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536 lines
21 KiB
C++
536 lines
21 KiB
C++
//===-- llvm/Mc/McInstrDesc.h - Instruction Descriptors -*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the MCOperandInfo and MCInstrDesc classes, which
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// are used to describe target instructions and their operands.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCINSTRDESC_H
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#define LLVM_MC_MCINSTRDESC_H
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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//===----------------------------------------------------------------------===//
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// Machine Operand Flags and Description
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//===----------------------------------------------------------------------===//
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namespace MCOI {
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// Operand constraints
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enum OperandConstraint {
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TIED_TO = 0, // Must be allocated the same register as.
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EARLY_CLOBBER // Operand is an early clobber register operand
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};
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/// OperandFlags - These are flags set on operands, but should be considered
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/// private, all access should go through the MCOperandInfo accessors.
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/// See the accessors for a description of what these are.
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enum OperandFlags {
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LookupPtrRegClass = 0,
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Predicate,
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OptionalDef
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};
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/// Operand Type - Operands are tagged with one of the values of this enum.
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enum OperandType {
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OPERAND_UNKNOWN,
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OPERAND_IMMEDIATE,
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OPERAND_REGISTER,
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OPERAND_MEMORY,
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OPERAND_PCREL
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};
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}
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/// MCOperandInfo - This holds information about one operand of a machine
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/// instruction, indicating the register class for register operands, etc.
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///
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class MCOperandInfo {
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public:
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/// RegClass - This specifies the register class enumeration of the operand
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/// if the operand is a register. If isLookupPtrRegClass is set, then this is
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/// an index that is passed to TargetRegisterInfo::getPointerRegClass(x) to
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/// get a dynamic register class.
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int16_t RegClass;
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/// Flags - These are flags from the MCOI::OperandFlags enum.
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uint8_t Flags;
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/// OperandType - Information about the type of the operand.
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uint8_t OperandType;
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/// Lower 16 bits are used to specify which constraints are set. The higher 16
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/// bits are used to specify the value of constraints (4 bits each).
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uint32_t Constraints;
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/// Currently no other information.
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/// isLookupPtrRegClass - Set if this operand is a pointer value and it
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/// requires a callback to look up its register class.
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bool isLookupPtrRegClass() const {return Flags&(1 <<MCOI::LookupPtrRegClass);}
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/// isPredicate - Set if this is one of the operands that made up of
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/// the predicate operand that controls an isPredicable() instruction.
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bool isPredicate() const { return Flags & (1 << MCOI::Predicate); }
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/// isOptionalDef - Set if this operand is a optional def.
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///
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bool isOptionalDef() const { return Flags & (1 << MCOI::OptionalDef); }
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};
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//===----------------------------------------------------------------------===//
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// Machine Instruction Flags and Description
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//===----------------------------------------------------------------------===//
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/// MCInstrDesc flags - These should be considered private to the
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/// implementation of the MCInstrDesc class. Clients should use the predicate
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/// methods on MCInstrDesc, not use these directly. These all correspond to
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/// bitfields in the MCInstrDesc::Flags field.
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namespace MCID {
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enum {
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Variadic = 0,
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HasOptionalDef,
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Pseudo,
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Return,
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Call,
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Barrier,
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Terminator,
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Branch,
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IndirectBranch,
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Compare,
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MoveImm,
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Bitcast,
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DelaySlot,
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FoldableAsLoad,
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MayLoad,
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MayStore,
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Predicable,
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NotDuplicable,
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UnmodeledSideEffects,
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Commutable,
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ConvertibleTo3Addr,
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UsesCustomInserter,
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HasPostISelHook,
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Rematerializable,
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CheapAsAMove,
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ExtraSrcRegAllocReq,
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ExtraDefRegAllocReq
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};
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}
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/// MCInstrDesc - Describe properties that are true of each instruction in the
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/// target description file. This captures information about side effects,
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/// register use and many other things. There is one instance of this struct
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/// for each target instruction class, and the MachineInstr class points to
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/// this struct directly to describe itself.
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class MCInstrDesc {
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public:
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unsigned short Opcode; // The opcode number
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unsigned short NumOperands; // Num of args (may be more if variable_ops)
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unsigned short NumDefs; // Num of args that are definitions
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unsigned short SchedClass; // enum identifying instr sched class
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unsigned short Size; // Number of bytes in encoding.
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unsigned Flags; // Flags identifying machine instr class
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uint64_t TSFlags; // Target Specific Flag values
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const uint16_t *ImplicitUses; // Registers implicitly read by this instr
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const uint16_t *ImplicitDefs; // Registers implicitly defined by this instr
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const MCOperandInfo *OpInfo; // 'NumOperands' entries about operands
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/// getOperandConstraint - Returns the value of the specific constraint if
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/// it is set. Returns -1 if it is not set.
