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Re: [Qemu-devel] [PATCH 3/5] tcg-i386: Implement small forward branches.
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From: |
Aurelien Jarno |
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Subject: |
Re: [Qemu-devel] [PATCH 3/5] tcg-i386: Implement small forward branches. |
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Date: |
Sun, 20 Dec 2009 00:11:27 +0100 |
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User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Sat, Dec 19, 2009 at 10:44:11AM -0800, Richard Henderson wrote:
> There are places, like brcond2, where we know that the destination
> of a forward branch will be within 127 bytes.
>
> Add the R_386_PC8 relocation type to support this. Add a flag to
> tcg_out_jxx and tcg_out_brcond* to enable it. Set the flag in the
> brcond2 label_next branches; pass along the input flag otherwise.
This looks ok, though I would appreciate someone else to review it in
details.
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> elf.h | 2 +
> tcg/i386/tcg-target.c | 116
> +++++++++++++++++++++++++++++++++----------------
> 2 files changed, 80 insertions(+), 38 deletions(-)
>
> diff --git a/elf.h b/elf.h
> index 11674d7..c84c8ab 100644
> --- a/elf.h
> +++ b/elf.h
> @@ -243,6 +243,8 @@ typedef struct {
> #define R_386_GOTOFF 9
> #define R_386_GOTPC 10
> #define R_386_NUM 11
> +/* Not a dynamic reloc, so not included in R_386_NUM. Used in TCG. */
> +#define R_386_PC8 23
>
> #define R_MIPS_NONE 0
> #define R_MIPS_16 1
> diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
> index 972b102..4c42caf 100644
> --- a/tcg/i386/tcg-target.c
> +++ b/tcg/i386/tcg-target.c
> @@ -61,6 +61,12 @@ static void patch_reloc(uint8_t *code_ptr, int type,
> case R_386_PC32:
> *(uint32_t *)code_ptr = value - (long)code_ptr;
> break;
> + case R_386_PC8:
> + value -= (long)code_ptr;
> + if (value != (int8_t)value)
> + tcg_abort();
> + *(uint8_t *)code_ptr = value;
> + break;
> default:
> tcg_abort();
> }
> @@ -305,7 +311,8 @@ static void tcg_out_addi(TCGContext *s, int reg,
> tcg_target_long val)
> tgen_arithi(s, ARITH_ADD, reg, val, 0);
> }
>
> -static void tcg_out_jxx(TCGContext *s, int opc, int label_index)
> +/* Use SMALL != 0 to force a short forward branch. */
> +static void tcg_out_jxx(TCGContext *s, int opc, int label_index, int small)
> {
> int32_t val, val1;
> TCGLabel *l = &s->labels[label_index];
> @@ -314,12 +321,16 @@ static void tcg_out_jxx(TCGContext *s, int opc, int
> label_index)
> val = l->u.value - (tcg_target_long)s->code_ptr;
> val1 = val - 2;
> if ((int8_t)val1 == val1) {
> - if (opc == -1)
> + if (opc == -1) {
> tcg_out8(s, 0xeb);
> - else
> + } else {
> tcg_out8(s, 0x70 + opc);
> + }
> tcg_out8(s, val1);
> } else {
> + if (small) {
> + tcg_abort();
> + }
> if (opc == -1) {
> tcg_out8(s, 0xe9);
> tcg_out32(s, val - 5);
> @@ -329,6 +340,14 @@ static void tcg_out_jxx(TCGContext *s, int opc, int
> label_index)
> tcg_out32(s, val - 6);
> }
> }
> + } else if (small) {
> + if (opc == -1) {
> + tcg_out8(s, 0xeb);
> + } else {
> + tcg_out8(s, 0x70 + opc);
> + }
> + tcg_out_reloc(s, s->code_ptr, R_386_PC8, label_index, -1);
> + s->code_ptr += 1;
> } else {
> if (opc == -1) {
> tcg_out8(s, 0xe9);
> @@ -343,7 +362,7 @@ static void tcg_out_jxx(TCGContext *s, int opc, int
> label_index)
>
> static void tcg_out_brcond(TCGContext *s, int cond,
> TCGArg arg1, TCGArg arg2, int const_arg2,
> - int label_index)
> + int label_index, int small)
> {
> if (const_arg2) {
> if (arg2 == 0) {
> @@ -355,64 +374,84 @@ static void tcg_out_brcond(TCGContext *s, int cond,
> } else {
> tcg_out_modrm(s, 0x01 | (ARITH_CMP << 3), arg2, arg1);
> }
> - tcg_out_jxx(s, tcg_cond_to_jcc[cond], label_index);
> + tcg_out_jxx(s, tcg_cond_to_jcc[cond], label_index, small);
> }
>
> /* XXX: we implement it at the target level to avoid having to
