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api: Store index register in operand struct

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Combined with some reordering of the struct fields, this reduces the
size of an FdInstr from 56 bytes to 48 bytes.
This commit is contained in:
Alexis Engelke
2020-05-17 11:16:48 +02:00
parent 7a364fcada
commit c3df15e19b
2 changed files with 11 additions and 11 deletions
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5
decode.c
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@@ -249,8 +249,7 @@ decode_modrm(const uint8_t* buffer, int len, DecodeMode mode, FdInstr* instr,
} }
out_o1->type = FD_OT_MEM; out_o1->type = FD_OT_MEM;
instr->idx_scale = scale; out_o1->misc = (scale << 6) | (!vsib && idx == 4 ? FD_REG_NONE : idx);
instr->idx_reg = !vsib && idx == 4 ? FD_REG_NONE : idx;
// RIP-relative addressing only if SIB-byte is absent // RIP-relative addressing only if SIB-byte is absent
if (mod == 0 && rm == 5 && mode == DECODE_64) if (mod == 0 && rm == 5 && mode == DECODE_64)
@@ -521,7 +520,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
FdOp* operand = &instr->operands[DESC_IMM_IDX(desc)]; FdOp* operand = &instr->operands[DESC_IMM_IDX(desc)];
operand->type = FD_OT_MEM; operand->type = FD_OT_MEM;
operand->reg = FD_REG_NONE; operand->reg = FD_REG_NONE;
instr->idx_reg = FD_REG_NONE; operand->misc = FD_REG_NONE;
if (UNLIKELY(off + addr_size > len)) if (UNLIKELY(off + addr_size > len))
return FD_ERR_PARTIAL; return FD_ERR_PARTIAL;

17
fadec.h
View File

@@ -82,7 +82,7 @@ typedef enum {
typedef struct { typedef struct {
uint8_t type; uint8_t type;
uint8_t size; uint8_t size;
int8_t reg; uint8_t reg;
uint8_t misc; uint8_t misc;
} FdOp; } FdOp;
@@ -92,12 +92,13 @@ typedef struct {
uint8_t segment; uint8_t segment;
uint8_t addrsz; uint8_t addrsz;
uint8_t operandsz; uint8_t operandsz;
uint8_t size;
uint8_t _pad0;
FdOp operands[4]; FdOp operands[4];
uint8_t idx_reg; int32_t disp;
uint8_t idx_scale; uint32_t _pad1;
uint8_t size;
intptr_t disp;
intptr_t imm; intptr_t imm;
uintptr_t address; uintptr_t address;
@@ -192,16 +193,16 @@ void fd_format(const FdInstr* instr, char* buf, size_t len);
/** Gets the index of the index register from a memory operand, or FD_REG_NONE, /** Gets the index of the index register from a memory operand, or FD_REG_NONE,
* if the memory operand has no scaled index register. * if the memory operand has no scaled index register.
* Only valid if FD_OP_TYPE == FD_OT_MEM **/ * Only valid if FD_OP_TYPE == FD_OT_MEM **/
#define FD_OP_INDEX(instr,idx) ((FdReg) (instr)->idx_reg) #define FD_OP_INDEX(instr,idx) ((FdReg) (instr)->operands[idx].misc & 0x3f)
/** Gets the scale of the index register from a memory operand when existent. /** Gets the scale of the index register from a memory operand when existent.
* This does /not/ return the scale in an absolute value but returns the amount * This does /not/ return the scale in an absolute value but returns the amount
* of bits the index register is shifted to the left (i.e. the value in in the * of bits the index register is shifted to the left (i.e. the value in in the
* range 0-3). The actual scale can be computed easily using 1<<FD_OP_SCALE. * range 0-3). The actual scale can be computed easily using 1<<FD_OP_SCALE.
* Only valid if FD_OP_TYPE == FD_OT_MEM and FD_OP_INDEX != FD_REG_NONE **/ * Only valid if FD_OP_TYPE == FD_OT_MEM and FD_OP_INDEX != FD_REG_NONE **/
#define FD_OP_SCALE(instr,idx) ((instr)->idx_scale) #define FD_OP_SCALE(instr,idx) ((instr)->operands[idx].misc >> 6)
/** Gets the sign-extended displacement of a memory operand. /** Gets the sign-extended displacement of a memory operand.
* Only valid if FD_OP_TYPE == FD_OT_MEM **/ * Only valid if FD_OP_TYPE == FD_OT_MEM **/
#define FD_OP_DISP(instr,idx) ((instr)->disp) #define FD_OP_DISP(instr,idx) ((int64_t) (instr)->disp)
/** Gets the (sign-extended) encoded constant for an immediate operand. /** Gets the (sign-extended) encoded constant for an immediate operand.
* Only valid if FD_OP_TYPE == FD_OT_IMM **/ * Only valid if FD_OP_TYPE == FD_OT_IMM **/
#define FD_OP_IMM(instr,idx) ((instr)->imm) #define FD_OP_IMM(instr,idx) ((instr)->imm)