/// computeTypeMapping - Loop over all of the linked values to compute type
/// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
/// we have two struct types 'Foo' but one got renamed when the module was
/// loaded into the same LLVMContext.
void ModuleLinker::computeTypeMapping() {
// Incorporate globals.
for (Module::global_iterator I = SrcM->global_begin(),
E = SrcM->global_end(); I != E; ++I) {
GlobalValue *DGV = getLinkedToGlobal(I);
if (DGV == 0) continue;
if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
TypeMap.addTypeMapping(DGV->getType(), I->getType());
continue;
}
// Unify the element type of appending arrays.
ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
}
// Incorporate functions.
for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
if (GlobalValue *DGV = getLinkedToGlobal(I))
TypeMap.addTypeMapping(DGV->getType(), I->getType());
}
// Incorporate types by name, scanning all the types in the source module.
// At this point, the destination module may have a type "%foo = { i32 }" for
// example. When the source module got loaded into the same LLVMContext, if
// it had the same type, it would have been renamed to "%foo.42 = { i32 }".
// Though it isn't required for correctness, attempt to link these up to clean
// up the IR.
std::vector<StructType*> SrcStructTypes;
SrcM->findUsedStructTypes(SrcStructTypes);
SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
SrcStructTypes.end());
for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
StructType *ST = SrcStructTypes[i];
if (!ST->hasName()) continue;
// Check to see if there is a dot in the name followed by a digit.
size_t DotPos = ST->getName().rfind('.');
if (DotPos == 0 || DotPos == StringRef::npos ||
ST->getName().back() == '.' || !isdigit(ST->getName()[DotPos+1]))
continue;
// Check to see if the destination module has a struct with the prefix name.
if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
// Don't use it if this actually came from the source module. They're in
// the same LLVMContext after all.
if (!SrcStructTypesSet.count(DST))
TypeMap.addTypeMapping(DST, ST);
}
// Don't bother incorporating aliases, they aren't generally typed well.
// Now that we have discovered all of the type equivalences, get a body for
// any 'opaque' types in the dest module that are now resolved.
TypeMap.linkDefinedTypeBodies();
}
/* Change linkages of global values, in order to
* improve alias analysis.
*/
bool DeadStoreEliminationPass::changeLinkageTypes(Module &M) {
DEBUG(errs() << "Changing linkages to private...\n");
for (Module::global_iterator git = M.global_begin(), gitE = M.global_end();
git != gitE; ++git) {
DEBUG(errs() << " " << *git << "\n");
if (!git->hasExternalLinkage() && !git->hasAppendingLinkage()) git->setLinkage(GlobalValue::PrivateLinkage);
}
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (!F->isDeclaration()) {
if (!F->hasExternalLinkage() && !F->hasAppendingLinkage()) F->setLinkage(GlobalValue::PrivateLinkage);
DEBUG(errs() << " " << F->getName() << "\n");
}
}
DEBUG(errs() << "\n");
return true;
}