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Fix an infinite loop; merging two functions will create a new function (if the

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two are weak, we make them thunks to a new strong function) so don't iterate
through the function list as we're modifying it.

Also add back the outermost loop which got removed during the cleanups.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112595 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2010-08-31 08:29:37 +00:00
parent 7c37f6d2d9
commit 65a0af3855
1 changed files with 46 additions and 32 deletions

78
lib/Transforms/IPO/MergeFunctions.cpp

@ -63,6 +63,7 @@
#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetData.h"
#include <vector>
using namespace llvm;
STATISTIC(NumFunctionsMerged, "Number of functions merged");
@ -82,7 +83,8 @@ namespace {
private:
/// MergeTwoFunctions - Merge two equivalent functions. Upon completion, G
/// is deleted.
/// may be deleted, or may be converted into a thunk. In either case, it
/// should never be visited again.
void MergeTwoFunctions(Function *F, Function *G) const;
/// WriteThunk - Replace G with a simple tail call to bitcast(F). Also
@ -598,41 +600,53 @@ struct MergeFunctionsEqualityInfo {
};
bool MergeFunctions::runOnModule(Module &M) {
bool Changed = false;
typedef DenseSet<ComparableFunction *, MergeFunctionsEqualityInfo> FnSetType;
bool Changed = false;
TD = getAnalysisIfAvailable<TargetData>();
typedef DenseSet<ComparableFunction *, MergeFunctionsEqualityInfo> FnSetType;
FnSetType FnSet;
for (Module::iterator F = M.begin(), E = M.end(); F != E;) {
if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
++F;
continue;
}
ComparableFunction *NewF = new ComparableFunction(F, TD);
++F;
std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
if (!Result.second) {
ComparableFunction *&OldF = *Result.first;
assert(OldF && "Expected a hash collision");
// NewF will be deleted in favour of OldF unless NewF is strong and OldF
// is weak in which case swap them to keep the strong definition.
if (OldF->Func->isWeakForLinker() && !NewF->Func->isWeakForLinker())
std::swap(OldF, NewF);
DEBUG(dbgs() << " " << OldF->Func->getName() << " == "
<< NewF->Func->getName() << '\n');
Changed = true;
Function *DeleteF = NewF->Func;
delete NewF;
MergeTwoFunctions(OldF->Func, DeleteF);
}
std::vector<Function *> Funcs;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage())
Funcs.push_back(F);
}
DeleteContainerPointers(FnSet);
bool LocalChanged;
do {
LocalChanged = false;
FnSetType FnSet;
for (unsigned i = 0, e = Funcs.size(); i != e;) {
Function *F = Funcs[i];
ComparableFunction *NewF = new ComparableFunction(F, TD);
std::pair<FnSetType::iterator, bool> Result = FnSet.insert(NewF);
if (!Result.second) {
ComparableFunction *&OldF = *Result.first;
assert(OldF && "Expected a hash collision");
// NewF will be deleted in favour of OldF unless NewF is strong and
// OldF is weak in which case swap them to keep the strong definition.
if (OldF->Func->isWeakForLinker() && !NewF->Func->isWeakForLinker())
std::swap(OldF, NewF);
DEBUG(dbgs() << " " << OldF->Func->getName() << " == "
<< NewF->Func->getName() << '\n');
Funcs.erase(Funcs.begin() + i);
--e;
Function *DeleteF = NewF->Func;
delete NewF;
MergeTwoFunctions(OldF->Func, DeleteF);
LocalChanged = true;
Changed = true;
} else {
++i;
}
}
DeleteContainerPointers(FnSet);
} while (LocalChanged);
return Changed;
}