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int getOperandConstraint(unsigned OpNum,
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MCOI::OperandConstraint Constraint) const {
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if (OpNum < NumOperands &&
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(OpInfo[OpNum].Constraints & (1 << Constraint))) {
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unsigned Pos = 16 + Constraint * 4;
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return (int)(OpInfo[OpNum].Constraints >> Pos) & 0xf;
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}
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return -1;
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}
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/// getOpcode - Return the opcode number for this descriptor.
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unsigned getOpcode() const {
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return Opcode;
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}
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/// getNumOperands - Return the number of declared MachineOperands for this
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/// MachineInstruction. Note that variadic (isVariadic() returns true)
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/// instructions may have additional operands at the end of the list, and note
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/// that the machine instruction may include implicit register def/uses as
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/// well.
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unsigned getNumOperands() const {
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return NumOperands;
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}
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/// getNumDefs - Return the number of MachineOperands that are register
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/// definitions. Register definitions always occur at the start of the
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/// machine operand list. This is the number of "outs" in the .td file,
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/// and does not include implicit defs.
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unsigned getNumDefs() const {
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return NumDefs;
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}
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/// getFlags - Return flags of this instruction.
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///
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unsigned getFlags() const { return Flags; }
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/// isVariadic - Return true if this instruction can have a variable number of
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/// operands. In this case, the variable operands will be after the normal
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/// operands but before the implicit definitions and uses (if any are
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/// present).
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bool isVariadic() const {
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return Flags & (1 << MCID::Variadic);
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}
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/// hasOptionalDef - Set if this instruction has an optional definition, e.g.
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/// ARM instructions which can set condition code if 's' bit is set.
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bool hasOptionalDef() const {
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return Flags & (1 << MCID::HasOptionalDef);
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}
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/// isPseudo - Return true if this is a pseudo instruction that doesn't
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/// correspond to a real machine instruction.
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///
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bool isPseudo() const {
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return Flags & (1 << MCID::Pseudo);
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}
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bool isReturn() const {
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return Flags & (1 << MCID::Return);
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}
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bool isCall() const {
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return Flags & (1 << MCID::Call);
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}
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/// isBarrier - Returns true if the specified instruction stops control flow
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/// from executing the instruction immediately following it. Examples include
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/// unconditional branches and return instructions.
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bool isBarrier() const {
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return Flags & (1 << MCID::Barrier);
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}
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/// isTerminator - Returns true if this instruction part of the terminator for
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/// a basic block. Typically this is things like return and branch
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/// instructions.
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///
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/// Various passes use this to insert code into the bottom of a basic block,
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/// but before control flow occurs.
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bool isTerminator() const {
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return Flags & (1 << MCID::Terminator);
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}
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/// isBranch - Returns true if this is a conditional, unconditional, or
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/// indirect branch. Predicates below can be used to discriminate between
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/// these cases, and the TargetInstrInfo::AnalyzeBranch method can be used to
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/// get more information.
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bool isBranch() const {
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return Flags & (1 << MCID::Branch);
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}
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/// isIndirectBranch - Return true if this is an indirect branch, such as a
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/// branch through a register.
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bool isIndirectBranch() const {
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return Flags & (1 << MCID::IndirectBranch);
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}
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/// isConditionalBranch - Return true if this is a branch which may fall
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/// through to the next instruction or may transfer control flow to some other
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/// block. The TargetInstrInfo::AnalyzeBranch method can be used to get more
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/// information about this branch.
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bool isConditionalBranch() const {
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return isBranch() & !isBarrier() & !isIndirectBranch();
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}
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/// isUnconditionalBranch - Return true if this is a branch which always
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/// transfers control flow to some other block. The
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/// TargetInstrInfo::AnalyzeBranch method can be used to get more information
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/// about this branch.
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bool isUnconditionalBranch() const {
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return isBranch() & isBarrier() & !isIndirectBranch();
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}
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// isPredicable - Return true if this instruction has a predicate operand that
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// controls execution. It may be set to 'always', or may be set to other
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/// values. There are various methods in TargetInstrInfo that can be used to
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/// control and modify the predicate in this instruction.
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bool isPredicable() const {
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return Flags & (1 << MCID::Predicable);
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}
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/// isCompare - Return true if this instruction is a comparison.
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bool isCompare() const {
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return Flags & (1 << MCID::Compare);
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}
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/// isMoveImmediate - Return true if this instruction is a move immediate
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/// (including conditional moves) instruction.
