x86: Use ud2 assembly mnemonic when available.
diff mbox

Message ID CAB=4xhrEQAf1ksLHfWZSabct4NF3HBxXUUBHuaYQ3dKGPZ315w@mail.gmail.com
State New
Headers show

Commit Message

Roland McGrath Feb. 13, 2014, 11:46 p.m. UTC
Non-ancient assemblers support the "ud2" mnemonic, so there is no need
to emit the literal opcode as data.

OK for trunk and 4.8?


Thanks,
Roland


gcc/
2014-02-13  Roland McGrath  <mcgrathr@google.com>

	* configure.ac (HAVE_AS_IX86_UD2): New test for 'ud2' mnemonic.
	* configure: Regenerated.
	* config.in: Regenerated.
	* config/i386/i386.md (trap) [HAVE_AS_IX86_UD2]: Use the mnemonic
	instead of ASM_SHORT.

Comments

Andrew Pinski Feb. 13, 2014, 11:50 p.m. UTC | #1
On Thu, Feb 13, 2014 at 3:46 PM, Roland McGrath <mcgrathr@google.com> wrote:
> Non-ancient assemblers support the "ud2" mnemonic, so there is no need
> to emit the literal opcode as data.
>
> OK for trunk and 4.8?

I changed this to use .word due to openbsd3.1:
http://gcc.gnu.org/ml/gcc-patches/2005-07/msg01347.html .  I no longer
have access to this older openbsd box so I don't object to this
change.  In fact I doubt we support any binutils that are pre 2.0 any
more; so maybe move over unconditionally to ud.

Thanks,
Andrew Pinski

>
>
> Thanks,
> Roland
>
>
> gcc/
> 2014-02-13  Roland McGrath  <mcgrathr@google.com>
>
>         * configure.ac (HAVE_AS_IX86_UD2): New test for 'ud2' mnemonic.
>         * configure: Regenerated.
>         * config.in: Regenerated.
>         * config/i386/i386.md (trap) [HAVE_AS_IX86_UD2]: Use the mnemonic
>         instead of ASM_SHORT.
>
> --- a/gcc/config.in
> +++ b/gcc/config.in
> @@ -375,6 +375,12 @@
>  #endif
>
>
> +/* Define if your assembler supports the 'ud2' mnemonic. */
> +#ifndef USED_FOR_TARGET
> +#undef HAVE_AS_IX86_UD2
> +#endif
> +
> +
>  /* Define if your assembler supports the lituse_jsrdirect relocation. */
>  #ifndef USED_FOR_TARGET
>  #undef HAVE_AS_JSRDIRECT_RELOCS
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -17843,7 +17843,13 @@
>  (define_insn "trap"
>    [(trap_if (const_int 1) (const_int 6))]
>    ""
> -  { return ASM_SHORT "0x0b0f"; }
> +{
> +#ifdef HAVE_AS_IX86_UD2
> +  return "ud2";
> +#else
> +  return ASM_SHORT "0x0b0f";
> +#endif
> +}
>    [(set_attr "length" "2")])
>
>  (define_expand "prefetch"
> --- a/gcc/configure
> +++ b/gcc/configure
> @@ -25109,6 +25109,37 @@ $as_echo "#define
> HAVE_AS_IX86_REP_LOCK_PREFIX 1" >>confdefs.h
>
>  fi
>
> +    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
> ud2 mnemonic" >&5
> +$as_echo_n "checking assembler for ud2 mnemonic... " >&6; }
> +if test "${gcc_cv_as_ix86_ud2+set}" = set; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  gcc_cv_as_ix86_ud2=no
> +  if test x$gcc_cv_as != x; then
> +    $as_echo 'ud2' > conftest.s
> +    if { ac_try='$gcc_cv_as $gcc_cv_as_flags  -o conftest.o conftest.s >&5'
> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> +  (eval $ac_try) 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; }
> +    then
> +       gcc_cv_as_ix86_ud2=yes
> +    else
> +      echo "configure: failed program was" >&5
> +      cat conftest.s >&5
> +    fi
> +    rm -f conftest.o conftest.s
> +  fi
> +fi
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_ix86_ud2" >&5
> +$as_echo "$gcc_cv_as_ix86_ud2" >&6; }
> +if test $gcc_cv_as_ix86_ud2 = yes; then
> +
> +$as_echo "#define HAVE_AS_IX86_UD2 1" >>confdefs.h
> +
> +fi
> +
>      { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
> R_386_TLS_GD_PLT reloc" >&5
>  $as_echo_n "checking assembler for R_386_TLS_GD_PLT reloc... " >&6; }
>  if test "${gcc_cv_as_ix86_tlsgdplt+set}" = set; then :
> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac
> @@ -3895,6 +3895,12 @@ foo:     nop
>          [AC_DEFINE(HAVE_AS_IX86_REP_LOCK_PREFIX, 1,
>            [Define if the assembler supports 'rep <insn>, lock <insn>'.])])
>
> +    gcc_GAS_CHECK_FEATURE([ud2 mnemonic],
> +       gcc_cv_as_ix86_ud2,,,
> +       [ud2],,
> +      [AC_DEFINE(HAVE_AS_IX86_UD2, 1,
> +       [Define if your assembler supports the 'ud2' mnemonic.])])
> +
>      gcc_GAS_CHECK_FEATURE([R_386_TLS_GD_PLT reloc],
>          gcc_cv_as_ix86_tlsgdplt,,,
>         [call    tls_gd@tlsgdplt],
Andrew Pinski Feb. 13, 2014, 11:52 p.m. UTC | #2
On Thu, Feb 13, 2014 at 3:50 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Thu, Feb 13, 2014 at 3:46 PM, Roland McGrath <mcgrathr@google.com> wrote:
>> Non-ancient assemblers support the "ud2" mnemonic, so there is no need
>> to emit the literal opcode as data.
>>
>> OK for trunk and 4.8?
>
> I changed this to use .word due to openbsd3.1:
> http://gcc.gnu.org/ml/gcc-patches/2005-07/msg01347.html .  I no longer
> have access to this older openbsd box so I don't object to this
> change.  In fact I doubt we support any binutils that are pre 2.0 any
> more; so maybe move over unconditionally to ud.


