--- /dev/null
+//===- 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/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 "Support/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
+
+// 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;
+}
+
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