#include "llvm/CallGraphSCCPass.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
+#include "llvm/LLVMContext.h"
#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/CallGraph.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/CFG.h"
-#include "llvm/Support/Compiler.h"
#include <set>
#include <algorithm>
using namespace llvm;
STATISTIC(NumRemoved, "Number of invokes removed");
STATISTIC(NumUnreach, "Number of noreturn calls optimized");
-STATISTIC(NumBBUnwind, "Number of unwind dest removed from blocks");
namespace {
- struct VISIBILITY_HIDDEN PruneEH : public CallGraphSCCPass {
+ struct PruneEH : public CallGraphSCCPass {
static char ID; // Pass identification, replacement for typeid
- PruneEH() : CallGraphSCCPass((intptr_t)&ID) {}
+ PruneEH() : CallGraphSCCPass(ID) {}
// runOnSCC - Analyze the SCC, performing the transformation if possible.
- bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
+ bool runOnSCC(CallGraphSCC &SCC);
bool SimplifyFunction(Function *F);
void DeleteBasicBlock(BasicBlock *BB);
};
-
- char PruneEH::ID = 0;
- RegisterPass<PruneEH> X("prune-eh", "Remove unused exception handling info");
}
+char PruneEH::ID = 0;
+INITIALIZE_PASS(PruneEH, "prune-eh",
+ "Remove unused exception handling info", false, false);
+
Pass *llvm::createPruneEHPass() { return new PruneEH(); }
-bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
+bool PruneEH::runOnSCC(CallGraphSCC &SCC) {
+ SmallPtrSet<CallGraphNode *, 8> SCCNodes;
CallGraph &CG = getAnalysis<CallGraph>();
bool MadeChange = false;
+ // Fill SCCNodes with the elements of the SCC. Used for quickly
+ // looking up whether a given CallGraphNode is in this SCC.
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+ SCCNodes.insert(*I);
+
// First pass, scan all of the functions in the SCC, simplifying them
// according to what we know.
- for (unsigned i = 0, e = SCC.size(); i != e; ++i)
- if (Function *F = SCC[i]->getFunction())
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+ if (Function *F = (*I)->getFunction())
MadeChange |= SimplifyFunction(F);
// Next, check to see if any callees might throw or if there are any external
// functions in this SCC: if so, we cannot prune any functions in this SCC.
+ // Definitions that are weak and not declared non-throwing might be
+ // overridden at linktime with something that throws, so assume that.
// If this SCC includes the unwind instruction, we KNOW it throws, so
// obviously the SCC might throw.
//
bool SCCMightUnwind = false, SCCMightReturn = false;
- for (unsigned i = 0, e = SCC.size();
- (!SCCMightUnwind || !SCCMightReturn) && i != e; ++i) {
- Function *F = SCC[i]->getFunction();
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end();
+ (!SCCMightUnwind || !SCCMightReturn) && I != E; ++I) {
+ Function *F = (*I)->getFunction();
if (F == 0) {
SCCMightUnwind = true;
SCCMightReturn = true;
- } else if (F->isDeclaration()) {
+ } else if (F->isDeclaration() || F->mayBeOverridden()) {
SCCMightUnwind |= !F->doesNotThrow();
SCCMightReturn |= !F->doesNotReturn();
} else {
CallGraphNode *CalleeNode = CG[Callee];
// If the callee is outside our current SCC then we may
// throw because it might.
- if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()){
+ if (!SCCNodes.count(CalleeNode)) {
SCCMightUnwind = true;
break;
}
// If the SCC doesn't unwind or doesn't throw, note this fact.
if (!SCCMightUnwind || !SCCMightReturn)
- for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
- ParameterAttributes NewAttributes = ParamAttr::None;
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+ Attributes NewAttributes = Attribute::None;
if (!SCCMightUnwind)
- NewAttributes |= ParamAttr::NoUnwind;
+ NewAttributes |= Attribute::NoUnwind;
if (!SCCMightReturn)
- NewAttributes |= ParamAttr::NoReturn;
+ NewAttributes |= Attribute::NoReturn;
- const PAListPtr &PAL = SCC[i]->getFunction()->getParamAttrs();
- SCC[i]->getFunction()->setParamAttrs(PAL.addAttr(0, NewAttributes));
+ Function *F = (*I)->getFunction();
+ const AttrListPtr &PAL = F->getAttributes();
+ const AttrListPtr &NPAL = PAL.addAttr(~0, NewAttributes);
+ if (PAL != NPAL) {
+ MadeChange = true;
+ F->setAttributes(NPAL);
+ }
}
- for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
// Convert any invoke instructions to non-throwing functions in this node
// into call instructions with a branch. This makes the exception blocks
// dead.
- if (Function *F = SCC[i]->getFunction())
+ if (Function *F = (*I)->getFunction())
MadeChange |= SimplifyFunction(F);
}
bool PruneEH::SimplifyFunction(Function *F) {
bool MadeChange = false;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
- bool couldUnwind = false;
-
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
if (II->doesNotThrow()) {
- SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
+ SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3);
// Insert a call instruction before the invoke.
- CallInst *Call = new CallInst(II->getCalledValue(),
- Args.begin(), Args.end(), "", II);
+ CallInst *Call = CallInst::Create(II->getCalledValue(),
+ Args.begin(), Args.end(), "", II);
Call->takeName(II);
Call->setCallingConv(II->getCallingConv());
- Call->setParamAttrs(II->getParamAttrs());
+ Call->setAttributes(II->getAttributes());
// Anything that used the value produced by the invoke instruction
- // now uses the value produced by the call instruction.
+ // now uses the value produced by the call instruction. Note that we
+ // do this even for void functions and calls with no uses so that the
+ // callgraph edge is updated.
II->replaceAllUsesWith(Call);
BasicBlock *UnwindBlock = II->getUnwindDest();
UnwindBlock->removePredecessor(II->getParent());
// Insert a branch to the normal destination right before the
// invoke.
- new BranchInst(II->getNormalDest(), II);
+ BranchInst::Create(II->getNormalDest(), II);
// Finally, delete the invoke instruction!
BB->getInstList().pop_back();
++NumRemoved;
MadeChange = true;
- } else {
- couldUnwind = true;
}
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
- if (CallInst *CI = dyn_cast<CallInst>(I++)) {
+ if (CallInst *CI = dyn_cast<CallInst>(I++))
if (CI->doesNotReturn() && !isa<UnreachableInst>(I)) {
// This call calls a function that cannot return. Insert an
// unreachable instruction after it and simplify the code. Do this
// Remove the uncond branch and add an unreachable.
BB->getInstList().pop_back();
- new UnreachableInst(BB);
+ new UnreachableInst(BB->getContext(), BB);
DeleteBasicBlock(New); // Delete the new BB.
MadeChange = true;
++NumUnreach;
break;
- } else if (!CI->doesNotThrow()) {
- couldUnwind = true;
}
- }
-
- // Strip 'unwindTo' off of BBs that have no calls/invokes without nounwind.
- if (!couldUnwind && BB->getUnwindDest()) {
- MadeChange = true;
- ++NumBBUnwind;
- BB->getUnwindDest()->removePredecessor(BB, false, true);
- BB->setUnwindDest(NULL);
- }
}
+
return MadeChange;
}
for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) {
--I;
if (CallInst *CI = dyn_cast<CallInst>(I)) {
- if (Function *Callee = CI->getCalledFunction())
- CGN->removeCallEdgeTo(CG[Callee]);
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
- if (Function *Callee = II->getCalledFunction())
- CGN->removeCallEdgeTo(CG[Callee]);
- }
+ if (!isa<DbgInfoIntrinsic>(I))
+ CGN->removeCallEdgeFor(CI);
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
+ CGN->removeCallEdgeFor(II);
if (!I->use_empty())
I->replaceAllUsesWith(UndefValue::get(I->getType()));
}
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