llvm-6502/include/llvm/CodeGen/FastISel.h
2013-07-09 20:08:46 +00:00

404 lines
16 KiB
C++

//===-- FastISel.h - Definition of the FastISel class ---*- mode: c++; -*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file defines the FastISel class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_FASTISEL_H
#define LLVM_CODEGEN_FASTISEL_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/ValueTypes.h"
namespace llvm {
class AllocaInst;
class Constant;
class ConstantFP;
class FunctionLoweringInfo;
class Instruction;
class LoadInst;
class MachineConstantPool;
class MachineFunction;
class MachineInstr;
class MachineFrameInfo;
class MachineRegisterInfo;
class DataLayout;
class TargetInstrInfo;
class TargetLibraryInfo;
class TargetLowering;
class TargetMachine;
class TargetRegisterClass;
class TargetRegisterInfo;
class User;
class Value;
/// This is a fast-path instruction selection class that generates poor code and
/// doesn't support illegal types or non-trivial lowering, but runs quickly.
class FastISel {
protected:
DenseMap<const Value *, unsigned> LocalValueMap;
FunctionLoweringInfo &FuncInfo;
MachineRegisterInfo &MRI;
MachineFrameInfo &MFI;
MachineConstantPool &MCP;
DebugLoc DL;
const TargetMachine &TM;
const DataLayout &TD;
const TargetInstrInfo &TII;
const TargetLowering &TLI;
const TargetRegisterInfo &TRI;
const TargetLibraryInfo *LibInfo;
/// The position of the last instruction for materializing constants for use
/// in the current block. It resets to EmitStartPt when it makes sense (for
/// example, it's usually profitable to avoid function calls between the
/// definition and the use)
MachineInstr *LastLocalValue;
/// The top most instruction in the current block that is allowed for emitting
/// local variables. LastLocalValue resets to EmitStartPt when it makes sense
/// (for example, on function calls)
MachineInstr *EmitStartPt;
public:
/// Return the position of the last instruction emitted for materializing
/// constants for use in the current block.
MachineInstr *getLastLocalValue() { return LastLocalValue; }
/// Update the position of the last instruction emitted for materializing
/// constants for use in the current block.
void setLastLocalValue(MachineInstr *I) {
EmitStartPt = I;
LastLocalValue = I;
}
/// Set the current block to which generated machine instructions will be
/// appended, and clear the local CSE map.
void startNewBlock();
/// Return current debug location information.
DebugLoc getCurDebugLoc() const { return DL; }
/// Do "fast" instruction selection for function arguments and append machine
/// instructions to the current block. Return true if it is successful.
bool LowerArguments();
/// Do "fast" instruction selection for the given LLVM IR instruction, and
/// append generated machine instructions to the current block. Return true if
/// selection was successful.
bool SelectInstruction(const Instruction *I);
/// Do "fast" instruction selection for the given LLVM IR operator
/// (Instruction or ConstantExpr), and append generated machine instructions
/// to the current block. Return true if selection was successful.
bool SelectOperator(const User *I, unsigned Opcode);
/// Create a virtual register and arrange for it to be assigned the value for
/// the given LLVM value.
unsigned getRegForValue(const Value *V);
/// Look up the value to see if its value is already cached in a register. It
/// may be defined by instructions across blocks or defined locally.
unsigned lookUpRegForValue(const Value *V);
/// This is a wrapper around getRegForValue that also takes care of truncating
/// or sign-extending the given getelementptr index value.
std::pair<unsigned, bool> getRegForGEPIndex(const Value *V);
/// \brief We're checking to see if we can fold \p LI into \p FoldInst. Note
/// that we could have a sequence where multiple LLVM IR instructions are
/// folded into the same machineinstr. For example we could have:
///
/// A: x = load i32 *P
/// B: y = icmp A, 42
/// C: br y, ...
///
/// In this scenario, \p LI is "A", and \p FoldInst is "C". We know about "B"
/// (and any other folded instructions) because it is between A and C.
///
/// If we succeed folding, return true.
bool tryToFoldLoad(const LoadInst *LI, const Instruction *FoldInst);
/// \brief The specified machine instr operand is a vreg, and that vreg is
/// being provided by the specified load instruction. If possible, try to
/// fold the load as an operand to the instruction, returning true if
/// possible.
