0 || F->isDeclaration()) continue;
// Walk the function body looking for call sites. Sync up the call sites in
// CGN with those actually in the function.
// Get the set of call sites currently in the function.
for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
// If this call site is null, then the function pass deleted the call
// entirely and the WeakVH nulled it out.
if (I->first == 0 ||
// If we've already seen this call site, then the FunctionPass RAUW'd
// one call with another, which resulted in two "uses" in the edge
// list of the same call.
CallSites.count(I->first) ||
// If the call edge is not from a call or invoke, then the function
// pass RAUW'd a call with another value. This can happen when
// constant folding happens of well known functions etc.
CallSite::get(I->first).getInstruction() == 0) {
assert(!CheckingMode &&
"CallGraphSCCPass did not update the CallGraph correctly!");
// Just remove the edge from the set of callees, keep track of whether
// I points to the last element of the vector.
bool WasLast = I + 1 == E;
CGN->removeCallEdge(I);
// If I pointed to the last element of the vector, we have to bail out:
// iterator checking rejects comparisons of the resultant pointer with
// end.
if (WasLast)
break;
E = CGN->end();
continue;
}
assert(!CallSites.count(I->first) &&
"Call site occurs in node multiple times");
CallSites.insert(std::make_pair(I->first, I->second));
++I;
}
// Loop over all of the instructions in the function, getting the callsites.
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
CallSite CS = CallSite::get(I);
if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue;
// If this call site already existed in the callgraph, just verify it
// matches up to expectations and remove it from CallSites.
DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
CallSites.find(CS.getInstruction());
if (ExistingIt != CallSites.end()) {
CallGraphNode *ExistingNode = ExistingIt->second;
// Remove from CallSites since we have now seen it.
CallSites.erase(ExistingIt);
// Verify that the callee is right.
if (ExistingNode->getFunction() == CS.getCalledFunction())
continue;
// If we are in checking mode, we are not allowed to actually mutate
// the callgraph. If this is a case where we can infer that the
// callgraph is less precise than it could be (e.g. an indirect call
// site could be turned direct), don't reject it in checking mode, and
// don't tweak it to be more precise.
if (CheckingMode && CS.getCalledFunction() &&
ExistingNode->getFunction() == 0)
continue;
assert(!CheckingMode &&
"CallGraphSCCPass did not update the CallGraph correctly!");
// If not, we either went from a direct call to indirect, indirect to
// direct, or direct to different direct.
CallGraphNode *CalleeNode;
if (Function *Callee = CS.getCalledFunction())
CalleeNode = CG.getOrInsertFunction(Callee);
else
CalleeNode = CG.getCallsExternalNode();
// Update the edge target in CGN.
for (CallGraphNode::iterator I = CGN->begin(); ; ++I) {
assert(I != CGN->end() && "Didn't find call entry");
if (I->first == CS.getInstruction()) {
I->second = CalleeNode;
break;
}
}
MadeChange = true;
continue;
}
assert(!CheckingMode &&
"CallGraphSCCPass did not update the CallGraph correctly!");
// If the call site didn't exist in the CGN yet, add it. We assume that
// newly introduced call sites won't be indirect. This could be fixed
// in the future.
CallGraphNode *CalleeNode;
if (Function *Callee = CS.getCalledFunction())
CalleeNode = CG.getOrInsertFunction(Callee);
else
CalleeNode = CG.getCallsExternalNode();
CGN->addCalledFunction(CS, CalleeNode);
MadeChange = true;
}
// After scanning this function, if we still have entries in callsites, then
// they are dangling pointers. WeakVH should save us for this, so abort if
// this happens.
assert(CallSites.empty() && "Dangling pointers found in call sites map");
// Periodically do an explicit clear to remove tombstones when processing
// large scc's.
if ((sccidx & 15) == 0)
CallSites.clear();
}
DEBUG(if (MadeChange) {
dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
CurSCC[i]->dump();
} else {
dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
}
);
}
/// run - Execute all of the passes scheduled for execution. Keep track of
/// whether any of the passes modifies the module, and if so, return true.
bool CGPassManager::runOnModule(Module &M) {
CallGraph &CG = getAnalysis<CallGraph>();
bool Changed = doInitialization(CG);
std::vector<CallGraphNode*> CurSCC;
// Walk the callgraph in bottom-up SCC order.
for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
CGI != E;) {
// Copy the current SCC and increment past it so that the pass can hack
// on the SCC if it wants to without invalidating our iterator.
