llvm-6502/lib/Target/SparcV9/SparcV9PreSelection.cpp

275 lines
11 KiB
C++
Raw Normal View History

//===- SparcV9PreSelection.cpp - Specialize LLVM code for SparcV9 ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the PreSelection pass which specializes LLVM code for
// the SparcV9 instruction selector, while remaining in legal portable LLVM
// form and preserving type information and type safety. This is meant to enable
// dataflow optimizations on SparcV9-specific operations such as accesses to
// constants, globals, and array indexing.
//
//===----------------------------------------------------------------------===//
#include "SparcV9Internals.h"
#include "SparcV9BurgISel.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/Scalar.h"
#include <algorithm>
using namespace llvm;
namespace {
//===--------------------------------------------------------------------===//
// PreSelection Pass - Specialize LLVM code for the SparcV9 instr. selector.
//
class PreSelection : public FunctionPass, public InstVisitor<PreSelection> {
const TargetInstrInfo &instrInfo;
public:
PreSelection(const TargetMachine &T)
: instrInfo(*T.getInstrInfo()) {}
// runOnFunction - apply this pass to each Function
bool runOnFunction(Function &F) {
visit(F);
return true;
}
const char *getPassName() const { return "SparcV9 Instr. Pre-selection"; }
// These methods do the actual work of specializing code
void visitInstruction(Instruction &I); // common work for every instr.
void visitGetElementPtrInst(GetElementPtrInst &I);
void visitCallInst(CallInst &I);
void visitPHINode(PHINode &PN);
// Helper functions for visiting operands of every instruction
//
// visitOperands() works on every operand in [firstOp, lastOp-1].
// If lastOp==0, lastOp defaults to #operands or #incoming Phi values.
//
// visitOneOperand() does all the work for one operand.
//
void visitOperands(Instruction &I, int firstOp=0);
void visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
Instruction& insertBefore);
};
#if 0
// Register the pass...
RegisterPass<PreSelection> X("preselect",
"Specialize LLVM code for a target machine"
createPreselectionPass);
#endif
} // end anonymous namespace
//------------------------------------------------------------------------------
// Helper functions used by methods of class PreSelection
//------------------------------------------------------------------------------
// getGlobalAddr(): Put address of a global into a v. register.
static GetElementPtrInst* getGlobalAddr(Value* ptr, Instruction& insertBefore) {
return (isa<GlobalVariable>(ptr))
? new GetElementPtrInst(ptr,
std::vector<Value*>(1, ConstantSInt::get(Type::LongTy, 0U)),
"addrOfGlobal:" + ptr->getName(), &insertBefore)
: NULL;
}
// Wrapper on Constant::classof to use in find_if
inline static bool nonConstant(const Use& U) {
return ! isa<Constant>(U);
}
static Instruction* DecomposeConstantExpr(ConstantExpr* CE,
Instruction& insertBefore)
{
Value *getArg1, *getArg2;
switch(CE->getOpcode())
{
case Instruction::Cast:
getArg1 = CE->getOperand(0);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
return new CastInst(getArg1, CE->getType(), "constantCast",&insertBefore);
case Instruction::GetElementPtr:
assert(find_if(CE->op_begin()+1, CE->op_end(),nonConstant) == CE->op_end()
&& "All indices in ConstantExpr getelementptr must be constant!");
getArg1 = CE->getOperand(0);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
else if (GetElementPtrInst* gep = getGlobalAddr(getArg1, insertBefore))
getArg1 = gep;
return new GetElementPtrInst(getArg1,
std::vector<Value*>(CE->op_begin()+1, CE->op_end()),
"constantGEP:" + getArg1->getName(), &insertBefore);
case Instruction::Select: {
Value *C, *S1, *S2;
C = CE->getOperand (0);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (C))
C = DecomposeConstantExpr (CEarg, insertBefore);
S1 = CE->getOperand (1);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S1))
S1 = DecomposeConstantExpr (CEarg, insertBefore);
S2 = CE->getOperand (2);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S2))
S2 = DecomposeConstantExpr (CEarg, insertBefore);
return new SelectInst (C, S1, S2, "constantSelect", &insertBefore);
}
default: // must be a binary operator
assert(CE->getOpcode() >= Instruction::BinaryOpsBegin &&
CE->getOpcode() < Instruction::BinaryOpsEnd &&
"Unhandled opcode in ConstantExpr");
getArg1 = CE->getOperand(0);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
getArg2 = CE->getOperand(1);
if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg2))
getArg2 = DecomposeConstantExpr(CEarg, insertBefore);
return BinaryOperator::create((Instruction::BinaryOps) CE->getOpcode(),
getArg1, getArg2,
"constantBinaryOp", &insertBefore);
}
}
static inline bool ConstantTypeMustBeLoaded(const Type* CVT) {
assert(CVT->isPrimitiveType() || isa<PointerType>(CVT));
return !(CVT->isIntegral() || isa<PointerType>(CVT));
}
//------------------------------------------------------------------------------
// Instruction visitor methods to perform instruction-specific operations
//------------------------------------------------------------------------------
inline void
PreSelection::visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
Instruction& insertBefore)
{
assert(&insertBefore != NULL && "Must have instruction to insert before.");
if (GetElementPtrInst* gep = getGlobalAddr(Op, insertBefore)) {
I.setOperand(opNum, gep); // replace global operand
return; // nothing more to do for this op.