///
/// This method should be implemented by targets.
virtual bool tryToFoldLoadIntoMI(MachineInstr * /*MI*/, unsigned /*OpNo*/,
const LoadInst * /*LI*/) {
return false;
}
/// Reset InsertPt to prepare for inserting instructions into the current
/// block.
void recomputeInsertPt();
/// Remove all dead instructions between the I and E.
void removeDeadCode(MachineBasicBlock::iterator I,
MachineBasicBlock::iterator E);
struct SavePoint {
MachineBasicBlock::iterator InsertPt;
DebugLoc DL;
};
/// Prepare InsertPt to begin inserting instructions into the local value area
/// and return the old insert position.
SavePoint enterLocalValueArea();
/// Reset InsertPt to the given old insert position.
void leaveLocalValueArea(SavePoint Old);
virtual ~FastISel();
protected:
explicit FastISel(FunctionLoweringInfo &funcInfo,
const TargetLibraryInfo *libInfo);
/// This method is called by target-independent code when the normal FastISel
/// process fails to select an instruction. This gives targets a chance to
/// emit code for anything that doesn't fit into FastISel's framework. It
/// returns true if it was successful.
virtual bool
TargetSelectInstruction(const Instruction *I) = 0;
/// This method is called by target-independent code to do target specific
/// argument lowering. It returns true if it was successful.
virtual bool FastLowerArguments();
/// This method is called by target-independent code to request that an
/// instruction with the given type and opcode be emitted.
virtual unsigned FastEmit_(MVT VT,
MVT RetVT,
unsigned Opcode);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and register operand be emitted.
virtual unsigned FastEmit_r(MVT VT,
MVT RetVT,
unsigned Opcode,
unsigned Op0, bool Op0IsKill);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and register operands be emitted.
virtual unsigned FastEmit_rr(MVT VT,
MVT RetVT,
unsigned Opcode,
unsigned Op0, bool Op0IsKill,
unsigned Op1, bool Op1IsKill);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and register and immediate
/// operands be emitted.
virtual unsigned FastEmit_ri(MVT VT,
MVT RetVT,
unsigned Opcode,
unsigned Op0, bool Op0IsKill,
uint64_t Imm);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and register and floating-point
/// immediate operands be emitted.
virtual unsigned FastEmit_rf(MVT VT,
MVT RetVT,
unsigned Opcode,
unsigned Op0, bool Op0IsKill,
const ConstantFP *FPImm);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and register and immediate
/// operands be emitted.
virtual unsigned FastEmit_rri(MVT VT,
MVT RetVT,
unsigned Opcode,
unsigned Op0, bool Op0IsKill,
unsigned Op1, bool Op1IsKill,
uint64_t Imm);
/// \brief This method is a wrapper of FastEmit_ri.
///
/// It first tries to emit an instruction with an immediate operand using
/// FastEmit_ri. If that fails, it materializes the immediate into a register
/// and try FastEmit_rr instead.
unsigned FastEmit_ri_(MVT VT,
unsigned Opcode,
unsigned Op0, bool Op0IsKill,
uint64_t Imm, MVT ImmType);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and immediate operand be emitted.
virtual unsigned FastEmit_i(MVT VT,
MVT RetVT,
unsigned Opcode,
uint64_t Imm);
/// This method is called by target-independent code to request that an
/// instruction with the given type, opcode, and floating-point immediate
/// operand be emitted.
virtual unsigned FastEmit_f(MVT VT,
MVT RetVT,
unsigned Opcode,
const ConstantFP *FPImm);
/// Emit a MachineInstr with no operands and a result register in the given
/// register class.
unsigned FastEmitInst_(unsigned MachineInstOpcode,
const TargetRegisterClass *RC);
/// Emit a MachineInstr with one register operand and a result register in the
/// given register class.
unsigned FastEmitInst_r(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill);
/// Emit a MachineInstr with two register operands and a result register in
/// the given register class.
