[PATCH] gas: extend \+ support to .rept

[PATCH] gas: extend \+ support to .rept

[Jan Beulich]

PR gas/31752

While not quite as macro-like as .irp / .irpc, this perhaps benefits from
supporting \+ even more than those: It allows, where desired, to get away
without maintaining an explicit count variable in source code.

Keep .rep (and custom per-arch uses of s_rept() / do_repeat()) behavior
unaltered.

--- a/gas/NEWS
+++ b/gas/NEWS
@@ -1,7 +1,7 @@
 -*- text -*-
 
-* Assembler macros as well as the bodies of .irp / .irpc can now use the
-  syntax \+ to access the number of times a given macro has been executed.
+* Assembler macros as well as the bodies of .irp / .irpc / .rept can now use
+  the syntax \+ to access the number of times a given macro has been executed.
   This is similar to the already existing \@ syntax, except that the count is
   maintained on a per-macro basis.
   
--- a/gas/doc/as.texi
+++ b/gas/doc/as.texi
@@ -6739,6 +6739,13 @@ is equivalent to assembling
 A count of zero is allowed, but nothing is generated.  Negative counts are not
 allowed and if encountered will be treated as if they were zero.
 
+Much like for macros, @code{.irp}, and @code{.irpc} the @samp{\+} sequence can
+be used to substitute in the number of iterations done so far.  In such cases,
+i.e. when any @samp{\+} character sequence is present between @code{.rept} and
+the corresponding @code{.endr}, other backslashes also need escaping by
+backslashes.  Naturally the amount of escaping necessary may increase when
+using nested constructs.
+
 @node Sbttl
 @section @code{.sbttl "@var{subheading}"}
 
--- a/gas/read.c
+++ b/gas/read.c
@@ -482,7 +482,7 @@ static const pseudo_typeS potable[] = {
   {"quad", cons, 8},
   {"reloc", s_reloc, 0},
   {"rep", s_rept, 0},
-  {"rept", s_rept, 0},
+  {"rept", s_rept, 1},
   {"rva", s_rva, 4},
   {"sbttl", listing_title, 1},	/* Subtitle of listing.  */
 /* scl  */
@@ -3066,19 +3066,21 @@ s_bad_end (int endr)
 /* Handle the .rept pseudo-op.  */
 
 void
-s_rept (int ignore ATTRIBUTE_UNUSED)
+s_rept (int expand_count)
 {
   size_t count;
 
   count = (size_t) get_absolute_expression ();
 
-  do_repeat (count, "REPT", "ENDR", NULL);
+  do_repeat (count, "REPT", "ENDR", expand_count ? "" : NULL);
 }
 
 /* This function provides a generic repeat block implementation.   It allows
    different directives to be used as the start/end keys.  Any text matching
    the optional EXPANDER in the block is replaced by the remaining iteration
-   count.  */
+   count.  Except when EXPANDER is the empty string, in which case \+ will
+   be looked for (as also recognized in macros as well as .irp and .irpc),
+   where the replacement will be the number of iterations done so far.  */
 
 void
 do_repeat (size_t count, const char *start, const char *end,
@@ -3101,7 +3103,58 @@ do_repeat (size_t count, const char *sta
       return;
     }
 
-  if (expander == NULL || strstr (one.ptr, expander) == NULL)
+  if (expander != NULL && !*expander && strstr (one.ptr, "\\+") != NULL)
+    {
+      /* The 3 here and below are arbitrary, added in an attempt to limit
+	 re-allocation needs in sb_add_...() for moderate repeat counts.  */
+      sb_build (&many, count * (one.len + 3));
+
+      for (size_t done = 0; count-- > 0; ++done)
+	{
+	  const char *ptr, *bs;
+	  sb processed;
+
+	  sb_build (&processed, one.len + 3);
+
+	  for (ptr = one.ptr;
+	       (bs = memchr (ptr, '\\', one.ptr + one.len - ptr)) != NULL; )
+	    {
+	      sb_add_buffer (&processed, ptr, bs - ptr);
+	      switch (bs[1])
+		{
+		  char scratch[24];
+
+		default:
+		  sb_add_char (&processed, '\\');
+		  sb_add_char (&processed, bs[1]);
+		  ptr = bs + 2;
+		  break;
+
+		case '\0':
+		  as_warn (_("`\\' at end of line/statement; ignored"));
+		  ptr = bs + 1;
+		  break;
+
+		case '\\':
+		  sb_add_char (&processed, '\\');
+		  ptr = bs + 2;
+		  break;
+
+		case '+':
+		  snprintf (scratch, ARRAY_SIZE (scratch), "%zu", done);
+		  sb_add_string (&processed, scratch);
+		  ptr = bs + 2;
+		  break;
+		}
+	    }
+
+	  sb_add_buffer (&processed, ptr, one.ptr + one.len - ptr);
+
+	  sb_add_sb (&many, &processed);
+	  sb_kill (&processed);
+	}
+    }
+  else if (expander == NULL || !*expander || strstr (one.ptr, expander) == NULL)
     {
       sb_build (&many, count * one.len);
       while (count-- > 0)
--- a/gas/testsuite/gas/macros/macros.exp
+++ b/gas/testsuite/gas/macros/macros.exp
@@ -105,3 +105,4 @@ run_list_test altmacro
 run_list_test count
 run_list_test irp-count
 run_list_test irpc-quote
+run_list_test rept-count
--- /dev/null
+++ b/gas/testsuite/gas/macros/rept-count.l
@@ -0,0 +1,15 @@
+#...
+>0<
+>1<
+>2<
+>3<
+>4<
+>0<
+>0:0<
+>0:1<
+>1<
+>1:0<
+>1:1<
+>2<
+>2:0<
+>2:1<
--- /dev/null
+++ b/gas/testsuite/gas/macros/rept-count.s
@@ -0,0 +1,10 @@
+	.rept 5
+	.print ">\+<"
+	.endr
+
+	.rept 3
+	.print ">\+<"
+	.rept 2
+	.print ">\+:\\+<"
+	.endr
+	.endr