}
Constant* CV = dyn_cast<Constant>(Op);
if (CV == NULL)
return;
if (ConstantExpr* CE = dyn_cast<ConstantExpr>(CV)) {
// load-time constant: factor it out so we optimize as best we can
Instruction* computeConst = DecomposeConstantExpr(CE, insertBefore);
I.setOperand(opNum, computeConst); // replace expr operand with result
} else if (ConstantTypeMustBeLoaded(CV->getType())) {
// load address of constant into a register, then load the constant
// this is now done during instruction selection
// the constant will live in the MachineConstantPool later on
} else if (ConstantMayNotFitInImmedField(CV, &I)) {
// put the constant into a virtual register using a cast
CastInst* castI = new CastInst(CV, CV->getType(), "copyConst",
&insertBefore);
I.setOperand(opNum, castI); // replace operand with copy in v.reg.
}
}
/// visitOperands - transform individual operands of all instructions:
/// -- Load "large" int constants into a virtual register. What is large
/// depends on the type of instruction and on the target architecture.
/// -- For any constants that cannot be put in an immediate field,
/// load address into virtual register first, and then load the constant.
///
/// firstOp and lastOp can be used to skip leading and trailing operands.
/// If lastOp is 0, it defaults to #operands or #incoming Phi values.
///
inline void PreSelection::visitOperands(Instruction &I, int firstOp) {
// For any instruction other than PHI, copies go just before the instr.
for (unsigned i = firstOp, e = I.getNumOperands(); i != e; ++i)
visitOneOperand(I, I.getOperand(i), i, I);
}
void PreSelection::visitPHINode(PHINode &PN) {
// For a PHI, operand copies must be before the terminator of the
// appropriate predecessor basic block. Remaining logic is simple
// so just handle PHIs and other instructions separately.
//
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
visitOneOperand(PN, PN.getIncomingValue(i),
PN.getOperandNumForIncomingValue(i),
*PN.getIncomingBlock(i)->getTerminator());
// do not call visitOperands!
}
// Common work for *all* instructions. This needs to be called explicitly
// by other visit<InstructionType> functions.
inline void PreSelection::visitInstruction(Instruction &I) {
visitOperands(I); // Perform operand transformations
}
// GetElementPtr instructions: check if pointer is a global
void PreSelection::visitGetElementPtrInst(GetElementPtrInst &I) {
Instruction* curI = &I;
// The Sparc backend doesn't handle array indexes that are not long types, so
// insert a cast from whatever it is to long, if the sequential type index is
// not a long already.
unsigned Idx = 1;
for (gep_type_iterator TI = gep_type_begin(I), E = gep_type_end(I); TI != E;
++TI, ++Idx)
if (isa<SequentialType>(*TI) &&
I.getOperand(Idx)->getType() != Type::LongTy) {
Value *Op = I.getOperand(Idx);
if (Op->getType()->isUnsigned()) // Must sign extend!
Op = new CastInst(Op, Op->getType()->getSignedVersion(), "v9", &I);
if (Op->getType() != Type::LongTy)
Op = new CastInst(Op, Type::LongTy, "v9", &I);
I.setOperand(Idx, Op);
}
// Decompose multidimensional array references
if (I.getNumIndices() >= 2) {
// DecomposeArrayRef() replaces I and deletes it, if successful,
// so remember predecessor in order to find the replacement instruction.
// Also remember the basic block in case there is no predecessor.
Instruction* prevI = I.getPrev();
BasicBlock* bb = I.getParent();
if (DecomposeArrayRef(&I))
// first instr. replacing I
curI = cast<GetElementPtrInst>(prevI? prevI->getNext() : &bb->front());
}
// Perform other transformations common to all instructions
visitInstruction(*curI);
}
void PreSelection::visitCallInst(CallInst &I) {
// Tell visitOperands to ignore the function name if this is a direct call.
visitOperands(I, (/*firstOp=*/ I.getCalledFunction()? 1 : 0));
}
/// createPreSelectionPass - Public entry point for the PreSelection pass
///
FunctionPass* llvm::createPreSelectionPass(const TargetMachine &TM) {
return new PreSelection(TM);
}