> handle cross basic blocks temporaries */
> -static void tcg_out_brcond2(TCGContext *s,
> - const TCGArg *args, const int *const_args)
> +static void tcg_out_brcond2(TCGContext *s, const TCGArg *args,
> + const int *const_args, int small)
> {
> int label_next;
> label_next = gen_new_label();
> switch(args[4]) {
> case TCG_COND_EQ:
> - tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2],
> label_next);
> - tcg_out_brcond(s, TCG_COND_EQ, args[1], args[3], const_args[3],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2],
> + label_next, small);
> + tcg_out_brcond(s, TCG_COND_EQ, args[1], args[3], const_args[3],
> + args[5], small);
> break;
> case TCG_COND_NE:
> - tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2],
> args[5]);
> - tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2],
> + args[5], small);
> + tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3],
> + args[5], small);
> break;
> case TCG_COND_LT:
> - tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_LE:
> - tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_LEU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_LEU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_GT:
> - tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_GTU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_GTU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_GE:
> - tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_GEU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_GEU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_LTU:
> - tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_LEU:
> - tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_LEU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_LEU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_GTU:
> - tcg_out_brcond(s, TCG_COND_GTU, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_GTU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_GTU, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_GTU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> case TCG_COND_GEU:
> - tcg_out_brcond(s, TCG_COND_GTU, args[1], args[3], const_args[3],
> args[5]);
> - tcg_out_jxx(s, JCC_JNE, label_next);
> - tcg_out_brcond(s, TCG_COND_GEU, args[0], args[2], const_args[2],
> args[5]);
> + tcg_out_brcond(s, TCG_COND_GTU, args[1], args[3], const_args[3],
> + args[5], small);
> + tcg_out_jxx(s, JCC_JNE, label_next, 1);
> + tcg_out_brcond(s, TCG_COND_GEU, args[0], args[2], const_args[2],
> + args[5], small);
> break;
> default:
> tcg_abort();
> @@ -913,7 +952,7 @@ static inline void tcg_out_op(TCGContext *s, int opc,
> }
> break;
> case INDEX_op_br:
> - tcg_out_jxx(s, JCC_JMP, args[0]);
> + tcg_out_jxx(s, JCC_JMP, args[0], 0);
> break;
> case INDEX_op_movi_i32:
> tcg_out_movi(s, TCG_TYPE_I32, args[0], args[1]);
> @@ -1044,10 +1083,11 @@ static inline void tcg_out_op(TCGContext *s, int opc,
> tcg_out_modrm(s, 0x01 | (ARITH_SBB << 3), args[5], args[1]);
> break;
> case INDEX_op_brcond_i32:
> - tcg_out_brcond(s, args[2], args[0], args[1], const_args[1], args[3]);
> + tcg_out_brcond(s, args[2], args[0], args[1], const_args[1],
> + args[3], 0);
> break;
> case INDEX_op_brcond2_i32:
> - tcg_out_brcond2(s, args, const_args);
> + tcg_out_brcond2(s, args, const_args, 0);
> break;
>
> case INDEX_op_bswap16_i32:
> --
> 1.6.5.2
>
>
>
>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH 0/5] tcg conditional set, round 4, Richard Henderson, 2009/12/19
- [Qemu-devel] [PATCH 2/5] tcg-x86_64: Implement setcond., Richard Henderson, 2009/12/19
- [Qemu-devel] [PATCH 3/5] tcg-i386: Implement small forward branches., Richard Henderson, 2009/12/19
- [Qemu-devel] [PATCH 5/5] tcg-i386: Implement setcond., Richard Henderson, 2009/12/19
- [Qemu-devel] [PATCH 4/5] tcg: Add tcg_invert_cond., Richard Henderson, 2009/12/19
- [Qemu-devel] [PATCH 1/5] tcg: Generic support for conditional set, Richard Henderson, 2009/12/19