llvm-6502/lib/Transforms/Scalar/LowerPacked.cpp

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//===- LowerPacked.cpp - Implementation of LowerPacked Transform ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Brad Jones and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements lowering Packed datatypes into more primitive
// Packed datatypes, and finally to scalar operations.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar.h"
#include "llvm/Argument.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/ADT/StringExtras.h"
#include <algorithm>
#include <map>
#include <iostream>
using namespace llvm;
namespace {
/// This pass converts packed operators to an
/// equivalent operations on smaller packed data, to possibly
/// scalar operations. Currently it supports lowering
/// to scalar operations.
///
/// @brief Transforms packed instructions to simpler instructions.
///
class LowerPacked : public FunctionPass, public InstVisitor<LowerPacked> {
public:
/// @brief Lowers packed operations to scalar operations.
/// @param F The fuction to process
virtual bool runOnFunction(Function &F);
/// @brief Lowers packed load instructions.
/// @param LI the load instruction to convert
void visitLoadInst(LoadInst& LI);
/// @brief Lowers packed store instructions.
/// @param SI the store instruction to convert
void visitStoreInst(StoreInst& SI);
/// @brief Lowers packed binary operations.
/// @param BO the binary operator to convert
void visitBinaryOperator(BinaryOperator& BO);
/// @brief Lowers packed select instructions.
/// @param SELI the select operator to convert
void visitSelectInst(SelectInst& SELI);
/// This function asserts if the instruction is a PackedType but
/// is handled by another function.
///
/// @brief Asserts if PackedType instruction is not handled elsewhere.
/// @param I the unhandled instruction
void visitInstruction(Instruction &I)
{
if(isa<PackedType>(I.getType())) {
std::cerr << "Unhandled Instruction with Packed ReturnType: " <<
I << '\n';
}
}
private:
/// @brief Retrieves lowered values for a packed value.
/// @param val the packed value
/// @return the lowered values
std::vector<Value*>& getValues(Value* val);
/// @brief Sets lowered values for a packed value.
/// @param val the packed value
/// @param values the corresponding lowered values
void setValues(Value* val,const std::vector<Value*>& values);
// Data Members
/// @brief whether we changed the function or not
bool Changed;
/// @brief a map from old packed values to new smaller packed values
std::map<Value*,std::vector<Value*> > packedToScalarMap;
/// Instructions in the source program to get rid of
/// after we do a pass (the old packed instructions)
std::vector<Instruction*> instrsToRemove;
};
RegisterOpt<LowerPacked>
X("lower-packed",
"lowers packed operations to operations on smaller packed datatypes");
} // end namespace
FunctionPass *llvm::createLowerPackedPass() { return new LowerPacked(); }
// This function sets lowered values for a corresponding
// packed value. Note, in the case of a forward reference
// getValues(Value*) will have already been called for
// the packed parameter. This function will then replace
// all references in the in the function of the "dummy"
// value the previous getValues(Value*) call
// returned with actual references.
void LowerPacked::setValues(Value* value,const std::vector<Value*>& values)
{
std::map<Value*,std::vector<Value*> >::iterator it =
packedToScalarMap.lower_bound(value);
if (it == packedToScalarMap.end() || it->first != value) {
// there was not a forward reference to this element
packedToScalarMap.insert(it,std::make_pair(value,values));
}
else {
// replace forward declarations with actual definitions
assert(it->second.size() == values.size() &&
"Error forward refences and actual definition differ in size");
for (unsigned i = 0, e = values.size(); i != e; ++i) {
// replace and get rid of old forward references
it->second[i]->replaceAllUsesWith(values[i]);
delete it->second[i];
it->second[i] = values[i];
}
}
}
// This function will examine the packed value parameter
// and if it is a packed constant or a forward reference
// properly create the lowered values needed. Otherwise
// it will simply retreive values from a
// setValues(Value*,const std::vector<Value*>&)
// call. Failing both of these cases, it will abort
// the program.
