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https://github.com/c64scene-ar/llvm-6502.git
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* Warnings were emitted all of the time and were really annoying * Functions could not be resolved unless they had external linkage. Linkonce linkage was not allowed * ConstantPointerRef's were not handled when linking functions we now actually handle cast (CPR) to X -> cast (NewCPR) to X git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5967 91177308-0d34-0410-b5e6-96231b3b80d8
392 lines
14 KiB
C++
392 lines
14 KiB
C++
//===- FunctionResolution.cpp - Resolve declarations to implementations ---===//
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//
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// Loop over the functions that are in the module and look for functions that
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// have the same name. More often than not, there will be things like:
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//
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// declare void %foo(...)
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// void %foo(int, int) { ... }
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//
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// because of the way things are declared in C. If this is the case, patch
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// things up.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Module.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Pass.h"
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#include "llvm/iOther.h"
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#include "llvm/Constants.h"
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#include "llvm/Assembly/Writer.h" // FIXME: remove when varargs implemented
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#include "Support/Statistic.h"
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#include <algorithm>
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namespace {
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Statistic<>NumResolved("funcresolve", "Number of varargs functions resolved");
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Statistic<> NumGlobals("funcresolve", "Number of global variables resolved");
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struct FunctionResolvingPass : public Pass {
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bool run(Module &M);
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};
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RegisterOpt<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
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}
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Pass *createFunctionResolvingPass() {
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return new FunctionResolvingPass();
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}
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// ConvertCallTo - Convert a call to a varargs function with no arg types
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// specified to a concrete nonvarargs function.
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//
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static void ConvertCallTo(CallInst *CI, Function *Dest) {
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const FunctionType::ParamTypes &ParamTys =
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Dest->getFunctionType()->getParamTypes();
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BasicBlock *BB = CI->getParent();
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// Keep an iterator to where we want to insert cast instructions if the
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// argument types don't agree.
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//
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unsigned NumArgsToCopy = CI->getNumOperands()-1;
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if (NumArgsToCopy != ParamTys.size() &&
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!(NumArgsToCopy > ParamTys.size() &&
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Dest->getFunctionType()->isVarArg())) {
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std::cerr << "WARNING: Call arguments do not match expected number of"
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<< " parameters.\n";
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std::cerr << "WARNING: In function '"
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<< CI->getParent()->getParent()->getName() << "': call: " << *CI;
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std::cerr << "Function resolved to: ";
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WriteAsOperand(std::cerr, Dest);
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std::cerr << "\n";
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if (NumArgsToCopy > ParamTys.size())
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NumArgsToCopy = ParamTys.size();
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}
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std::vector<Value*> Params;
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// Convert all of the call arguments over... inserting cast instructions if
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// the types are not compatible.
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for (unsigned i = 1; i <= NumArgsToCopy; ++i) {
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Value *V = CI->getOperand(i);
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if (i-1 < ParamTys.size() && V->getType() != ParamTys[i-1]) {
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// Must insert a cast...
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V = new CastInst(V, ParamTys[i-1], "argcast", CI);
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}
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Params.push_back(V);
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}
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// Replace the old call instruction with a new call instruction that calls
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// the real function.
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//
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Instruction *NewCall = new CallInst(Dest, Params, "", CI);
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std::string Name = CI->getName(); CI->setName("");
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// Transfer the name over...
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if (NewCall->getType() != Type::VoidTy)
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NewCall->setName(Name);
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// Replace uses of the old instruction with the appropriate values...
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//
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if (NewCall->getType() == CI->getType()) {
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CI->replaceAllUsesWith(NewCall);
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NewCall->setName(Name);
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} else if (NewCall->getType() == Type::VoidTy) {
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// Resolved function does not return a value but the prototype does. This
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// often occurs because undefined functions default to returning integers.
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// Just replace uses of the call (which are broken anyway) with dummy
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// values.
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CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
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} else if (CI->getType() == Type::VoidTy) {
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// If we are gaining a new return value, we don't have to do anything
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// special here, because it will automatically be ignored.
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} else {
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// Insert a cast instruction to convert the return value of the function
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// into it's new type. Of course we only need to do this if the return
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// value of the function is actually USED.
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//
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if (!CI->use_empty()) {
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// Insert the new cast instruction...
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CastInst *NewCast = new CastInst(NewCall, CI->getType(), Name, CI);
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CI->replaceAllUsesWith(NewCast);
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}
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}
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// The old instruction is no longer needed, destroy it!
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BB->getInstList().erase(CI);
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}
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static bool ResolveFunctions(Module &M, std::vector<GlobalValue*> &Globals,
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Function *Concrete) {
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bool Changed = false;
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for (unsigned i = 0; i != Globals.size(); ++i)
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if (Globals[i] != Concrete) {
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Function *Old = cast<Function>(Globals[i]);
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const FunctionType *OldMT = Old->getFunctionType();
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const FunctionType *ConcreteMT = Concrete->getFunctionType();
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if (OldMT->getParamTypes().size() > ConcreteMT->getParamTypes().size() &&
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!ConcreteMT->isVarArg())
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if (!Old->use_empty()) {
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std::cerr << "WARNING: Linking function '" << Old->getName()
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<< "' is causing arguments to be dropped.\n";
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std::cerr << "WARNING: Prototype: ";
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WriteAsOperand(std::cerr, Old);
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std::cerr << " resolved to ";
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WriteAsOperand(std::cerr, Concrete);
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std::cerr << "\n";
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}
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// Check to make sure that if there are specified types, that they
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// match...
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//
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unsigned NumArguments = std::min(OldMT->getParamTypes().size(),
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ConcreteMT->getParamTypes().size());
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if (!Old->use_empty() && !Concrete->use_empty())
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for (unsigned i = 0; i < NumArguments; ++i)
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if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
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std::cerr << "WARNING: Function [" << Old->getName()
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<< "]: Parameter types conflict for: '" << OldMT
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<< "' and '" << ConcreteMT << "'\n";
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return Changed;
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}
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// Attempt to convert all of the uses of the old function to the concrete
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// form of the function. If there is a use of the fn that we don't
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// understand here we punt to avoid making a bad transformation.
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//
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// At this point, we know that the return values are the same for our two
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// functions and that the Old function has no varargs fns specified. In
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// otherwords it's just <retty> (...)
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//
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for (unsigned i = 0; i < Old->use_size(); ) {
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User *U = *(Old->use_begin()+i);
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if (CastInst *CI = dyn_cast<CastInst>(U)) {
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// Convert casts directly
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assert(CI->getOperand(0) == Old);
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CI->setOperand(0, Concrete);
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Changed = true;
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++NumResolved;
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} else if (CallInst *CI = dyn_cast<CallInst>(U)) {
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// Can only fix up calls TO the argument, not args passed in.
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if (CI->getCalledValue() == Old) {
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ConvertCallTo(CI, Concrete);
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Changed = true;
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++NumResolved;
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} else {
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std::cerr << "Couldn't cleanup this function call, must be an"
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<< " argument or something!" << CI;
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++i;
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}
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} else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(U)) {
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if (CPR->use_size() == 1 && isa<ConstantExpr>(CPR->use_back()) &&
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cast<ConstantExpr>(CPR->use_back())->getOpcode() ==
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Instruction::Cast) {
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ConstantExpr *CE = cast<ConstantExpr>(CPR->use_back());
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Constant *NewCPR = ConstantPointerRef::get(Concrete);
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CE->replaceAllUsesWith(ConstantExpr::getCast(NewCPR,CE->getType()));
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CPR->destroyConstant();
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} else {
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std::cerr << "Cannot convert use of function: " << CPR << "\n";
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++i;
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}
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} else {
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std::cerr << "Cannot convert use of function: " << U << "\n";
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++i;
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}
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}
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}
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return Changed;
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}
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static bool ResolveGlobalVariables(Module &M,
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std::vector<GlobalValue*> &Globals,
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GlobalVariable *Concrete) {
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bool Changed = false;
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assert(isa<ArrayType>(Concrete->getType()->getElementType()) &&
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"Concrete version should be an array type!");
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// Get the type of the things that may be resolved to us...
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const ArrayType *CATy =cast<ArrayType>(Concrete->getType()->getElementType());
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const Type *AETy = CATy->getElementType();
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Constant *CCPR = ConstantPointerRef::get(Concrete);
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for (unsigned i = 0; i != Globals.size(); ++i)
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if (Globals[i] != Concrete) {
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GlobalVariable *Old = cast<GlobalVariable>(Globals[i]);
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const ArrayType *OATy = cast<ArrayType>(Old->getType()->getElementType());
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if (OATy->getElementType() != AETy || OATy->getNumElements() != 0) {
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std::cerr << "WARNING: Two global variables exist with the same name "
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<< "that cannot be resolved!\n";
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return false;
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}
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Old->replaceAllUsesWith(ConstantExpr::getCast(CCPR, Old->getType()));
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// Since there are no uses of Old anymore, remove it from the module.
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M.getGlobalList().erase(Old);
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++NumGlobals;
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Changed = true;
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}
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return Changed;
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}
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static bool ProcessGlobalsWithSameName(Module &M,
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std::vector<GlobalValue*> &Globals) {
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assert(!Globals.empty() && "Globals list shouldn't be empty here!");
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bool isFunction = isa<Function>(Globals[0]); // Is this group all functions?
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GlobalValue *Concrete = 0; // The most concrete implementation to resolve to
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assert((isFunction ^ isa<GlobalVariable>(Globals[0])) &&
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"Should either be function or gvar!");
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for (unsigned i = 0; i != Globals.size(); ) {
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if (isa<Function>(Globals[i]) != isFunction) {
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std::cerr << "WARNING: Found function and global variable with the "
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<< "same name: '" << Globals[i]->getName() << "'.\n";
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return false; // Don't know how to handle this, bail out!
