On 07/11/2014 11:32, Pavel Dovgalyuk wrote:
> This patch denies crossing the boundary of the pages in the replay mode,
> because it can cause an exception. Do it only when boundary is
> crossed by the first instruction in the block.
> If current instruction already crossed the bound - it's ok,
> because an exception hasn't stopped this code.
>
> Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
> ---
> target-i386/cpu.h | 7 +++++++
> target-i386/translate.c | 14 ++++++++++++++
> 2 files changed, 21 insertions(+), 0 deletions(-)
>
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 2968749..bc3f9f5 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -28,6 +28,13 @@
> #define TARGET_LONG_BITS 32
> #endif
>
> +/* Maximum instruction code size */
> +#ifdef TARGET_X86_64
> +#define TARGET_MAX_INSN_SIZE 16
> +#else
> +#define TARGET_MAX_INSN_SIZE 16
> +#endif
> +
> /* target supports implicit self modifying code */
> #define TARGET_HAS_SMC
> /* support for self modifying code even if the modified instruction is
> diff --git a/target-i386/translate.c b/target-i386/translate.c
> index 4d5dfb3..a264908 100644
> --- a/target-i386/translate.c
> +++ b/target-i386/translate.c
> @@ -8035,6 +8035,20 @@ static inline void
> gen_intermediate_code_internal(X86CPU *cpu,
> gen_eob(dc);
> break;
> }
> + /* Do not cross the boundary of the pages in icount mode,
> + it can cause an exception. Do it only when boundary is
> + crossed by the first instruction in the block.
> + If current instruction already crossed the bound - it's ok,
> + because an exception hasn't stopped this code.
> + */
> + if (use_icount
> + && ((pc_ptr & TARGET_PAGE_MASK)
> + != ((pc_ptr + TARGET_MAX_INSN_SIZE - 1) & TARGET_PAGE_MASK)
> + || (pc_ptr & ~TARGET_PAGE_MASK) == 0)) {
> + gen_jmp_im(pc_ptr - dc->cs_base);
> + gen_eob(dc);
> + break;
> + }
> /* if too long translation, stop generation too */
> if (tcg_ctx.gen_opc_ptr >= gen_opc_end ||
> (pc_ptr - pc_start) >= (TARGET_PAGE_SIZE - 32) ||
>
Why only in icount mode? Does it have a sensible performance problem?
Paolo