Oh looking into this further, it looks like Sun's assembler does not
support it either:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23359

Thanks,
Andrew

>
> Thanks,
> Andrew Pinski
>
>>
>>
>> Thanks,
>> Roland
>>
>>
>> gcc/
>> 2014-02-13  Roland McGrath  <mcgrathr@google.com>
>>
>>         * configure.ac (HAVE_AS_IX86_UD2): New test for 'ud2' mnemonic.
>>         * configure: Regenerated.
>>         * config.in: Regenerated.
>>         * config/i386/i386.md (trap) [HAVE_AS_IX86_UD2]: Use the mnemonic
>>         instead of ASM_SHORT.
>>
>> --- a/gcc/config.in
>> +++ b/gcc/config.in
>> @@ -375,6 +375,12 @@
>>  #endif
>>
>>
>> +/* Define if your assembler supports the 'ud2' mnemonic. */
>> +#ifndef USED_FOR_TARGET
>> +#undef HAVE_AS_IX86_UD2
>> +#endif
>> +
>> +
>>  /* Define if your assembler supports the lituse_jsrdirect relocation. */
>>  #ifndef USED_FOR_TARGET
>>  #undef HAVE_AS_JSRDIRECT_RELOCS
>> --- a/gcc/config/i386/i386.md
>> +++ b/gcc/config/i386/i386.md
>> @@ -17843,7 +17843,13 @@
>>  (define_insn "trap"
>>    [(trap_if (const_int 1) (const_int 6))]
>>    ""
>> -  { return ASM_SHORT "0x0b0f"; }
>> +{
>> +#ifdef HAVE_AS_IX86_UD2
>> +  return "ud2";
>> +#else
>> +  return ASM_SHORT "0x0b0f";
>> +#endif
>> +}
>>    [(set_attr "length" "2")])
>>
>>  (define_expand "prefetch"
>> --- a/gcc/configure
>> +++ b/gcc/configure
>> @@ -25109,6 +25109,37 @@ $as_echo "#define
>> HAVE_AS_IX86_REP_LOCK_PREFIX 1" >>confdefs.h
>>
>>  fi
>>
>> +    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
>> ud2 mnemonic" >&5
>> +$as_echo_n "checking assembler for ud2 mnemonic... " >&6; }
>> +if test "${gcc_cv_as_ix86_ud2+set}" = set; then :
>> +  $as_echo_n "(cached) " >&6
>> +else
>> +  gcc_cv_as_ix86_ud2=no
>> +  if test x$gcc_cv_as != x; then
>> +    $as_echo 'ud2' > conftest.s
>> +    if { ac_try='$gcc_cv_as $gcc_cv_as_flags  -o conftest.o conftest.s >&5'
>> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
>> +  (eval $ac_try) 2>&5
>> +  ac_status=$?
>> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
>> +  test $ac_status = 0; }; }
>> +    then
>> +       gcc_cv_as_ix86_ud2=yes
>> +    else
>> +      echo "configure: failed program was" >&5
>> +      cat conftest.s >&5
>> +    fi
>> +    rm -f conftest.o conftest.s
>> +  fi
>> +fi
>> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_ix86_ud2" >&5
>> +$as_echo "$gcc_cv_as_ix86_ud2" >&6; }
>> +if test $gcc_cv_as_ix86_ud2 = yes; then
>> +
>> +$as_echo "#define HAVE_AS_IX86_UD2 1" >>confdefs.h
>> +
>> +fi
>> +
>>      { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
>> R_386_TLS_GD_PLT reloc" >&5
>>  $as_echo_n "checking assembler for R_386_TLS_GD_PLT reloc... " >&6; }
>>  if test "${gcc_cv_as_ix86_tlsgdplt+set}" = set; then :
>> --- a/gcc/configure.ac
>> +++ b/gcc/configure.ac
>> @@ -3895,6 +3895,12 @@ foo:     nop
>>          [AC_DEFINE(HAVE_AS_IX86_REP_LOCK_PREFIX, 1,
>>            [Define if the assembler supports 'rep <insn>, lock <insn>'.])])
>>
>> +    gcc_GAS_CHECK_FEATURE([ud2 mnemonic],
>> +       gcc_cv_as_ix86_ud2,,,
>> +       [ud2],,
>> +      [AC_DEFINE(HAVE_AS_IX86_UD2, 1,
>> +       [Define if your assembler supports the 'ud2' mnemonic.])])
>> +
>>      gcc_GAS_CHECK_FEATURE([R_386_TLS_GD_PLT reloc],
>>          gcc_cv_as_ix86_tlsgdplt,,,
>>         [call    tls_gd@tlsgdplt],
Roland McGrath Feb. 13, 2014, 11:56 p.m. UTC | #3
Did you read the patch?  It uses an empirical configure check to
discover if the assembler does in fact support ud2.