unsigned FastEmitInst_rr(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
unsigned Op1, bool Op1IsKill);
/// Emit a MachineInstr with three register operands and a result register in
/// the given register class.
unsigned FastEmitInst_rrr(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
unsigned Op1, bool Op1IsKill,
unsigned Op2, bool Op2IsKill);
/// Emit a MachineInstr with a register operand, an immediate, and a result
/// register in the given register class.
unsigned FastEmitInst_ri(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
uint64_t Imm);
/// Emit a MachineInstr with one register operand and two immediate operands.
unsigned FastEmitInst_rii(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
uint64_t Imm1, uint64_t Imm2);
/// Emit a MachineInstr with two register operands and a result register in
/// the given register class.
unsigned FastEmitInst_rf(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
const ConstantFP *FPImm);
/// Emit a MachineInstr with two register operands, an immediate, and a result
/// register in the given register class.
unsigned FastEmitInst_rri(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
unsigned Op1, bool Op1IsKill,
uint64_t Imm);
/// Emit a MachineInstr with two register operands, two immediates operands,
/// and a result register in the given register class.
unsigned FastEmitInst_rrii(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, bool Op0IsKill,
unsigned Op1, bool Op1IsKill,
uint64_t Imm1, uint64_t Imm2);
/// Emit a MachineInstr with a single immediate operand, and a result register
/// in the given register class.
unsigned FastEmitInst_i(unsigned MachineInstrOpcode,
const TargetRegisterClass *RC,
uint64_t Imm);
/// Emit a MachineInstr with a two immediate operands.
unsigned FastEmitInst_ii(unsigned MachineInstrOpcode,
const TargetRegisterClass *RC,
uint64_t Imm1, uint64_t Imm2);
/// Emit a MachineInstr for an extract_subreg from a specified index of a
/// superregister to a specified type.
unsigned FastEmitInst_extractsubreg(MVT RetVT,
unsigned Op0, bool Op0IsKill,
uint32_t Idx);
/// Emit MachineInstrs to compute the value of Op with all but the least
/// significant bit set to zero.
unsigned FastEmitZExtFromI1(MVT VT,
unsigned Op0, bool Op0IsKill);
/// Emit an unconditional branch to the given block, unless it is the
/// immediate (fall-through) successor, and update the CFG.
void FastEmitBranch(MachineBasicBlock *MBB, DebugLoc DL);
void UpdateValueMap(const Value* I, unsigned Reg, unsigned NumRegs = 1);
unsigned createResultReg(const TargetRegisterClass *RC);
/// Emit a constant in a register using target-specific logic, such as
/// constant pool loads.
virtual unsigned TargetMaterializeConstant(const Constant* C) {
return 0;
}
/// Emit an alloca address in a register using target-specific logic.
virtual unsigned TargetMaterializeAlloca(const AllocaInst* C) {
return 0;
}
virtual unsigned TargetMaterializeFloatZero(const ConstantFP* CF) {
return 0;
}
private:
bool SelectBinaryOp(const User *I, unsigned ISDOpcode);
bool SelectFNeg(const User *I);
bool SelectGetElementPtr(const User *I);
bool SelectCall(const User *I);
bool SelectBitCast(const User *I);
bool SelectCast(const User *I, unsigned Opcode);
bool SelectExtractValue(const User *I);
bool SelectInsertValue(const User *I);
/// \brief Handle PHI nodes in successor blocks.
///
/// Emit code to ensure constants are copied into registers when needed.
/// Remember the virtual registers that need to be added to the Machine PHI
/// nodes as input. We cannot just directly add them, because expansion might
/// result in multiple MBB's for one BB. As such, the start of the BB might
/// correspond to a different MBB than the end.
bool HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB);
/// Helper for getRegForVale. This function is called when the value isn't
/// already available in a register and must be materialized with new
/// instructions.
unsigned materializeRegForValue(const Value *V, MVT VT);
/// Clears LocalValueMap and moves the area for the new local variables to the
/// beginning of the block. It helps to avoid spilling cached variables across
/// heavy instructions like calls.
void flushLocalValueMap();
/// Test whether the given value has exactly one use.
bool hasTrivialKill(const Value *V) const;
};
}
#endif