mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-31 12:30:06 +00:00
MCInst it came from. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95767 91177308-0d34-0410-b5e6-96231b3b80d8
97 lines
3.3 KiB
C++
97 lines
3.3 KiB
C++
//===-- llvm/MC/MCFixup.h - Instruction Relocation and Patching -*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_MC_MCFIXUP_H
|
|
#define LLVM_MC_MCFIXUP_H
|
|
|
|
#include <cassert>
|
|
|
|
namespace llvm {
|
|
class MCExpr;
|
|
|
|
// Private constants, do not use.
|
|
//
|
|
// This is currently laid out so that the MCFixup fields can be efficiently
|
|
// accessed, while keeping the offset field large enough that the assembler
|
|
// backend can reasonably use the MCFixup representation for an entire fragment
|
|
// (splitting any overly large fragments).
|
|
//
|
|
// The division of bits between the kind and the opindex can be tweaked if we
|
|
// end up needing more bits for target dependent kinds.
|
|
enum {
|
|
MCFIXUP_NUM_GENERIC_KINDS = 128,
|
|
MCFIXUP_NUM_KIND_BITS = 16,
|
|
MCFIXUP_NUM_OFFSET_BITS = (32 - MCFIXUP_NUM_KIND_BITS)
|
|
};
|
|
|
|
/// MCFixupKind - Extensible enumeration to represent the type of a fixup.
|
|
enum MCFixupKind {
|
|
FK_Data_1 = 0, ///< A one-byte fixup.
|
|
FK_Data_2, ///< A two-byte fixup.
|
|
FK_Data_4, ///< A four-byte fixup.
|
|
FK_Data_8, ///< A eight-byte fixup.
|
|
|
|
FirstTargetFixupKind = MCFIXUP_NUM_GENERIC_KINDS,
|
|
|
|
MaxTargetFixupKind = (1 << MCFIXUP_NUM_KIND_BITS)
|
|
};
|
|
|
|
/// MCFixup - Encode information on a single operation to perform on an byte
|
|
/// sequence (e.g., an encoded instruction) which requires assemble- or run-
|
|
/// time patching.
|
|
///
|
|
/// Fixups are used any time the target instruction encoder needs to represent
|
|
/// some value in an instruction which is not yet concrete. The encoder will
|
|
/// encode the instruction assuming the value is 0, and emit a fixup which
|
|
/// communicates to the assembler backend how it should rewrite the encoded
|
|
/// value.
|
|
///
|
|
/// During the process of relaxation, the assembler will apply fixups as
|
|
/// symbolic values become concrete. When relaxation is complete, any remaining
|
|
/// fixups become relocations in the object file (or errors, if the fixup cannot
|
|
/// be encoded on the target).
|
|
class MCFixup {
|
|
static const unsigned MaxOffset = 1 << MCFIXUP_NUM_KIND_BITS;
|
|
|
|
/// The value to put into the fixup location. The exact interpretation of the
|
|
/// expression is target dependent, usually it will one of the operands to an
|
|
/// instruction or an assembler directive.
|
|
const MCExpr *Value;
|
|
|
|
/// The byte index of start of the relocation inside the encoded instruction.
|
|
unsigned Offset : MCFIXUP_NUM_OFFSET_BITS;
|
|
|
|
/// The target dependent kind of fixup item this is. The kind is used to
|
|
/// determine how the operand value should be encoded into the instruction.
|
|
unsigned Kind : MCFIXUP_NUM_KIND_BITS;
|
|
|
|
public:
|
|
static MCFixup Create(unsigned Offset, const MCExpr *Value,
|
|
MCFixupKind Kind) {
|
|
MCFixup FI;
|
|
FI.Value = Value;
|
|
FI.Offset = Offset;
|
|
FI.Kind = unsigned(Kind);
|
|
|
|
assert(Offset == FI.getOffset() && "Offset out of range!");
|
|
assert(Kind == FI.getKind() && "Kind out of range!");
|
|
return FI;
|
|
}
|
|
|
|
MCFixupKind getKind() const { return MCFixupKind(Kind); }
|
|
|
|
unsigned getOffset() const { return Offset; }
|
|
|
|
const MCExpr *getValue() const { return Value; }
|
|
};
|
|
|
|
} // End llvm namespace
|
|
|
|
#endif
|