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https://github.com/c64scene-ar/llvm-6502.git
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f4de63f65f
out how to run a collection of passes optimially given their behaviors and charactaristics. Convert code to use it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1507 91177308-0d34-0410-b5e6-96231b3b80d8
126 lines
4.7 KiB
C++
126 lines
4.7 KiB
C++
//===- llvm/Transforms/LowerAllocations.h - Remove Malloc & Free Insts ------=//
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//
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// This file implements a pass that lowers malloc and free instructions to
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// calls to %malloc & %free functions. This transformation is a target
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// dependant tranformation because we depend on the size of data types and
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// alignment constraints.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/LowerAllocations.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/iMemory.h"
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#include "llvm/iOther.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/ConstantVals.h"
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using std::vector;
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// doInitialization - For the lower allocations pass, this ensures that a
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// module contains a declaration for a malloc and a free function.
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//
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// This function is always successful.
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//
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bool LowerAllocations::doInitialization(Module *M) {
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bool Changed = false;
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const MethodType *MallocType =
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MethodType::get(PointerType::get(Type::SByteTy),
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vector<const Type*>(1, Type::UIntTy), false);
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SymbolTable *SymTab = M->getSymbolTableSure();
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// Check for a definition of malloc
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if (Value *V = SymTab->lookup(PointerType::get(MallocType), "malloc")) {
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MallocMeth = cast<Method>(V); // Yup, got it
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} else { // Nope, add one
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M->getMethodList().push_back(MallocMeth = new Method(MallocType, false,
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"malloc"));
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Changed = true;
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}
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const MethodType *FreeType =
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MethodType::get(Type::VoidTy,
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vector<const Type*>(1, PointerType::get(Type::SByteTy)),
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false);
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// Check for a definition of free
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if (Value *V = SymTab->lookup(PointerType::get(FreeType), "free")) {
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FreeMeth = cast<Method>(V); // Yup, got it
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} else { // Nope, add one
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M->getMethodList().push_back(FreeMeth = new Method(FreeType, false,"free"));
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Changed = true;
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}
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return Changed; // Always successful
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}
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// runOnMethod - This method does the actual work of converting
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// instructions over, assuming that the pass has already been initialized.
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//
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bool LowerAllocations::runOnMethod(Method *M) {
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bool Changed = false;
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assert(MallocMeth && FreeMeth && M && "Pass not initialized!");
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// Loop over all of the instructions, looking for malloc or free instructions
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for (Method::iterator BBI = M->begin(), BBE = M->end(); BBI != BBE; ++BBI) {
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BasicBlock *BB = *BBI;
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for (unsigned i = 0; i < BB->size(); ++i) {
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BasicBlock::InstListType &BBIL = BB->getInstList();
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if (MallocInst *MI = dyn_cast<MallocInst>(*(BBIL.begin()+i))) {
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BBIL.remove(BBIL.begin()+i); // remove the malloc instr...
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const Type *AllocTy =cast<PointerType>(MI->getType())->getElementType();
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// Get the number of bytes to be allocated for one element of the
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// requested type...
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unsigned Size = DataLayout.getTypeSize(AllocTy);
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// malloc(type) becomes sbyte *malloc(constint)
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Value *MallocArg = ConstantUInt::get(Type::UIntTy, Size);
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if (MI->getNumOperands() && Size == 1) {
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MallocArg = MI->getOperand(0); // Operand * 1 = Operand
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} else if (MI->getNumOperands()) {
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// Multiply it by the array size if neccesary...
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MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0),
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MallocArg);
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BBIL.insert(BBIL.begin()+i++, cast<Instruction>(MallocArg));
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}
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// Create the call to Malloc...
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CallInst *MCall = new CallInst(MallocMeth,
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vector<Value*>(1, MallocArg));
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BBIL.insert(BBIL.begin()+i, MCall);
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// Create a cast instruction to convert to the right type...
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CastInst *MCast = new CastInst(MCall, MI->getType());
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BBIL.insert(BBIL.begin()+i+1, MCast);
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// Replace all uses of the old malloc inst with the cast inst
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MI->replaceAllUsesWith(MCast);
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delete MI; // Delete the malloc inst
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Changed = true;
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} else if (FreeInst *FI = dyn_cast<FreeInst>(*(BBIL.begin()+i))) {
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BBIL.remove(BB->getInstList().begin()+i);
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// Cast the argument to free into a ubyte*...
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CastInst *MCast = new CastInst(FI->getOperand(0),
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PointerType::get(Type::UByteTy));
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BBIL.insert(BBIL.begin()+i, MCast);
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// Insert a call to the free function...
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CallInst *FCall = new CallInst(FreeMeth,
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vector<Value*>(1, MCast));
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BBIL.insert(BBIL.begin()+i+1, FCall);
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// Delete the old free instruction
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delete FI;
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Changed = true;
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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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