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-rw-r--r--lib/Analysis/IPA/CallGraphSCCPass.cpp360
1 files changed, 246 insertions, 114 deletions
diff --git a/lib/Analysis/IPA/CallGraphSCCPass.cpp b/lib/Analysis/IPA/CallGraphSCCPass.cpp
index fb0804190ac1..0c01ee5b8284 100644
--- a/lib/Analysis/IPA/CallGraphSCCPass.cpp
+++ b/lib/Analysis/IPA/CallGraphSCCPass.cpp
@@ -22,11 +22,18 @@
#include "llvm/PassManagers.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/ADT/SCCIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
+static cl::opt<unsigned>
+MaxIterations("max-cg-scc-iterations", cl::ReallyHidden, cl::init(4));
+
+STATISTIC(MaxSCCIterations, "Maximum CGSCCPassMgr iterations on one SCC");
+
//===----------------------------------------------------------------------===//
// CGPassManager
//
@@ -81,55 +88,31 @@ public:
}
private:
- bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
- CallGraph &CG, bool &CallGraphUpToDate);
- void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
+ bool RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
+ bool &DevirtualizedCall);
+
+ bool RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
+ CallGraph &CG, bool &CallGraphUpToDate,
+ bool &DevirtualizedCall);
+ bool RefreshCallGraph(CallGraphSCC &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 CGPassManager::RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
+ CallGraph &CG, bool &CallGraphUpToDate,
+ bool &DevirtualizedCall) {
bool Changed = false;
PMDataManager *PM = P->getAsPMDataManager();
if (PM == 0) {
CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P;
if (!CallGraphUpToDate) {
- RefreshCallGraph(CurSCC, CG, false);
+ DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false);
CallGraphUpToDate = true;
}
@@ -154,8 +137,9 @@ bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
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()) {
+ for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+ I != E; ++I) {
+ if (Function *F = (*I)->getFunction()) {
dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
TimeRegion PassTimer(getPassTimer(FPP));
Changed |= FPP->runOnFunction(*F);
@@ -178,26 +162,39 @@ bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
/// 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,
+/// This function returns true if it devirtualized an existing function call,
+/// meaning it turned an indirect call into a direct call. This happens when
+/// a function pass like GVN optimizes away stuff feeding the indirect call.
+/// This never happens in checking mode.
+///
+bool CGPassManager::RefreshCallGraph(CallGraphSCC &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();
+ for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+ I != E; ++I)
+ (*I)->dump();
);
bool MadeChange = false;
+ bool DevirtualizedCall = false;
// Scan all functions in the SCC.
- for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
- CallGraphNode *CGN = CurSCC[sccidx];
+ unsigned FunctionNo = 0;
+ for (CallGraphSCC::iterator SCCIdx = CurSCC.begin(), E = CurSCC.end();
+ SCCIdx != E; ++SCCIdx, ++FunctionNo) {
+ CallGraphNode *CGN = *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.
+
+ // Keep track of the number of direct and indirect calls that were
+ // invalidated and removed.
+ unsigned NumDirectRemoved = 0, NumIndirectRemoved = 0;
// Get the set of call sites currently in the function.
for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
@@ -216,6 +213,12 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
assert(!CheckingMode &&
"CallGraphSCCPass did not update the CallGraph correctly!");
+ // If this was an indirect call site, count it.
+ if (I->second->getFunction() == 0)
+ ++NumIndirectRemoved;
+ else
+ ++NumDirectRemoved;
+
// 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;
@@ -237,6 +240,9 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
}
// Loop over all of the instructions in the function, getting the callsites.
+ // Keep track of the number of direct/indirect calls added.
+ unsigned NumDirectAdded = 0, NumIndirectAdded = 0;
+
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);
@@ -271,19 +277,21 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
// 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())
+ if (Function *Callee = CS.getCalledFunction()) {
CalleeNode = CG.getOrInsertFunction(Callee);
- else
+ // Keep track of whether we turned an indirect call into a direct
+ // one.
+ if (ExistingNode->getFunction() == 0) {
+ DevirtualizedCall = true;
+ DEBUG(dbgs() << " CGSCCPASSMGR: Devirtualized call to '"
+ << Callee->getName() << "'\n");
+ }
+ } 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;
- }
- }
+ CGN->replaceCallEdge(CS, CS, CalleeNode);
MadeChange = true;
continue;
}
@@ -291,19 +299,34 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
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.
+ // If the call site didn't exist in the CGN yet, add it.
CallGraphNode *CalleeNode;
- if (Function *Callee = CS.getCalledFunction())
+ if (Function *Callee = CS.getCalledFunction()) {
CalleeNode = CG.getOrInsertFunction(Callee);
- else
+ ++NumDirectAdded;
+ } else {
CalleeNode = CG.getCallsExternalNode();
+ ++NumIndirectAdded;
+ }
CGN->addCalledFunction(CS, CalleeNode);
MadeChange = true;
}
+ // We scanned the old callgraph node, removing invalidated call sites and
+ // then added back newly found call sites. One thing that can happen is
+ // that an old indirect call site was deleted and replaced with a new direct
+ // call. In this case, we have devirtualized a call, and CGSCCPM would like
+ // to iteratively optimize the new code. Unfortunately, we don't really
+ // have a great way to detect when this happens. As an approximation, we
+ // just look at whether the number of indirect calls is reduced and the
+ // number of direct calls is increased. There are tons of ways to fool this
+ // (e.g. DCE'ing an indirect call and duplicating an unrelated block with a
+ // direct call) but this is close enough.