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bool isMoveImmediate() const {
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return Flags & (1 << MCID::MoveImm);
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}
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/// isBitcast - Return true if this instruction is a bitcast instruction.
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///
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bool isBitcast() const {
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return Flags & (1 << MCID::Bitcast);
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}
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/// isNotDuplicable - Return true if this instruction cannot be safely
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/// duplicated. For example, if the instruction has a unique labels attached
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/// to it, duplicating it would cause multiple definition errors.
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bool isNotDuplicable() const {
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return Flags & (1 << MCID::NotDuplicable);
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}
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/// hasDelaySlot - Returns true if the specified instruction has a delay slot
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/// which must be filled by the code generator.
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bool hasDelaySlot() const {
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return Flags & (1 << MCID::DelaySlot);
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}
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/// canFoldAsLoad - Return true for instructions that can be folded as
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/// memory operands in other instructions. The most common use for this
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/// is instructions that are simple loads from memory that don't modify
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/// the loaded value in any way, but it can also be used for instructions
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/// that can be expressed as constant-pool loads, such as V_SETALLONES
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/// on x86, to allow them to be folded when it is beneficial.
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/// This should only be set on instructions that return a value in their
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/// only virtual register definition.
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bool canFoldAsLoad() const {
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return Flags & (1 << MCID::FoldableAsLoad);
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}
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//===--------------------------------------------------------------------===//
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// Side Effect Analysis
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//===--------------------------------------------------------------------===//
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/// mayLoad - Return true if this instruction could possibly read memory.
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/// Instructions with this flag set are not necessarily simple load
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/// instructions, they may load a value and modify it, for example.
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bool mayLoad() const {
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return Flags & (1 << MCID::MayLoad);
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}
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/// mayStore - Return true if this instruction could possibly modify memory.
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/// Instructions with this flag set are not necessarily simple store
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/// instructions, they may store a modified value based on their operands, or
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/// may not actually modify anything, for example.
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bool mayStore() const {
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return Flags & (1 << MCID::MayStore);
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}
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/// hasUnmodeledSideEffects - Return true if this instruction has side
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/// effects that are not modeled by other flags. This does not return true
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/// for instructions whose effects are captured by:
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///
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/// 1. Their operand list and implicit definition/use list. Register use/def
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/// info is explicit for instructions.
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/// 2. Memory accesses. Use mayLoad/mayStore.
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/// 3. Calling, branching, returning: use isCall/isReturn/isBranch.
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///
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/// Examples of side effects would be modifying 'invisible' machine state like
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/// a control register, flushing a cache, modifying a register invisible to
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/// LLVM, etc.
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///
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bool hasUnmodeledSideEffects() const {
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return Flags & (1 << MCID::UnmodeledSideEffects);
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}
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//===--------------------------------------------------------------------===//
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// Flags that indicate whether an instruction can be modified by a method.
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//===--------------------------------------------------------------------===//
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/// isCommutable - Return true if this may be a 2- or 3-address
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/// instruction (of the form "X = op Y, Z, ..."), which produces the same
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/// result if Y and Z are exchanged. If this flag is set, then the
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/// TargetInstrInfo::commuteInstruction method may be used to hack on the
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/// instruction.
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///
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/// Note that this flag may be set on instructions that are only commutable
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/// sometimes. In these cases, the call to commuteInstruction will fail.
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/// Also note that some instructions require non-trivial modification to
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/// commute them.
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bool isCommutable() const {
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return Flags & (1 << MCID::Commutable);
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}
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/// isConvertibleTo3Addr - Return true if this is a 2-address instruction
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/// which can be changed into a 3-address instruction if needed. Doing this
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/// transformation can be profitable in the register allocator, because it
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/// means that the instruction can use a 2-address form if possible, but
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/// degrade into a less efficient form if the source and dest register cannot
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/// be assigned to the same register. For example, this allows the x86
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/// backend to turn a "shl reg, 3" instruction into an LEA instruction, which
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/// is the same speed as the shift but has bigger code size.
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///
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/// If this returns true, then the target must implement the
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/// TargetInstrInfo::convertToThreeAddress method for this instruction, which
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/// is allowed to fail if the transformation isn't valid for this specific
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/// instruction (e.g. shl reg, 4 on x86).
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///
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bool isConvertibleTo3Addr() const {
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return Flags & (1 << MCID::ConvertibleTo3Addr);
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}
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/// usesCustomInsertionHook - Return true if this instruction requires
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/// custom insertion support when the DAG scheduler is inserting it into a
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/// machine basic block. If this is true for the instruction, it basically
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/// means that it is a pseudo instruction used at SelectionDAG time that is
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/// expanded out into magic code by the target when MachineInstrs are formed.
