llvm-6502/lib/Transforms/IPO/FunctionResolution.cpp

298 lines
11 KiB
C++

//===- FunctionResolution.cpp - Resolve declarations to implementations ---===//
//
// Loop over the functions that are in the module and look for functions that
// have the same name. More often than not, there will be things like:
//
// declare void %foo(...)
// void %foo(int, int) { ... }
//
// because of the way things are declared in C. If this is the case, patch
// things up.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO.h"
#include "llvm/Module.h"
#include "llvm/SymbolTable.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Pass.h"
#include "llvm/iOther.h"
#include "llvm/Constants.h"
#include "llvm/Assembly/Writer.h" // FIXME: remove when varargs implemented
#include "Support/Statistic.h"
#include <algorithm>
namespace {
Statistic<>NumResolved("funcresolve", "Number of varargs functions resolved");
Statistic<> NumGlobals("funcresolve", "Number of global variables resolved");
struct FunctionResolvingPass : public Pass {
bool run(Module &M);
};
RegisterOpt<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
}
Pass *createFunctionResolvingPass() {
return new FunctionResolvingPass();
}
static bool ResolveFunctions(Module &M, std::vector<GlobalValue*> &Globals,
Function *Concrete) {
bool Changed = false;
for (unsigned i = 0; i != Globals.size(); ++i)
if (Globals[i] != Concrete) {
Function *Old = cast<Function>(Globals[i]);
const FunctionType *OldMT = Old->getFunctionType();
const FunctionType *ConcreteMT = Concrete->getFunctionType();
if (OldMT->getParamTypes().size() > ConcreteMT->getParamTypes().size() &&
!ConcreteMT->isVarArg())
if (!Old->use_empty()) {
std::cerr << "WARNING: Linking function '" << Old->getName()
<< "' is causing arguments to be dropped.\n";
std::cerr << "WARNING: Prototype: ";
WriteAsOperand(std::cerr, Old);
std::cerr << " resolved to ";
WriteAsOperand(std::cerr, Concrete);
std::cerr << "\n";
}
// Check to make sure that if there are specified types, that they
// match...
//
unsigned NumArguments = std::min(OldMT->getParamTypes().size(),
ConcreteMT->getParamTypes().size());
if (!Old->use_empty() && !Concrete->use_empty())
for (unsigned i = 0; i < NumArguments; ++i)
if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
std::cerr << "WARNING: Function [" << Old->getName()
<< "]: Parameter types conflict for: '" << OldMT
<< "' and '" << ConcreteMT << "'\n";
return Changed;
}
// Attempt to convert all of the uses of the old function to the concrete
// form of the function. If there is a use of the fn that we don't
// understand here we punt to avoid making a bad transformation.
//
// At this point, we know that the return values are the same for our two
// functions and that the Old function has no varargs fns specified. In
// otherwords it's just <retty> (...)
//
Value *Replacement = Concrete;
if (Concrete->getType() != Old->getType())
Replacement = ConstantExpr::getCast(ConstantPointerRef::get(Concrete),
Old->getType());
NumResolved += Old->use_size();
Old->replaceAllUsesWith(Replacement);
// Since there are no uses of Old anymore, remove it from the module.
M.getFunctionList().erase(Old);
}
return Changed;
}
static bool ResolveGlobalVariables(Module &M,
std::vector<GlobalValue*> &Globals,
GlobalVariable *Concrete) {
bool Changed = false;
assert(isa<ArrayType>(Concrete->getType()->getElementType()) &&
"Concrete version should be an array type!");
// Get the type of the things that may be resolved to us...
const ArrayType *CATy =cast<ArrayType>(Concrete->getType()->getElementType());
const Type *AETy = CATy->getElementType();
Constant *CCPR = ConstantPointerRef::get(Concrete);
for (unsigned i = 0; i != Globals.size(); ++i)
if (Globals[i] != Concrete) {
GlobalVariable *Old = cast<GlobalVariable>(Globals[i]);
const ArrayType *OATy = cast<ArrayType>(Old->getType()->getElementType());
if (OATy->getElementType() != AETy || OATy->getNumElements() != 0) {
std::cerr << "WARNING: Two global variables exist with the same name "
<< "that cannot be resolved!\n";
return false;
}
Old->replaceAllUsesWith(ConstantExpr::getCast(CCPR, Old->getType()));
// Since there are no uses of Old anymore, remove it from the module.
M.getGlobalList().erase(Old);
++NumGlobals;
Changed = true;
}
return Changed;
}
static bool ProcessGlobalsWithSameName(Module &M,
std::vector<GlobalValue*> &Globals) {
assert(!Globals.empty() && "Globals list shouldn't be empty here!");
bool isFunction = isa<Function>(Globals[0]); // Is this group all functions?
GlobalValue *Concrete = 0; // The most concrete implementation to resolve to
assert((isFunction ^ isa<GlobalVariable>(Globals[0])) &&
"Should either be function or gvar!");
for (unsigned i = 0; i != Globals.size(); ) {
if (isa<Function>(Globals[i]) != isFunction) {
std::cerr << "WARNING: Found function and global variable with the "
<< "same name: '" << Globals[i]->getName() << "'.\n";
return false; // Don't know how to handle this, bail out!
