llvm-6502/include/llvm/Target/TargetInstrInfo.h
Dan Gohman 61e804f22b Clarify the comments here, to make slightly more clear the
difference in purpose of TargetInstrInfo and TargetInstrDesc,
which isn't immediately obvious from the name.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53683 91177308-0d34-0410-b5e6-96231b3b80d8
2008-07-16 16:02:59 +00:00

435 lines
19 KiB
C++

//===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file describes the target machine instruction set to the code generator.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_TARGETINSTRINFO_H
#define LLVM_TARGET_TARGETINSTRINFO_H
#include "llvm/Target/TargetInstrDesc.h"
#include "llvm/CodeGen/MachineFunction.h"
namespace llvm {
class TargetRegisterClass;
class LiveVariables;
class CalleeSavedInfo;
class SDNode;
class SelectionDAG;
template<class T> class SmallVectorImpl;
//---------------------------------------------------------------------------
///
/// TargetInstrInfo - Interface to description of machine instruction set
///
class TargetInstrInfo {
const TargetInstrDesc *Descriptors; // Raw array to allow static init'n
unsigned NumOpcodes; // Number of entries in the desc array
TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
public:
TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes);
virtual ~TargetInstrInfo();
// Invariant opcodes: All instruction sets have these as their low opcodes.
enum {
PHI = 0,
INLINEASM = 1,
DBG_LABEL = 2,
EH_LABEL = 3,
GC_LABEL = 4,
DECLARE = 5,
EXTRACT_SUBREG = 6,
INSERT_SUBREG = 7,
IMPLICIT_DEF = 8,
SUBREG_TO_REG = 9
};
unsigned getNumOpcodes() const { return NumOpcodes; }
/// get - Return the machine instruction descriptor that corresponds to the
/// specified instruction opcode.
///
const TargetInstrDesc &get(unsigned Opcode) const {
assert(Opcode < NumOpcodes && "Invalid opcode!");
return Descriptors[Opcode];
}
/// isTriviallyReMaterializable - Return true if the instruction is trivially
/// rematerializable, meaning it has no side effects and requires no operands
/// that aren't always available.
bool isTriviallyReMaterializable(const MachineInstr *MI) const {
return MI->getDesc().isRematerializable() &&
isReallyTriviallyReMaterializable(MI);
}
protected:
/// isReallyTriviallyReMaterializable - For instructions with opcodes for
/// which the M_REMATERIALIZABLE flag is set, this function tests whether the
/// instruction itself is actually trivially rematerializable, considering
/// its operands. This is used for targets that have instructions that are
/// only trivially rematerializable for specific uses. This predicate must
/// return false if the instruction has any side effects other than
/// producing a value, or if it requres any address registers that are not
/// always available.
virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI) const {
return true;
}
public:
/// Return true if the instruction is a register to register move
/// and leave the source and dest operands in the passed parameters.
virtual bool isMoveInstr(const MachineInstr& MI,
unsigned& sourceReg,
unsigned& destReg) const {
return false;
}
/// isLoadFromStackSlot - If the specified machine instruction is a direct
/// load from a stack slot, return the virtual or physical register number of
/// the destination along with the FrameIndex of the loaded stack slot. If
/// not, return 0. This predicate must return 0 if the instruction has
/// any side effects other than loading from the stack slot.
virtual unsigned isLoadFromStackSlot(MachineInstr *MI, int &FrameIndex) const{
return 0;
}
/// isStoreToStackSlot - If the specified machine instruction is a direct
/// store to a stack slot, return the virtual or physical register number of
/// the source reg along with the FrameIndex of the loaded stack slot. If
/// not, return 0. This predicate must return 0 if the instruction has
/// any side effects other than storing to the stack slot.
virtual unsigned isStoreToStackSlot(MachineInstr *MI, int &FrameIndex) const {
return 0;
}
/// reMaterialize - Re-issue the specified 'original' instruction at the
/// specific location targeting a new destination register.
virtual void reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg,
const MachineInstr *Orig) const = 0;
/// isInvariantLoad - Return true if the specified instruction (which is
/// marked mayLoad) is loading from a location whose value is invariant across
/// the function. For example, loading a value from the constant pool or from
/// from the argument area of a function if it does not change. This should
/// only return true of *all* loads the instruction does are invariant (if it
/// does multiple loads).
virtual bool isInvariantLoad(MachineInstr *MI) const {
return false;
}
/// convertToThreeAddress - This method must be implemented by targets that
/// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
/// may be able to convert a two-address instruction into one or more true
/// three-address instructions on demand. This allows the X86 target (for
/// example) to convert ADD and SHL instructions into LEA instructions if they
/// would require register copies due to two-addressness.