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}
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if (isFunction) {
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// For functions, we look to merge functions definitions of "int (...)"
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// to 'int (int)' or 'int ()' or whatever else is not completely generic.
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//
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Function *F = cast<Function>(Globals[i]);
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if (!F->isExternal()) {
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if (Concrete && !Concrete->isExternal())
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return false; // Found two different functions types. Can't choose!
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Concrete = Globals[i];
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} else if (Concrete) {
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if (Concrete->isExternal()) // If we have multiple external symbols...x
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if (F->getFunctionType()->getNumParams() >
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cast<Function>(Concrete)->getFunctionType()->getNumParams())
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Concrete = F; // We are more concrete than "Concrete"!
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} else {
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Concrete = F;
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}
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} else {
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// For global variables, we have to merge C definitions int A[][4] with
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// int[6][4]. A[][4] is represented as A[0][4] by the CFE.
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GlobalVariable *GV = cast<GlobalVariable>(Globals[i]);
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if (!isa<ArrayType>(GV->getType()->getElementType())) {
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Concrete = 0;
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break; // Non array's cannot be compatible with other types.
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} else if (Concrete == 0) {
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Concrete = GV;
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} else {
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// Must have different types... allow merging A[0][4] w/ A[6][4] if
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// A[0][4] is external.
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const ArrayType *NAT = cast<ArrayType>(GV->getType()->getElementType());
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const ArrayType *CAT =
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cast<ArrayType>(Concrete->getType()->getElementType());
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if (NAT->getElementType() != CAT->getElementType()) {
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Concrete = 0; // Non-compatible types
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break;
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} else if (NAT->getNumElements() == 0 && GV->isExternal()) {
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// Concrete remains the same
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} else if (CAT->getNumElements() == 0 && Concrete->isExternal()) {
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Concrete = GV; // Concrete becomes GV
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} else {
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Concrete = 0; // Cannot merge these types...
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break;
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}
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}
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}
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++i;
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}
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if (Globals.size() > 1) { // Found a multiply defined global...
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// We should find exactly one concrete function definition, which is
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// probably the implementation. Change all of the function definitions and
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// uses to use it instead.
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//
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if (!Concrete) {
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std::cerr << "WARNING: Found global types that are not compatible:\n";
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for (unsigned i = 0; i < Globals.size(); ++i) {
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std::cerr << "\t" << Globals[i]->getType()->getDescription() << " %"
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<< Globals[i]->getName() << "\n";
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}
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std::cerr << " No linkage of globals named '" << Globals[0]->getName()
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<< "' performed!\n";
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return false;
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}
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if (isFunction)
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return ResolveFunctions(M, Globals, cast<Function>(Concrete));
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else
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return ResolveGlobalVariables(M, Globals,
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cast<GlobalVariable>(Concrete));
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}
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return false;
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}
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bool FunctionResolvingPass::run(Module &M) {
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SymbolTable &ST = M.getSymbolTable();
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std::map<std::string, std::vector<GlobalValue*> > Globals;
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// Loop over the entries in the symbol table. If an entry is a func pointer,
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// then add it to the Functions map. We do a two pass algorithm here to avoid
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// problems with iterators getting invalidated if we did a one pass scheme.
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//
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for (SymbolTable::iterator I = ST.begin(), E = ST.end(); I != E; ++I)
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if (const PointerType *PT = dyn_cast<PointerType>(I->first)) {
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SymbolTable::VarMap &Plane = I->second;
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for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
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PI != PE; ++PI) {
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GlobalValue *GV = cast<GlobalValue>(PI->second);
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assert(PI->first == GV->getName() &&
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"Global name and symbol table do not agree!");
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if (!GV->hasInternalLinkage()) // Only resolve decls to external fns
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Globals[PI->first].push_back(GV);
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}
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}
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bool Changed = false;
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// Now we have a list of all functions with a particular name. If there is
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// more than one entry in a list, merge the functions together.
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//
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for (std::map<std::string, std::vector<GlobalValue*> >::iterator
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I = Globals.begin(), E = Globals.end(); I != E; ++I)
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Changed |= ProcessGlobalsWithSameName(M, I->second);
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// Now loop over all of the globals, checking to see if any are trivially
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// dead. If so, remove them now.
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for (Module::iterator I = M.begin(), E = M.end(); I != E; )
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if (I->isExternal() && I->use_empty()) {
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Function *F = I;
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++I;
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M.getFunctionList().erase(F);
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++NumResolved;
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Changed = true;
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} else {
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++I;
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}
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for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; )
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if (I->isExternal() && I->use_empty()) {
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GlobalVariable *GV = I;
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++I;
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M.getGlobalList().erase(GV);
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++NumGlobals;
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Changed = true;
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} else {
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++I;
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}
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return Changed;
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}
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