}
if (isFunction) {
// For functions, we look to merge functions definitions of "int (...)"
// to 'int (int)' or 'int ()' or whatever else is not completely generic.
//
Function *F = cast<Function>(Globals[i]);
if (!F->isExternal()) {
if (Concrete && !Concrete->isExternal())
return false; // Found two different functions types. Can't choose!
Concrete = Globals[i];
} else if (Concrete) {
if (Concrete->isExternal()) // If we have multiple external symbols...x
if (F->getFunctionType()->getNumParams() >
cast<Function>(Concrete)->getFunctionType()->getNumParams())
Concrete = F; // We are more concrete than "Concrete"!
} else {
Concrete = F;
}
} else {
// For global variables, we have to merge C definitions int A[][4] with
// int[6][4]. A[][4] is represented as A[0][4] by the CFE.
GlobalVariable *GV = cast<GlobalVariable>(Globals[i]);
if (!isa<ArrayType>(GV->getType()->getElementType())) {
Concrete = 0;
break; // Non array's cannot be compatible with other types.
} else if (Concrete == 0) {
Concrete = GV;
} else {
// Must have different types... allow merging A[0][4] w/ A[6][4] if
// A[0][4] is external.
const ArrayType *NAT = cast<ArrayType>(GV->getType()->getElementType());
const ArrayType *CAT =
cast<ArrayType>(Concrete->getType()->getElementType());
if (NAT->getElementType() != CAT->getElementType()) {
Concrete = 0; // Non-compatible types
break;
} else if (NAT->getNumElements() == 0 && GV->isExternal()) {
// Concrete remains the same
} else if (CAT->getNumElements() == 0 && Concrete->isExternal()) {
Concrete = GV; // Concrete becomes GV
} else {
Concrete = 0; // Cannot merge these types...
break;
}
}
}
++i;
}
if (Globals.size() > 1) { // Found a multiply defined global...
// If there are no external declarations, and there is at most one
// externally visible instance of the global, then there is nothing to do.
//
bool HasExternal = false;
unsigned NumInstancesWithExternalLinkage = 0;
for (unsigned i = 0, e = Globals.size(); i != e; ++i) {
if (Globals[i]->isExternal())
HasExternal = true;
else if (!Globals[i]->hasInternalLinkage())
NumInstancesWithExternalLinkage++;
}
if (!HasExternal && NumInstancesWithExternalLinkage <= 1)
return false; // Nothing to do? Must have multiple internal definitions.
// We should find exactly one concrete function definition, which is
// probably the implementation. Change all of the function definitions and
// uses to use it instead.
//
if (!Concrete) {
std::cerr << "WARNING: Found global types that are not compatible:\n";
for (unsigned i = 0; i < Globals.size(); ++i) {
std::cerr << "\t" << Globals[i]->getType()->getDescription() << " %"
<< Globals[i]->getName() << "\n";
}
std::cerr << " No linkage of globals named '" << Globals[0]->getName()
<< "' performed!\n";
return false;
}
if (isFunction)
return ResolveFunctions(M, Globals, cast<Function>(Concrete));
else
return ResolveGlobalVariables(M, Globals,
cast<GlobalVariable>(Concrete));
}
return false;
}
bool FunctionResolvingPass::run(Module &M) {
SymbolTable &ST = M.getSymbolTable();
std::map<std::string, std::vector<GlobalValue*> > Globals;
// Loop over the entries in the symbol table. If an entry is a func pointer,
// then add it to the Functions map. We do a two pass algorithm here to avoid
// problems with iterators getting invalidated if we did a one pass scheme.
//
for (SymbolTable::iterator I = ST.begin(), E = ST.end(); I != E; ++I)
if (const PointerType *PT = dyn_cast<PointerType>(I->first)) {
SymbolTable::VarMap &Plane = I->second;
for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
PI != PE; ++PI) {
GlobalValue *GV = cast<GlobalValue>(PI->second);
assert(PI->first == GV->getName() &&
"Global name and symbol table do not agree!");
Globals[PI->first].push_back(GV);
}
}
bool Changed = false;
// Now we have a list of all functions with a particular name. If there is
// more than one entry in a list, merge the functions together.
//
for (std::map<std::string, std::vector<GlobalValue*> >::iterator
I = Globals.begin(), E = Globals.end(); I != E; ++I)
Changed |= ProcessGlobalsWithSameName(M, I->second);
// Now loop over all of the globals, checking to see if any are trivially
// dead. If so, remove them now.
for (Module::iterator I = M.begin(), E = M.end(); I != E; )
if (I->isExternal() && I->use_empty()) {
Function *F = I;
++I;
M.getFunctionList().erase(F);
++NumResolved;
Changed = true;
} else {
++I;
}
for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; )
if (I->isExternal() && I->use_empty()) {
GlobalVariable *GV = I;
++I;
M.getGlobalList().erase(GV);
++NumGlobals;
Changed = true;
} else {
++I;
}
return Changed;
}