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//===-- llvm/Target/TargetOpcodes.h - Target Indep Opcodes ------*- 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 target independent instruction opcodes.


namespace llvm {

/// Invariant opcodes: All instruction sets have these as their low opcodes.
/// Every instruction defined here must also appear in Target.td and the order
/// must be the same as in CodeGenTarget.cpp.
namespace TargetOpcode {
  enum {
    PHI = 0,
    INLINEASM = 1,
    EH_LABEL = 3,
    GC_LABEL = 4,

    /// KILL - This instruction is a noop that is used only to adjust the
    /// liveness of registers. This can be useful when dealing with
    /// sub-registers.
    KILL = 5,

    /// EXTRACT_SUBREG - This instruction takes two operands: a register
    /// that has subregisters, and a subregister index. It returns the
    /// extracted subregister value. This is commonly used to implement
    /// truncation operations on target architectures which support it.

    /// INSERT_SUBREG - This instruction takes three operands: a register that
    /// has subregisters, a register providing an insert value, and a
    /// subregister index. It returns the value of the first register with the
    /// value of the second register inserted. The first register is often
    /// defined by an IMPLICIT_DEF, because it is commonly used to implement
    /// anyext operations on target architectures which support it.

    /// IMPLICIT_DEF - This is the MachineInstr-level equivalent of undef.

    /// SUBREG_TO_REG - This instruction is similar to INSERT_SUBREG except that
    /// the first operand is an immediate integer constant. This constant is
    /// often zero, because it is commonly used to assert that the instruction
    /// defining the register implicitly clears the high bits.
    SUBREG_TO_REG = 9,

    /// COPY_TO_REGCLASS - This instruction is a placeholder for a plain
    /// register-to-register copy into a specific register class. This is only
    /// used between instruction selection and MachineInstr creation, before
    /// virtual registers have been created for all the instructions, and it's
    /// only needed in cases where the register classes implied by the
    /// instructions are insufficient. It is emitted as a COPY MachineInstr.

    /// DBG_VALUE - a mapping of the llvm.dbg.value intrinsic
    DBG_VALUE = 11,

    /// REG_SEQUENCE - This variadic instruction is used to form a register that
    /// represent a consecutive sequence of sub-registers. It's used as register
    /// coalescing / allocation aid and must be eliminated before code emission.
    // In SDNode form, the first operand encodes the register class created by
    // the REG_SEQUENCE, while each subsequent pair names a vreg + subreg index
    // pair.  Once it has been lowered to a MachineInstr, the regclass operand
    // is no longer present.
    /// e.g. v1027 = REG_SEQUENCE v1024, 3, v1025, 4, v1026, 5
    /// After register coalescing references of v1024 should be replace with
    /// v1027:3, v1025 with v1027:4, etc.
    REG_SEQUENCE = 12,

    /// COPY - Target-independent register copy. This instruction can also be
    /// used to copy between subregisters of virtual registers.
    COPY = 13,

    /// BUNDLE - This instruction represents an instruction bundle. Instructions
    /// which immediately follow a BUNDLE instruction which are marked with
    /// 'InsideBundle' flag are inside the bundle.
} // end namespace TargetOpcode
} // end namespace llvm