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Re: [PATCH, i386, Pointer Bounds Checker 30/x] Size relocation


2014-09-18 18:00 GMT+04:00 Ilya Enkovich <enkovich.gnu@gmail.com>:
> On 17 Sep 20:51, Uros Bizjak wrote:
>> On Wed, Sep 17, 2014 at 8:35 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> > On 16 Sep 12:22, Uros Bizjak wrote:
>> >> On Tue, Sep 16, 2014 at 11:37 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> >> > 2014-09-16 13:08 GMT+04:00 Uros Bizjak <ubizjak@gmail.com>:
>> >> >>
>> >> >> Can x86_64_immediate_operand predicate be used here?
>> >> >
>> >> > I think it cannot be used because of TLS symbols not counting as immediate.
>> >>
>> >> OK, please introduce a new predicate, similar to
>> >> x86_64_immediate_operand, perhaps x86_64_immediate_size_operand, so we
>> >> can add some comments there. This will also help to macroize the insn,
>> >> x86_64_immediate_operand has !TARGET_64BIT shortcut for this case.
>> >>
>> >> Uros.
>> >
>> > I don't see how new predicate would help to macroize insn.  Single template may look as following patch.
>>
>> You put early return for !TARGET_64BITS. Please see
>> x86_64_immediate_operand predicate.
>>
>> So,
>>
>> /* Here comes comment. */
>> (define_predicate "x86_64_immediate_size_operand"
>>   (match_code "symbol_ref")
>> {
>>   if (!TARGET_64BIT)
>>     return true;
>>
>>   /* Comment here explaining these conditions.  */
>>   return (ix86_cmodel == CM_SMALL || ix86_cmodel == CM_KERNEL);
>> }
>>
>> And then in the pattern itself:
>>
>> if (x86_64_immediate_size_operand (operands[1], VOIDmode)
>>   return "mov{l}\t{%1@SIZE, %k0|%k0, %1@SIZE}";
>> else
>>   return "movabs{q}\t{%1@SIZE, %0|%0, %1@SIZE}";
>>
>> Uros.
>
> Here is a version with check in a form you suggest.
>
> Thanks,
> Ilya
> --
> 2014-09-18  Ilya Enkovich  <ilya.enkovich@intel.com>
>
>         * config/i386/i386.md (UNSPEC_SIZEOF): New.
>         (move_size_reloc_<mode>): New.
>         * config/i386/predicates.md (symbol_operand): New.
>         (x86_64_immediate_size_operand): New.
>
>
> diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
> index 2c367b2..db22b06 100644
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -79,6 +79,7 @@
>    UNSPEC_PLTOFF
>    UNSPEC_MACHOPIC_OFFSET
>    UNSPEC_PCREL
> +  UNSPEC_SIZEOF
>
>    ;; Prologue support
>    UNSPEC_STACK_ALLOC
> @@ -18554,6 +18555,21 @@
>    "bndstx\t{%2, %3|%3, %2}"
>    [(set_attr "type" "mpxst")])
>
> +(define_insn "move_size_reloc_<mode>"
> +  [(set (match_operand:SWI48 0 "register_operand" "=r")
> +       (unspec:SWI48
> +        [(match_operand:SWI48 1 "symbol_operand")]
> +        UNSPEC_SIZEOF))]
> +  "TARGET_MPX"
> +{
> +  if (x86_64_immediate_size_operand (operands[1], VOIDmode))
> +    return "mov{l}\t{%1@SIZE, %k0|%k0, %1@SIZE}";
> +  else
> +    return "movabs{q}\t{%1@SIZE, %0|%0, %1@SIZE}";
> +}
> +  [(set_attr "type" "imov")
> +   (set_attr "mode" "<MODE>")])
> +
>  (include "mmx.md")
>  (include "sse.md")
>  (include "sync.md")
> diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
> index cd542b7..da01c9a 100644
> --- a/gcc/config/i386/predicates.md
> +++ b/gcc/config/i386/predicates.md
> @@ -124,6 +124,10 @@
>         (match_test "TARGET_64BIT")
>         (match_test "REGNO (op) > BX_REG")))
>
> +;; Return true if VALUE is symbol reference
> +(define_predicate "symbol_operand"
> +  (match_code "symbol_ref"))
> +
>  ;; Return true if VALUE can be stored in a sign extended immediate field.
>  (define_predicate "x86_64_immediate_operand"
>    (match_code "const_int,symbol_ref,label_ref,const")
> @@ -336,6 +340,19 @@
>    return false;
>  })
>
> +;; Return true if size of VALUE can be stored in a sign
> +;; extended immediate field.
> +(define_predicate "x86_64_immediate_size_operand"
> +  (match_code "symbol_ref")
> +{
> +  if (!TARGET_64BIT)
> +    return true;
> +
> +  /* For 64 bit target we may assume size of object fits
> +     immediate only when code model guarantees that.  */
> +  return (ix86_cmodel == CM_SMALL || ix86_cmodel == CM_KERNEL);
> +})
> +

This predicate causes bootstrap error:
predicates.md:362:38: error: unused parameter 'op' [-Werror=unused-parameter]

Would it be OK to work it around with a fake use?

if (GET_CODE (op) != SYMBOL_REF)
  gcc_unreachable ();

Thanks,
Ilya

>  ;; Return true if OP is general operand representable on x86_64.
>  (define_predicate "x86_64_general_operand"
>    (if_then_else (match_test "TARGET_64BIT")


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