CurSCC = *CGI;
++CGI;
// CallGraphUpToDate - Keep track of whether the callgraph is known to be
// up-to-date or not. The CGSSC pass manager runs two types of passes:
// CallGraphSCC Passes and other random function passes. Because other
// random function passes are not CallGraph aware, they may clobber the
// call graph by introducing new calls or deleting other ones. This flag
// is set to false when we run a function pass so that we know to clean up
// the callgraph when we need to run a CGSCCPass again.
bool CallGraphUpToDate = true;
// Run all passes on current SCC.
for (unsigned PassNo = 0, e = getNumContainedPasses();
PassNo != e; ++PassNo) {
Pass *P = getContainedPass(PassNo);
// If we're in -debug-pass=Executions mode, construct the SCC node list,
// otherwise avoid constructing this string as it is expensive.
if (isPassDebuggingExecutionsOrMore()) {
std::string Functions;
#ifndef NDEBUG
raw_string_ostream OS(Functions);
for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
if (i) OS << ", ";
CurSCC[i]->print(OS);
}
OS.flush();
#endif
dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions);
}
dumpRequiredSet(P);
initializeAnalysisImpl(P);
// Actually run this pass on the current SCC.
Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
if (Changed)
dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
dumpPreservedSet(P);
verifyPreservedAnalysis(P);
removeNotPreservedAnalysis(P);
recordAvailableAnalysis(P);
removeDeadPasses(P, "", ON_CG_MSG);
}
// If the callgraph was left out of date (because the last pass run was a
// functionpass), refresh it before we move on to the next SCC.
if (!CallGraphUpToDate)
RefreshCallGraph(CurSCC, CG, false);
}
Changed |= doFinalization(CG);
return Changed;
}
/// Initialize CG
bool CGPassManager::doInitialization(CallGraph &CG) {
bool Changed = false;
for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
"Invalid CGPassManager member");
Changed |= ((FPPassManager*)PM)->doInitialization(CG.getModule());
} else {
Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doInitialization(CG);
}
}
return Changed;
}
/// Finalize CG
bool CGPassManager::doFinalization(CallGraph &CG) {
bool Changed = false;
for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
"Invalid CGPassManager member");
Changed |= ((FPPassManager*)PM)->doFinalization(CG.getModule());
} else {
Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doFinalization(CG);
}
}
return Changed;
}
Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
const std::string &Banner) const {
return new PrintCallGraphPass(Banner, O);
}
/// Assign pass manager to manage this pass.
void CallGraphSCCPass::assignPassManager(PMStack &PMS,
PassManagerType PreferredType) {
// Find CGPassManager
while (!PMS.empty() &&
PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
PMS.pop();
assert(!PMS.empty() && "Unable to handle Call Graph Pass");
CGPassManager *CGP;
if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager)
CGP = (CGPassManager*)PMS.top();
else {
// Create new Call Graph SCC Pass Manager if it does not exist.
assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");
PMDataManager *PMD = PMS.top();
// [1] Create new Call Graph Pass Manager
CGP = new CGPassManager(PMD->getDepth() + 1);
// [2] Set up new manager's top level manager
PMTopLevelManager *TPM = PMD->getTopLevelManager();
TPM->addIndirectPassManager(CGP);
// [3] Assign manager to manage this new manager. This may create
// and push new managers into PMS
Pass *P = CGP;
TPM->schedulePass(P);
// [4] Push new manager into PMS
PMS.push(CGP);
}
CGP->add(this);
}
/// 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 CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<CallGraph>();
AU.addPreserved<CallGraph>();
}