[Mono-dev] [PATCH]: Fix abort when generating sparc V9 code

[Zoltan Varga]

Hi,

This is now in SVN.

   thanks

       Zoltan

On 11/2/07, David Miller <davem at davemloft.net> wrote:
>
> In current SVN the testsuite gives an abort on sparc because the JIT
> generates a branch whose relocation cannot fit.
>
> It's a branch to an exception stub, so the branch is to the end of the
> code generation area where the exception handler stubs are placed.
>
> The V9 branch can only handle signed 19-bit offsets, and in this
> case the code area is so big that the displacement to the exception
> area is too large to fit into the relocation.
>
> For these cases we only need the 32-bit icc condition codes.  So we
> can expand the range of offsets that can be handled by using the
> pre-v9 branches in this case.  This gives us a signed 22-bit offset to
> work with.
>
> This is not even sub-optimal for v9 chips because v9 chips use a
> default prediction of not-taken for pre-v9 branches, and since
> exceptions are "exceptional"...
>
> While working on this patch I noticed a NULL pointer assertion in the
> exception handler stub emitter that was after the first dereference of
> that pointer, making it useless.
>
> Please apply, thanks.
>
> 2007-11-01  David S. Miller  <davem at davemloft.net>
>
>         * mini-sparc.c (EMIT_COND_SYSTEM_EXCEPTION_GENERAL): Even if
>         sparcv9, use non-v9 branch if using sparc_icc_short.
>         (mono_arch_emit_exceptions): Move NULL pointer assertion before
>         first dereference.
>
> Index: mono/mini/mini-sparc.c
> ===================================================================
> --- mono/mini/mini-sparc.c      (revision 88629)
> +++ mono/mini/mini-sparc.c      (working copy)
> @@ -1387,7 +1387,7 @@ if (ins->flags & MONO_INST_BRLABEL) { \
>  #define EMIT_COND_SYSTEM_EXCEPTION_GENERAL(ins,cond,sexc_name,filldelay,icc) do {     \
>                 mono_add_patch_info (cfg, (guint8*)(code) - (cfg)->native_code,   \
>                                     MONO_PATCH_INFO_EXC, sexc_name);  \
> -        if (sparcv9) { \
> +       if (sparcv9 && ((icc) != sparc_icc_short)) {          \
>             sparc_branchp (code, 0, (cond), (icc), 0, 0); \
>          } \
>          else { \
> @@ -4207,8 +4207,8 @@ mono_arch_emit_exceptions (MonoCompile *
>                         sparc_patch ((guint32*)(cfg->native_code + patch_info->ip.i), code);
>
>                         exc_class = mono_class_from_name (mono_defaults.corlib, "System", patch_info->data.name);
> -                       type_idx = exc_class->type_token - MONO_TOKEN_TYPE_DEF;
>                         g_assert (exc_class);
> +                       type_idx = exc_class->type_token - MONO_TOKEN_TYPE_DEF;
>                         throw_ip = patch_info->ip.i;
>
>                         /* Find a throw sequence for the same exception class */
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