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///
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/// If this is true, the TargetLoweringInfo::InsertAtEndOfBasicBlock method
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/// is used to insert this into the MachineBasicBlock.
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bool usesCustomInsertionHook() const {
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return Flags & (1 << MCID::UsesCustomInserter);
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}
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/// hasPostISelHook - Return true if this instruction requires *adjustment*
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/// after instruction selection by calling a target hook. For example, this
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/// can be used to fill in ARM 's' optional operand depending on whether
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/// the conditional flag register is used.
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bool hasPostISelHook() const {
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return Flags & (1 << MCID::HasPostISelHook);
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}
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/// isRematerializable - Returns true if this instruction is a candidate for
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/// remat. This flag is deprecated, please don't use it anymore. If this
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/// flag is set, the isReallyTriviallyReMaterializable() method is called to
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/// verify the instruction is really rematable.
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bool isRematerializable() const {
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return Flags & (1 << MCID::Rematerializable);
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}
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/// isAsCheapAsAMove - Returns true if this instruction has the same cost (or
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/// less) than a move instruction. This is useful during certain types of
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/// optimizations (e.g., remat during two-address conversion or machine licm)
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/// where we would like to remat or hoist the instruction, but not if it costs
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/// more than moving the instruction into the appropriate register. Note, we
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/// are not marking copies from and to the same register class with this flag.
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bool isAsCheapAsAMove() const {
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return Flags & (1 << MCID::CheapAsAMove);
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}
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/// hasExtraSrcRegAllocReq - Returns true if this instruction source operands
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/// have special register allocation requirements that are not captured by the
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/// operand register classes. e.g. ARM::STRD's two source registers must be an
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/// even / odd pair, ARM::STM registers have to be in ascending order.
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/// Post-register allocation passes should not attempt to change allocations
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/// for sources of instructions with this flag.
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bool hasExtraSrcRegAllocReq() const {
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return Flags & (1 << MCID::ExtraSrcRegAllocReq);
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}
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/// hasExtraDefRegAllocReq - Returns true if this instruction def operands
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/// have special register allocation requirements that are not captured by the
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/// operand register classes. e.g. ARM::LDRD's two def registers must be an
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/// even / odd pair, ARM::LDM registers have to be in ascending order.
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/// Post-register allocation passes should not attempt to change allocations
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/// for definitions of instructions with this flag.
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bool hasExtraDefRegAllocReq() const {
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return Flags & (1 << MCID::ExtraDefRegAllocReq);
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}
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/// getImplicitUses - Return a list of registers that are potentially
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/// read by any instance of this machine instruction. For example, on X86,
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/// the "adc" instruction adds two register operands and adds the carry bit in
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/// from the flags register. In this case, the instruction is marked as
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/// implicitly reading the flags. Likewise, the variable shift instruction on
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/// X86 is marked as implicitly reading the 'CL' register, which it always
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/// does.
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///
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/// This method returns null if the instruction has no implicit uses.
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const uint16_t *getImplicitUses() const {
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return ImplicitUses;
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}
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/// getNumImplicitUses - Return the number of implicit uses this instruction
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/// has.
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unsigned getNumImplicitUses() const {
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if (ImplicitUses == 0) return 0;
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unsigned i = 0;
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for (; ImplicitUses[i]; ++i) /*empty*/;
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return i;
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}
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/// getImplicitDefs - Return a list of registers that are potentially
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/// written by any instance of this machine instruction. For example, on X86,
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/// many instructions implicitly set the flags register. In this case, they
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/// are marked as setting the FLAGS. Likewise, many instructions always
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/// deposit their result in a physical register. For example, the X86 divide
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/// instruction always deposits the quotient and remainder in the EAX/EDX
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/// registers. For that instruction, this will return a list containing the
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/// EAX/EDX/EFLAGS registers.
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///
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/// This method returns null if the instruction has no implicit defs.
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const uint16_t *getImplicitDefs() const {
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return ImplicitDefs;
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}
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/// getNumImplicitDefs - Return the number of implicit defs this instruction
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/// has.
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unsigned getNumImplicitDefs() const {
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if (ImplicitDefs == 0) return 0;
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unsigned i = 0;
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for (; ImplicitDefs[i]; ++i) /*empty*/;
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return i;
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}
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/// hasImplicitUseOfPhysReg - Return true if this instruction implicitly
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/// uses the specified physical register.
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bool hasImplicitUseOfPhysReg(unsigned Reg) const {
|
|
if (const uint16_t *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 uint16_t *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;
|
|
}
|
|
|
|
/// 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;
|
|
}
|
|
};
|
|
|
|
} // end namespace llvm
|
|
|
|
#endif
|