///
/// This method returns a null pointer if the transformation cannot be
/// performed, otherwise it returns the last new instruction.
///
virtual MachineInstr *
convertToThreeAddress(MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const {
return 0;
}
/// commuteInstruction - If a target has any instructions that are commutable,
/// but require converting to a different instruction or making non-trivial
/// changes to commute them, this method can overloaded to do this. The
/// default implementation of this method simply swaps the first two operands
/// of MI and returns it.
///
/// If a target wants to make more aggressive changes, they can construct and
/// return a new machine instruction. If an instruction cannot commute, it
/// can also return null.
///
/// If NewMI is true, then a new machine instruction must be created.
///
virtual MachineInstr *commuteInstruction(MachineInstr *MI,
bool NewMI = false) const = 0;
/// CommuteChangesDestination - Return true if commuting the specified
/// instruction will also changes the destination operand. Also return the
/// current operand index of the would be new destination register by
/// reference. This can happen when the commutable instruction is also a
/// two-address instruction.
virtual bool CommuteChangesDestination(MachineInstr *MI,
unsigned &OpIdx) const = 0;
/// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
/// true if it cannot be understood (e.g. it's a switch dispatch or isn't
/// implemented for a target). Upon success, this returns false and returns
/// with the following information in various cases:
///
/// 1. If this block ends with no branches (it just falls through to its succ)
/// just return false, leaving TBB/FBB null.
/// 2. If this block ends with only an unconditional branch, it sets TBB to be
/// the destination block.
/// 3. If this block ends with an conditional branch and it falls through to
/// an successor block, it sets TBB to be the branch destination block and a
/// list of operands that evaluate the condition. These
/// operands can be passed to other TargetInstrInfo methods to create new
/// branches.
/// 4. If this block ends with an conditional branch and an unconditional
/// block, it returns the 'true' destination in TBB, the 'false' destination
/// in FBB, and a list of operands that evaluate the condition. These
/// operands can be passed to other TargetInstrInfo methods to create new
/// branches.
///
/// Note that RemoveBranch and InsertBranch must be implemented to support
/// cases where this method returns success.
///
virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
std::vector<MachineOperand> &Cond) const {
return true;
}
/// RemoveBranch - Remove the branching code at the end of the specific MBB.
/// this is only invoked in cases where AnalyzeBranch returns success. It
/// returns the number of instructions that were removed.
virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
return 0;
}
/// InsertBranch - Insert a branch into the end of the specified
/// MachineBasicBlock. This operands to this method are the same as those
/// returned by AnalyzeBranch. This is invoked in cases where AnalyzeBranch
/// returns success and when an unconditional branch (TBB is non-null, FBB is
/// null, Cond is empty) needs to be inserted. It returns the number of
/// instructions inserted.
virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const std::vector<MachineOperand> &Cond) const {
assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
return 0;
}
/// copyRegToReg - Add a copy between a pair of registers
virtual void copyRegToReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, unsigned SrcReg,
const TargetRegisterClass *DestRC,
const TargetRegisterClass *SrcRC) const {
assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!");
}
virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned SrcReg, bool isKill, int FrameIndex,
const TargetRegisterClass *RC) const {
assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
}
virtual void storeRegToAddr(MachineFunction &MF, unsigned SrcReg, bool isKill,
SmallVectorImpl<MachineOperand> &Addr,
const TargetRegisterClass *RC,
SmallVectorImpl<MachineInstr*> &NewMIs) const {
assert(0 && "Target didn't implement TargetInstrInfo::storeRegToAddr!");
}
virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg, int FrameIndex,
const TargetRegisterClass *RC) const {
assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
}
virtual void loadRegFromAddr(MachineFunction &MF, unsigned DestReg,
SmallVectorImpl<MachineOperand> &Addr,
const TargetRegisterClass *RC,
SmallVectorImpl<MachineInstr*> &NewMIs) const {
assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromAddr!");
}
/// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
/// saved registers and returns true if it isn't possible / profitable to do
/// so by issuing a series of store instructions via
/// storeRegToStackSlot(). Returns false otherwise.
virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI) const {
return false;
}
/// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee
/// saved registers and returns true if it isn't possible / profitable to do
/// so by issuing a series of load instructions via loadRegToStackSlot().
/// Returns false otherwise.
virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI) const {
return false;
}
/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
/// slot into the specified machine instruction for the specified operand(s).
