-//===- LowerAllocations.cpp - Remove Malloc & Free Instructions -------------=//
+//===- LowerAllocations.cpp - Reduce malloc & free insts to calls ---------===//
//
-// This file implements a pass that lowers malloc and free instructions to
-// calls to %malloc & %free functions. This transformation is a target
-// dependant tranformation because we depend on the size of data types and
-// alignment constraints.
+// The LowerAllocations transformation is a target dependant tranformation
+// because it depends on the size of data types and alignment constraints.
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/LowerAllocations.h"
-#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Module.h"
#include "llvm/DerivedTypes.h"
#include "llvm/iMemory.h"
#include "llvm/iOther.h"
-#include "llvm/SymbolTable.h"
-#include "llvm/ConstantVals.h"
+#include "llvm/Constants.h"
+#include "llvm/Pass.h"
+#include "llvm/Target/TargetData.h"
+#include "Support/Statistic.h"
+
using std::vector;
+namespace {
+ Statistic<> NumLowered("lowerallocs", "Number of allocations lowered");
+
+ /// LowerAllocations - Turn malloc and free instructions into %malloc and
+ /// %free calls.
+ ///
+ class LowerAllocations : public BasicBlockPass {
+ Function *MallocFunc; // Functions in the module we are processing
+ Function *FreeFunc; // Initialized by doInitialization
+ public:
+ LowerAllocations() : MallocFunc(0), FreeFunc(0) {}
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetData>();
+ }
+
+ /// doPassInitialization - For the lower allocations pass, this ensures that
+ /// a module contains a declaration for a malloc and a free function.
+ ///
+ bool doInitialization(Module &M);
+
+ /// runOnBasicBlock - This method does the actual work of converting
+ /// instructions over, assuming that the pass has already been initialized.
+ ///
+ bool runOnBasicBlock(BasicBlock &BB);
+ };
+
+ RegisterOpt<LowerAllocations>
+ X("lowerallocs", "Lower allocations from instructions to calls");
+}
+
+// createLowerAllocationsPass - Interface to this file...
+Pass *createLowerAllocationsPass() {
+ return new LowerAllocations();
+}
+
// doInitialization - For the lower allocations pass, this ensures that a
// module contains a declaration for a malloc and a free function.
//
// This function is always successful.
//
-bool LowerAllocations::doInitialization(Module *M) {
- bool Changed = false;
- const MethodType *MallocType =
- MethodType::get(PointerType::get(Type::SByteTy),
- vector<const Type*>(1, Type::UIntTy), false);
-
- SymbolTable *SymTab = M->getSymbolTableSure();
-
- // Check for a definition of malloc
- if (Value *V = SymTab->lookup(PointerType::get(MallocType), "malloc")) {
- MallocMeth = cast<Method>(V); // Yup, got it
- } else { // Nope, add one
- M->getMethodList().push_back(MallocMeth = new Method(MallocType, false,
- "malloc"));
- Changed = true;
- }
+bool LowerAllocations::doInitialization(Module &M) {
+ const FunctionType *MallocType =
+ FunctionType::get(PointerType::get(Type::SByteTy),
+ vector<const Type*>(1, Type::UIntTy), false);
+ const FunctionType *FreeType =
+ FunctionType::get(Type::VoidTy,
+ vector<const Type*>(1, PointerType::get(Type::SByteTy)),
+ false);
- const MethodType *FreeType =
- MethodType::get(Type::VoidTy,
- vector<const Type*>(1, PointerType::get(Type::SByteTy)),
- false);
-
- // Check for a definition of free
- if (Value *V = SymTab->lookup(PointerType::get(FreeType), "free")) {
- FreeMeth = cast<Method>(V); // Yup, got it
- } else { // Nope, add one
- M->getMethodList().push_back(FreeMeth = new Method(FreeType, false,"free"));
- Changed = true;
- }
+ MallocFunc = M.getOrInsertFunction("malloc", MallocType);
+ FreeFunc = M.getOrInsertFunction("free" , FreeType);
- return Changed;
+ return true;
}
// runOnBasicBlock - This method does the actual work of converting
// instructions over, assuming that the pass has already been initialized.
//
-bool LowerAllocations::runOnBasicBlock(BasicBlock *BB) {
+bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
bool Changed = false;
- assert(MallocMeth && FreeMeth && BB && "Pass not initialized!");
+ assert(MallocFunc && FreeFunc && "Pass not initialized!");
+
+ BasicBlock::InstListType &BBIL = BB.getInstList();
+ TargetData &DataLayout = getAnalysis<TargetData>();
// Loop over all of the instructions, looking for malloc or free instructions
- for (unsigned i = 0; i < BB->size(); ++i) {
- BasicBlock::InstListType &BBIL = BB->getInstList();
- if (MallocInst *MI = dyn_cast<MallocInst>(*(BBIL.begin()+i))) {
- BBIL.remove(BBIL.begin()+i); // remove the malloc instr...
-
- const Type *AllocTy =cast<PointerType>(MI->getType())->getElementType();
+ for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
+ if (MallocInst *MI = dyn_cast<MallocInst>(&*I)) {
+ const Type *AllocTy = MI->getType()->getElementType();
// Get the number of bytes to be allocated for one element of the
// requested type...
MallocArg = MI->getOperand(0); // Operand * 1 = Operand
} else if (MI->getNumOperands()) {
// Multiply it by the array size if neccesary...
- MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0),
- MallocArg);
- BBIL.insert(BBIL.begin()+i++, cast<Instruction>(MallocArg));
+ MallocArg = BinaryOperator::create(Instruction::Mul, MI->getOperand(0),
+ MallocArg, "", I);
}
// Create the call to Malloc...
- CallInst *MCall = new CallInst(MallocMeth,
- vector<Value*>(1, MallocArg));
- BBIL.insert(BBIL.begin()+i, MCall);
+ CallInst *MCall = new CallInst(MallocFunc,
+ vector<Value*>(1, MallocArg), "", I);
// Create a cast instruction to convert to the right type...
- CastInst *MCast = new CastInst(MCall, MI->getType());
- BBIL.insert(BBIL.begin()+i+1, MCast);
+ CastInst *MCast = new CastInst(MCall, MI->getType(), "", I);
// Replace all uses of the old malloc inst with the cast inst
MI->replaceAllUsesWith(MCast);
- delete MI; // Delete the malloc inst
+ I = --BBIL.erase(I); // remove and delete the malloc instr...
Changed = true;
- } else if (FreeInst *FI = dyn_cast<FreeInst>(*(BBIL.begin()+i))) {
- BBIL.remove(BB->getInstList().begin()+i);
-
+ ++NumLowered;
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(&*I)) {
// Cast the argument to free into a ubyte*...
CastInst *MCast = new CastInst(FI->getOperand(0),
- PointerType::get(Type::UByteTy));
- BBIL.insert(BBIL.begin()+i, MCast);
+ PointerType::get(Type::UByteTy), "", I);
// Insert a call to the free function...
- CallInst *FCall = new CallInst(FreeMeth,
- vector<Value*>(1, MCast));
- BBIL.insert(BBIL.begin()+i+1, FCall);
+ CallInst *FCall = new CallInst(FreeFunc, vector<Value*>(1, MCast), "", I);
// Delete the old free instruction
- delete FI;
+ I = --BBIL.erase(I);
Changed = true;
+ ++NumLowered;
}
}
return Changed;
}
-
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