Patchwork [3/5] tcg-i386: Implement small forward branches.

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Submitter Richard Henderson
Date Dec. 19, 2009, 6:44 p.m.
Message ID <9f38711e7d93ded68cad15e5cdbeecbf2c9ae521.1261248772.git.rth@twiddle.net>
Download mbox | patch
Permalink /patch/41467/
State New
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Comments

Richard Henderson - Dec. 19, 2009, 6:44 p.m.
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.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 elf.h                 |    2 +
 tcg/i386/tcg-target.c |  116 +++++++++++++++++++++++++++++++++----------------
 2 files changed, 80 insertions(+), 38 deletions(-)
Aurelien Jarno - Dec. 19, 2009, 11:11 p.m.
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 <rth@twiddle.net>
> ---
>  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
> 
> 
> 
>
Laurent Desnogues - Dec. 19, 2009, 11:32 p.m.
On Sat, Dec 19, 2009 at 7:44 PM, Richard Henderson <rth@twiddle.net> 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.
>
> Signed-off-by: Richard Henderson <rth@twiddle.net>
>
> ---
>  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);

Shouldn't it be 1 instead of small?

The rest is OK.


Laurent

> +        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
>
>
>
>
Richard Henderson - Dec. 20, 2009, 1:17 a.m.
On 12/19/2009 03:32 PM, Laurent Desnogues wrote:
>>      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);
>
> Shouldn't it be 1 instead of small?

Sigh, yes indeed.


r~

Patch

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: