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This analysis doesn't take 'throwing' into consideration, it looks at

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'unwinding'


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21581 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-04-26 23:53:25 +00:00
parent 0ddf0d6bec
commit bc9fa589ef
1 changed files with 13 additions and 13 deletions
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26
lib/Transforms/IPO/PruneEH.cpp
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@ -29,9 +29,9 @@ namespace {
Statistic<> NumRemoved("prune-eh", "Number of invokes removed");
struct PruneEH : public CallGraphSCCPass {
/// DoesNotThrow - This set contains all of the functions which we have
/// DoesNotUnwind - This set contains all of the functions which we have
/// determined cannot throw exceptions.
std::set<CallGraphNode*> DoesNotThrow;
std::set<CallGraphNode*> DoesNotUnwind;
// runOnSCC - Analyze the SCC, performing the transformation if possible.
bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
@ -50,17 +50,17 @@ bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
// If this SCC includes the unwind instruction, we KNOW it throws, so
// obviously the SCC might throw.
//
bool SCCMightThrow = false;
for (unsigned i = 0, e = SCC.size(); !SCCMightThrow && i != e; ++i) {
bool SCCMightUnwind = false;
for (unsigned i = 0, e = SCC.size(); !SCCMightUnwind && i != e; ++i) {
Function *F = SCC[i]->getFunction();
if (F == 0 || (F->isExternal() && !F->getIntrinsicID())) {
SCCMightThrow = true;
SCCMightUnwind = true;
} else {
// Check to see if this function performs an unwind or calls an
// unwinding function.
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
if (isa<UnwindInst>(BB->getTerminator())) { // Uses unwind!
SCCMightThrow = true;
SCCMightUnwind = true;
break;
}
@ -73,18 +73,18 @@ bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
// If the callee is outside our current SCC, or if it is not
// known to throw, then we might throw also.
if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()&&
!DoesNotThrow.count(CalleeNode)) {
SCCMightThrow = true;
!DoesNotUnwind.count(CalleeNode)) {
SCCMightUnwind = true;
break;
}
} else {
// Indirect call, it might throw.
SCCMightThrow = true;
SCCMightUnwind = true;
break;
}
}
if (SCCMightThrow) break;
if (SCCMightUnwind) break;
}
}
}
@ -92,8 +92,8 @@ bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
// If the SCC can't throw, remember this for callers...
if (!SCCMightThrow)
DoesNotThrow.insert(SCC[i]);
if (!SCCMightUnwind)
DoesNotUnwind.insert(SCC[i]);
// Convert any invoke instructions to non-throwing functions in this node
// into call instructions with a branch. This makes the exception blocks
@ -102,7 +102,7 @@ bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
if (InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator()))
if (Function *F = II->getCalledFunction())
if (DoesNotThrow.count(CG[F])) {
if (DoesNotUnwind.count(CG[F])) {
// Insert a call instruction before the invoke...
std::string Name = II->getName(); II->setName("");
Value *Call = new CallInst(II->getCalledValue(),