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MC: Simplify MCFixup and increase the available offset size.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104698 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2010-05-26 15:18:40 +00:00
parent 482ad802f1
commit 0dd0c941c9
1 changed files with 14 additions and 29 deletions
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43
include/llvm/MC/MCFixup.h
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@ -10,26 +10,12 @@
#ifndef LLVM_MC_MCFIXUP_H
#define LLVM_MC_MCFIXUP_H
#include "llvm/System/DataTypes.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.
@ -37,12 +23,14 @@ enum MCFixupKind {
FK_Data_4, ///< A four-byte fixup.
FK_Data_8, ///< A eight-byte fixup.
FirstTargetFixupKind = MCFIXUP_NUM_GENERIC_KINDS,
FirstTargetFixupKind = 128,
MaxTargetFixupKind = (1 << MCFIXUP_NUM_KIND_BITS)
// Limit range of target fixups, in case we want to pack more efficiently
// later.
MaxTargetFixupKind = (1 << 8)
};
/// MCFixup - Encode information on a single operation to perform on an byte
/// MCFixup - Encode information on a single operation to perform on a byte
/// sequence (e.g., an encoded instruction) which requires assemble- or run-
/// time patching.
///
@ -57,36 +45,33 @@ enum MCFixupKind {
/// 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.
/// expression is target dependent, usually it will be 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;
uint32_t Offset;
/// 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;
unsigned Kind;
public:
static MCFixup Create(unsigned Offset, const MCExpr *Value,
static MCFixup Create(uint32_t Offset, const MCExpr *Value,
MCFixupKind Kind) {
assert(unsigned(Kind) < MaxTargetFixupKind && "Kind out of range!");
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; }
uint32_t getOffset() const { return Offset; }
void setOffset(uint32_t Value) { Offset = Value; }
const MCExpr *getValue() const { return Value; }