//===-- llvm/Mc/McInstrDesc.h - Instruction Descriptors -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the MCOperandInfo and MCInstrDesc classes, which
// are used to describe target instructions and their operands.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCINSTRDESC_H
#define LLVM_MC_MCINSTRDESC_H
#include "llvm/Support/DataTypes.h"
namespace llvm {
//===----------------------------------------------------------------------===//
// Machine Operand Flags and Description
//===----------------------------------------------------------------------===//
namespace MCOI {
// Operand constraints
enum OperandConstraint {
TIED_TO = 0, // Must be allocated the same register as.
EARLY_CLOBBER // Operand is an early clobber register operand
};
/// OperandFlags - These are flags set on operands, but should be considered
/// private, all access should go through the MCOperandInfo accessors.
/// See the accessors for a description of what these are.
enum OperandFlags {
LookupPtrRegClass = 0,
Predicate,
OptionalDef
};
/// Operand Type - Operands are tagged with one of the values of this enum.
enum OperandType {
OPERAND_UNKNOWN,
OPERAND_IMMEDIATE,
OPERAND_REGISTER,
OPERAND_MEMORY,
OPERAND_PCREL
};
}
/// MCOperandInfo - This holds information about one operand of a machine
/// instruction, indicating the register class for register operands, etc.
///
class MCOperandInfo {
public:
/// RegClass - This specifies the register class enumeration of the operand
/// if the operand is a register. If isLookupPtrRegClass is set, then this is
/// an index that is passed to TargetRegisterInfo::getPointerRegClass(x) to
/// get a dynamic register class.
short RegClass;
/// Flags - These are flags from the MCOI::OperandFlags enum.
unsigned short Flags;
/// Lower 16 bits are used to specify which constraints are set. The higher 16
/// bits are used to specify the value of constraints (4 bits each).
unsigned Constraints;
/// OperandType - Information about the type of the operand.
MCOI::OperandType OperandType;
/// Currently no other information.
/// isLookupPtrRegClass - Set if this operand is a pointer value and it
/// requires a callback to look up its register class.
bool isLookupPtrRegClass() const {return Flags&(1 <<MCOI::LookupPtrRegClass);}
/// isPredicate - Set if this is one of the operands that made up of
/// the predicate operand that controls an isPredicable() instruction.
bool isPredicate() const { return Flags & (1 << MCOI::Predicate); }
/// isOptionalDef - Set if this operand is a optional def.
///
bool isOptionalDef() const { return Flags & (1 << MCOI::OptionalDef); }
};
//===----------------------------------------------------------------------===//
// Machine Instruction Flags and Description
//===----------------------------------------------------------------------===//
/// MCInstrDesc flags - These should be considered private to the
/// implementation of the MCInstrDesc class. Clients should use the predicate
/// methods on MCInstrDesc, not use these directly. These all correspond to
/// bitfields in the MCInstrDesc::Flags field.
namespace MCID {
enum {
Variadic = 0,
HasOptionalDef,
Pseudo,
Return,
Call,
Barrier,
Terminator,
Branch,
IndirectBranch,
Compare,
MoveImm,
Bitcast,
DelaySlot,
FoldableAsLoad,
MayLoad,
MayStore,
Predicable,
NotDuplicable,
UnmodeledSideEffects,
Commutable,
ConvertibleTo3Addr,
UsesCustomInserter,
HasPostISelHook,
Rematerializable,
CheapAsAMove,
ExtraSrcRegAllocReq,
ExtraDefRegAllocReq
};
}
/// MCInstrDesc - Describe properties that are true of each instruction in the
/// target description file. This captures information about side effects,
/// register use and many other things. There is one instance of this struct
/// for each target instruction class, and the MachineInstr class points to
/// this struct directly to describe itself.
class MCInstrDesc {
public:
unsigned short Opcode; // The opcode number
unsigned short NumOperands; // Num of args (may be more if variable_ops)
unsigned short NumDefs; // Num of args that are definitions
unsigned short SchedClass; // enum identifying instr sched class
unsigned short Size; // Number of bytes in encoding.
const char * Name; // Name of the instruction record in td file
unsigned Flags; // Flags identifying machine instr class
uint64_t TSFlags; // Target Specific Flag values
const unsigned *ImplicitUses; // Registers implicitly read by this instr
const unsigned *ImplicitDefs; // Registers implicitly defined by this instr
const MCOperandInfo *OpInfo; // 'NumOperands' entries about operands
/// getOperandConstraint - Returns the value of the specific constraint if
/// it is set. Returns -1 if it is not set.