std::vector<Value*>& LowerPacked::getValues(Value* value)
{
assert(isa<PackedType>(value->getType()) &&
"Value must be PackedType");
// reject further processing if this one has
// already been handled
std::map<Value*,std::vector<Value*> >::iterator it =
packedToScalarMap.lower_bound(value);
if (it != packedToScalarMap.end() && it->first == value) {
return it->second;
}
if (ConstantPacked* CP = dyn_cast<ConstantPacked>(value)) {
// non-zero constant case
std::vector<Value*> results;
results.reserve(CP->getNumOperands());
for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
results.push_back(CP->getOperand(i));
}
return packedToScalarMap.insert(it,
std::make_pair(value,results))->second;
}
else if (ConstantAggregateZero* CAZ =
dyn_cast<ConstantAggregateZero>(value)) {
// zero constant
const PackedType* PKT = cast<PackedType>(CAZ->getType());
std::vector<Value*> results;
results.reserve(PKT->getNumElements());
Constant* C = Constant::getNullValue(PKT->getElementType());
for (unsigned i = 0, e = PKT->getNumElements(); i != e; ++i) {
results.push_back(C);
}
return packedToScalarMap.insert(it,
std::make_pair(value,results))->second;
}
else if (isa<Instruction>(value)) {
// foward reference
const PackedType* PKT = cast<PackedType>(value->getType());
std::vector<Value*> results;
results.reserve(PKT->getNumElements());
for (unsigned i = 0, e = PKT->getNumElements(); i != e; ++i) {
results.push_back(new Argument(PKT->getElementType()));
}
return packedToScalarMap.insert(it,
std::make_pair(value,results))->second;
}
else {
// we don't know what it is, and we are trying to retrieve
// a value for it
assert(false && "Unhandled PackedType value");
abort();
}
}
void LowerPacked::visitLoadInst(LoadInst& LI)
{
// Make sure what we are dealing with is a packed type
if (const PackedType* PKT = dyn_cast<PackedType>(LI.getType())) {
// Initialization, Idx is needed for getelementptr needed later
std::vector<Value*> Idx(2);
Idx[0] = ConstantUInt::get(Type::UIntTy,0);
ArrayType* AT = ArrayType::get(PKT->getContainedType(0),
PKT->getNumElements());
PointerType* APT = PointerType::get(AT);
// Cast the packed type to an array
Value* array = new CastInst(LI.getPointerOperand(),
APT,
LI.getName() + ".a",
&LI);
// Convert this load into num elements number of loads
std::vector<Value*> values;
values.reserve(PKT->getNumElements());
for (unsigned i = 0, e = PKT->getNumElements(); i != e; ++i) {
// Calculate the second index we will need
Idx[1] = ConstantUInt::get(Type::UIntTy,i);
// Get the pointer
Value* val = new GetElementPtrInst(array,
Idx,
LI.getName() +
".ge." + utostr(i),
&LI);
// generate the new load and save the result in packedToScalar map
values.push_back(new LoadInst(val,
LI.getName()+"."+utostr(i),
LI.isVolatile(),
&LI));
}
setValues(&LI,values);
Changed = true;
instrsToRemove.push_back(&LI);
}
}
void LowerPacked::visitBinaryOperator(BinaryOperator& BO)
{
// Make sure both operands are PackedTypes
if (isa<PackedType>(BO.getOperand(0)->getType())) {
std::vector<Value*>& op0Vals = getValues(BO.getOperand(0));
std::vector<Value*>& op1Vals = getValues(BO.getOperand(1));
std::vector<Value*> result;
assert((op0Vals.size() == op1Vals.size()) &&
"The two packed operand to scalar maps must be equal in size.");
result.reserve(op0Vals.size());
// generate the new binary op and save the result
for (unsigned i = 0; i != op0Vals.size(); ++i) {
result.push_back(BinaryOperator::create(BO.getOpcode(),
op0Vals[i],
op1Vals[i],
BO.getName() +
"." + utostr(i),
&BO));
}
setValues(&BO,result);
Changed = true;
instrsToRemove.push_back(&BO);
}
}
void LowerPacked::visitStoreInst(StoreInst& SI)
{
if (const PackedType* PKT =
dyn_cast<PackedType>(SI.getOperand(0)->getType())) {
// We will need this for getelementptr
std::vector<Value*> Idx(2);
Idx[0] = ConstantUInt::get(Type::UIntTy,0);
ArrayType* AT = ArrayType::get(PKT->getContainedType(0),
PKT->getNumElements());
PointerType* APT = PointerType::get(AT);
// cast the packed to an array type
Value* array = new CastInst(SI.getPointerOperand(),
APT,
"store.ge.a.",
&SI);
std::vector<Value*>& values = getValues(SI.getOperand(0));
assert((values.size() == PKT->getNumElements()) &&
"Scalar must have the same number of elements as Packed Type");
for (unsigned i = 0, e = PKT->getNumElements(); i != e; ++i) {
// Generate the indices for getelementptr
Idx[1] = ConstantUInt::get(Type::UIntTy,i);
Value* val = new GetElementPtrInst(array,
Idx,
"store.ge." +
utostr(i) + ".",
&SI);
new StoreInst(values[i], val, SI.isVolatile(),&SI);
}
Changed = true;
instrsToRemove.push_back(&SI);
}
}
void LowerPacked::visitSelectInst(SelectInst& SELI)
{
// Make sure both operands are PackedTypes
if (isa<PackedType>(SELI.getType())) {
std::vector<Value*>& op0Vals = getValues(SELI.getTrueValue());
std::vector<Value*>& op1Vals = getValues(SELI.getFalseValue());
std::vector<Value*> result;
assert((op0Vals.size() == op1Vals.size()) &&
"The two packed operand to scalar maps must be equal in size.");
for (unsigned i = 0; i != op0Vals.size(); ++i) {
result.push_back(new SelectInst(SELI.getCondition(),
op0Vals[i],
op1Vals[i],
SELI.getName()+ "." + utostr(i),
&SELI));
}
setValues(&SELI,result);
Changed = true;
instrsToRemove.push_back(&SELI);
}
}
bool LowerPacked::runOnFunction(Function& F)
{
// initialize
Changed = false;
// Does three passes:
// Pass 1) Converts Packed Operations to
// new Packed Operations on smaller
// datatypes
visit(F);
// Pass 2) Drop all references
std::for_each(instrsToRemove.begin(),
instrsToRemove.end(),
std::mem_fun(&Instruction::dropAllReferences));
// Pass 3) Delete the Instructions to remove aka packed instructions
for (std::vector<Instruction*>::iterator i = instrsToRemove.begin(),
e = instrsToRemove.end();
i != e; ++i) {
(*i)->getParent()->getInstList().erase(*i);
}
// clean-up
packedToScalarMap.clear();
instrsToRemove.clear();
return Changed;
}