+ if (NumIndirectRemoved > NumIndirectAdded &&
+ NumDirectRemoved < NumDirectAdded)
+ DevirtualizedCall = 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.
@@ -311,18 +334,85 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
// Periodically do an explicit clear to remove tombstones when processing
// large scc's.
- if ((sccidx & 15) == 0)
+ if ((FunctionNo & 15) == 15)
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();
+ for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+ I != E; ++I)
+ (*I)->dump();
+ if (DevirtualizedCall)
+ dbgs() << "CGSCCPASSMGR: Refresh devirtualized a call!\n";
+
} else {
dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
}
);
+
+ return DevirtualizedCall;
+}
+
+/// RunAllPassesOnSCC - Execute the body of the entire pass manager on the
+/// specified SCC. This keeps track of whether a function pass devirtualizes
+/// any calls and returns it in DevirtualizedCall.
+bool CGPassManager::RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
+ bool &DevirtualizedCall) {
+ bool Changed = false;
+
+ // 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 (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+ I != E; ++I) {
+ if (I != CurSCC.begin()) OS << ", ";
+ (*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, DevirtualizedCall);
+
+ 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)
+ DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false);
+ return Changed;
}
/// run - Execute all of the passes scheduled for execution. Keep track of
@@ -330,72 +420,53 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
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;) {
+ scc_iterator<CallGraph*> CGI = scc_begin(&CG);
+
+ CallGraphSCC CurSCC(&CGI);
+ while (!CGI.isAtEnd()) {
// 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;
+ std::vector<CallGraphNode*> &NodeVec = *CGI;
+ CurSCC.initialize(&NodeVec[0], &NodeVec[0]+NodeVec.size());
++CGI;
+ // At the top level, we run all the passes in this pass manager on the
+ // functions in this SCC. However, we support iterative compilation in the
+ // case where a function pass devirtualizes a call to a function. For
+ // example, it is very common for a function pass (often GVN or instcombine)
+ // to eliminate the addressing that feeds into a call. With that improved
+ // information, we would like the call to be an inline candidate, infer
+ // mod-ref information etc.
+ //
+ // Because of this, we allow iteration up to a specified iteration count.
+ // This only happens in the case of a devirtualized call, so we only burn
+ // compile time in the case that we're making progress. We also have a hard
+ // iteration count limit in case there is crazy code.
+ unsigned Iteration = 0;
+ bool DevirtualizedCall = false;
+ do {
+ DEBUG(if (Iteration)
+ dbgs() << " SCCPASSMGR: Re-visiting SCC, iteration #"
+ << Iteration << '\n');
+ DevirtualizedCall = false;
+ Changed |= RunAllPassesOnSCC(CurSCC, CG, DevirtualizedCall);
+ } while (Iteration++ < MaxIterations && DevirtualizedCall);
- // 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;
+ if (DevirtualizedCall)
+ DEBUG(dbgs() << " CGSCCPASSMGR: Stopped iteration after " << Iteration
+ << " times, due to -max-cg-scc-iterations\n");
- // 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 (Iteration > MaxSCCIterations)
+ MaxSCCIterations = Iteration;
- // 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;
@@ -426,11 +497,32 @@ bool CGPassManager::doFinalization(CallGraph &CG) {
return Changed;
}
-Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
- const std::string &Banner) const {
- return new PrintCallGraphPass(Banner, O);
+//===----------------------------------------------------------------------===//
+// CallGraphSCC Implementation
+//===----------------------------------------------------------------------===//
+
+/// 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 CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
+ assert(Old != New && "Should not replace node with self");
+ for (unsigned i = 0; ; ++i) {
+ assert(i != Nodes.size() && "Node not in SCC");
+ if (Nodes[i] != Old) continue;
+ Nodes[i] = New;
+ break;
+ }
+
+ // Update the active scc_iterator so that it doesn't contain dangling
+ // pointers to the old CallGraphNode.
+ scc_iterator<CallGraph*> *CGI = (scc_iterator<CallGraph*>*)Context;
+ CGI->ReplaceNode(Old, New);
}
+
+//===----------------------------------------------------------------------===//
+// CallGraphSCCPass Implementation
+//===----------------------------------------------------------------------===//
+
/// Assign pass manager to manage this pass.
void CallGraphSCCPass::assignPassManager(PMStack &PMS,
PassManagerType PreferredType) {
@@ -475,3 +567,43 @@ void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<CallGraph>();
AU.addPreserved<CallGraph>();
}
+
+
+//===----------------------------------------------------------------------===//
+// PrintCallGraphPass Implementation
+//===----------------------------------------------------------------------===//
+
+namespace {
+ /// PrintCallGraphPass - Print a Module corresponding to a call graph.
+ ///
+ class PrintCallGraphPass : public CallGraphSCCPass {
+ 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(CallGraphSCC &SCC) {
+ Out << Banner;
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+ (*I)->getFunction()->print(Out);
+ return false;
+ }
+ };
+
+} // end anonymous namespace.
+
+char PrintCallGraphPass::ID = 0;
+
+Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
+ const std::string &Banner) const {
+ return new PrintCallGraphPass(Banner, O);
+}
+
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