int getOperandConstraint(unsigned OpNum,
MCOI::OperandConstraint Constraint) const {
if (OpNum < NumOperands &&
(OpInfo[OpNum].Constraints & (1 << Constraint))) {
unsigned Pos = 16 + Constraint * 4;
return (int)(OpInfo[OpNum].Constraints >> Pos) & 0xf;
}
return -1;
}
/// getOpcode - Return the opcode number for this descriptor.
unsigned getOpcode() const {
return Opcode;
}
/// getName - Return the name of the record in the .td file for this
/// instruction, for example "ADD8ri".
const char *getName() const {
return Name;
}
/// getNumOperands - Return the number of declared MachineOperands for this
/// MachineInstruction. Note that variadic (isVariadic() returns true)
/// instructions may have additional operands at the end of the list, and note
/// that the machine instruction may include implicit register def/uses as
/// well.
unsigned getNumOperands() const {
return NumOperands;
}
/// getNumDefs - Return the number of MachineOperands that are register
/// definitions. Register definitions always occur at the start of the
/// machine operand list. This is the number of "outs" in the .td file,
/// and does not include implicit defs.
unsigned getNumDefs() const {
return NumDefs;
}
/// isVariadic - Return true if this instruction can have a variable number of
/// operands. In this case, the variable operands will be after the normal
/// operands but before the implicit definitions and uses (if any are
/// present).
bool isVariadic() const {
return Flags & (1 << MCID::Variadic);
}
/// hasOptionalDef - Set if this instruction has an optional definition, e.g.
/// ARM instructions which can set condition code if 's' bit is set.
bool hasOptionalDef() const {
return Flags & (1 << MCID::HasOptionalDef);
}
/// getImplicitUses - Return a list of registers that are potentially
/// read by any instance of this machine instruction. For example, on X86,
/// the "adc" instruction adds two register operands and adds the carry bit in
/// from the flags register. In this case, the instruction is marked as
/// implicitly reading the flags. Likewise, the variable shift instruction on
/// X86 is marked as implicitly reading the 'CL' register, which it always
/// does.
///
/// This method returns null if the instruction has no implicit uses.
const unsigned *getImplicitUses() const {
return ImplicitUses;
}
/// getNumImplicitUses - Return the number of implicit uses this instruction
/// has.
unsigned getNumImplicitUses() const {
if (ImplicitUses == 0) return 0;
unsigned i = 0;
for (; ImplicitUses[i]; ++i) /*empty*/;
return i;
}
/// getImplicitDefs - Return a list of registers that are potentially
/// written by any instance of this machine instruction. For example, on X86,
/// many instructions implicitly set the flags register. In this case, they
/// are marked as setting the FLAGS. Likewise, many instructions always
/// deposit their result in a physical register. For example, the X86 divide
/// instruction always deposits the quotient and remainder in the EAX/EDX
/// registers. For that instruction, this will return a list containing the
/// EAX/EDX/EFLAGS registers.
///
/// This method returns null if the instruction has no implicit defs.
const unsigned *getImplicitDefs() const {
return ImplicitDefs;
}
/// getNumImplicitDefs - Return the number of implicit defs this instruction
/// has.
unsigned getNumImplicitDefs() const {
if (ImplicitDefs == 0) return 0;
unsigned i = 0;
for (; ImplicitDefs[i]; ++i) /*empty*/;
return i;
}
/// hasImplicitUseOfPhysReg - Return true if this instruction implicitly
/// uses the specified physical register.
bool hasImplicitUseOfPhysReg(unsigned Reg) const {
if (const unsigned *ImpUses = ImplicitUses)
for (; *ImpUses; ++ImpUses)
if (*ImpUses == Reg) return true;
return false;
}
/// hasImplicitDefOfPhysReg - Return true if this instruction implicitly
/// defines the specified physical register.
bool hasImplicitDefOfPhysReg(unsigned Reg) const {
if (const unsigned *ImpDefs = ImplicitDefs)
for (; *ImpDefs; ++ImpDefs)
if (*ImpDefs == Reg) return true;
return false;
}
/// getSchedClass - Return the scheduling class for this instruction. The
/// scheduling class is an index into the InstrItineraryData table. This
/// returns zero if there is no known scheduling information for the
/// instruction.
///
unsigned getSchedClass() const {
return SchedClass;
}
/// getSize - Return the number of bytes in the encoding of this instruction,
/// or zero if the encoding size cannot be known from the opcode.
unsigned getSize() const {
return Size;
}
/// isPseudo - Return true if this is a pseudo instruction that doesn't
/// correspond to a real machine instruction.
///
bool isPseudo() const {
return Flags & (1 << MCID::Pseudo);
}
bool isReturn() const {
return Flags & (1 << MCID::Return);
}
bool isCall() const {
return Flags & (1 << MCID::Call);
}
/// isBarrier - Returns true if the specified instruction stops control flow
/// from executing the instruction immediately following it. Examples include
/// unconditional branches and return instructions.
bool isBarrier() const {
return Flags & (1 << MCID::Barrier);
}
/// findFirstPredOperandIdx() - Find the index of the first operand in the
/// operand list that is used to represent the predicate. It returns -1 if
/// none is found.
int findFirstPredOperandIdx() const {
if (isPredicable()) {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (OpInfo[i].isPredicate())
return i;
}
return -1;
}
/// isTerminator - Returns true if this instruction part of the terminator for
/// a basic block. Typically this is things like return and branch
/// instructions.
///
/// Various passes use this to insert code into the bottom of a basic block,
/// but before control flow occurs.
bool isTerminator() const {
return Flags & (1 << MCID::Terminator);
}
/// isBranch - Returns true if this is a conditional, unconditional, or
/// indirect branch. Predicates below can be used to discriminate between
/// these cases, and the TargetInstrInfo::AnalyzeBranch method can be used to
/// get more information.
bool isBranch() const {
return Flags & (1 << MCID::Branch);
}
/// isIndirectBranch - Return true if this is an indirect branch, such as a
/// branch through a register.
bool isIndirectBranch() const {
return Flags & (1 << MCID::IndirectBranch);
}
/// isConditionalBranch - Return true if this is a branch which may fall
/// through to the next instruction or may transfer control flow to some other
/// block. The TargetInstrInfo::AnalyzeBranch method can be used to get more
/// information about this branch.
bool isConditionalBranch() const {
return isBranch() & !isBarrier() & !isIndirectBranch();
}
/// isUnconditionalBranch - Return true if this is a branch which always
/// transfers control flow to some other block. The
/// TargetInstrInfo::AnalyzeBranch method can be used to get more information
/// about this branch.
bool isUnconditionalBranch() const {
return isBranch() & isBarrier() & !isIndirectBranch();
}
// isPredicable - Return true if this instruction has a predicate operand that
// controls execution. It may be set to 'always', or may be set to other
/// values. There are various methods in TargetInstrInfo that can be used to
/// control and modify the predicate in this instruction.
bool isPredicable() const {
return Flags & (1 << MCID::Predicable);
}
/// isCompare - Return true if this instruction is a comparison.
bool isCompare() const {
return Flags & (1 << MCID::Compare);
}
/// isMoveImmediate - Return true if this instruction is a move immediate
/// (including conditional moves) instruction.
bool isMoveImmediate() const {
return Flags & (1 << MCID::MoveImm);
}
/// isBitcast - Return true if this instruction is a bitcast instruction.
///
bool isBitcast() const {
return Flags & (1 << MCID::Bitcast);
}
/// isNotDuplicable - Return true if this instruction cannot be safely
/// duplicated. For example, if the instruction has a unique labels attached
/// to it, duplicating it would cause multiple definition errors.
bool isNotDuplicable() const {
return Flags & (1 << MCID::NotDuplicable);
}
/// hasDelaySlot - Returns true if the specified instruction has a delay slot
/// which must be filled by the code generator.
bool hasDelaySlot() const {
return Flags & (1 << MCID::DelaySlot);
}
/// canFoldAsLoad - Return true for instructions that can be folded as
/// memory operands in other instructions. The most common use for this
/// is instructions that are simple loads from memory that don't modify
/// the loaded value in any way, but it can also be used for instructions
/// that can be expressed as constant-pool loads, such as V_SETALLONES
/// on x86, to allow them to be folded when it is beneficial.
/// This should only be set on instructions that return a value in their
/// only virtual register definition.
bool canFoldAsLoad() const {
return Flags & (1 << MCID::FoldableAsLoad);
}
//===--------------------------------------------------------------------===//
// Side Effect Analysis
//===--------------------------------------------------------------------===//
/// mayLoad - Return true if this instruction could possibly read memory.
/// Instructions with this flag set are not necessarily simple load
/// instructions, they may load a value and modify it, for example.
bool mayLoad() const {
return Flags & (1 << MCID::MayLoad);
}
/// mayStore - Return true if this instruction could possibly modify memory.
/// Instructions with this flag set are not necessarily simple store
/// instructions, they may store a modified value based on their operands, or
/// may not actually modify anything, for example.
bool mayStore() const {
return Flags & (1 << MCID::MayStore);
}
/// hasUnmodeledSideEffects - Return true if this instruction has side
/// effects that are not modeled by other flags. This does not return true
/// for instructions whose effects are captured by:
///
/// 1. Their operand list and implicit definition/use list. Register use/def
/// info is explicit for instructions.
/// 2. Memory accesses. Use mayLoad/mayStore.
/// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
///
/// Examples of side effects would be modifying 'invisible' machine state like
/// a control register, flushing a cache, modifying a register invisible to
/// LLVM, etc.
///
bool hasUnmodeledSideEffects() const {
return Flags & (1 << MCID::UnmodeledSideEffects);
}
//===--------------------------------------------------------------------===//
// Flags that indicate whether an instruction can be modified by a method.
//===--------------------------------------------------------------------===//
/// isCommutable - Return true if this may be a 2- or 3-address
/// instruction (of the form "X = op Y, Z, ..."), which produces the same
/// result if Y and Z are exchanged. If this flag is set, then the
/// TargetInstrInfo::commuteInstruction method may be used to hack on the
/// instruction.
///
/// Note that this flag may be set on instructions that are only commutable
/// sometimes. In these cases, the call to commuteInstruction will fail.
/// Also note that some instructions require non-trivial modification to
/// commute them.
bool isCommutable() const {
return Flags & (1 << MCID::Commutable);
}
/// isConvertibleTo3Addr - Return true if this is a 2-address instruction
/// which can be changed into a 3-address instruction if needed. Doing this
/// transformation can be profitable in the register allocator, because it
/// means that the instruction can use a 2-address form if possible, but
/// degrade into a less efficient form if the source and dest register cannot
/// be assigned to the same register. For example, this allows the x86
/// backend to turn a "shl reg, 3" instruction into an LEA instruction, which
/// is the same speed as the shift but has bigger code size.
///
/// If this returns true, then the target must implement the
/// TargetInstrInfo::convertToThreeAddress method for this instruction, which
/// is allowed to fail if the transformation isn't valid for this specific
/// instruction (e.g. shl reg, 4 on x86).
///
bool isConvertibleTo3Addr() const {
return Flags & (1 << MCID::ConvertibleTo3Addr);
}
/// usesCustomInsertionHook - Return true if this instruction requires
/// custom insertion support when the DAG scheduler is inserting it into a
/// machine basic block. If this is true for the instruction, it basically
/// means that it is a pseudo instruction used at SelectionDAG time that is
/// expanded out into magic code by the target when MachineInstrs are formed.
///
/// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
/// is used to insert this into the MachineBasicBlock.
bool usesCustomInsertionHook() const {
return Flags & (1 << MCID::UsesCustomInserter);
}
/// hasPostISelHook - Return true if this instruction requires *adjustment*
/// after instruction selection by calling a target hook. For example, this
/// can be used to fill in ARM 's' optional operand depending on whether
/// the conditional flag register is used.
bool hasPostISelHook() const {
return Flags & (1 << MCID::HasPostISelHook);
}
/// isRematerializable - Returns true if this instruction is a candidate for
/// remat. This flag is deprecated, please don't use it anymore. If this
/// flag is set, the isReallyTriviallyReMaterializable() method is called to
/// verify the instruction is really rematable.
bool isRematerializable() const {
return Flags & (1 << MCID::Rematerializable);
}
/// isAsCheapAsAMove - Returns true if this instruction has the same cost (or
/// less) than a move instruction. This is useful during certain types of
/// optimizations (e.g., remat during two-address conversion or machine licm)
/// where we would like to remat or hoist the instruction, but not if it costs
/// more than moving the instruction into the appropriate register. Note, we
/// are not marking copies from and to the same register class with this flag.
bool isAsCheapAsAMove() const {
return Flags & (1 << MCID::CheapAsAMove);
}
/// hasExtraSrcRegAllocReq - Returns true if this instruction source operands
/// have special register allocation requirements that are not captured by the
/// operand register classes. e.g. ARM::STRD's two source registers must be an
/// even / odd pair, ARM::STM registers have to be in ascending order.
/// Post-register allocation passes should not attempt to change allocations
/// for sources of instructions with this flag.
bool hasExtraSrcRegAllocReq() const {
return Flags & (1 << MCID::ExtraSrcRegAllocReq);
}
/// hasExtraDefRegAllocReq - Returns true if this instruction def operands
/// have special register allocation requirements that are not captured by the
/// operand register classes. e.g. ARM::LDRD's two def registers must be an
/// even / odd pair, ARM::LDM registers have to be in ascending order.
/// Post-register allocation passes should not attempt to change allocations
/// for definitions of instructions with this flag.
bool hasExtraDefRegAllocReq() const {
return Flags & (1 << MCID::ExtraDefRegAllocReq);
}
};
} // end namespace llvm
#endif