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tcg-i386: Introduce limited deposit support 

x86 cannot provide an optimized generic deposit implementation. But at
least for a few special cases, namely for writing bits 0..7, 8..15, and
0..15, versions using only a single instruction are feasible.
Introducing such limited support improves emulating 16-bit x86 code on
x86, but also rarer cases where 32-bit or 64-bit code accesses bytes or
words.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Jan Kiszka 2011-09-29 18:52:11 +02:00 committed by Blue Swirl
parent 7e17a21706
commit a4773324b4
4 changed files with 40 additions and 4 deletions
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24
tcg/i386/tcg-target.c
View File

@ -168,6 +168,10 @@ static int target_parse_constraint(TCGArgConstraint *ct, const char **pct_str)
tcg_regset_set32(ct->u.regs, 0, 0xf);
}
break;
case 'Q':
ct->ct |= TCG_CT_REG;
tcg_regset_set32(ct->u.regs, 0, 0xf);
break;
case 'r':
ct->ct |= TCG_CT_REG;
if (TCG_TARGET_REG_BITS == 64) {
@ -1747,6 +1751,22 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
break;
#endif
OP_32_64(deposit):
if (args[3] == 0 && args[4] == 8) {
/* load bits 0..7 */
tcg_out_modrm(s, OPC_MOVB_EvGv | P_REXB_R | P_REXB_RM,
args[2], args[0]);
} else if (args[3] == 8 && args[4] == 8) {
/* load bits 8..15 */
tcg_out_modrm(s, OPC_MOVB_EvGv, args[2], args[0] + 4);
} else if (args[3] == 0 && args[4] == 16) {
/* load bits 0..15 */
tcg_out_modrm(s, OPC_MOVL_EvGv | P_DATA16, args[2], args[0]);
} else {
tcg_abort();
}
break;
default:
tcg_abort();
}
@ -1802,6 +1822,8 @@ static const TCGTargetOpDef x86_op_defs[] = {
{ INDEX_op_setcond_i32, { "q", "r", "ri" } },
{ INDEX_op_deposit_i32, { "Q", "0", "Q" } },
#if TCG_TARGET_REG_BITS == 32
{ INDEX_op_mulu2_i32, { "a", "d", "a", "r" } },
{ INDEX_op_add2_i32, { "r", "r", "0", "1", "ri", "ri" } },
@ -1853,6 +1875,8 @@ static const TCGTargetOpDef x86_op_defs[] = {
{ INDEX_op_ext8u_i64, { "r", "r" } },
{ INDEX_op_ext16u_i64, { "r", "r" } },
{ INDEX_op_ext32u_i64, { "r", "r" } },
{ INDEX_op_deposit_i64, { "Q", "0", "Q" } },
#endif
#if TCG_TARGET_REG_BITS == 64

9
tcg/i386/tcg-target.h
View File

@ -90,7 +90,7 @@ enum {
#define TCG_TARGET_HAS_eqv_i32 0
#define TCG_TARGET_HAS_nand_i32 0
#define TCG_TARGET_HAS_nor_i32 0
#define TCG_TARGET_HAS_deposit_i32 0
#define TCG_TARGET_HAS_deposit_i32 1
#if TCG_TARGET_REG_BITS == 64
#define TCG_TARGET_HAS_div2_i64 1
@ -111,9 +111,14 @@ enum {
#define TCG_TARGET_HAS_eqv_i64 0
#define TCG_TARGET_HAS_nand_i64 0
#define TCG_TARGET_HAS_nor_i64 0
#define TCG_TARGET_HAS_deposit_i64 0
#define TCG_TARGET_HAS_deposit_i64 1
#endif
#define TCG_TARGET_deposit_i32_valid(ofs, len) \
(((ofs) == 0 && (len) == 8) || ((ofs) == 8 && (len) == 8) || \
((ofs) == 0 && (len) == 16))
#define TCG_TARGET_deposit_i64_valid TCG_TARGET_deposit_i32_valid
#define TCG_TARGET_HAS_GUEST_BASE
/* Note: must be synced with dyngen-exec.h */

4
tcg/tcg-op.h
View File

@ -2045,7 +2045,7 @@ static inline void tcg_gen_deposit_i32(TCGv_i32 ret, TCGv_i32 arg1,
TCGv_i32 arg2, unsigned int ofs,
unsigned int len)
{
if (TCG_TARGET_HAS_deposit_i32) {
if (TCG_TARGET_HAS_deposit_i32 && TCG_TARGET_deposit_i32_valid(ofs, len)) {
tcg_gen_op5ii_i32(INDEX_op_deposit_i32, ret, arg1, arg2, ofs, len);
} else {
uint32_t mask = (1u << len) - 1;
@ -2064,7 +2064,7 @@ static inline void tcg_gen_deposit_i64(TCGv_i64 ret, TCGv_i64 arg1,
TCGv_i64 arg2, unsigned int ofs,
unsigned int len)
{
if (TCG_TARGET_HAS_deposit_i64) {
if (TCG_TARGET_HAS_deposit_i64 && TCG_TARGET_deposit_i64_valid(ofs, len)) {
tcg_gen_op5ii_i64(INDEX_op_deposit_i64, ret, arg1, arg2, ofs, len);
} else {
uint64_t mask = (1ull << len) - 1;

7
tcg/tcg.h
View File

@ -81,6 +81,13 @@ typedef uint64_t TCGRegSet;
#define TCG_TARGET_HAS_deposit_i64 0
#endif
#ifndef TCG_TARGET_deposit_i32_valid
#define TCG_TARGET_deposit_i32_valid(ofs, len) 1
#endif
#ifndef TCG_TARGET_deposit_i64_valid
#define TCG_TARGET_deposit_i64_valid(ofs, len) 1
#endif
/* Only one of DIV or DIV2 should be defined. */
#if defined(TCG_TARGET_HAS_div_i32)
#define TCG_TARGET_HAS_div2_i32 0