Patch
diff mbox

--- a/gcc/config.in
+++ b/gcc/config.in
@@ -375,6 +375,12 @@ 
 #endif


+/* Define if your assembler supports the 'ud2' mnemonic. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_IX86_UD2
+#endif
+
+
 /* Define if your assembler supports the lituse_jsrdirect relocation. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_AS_JSRDIRECT_RELOCS
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -17843,7 +17843,13 @@ 
 (define_insn "trap"
   [(trap_if (const_int 1) (const_int 6))]
   ""
-  { return ASM_SHORT "0x0b0f"; }
+{
+#ifdef HAVE_AS_IX86_UD2
+  return "ud2";
+#else
+  return ASM_SHORT "0x0b0f";
+#endif
+}
   [(set_attr "length" "2")])

 (define_expand "prefetch"
--- a/gcc/configure
+++ b/gcc/configure
@@ -25109,6 +25109,37 @@  $as_echo "#define
HAVE_AS_IX86_REP_LOCK_PREFIX 1" >>confdefs.h

 fi

+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
ud2 mnemonic" >&5
+$as_echo_n "checking assembler for ud2 mnemonic... " >&6; }
+if test "${gcc_cv_as_ix86_ud2+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_ix86_ud2=no
+  if test x$gcc_cv_as != x; then
+    $as_echo 'ud2' > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags  -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	gcc_cv_as_ix86_ud2=yes
+    else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_ix86_ud2" >&5
+$as_echo "$gcc_cv_as_ix86_ud2" >&6; }
+if test $gcc_cv_as_ix86_ud2 = yes; then
+
+$as_echo "#define HAVE_AS_IX86_UD2 1" >>confdefs.h
+
+fi
+
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for
R_386_TLS_GD_PLT reloc" >&5
 $as_echo_n "checking assembler for R_386_TLS_GD_PLT reloc... " >&6; }
 if test "${gcc_cv_as_ix86_tlsgdplt+set}" = set; then :
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -3895,6 +3895,12 @@  foo:	nop
         [AC_DEFINE(HAVE_AS_IX86_REP_LOCK_PREFIX, 1,
           [Define if the assembler supports 'rep <insn>, lock <insn>'.])])

+    gcc_GAS_CHECK_FEATURE([ud2 mnemonic],
+	gcc_cv_as_ix86_ud2,,,
+	[ud2],,
+      [AC_DEFINE(HAVE_AS_IX86_UD2, 1,
+	[Define if your assembler supports the 'ud2' mnemonic.])])
+
     gcc_GAS_CHECK_FEATURE([R_386_TLS_GD_PLT reloc],
         gcc_cv_as_ix86_tlsgdplt,,,
 	[call    tls_gd@tlsgdplt],