/// If this is possible, a new instruction is returned with the specified
/// operand folded, otherwise NULL is returned. The client is responsible for
/// removing the old instruction and adding the new one in the instruction
/// stream.
virtual MachineInstr* foldMemoryOperand(MachineFunction &MF,
MachineInstr* MI,
SmallVectorImpl<unsigned> &Ops,
int FrameIndex) const {
return 0;
}
/// foldMemoryOperand - Same as the previous version except it allows folding
/// of any load and store from / to any address, not just from a specific
/// stack slot.
virtual MachineInstr* foldMemoryOperand(MachineFunction &MF,
MachineInstr* MI,
SmallVectorImpl<unsigned> &Ops,
MachineInstr* LoadMI) const {
return 0;
}
/// canFoldMemoryOperand - Returns true if the specified load / store is
/// folding is possible.
virtual
bool canFoldMemoryOperand(MachineInstr *MI,
SmallVectorImpl<unsigned> &Ops) const{
return false;
}
/// unfoldMemoryOperand - Separate a single instruction which folded a load or
/// a store or a load and a store into two or more instruction. If this is
/// possible, returns true as well as the new instructions by reference.
virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
SmallVectorImpl<MachineInstr*> &NewMIs) const{
return false;
}
virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
SmallVectorImpl<SDNode*> &NewNodes) const {
return false;
}
/// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
/// instruction after load / store are unfolded from an instruction of the
/// specified opcode. It returns zero if the specified unfolding is not
/// possible.
virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
bool UnfoldLoad, bool UnfoldStore) const {
return 0;
}
/// BlockHasNoFallThrough - Return true if the specified block does not
/// fall-through into its successor block. This is primarily used when a
/// branch is unanalyzable. It is useful for things like unconditional
/// indirect branches (jump tables).
virtual bool BlockHasNoFallThrough(MachineBasicBlock &MBB) const {
return false;
}
/// ReverseBranchCondition - Reverses the branch condition of the specified
/// condition list, returning false on success and true if it cannot be
/// reversed.
virtual bool ReverseBranchCondition(std::vector<MachineOperand> &Cond) const {
return true;
}
/// insertNoop - Insert a noop into the instruction stream at the specified
/// point.
virtual void insertNoop(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
assert(0 && "Target didn't implement insertNoop!");
abort();
}
/// isPredicated - Returns true if the instruction is already predicated.
///
virtual bool isPredicated(const MachineInstr *MI) const {
return false;
}
/// isUnpredicatedTerminator - Returns true if the instruction is a
/// terminator instruction that has not been predicated.
virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
/// PredicateInstruction - Convert the instruction into a predicated
/// instruction. It returns true if the operation was successful.
virtual
bool PredicateInstruction(MachineInstr *MI,
const std::vector<MachineOperand> &Pred) const = 0;
/// SubsumesPredicate - Returns true if the first specified predicate
/// subsumes the second, e.g. GE subsumes GT.
virtual
bool SubsumesPredicate(const std::vector<MachineOperand> &Pred1,
const std::vector<MachineOperand> &Pred2) const {
return false;
}
/// DefinesPredicate - If the specified instruction defines any predicate
/// or condition code register(s) used for predication, returns true as well
/// as the definition predicate(s) by reference.
virtual bool DefinesPredicate(MachineInstr *MI,
std::vector<MachineOperand> &Pred) const {
return false;
}
/// getPointerRegClass - Returns a TargetRegisterClass used for pointer
/// values.
virtual const TargetRegisterClass *getPointerRegClass() const {
assert(0 && "Target didn't implement getPointerRegClass!");
abort();
return 0; // Must return a value in order to compile with VS 2005
}
/// GetInstSize - Returns the size of the specified Instruction.
///
virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const {
assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!");
return 0;
}
/// GetFunctionSizeInBytes - Returns the size of the specified MachineFunction.
///
virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0;
};
/// TargetInstrInfoImpl - This is the default implementation of
/// TargetInstrInfo, which just provides a couple of default implementations
/// for various methods. This separated out because it is implemented in
/// libcodegen, not in libtarget.
class TargetInstrInfoImpl : public TargetInstrInfo {
protected:
TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes)
: TargetInstrInfo(desc, NumOpcodes) {}
public:
virtual MachineInstr *commuteInstruction(MachineInstr *MI,
bool NewMI = false) const;
virtual bool CommuteChangesDestination(MachineInstr *MI,
unsigned &OpIdx) const;
virtual bool PredicateInstruction(MachineInstr *MI,
const std::vector<MachineOperand> &Pred) const;
virtual void reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned DestReg,
const MachineInstr *Orig) const;
virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const;
};
} // End llvm namespace
#endif