Re: [PATCH] gas: extend \+ support to .rept

[Fangrui Song]

On Mon, May 27, 2024 at 4:51 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> PR gas/31752
>
> While not quite as macro-like as .irp / .irpc, this perhaps benefits from
> supporting \+ even more than those: It allows, where desired, to get away
> without maintaining an explicit count variable in source code.
>
> Keep .rep (and custom per-arch uses of s_rept() / do_repeat()) behavior
> unaltered.
>
> --- a/gas/NEWS
> +++ b/gas/NEWS
> @@ -1,7 +1,7 @@
>  -*- text -*-
>
> -* Assembler macros as well as the bodies of .irp / .irpc can now use the
> -  syntax \+ to access the number of times a given macro has been executed.
> +* Assembler macros as well as the bodies of .irp / .irpc / .rept can now use
> +  the syntax \+ to access the number of times a given macro has been executed.
>    This is similar to the already existing \@ syntax, except that the count is
>    maintained on a per-macro basis.
>
> --- a/gas/doc/as.texi
> +++ b/gas/doc/as.texi
> @@ -6739,6 +6739,13 @@ is equivalent to assembling
>  A count of zero is allowed, but nothing is generated.  Negative counts are not
>  allowed and if encountered will be treated as if they were zero.
>
> +Much like for macros, @code{.irp}, and @code{.irpc} the @samp{\+} sequence can
> +be used to substitute in the number of iterations done so far.  In such cases,
> +i.e. when any @samp{\+} character sequence is present between @code{.rept} and
> +the corresponding @code{.endr}, other backslashes also need escaping by
> +backslashes.  Naturally the amount of escaping necessary may increase when
> +using nested constructs.
> +
>  @node Sbttl
>  @section @code{.sbttl "@var{subheading}"}
>
> --- a/gas/read.c
> +++ b/gas/read.c
> @@ -482,7 +482,7 @@ static const pseudo_typeS potable[] = {
>    {"quad", cons, 8},
>    {"reloc", s_reloc, 0},
>    {"rep", s_rept, 0},
> -  {"rept", s_rept, 0},
> +  {"rept", s_rept, 1},
>    {"rva", s_rva, 4},
>    {"sbttl", listing_title, 1}, /* Subtitle of listing.  */
>  /* scl  */
> @@ -3066,19 +3066,21 @@ s_bad_end (int endr)
>  /* Handle the .rept pseudo-op.  */
>
>  void
> -s_rept (int ignore ATTRIBUTE_UNUSED)
> +s_rept (int expand_count)
>  {
>    size_t count;
>
>    count = (size_t) get_absolute_expression ();
>
> -  do_repeat (count, "REPT", "ENDR", NULL);
> +  do_repeat (count, "REPT", "ENDR", expand_count ? "" : NULL);
>  }
>
>  /* This function provides a generic repeat block implementation.   It allows
>     different directives to be used as the start/end keys.  Any text matching
>     the optional EXPANDER in the block is replaced by the remaining iteration
> -   count.  */
> +   count.  Except when EXPANDER is the empty string, in which case \+ will
> +   be looked for (as also recognized in macros as well as .irp and .irpc),
> +   where the replacement will be the number of iterations done so far.  */
>
>  void
>  do_repeat (size_t count, const char *start, const char *end,
> @@ -3101,7 +3103,58 @@ do_repeat (size_t count, const char *sta
>        return;
>      }
>
> -  if (expander == NULL || strstr (one.ptr, expander) == NULL)
> +  if (expander != NULL && !*expander && strstr (one.ptr, "\\+") != NULL)
> +    {
> +      /* The 3 here and below are arbitrary, added in an attempt to limit
> +        re-allocation needs in sb_add_...() for moderate repeat counts.  */
> +      sb_build (&many, count * (one.len + 3));
> +
> +      for (size_t done = 0; count-- > 0; ++done)
> +       {
> +         const char *ptr, *bs;
> +         sb processed;
> +
> +         sb_build (&processed, one.len + 3);
> +
> +         for (ptr = one.ptr;
> +              (bs = memchr (ptr, '\\', one.ptr + one.len - ptr)) != NULL; )
> +           {
> +             sb_add_buffer (&processed, ptr, bs - ptr);
> +             switch (bs[1])
> +               {
> +                 char scratch[24];
> +
> +               default:
> +                 sb_add_char (&processed, '\\');
> +                 sb_add_char (&processed, bs[1]);
> +                 ptr = bs + 2;
> +                 break;
> +
> +               case '\0':
> +                 as_warn (_("`\\' at end of line/statement; ignored"));
> +                 ptr = bs + 1;
> +                 break;
> +
> +               case '\\':
> +                 sb_add_char (&processed, '\\');
> +                 ptr = bs + 2;
> +                 break;
> +
> +               case '+':
> +                 snprintf (scratch, ARRAY_SIZE (scratch), "%zu", done);
> +                 sb_add_string (&processed, scratch);
> +                 ptr = bs + 2;
> +                 break;
> +               }
> +           }
> +
> +         sb_add_buffer (&processed, ptr, one.ptr + one.len - ptr);
> +
> +         sb_add_sb (&many, &processed);
> +         sb_kill (&processed);
> +       }
> +    }
> +  else if (expander == NULL || !*expander || strstr (one.ptr, expander) == NULL)
>      {
>        sb_build (&many, count * one.len);
>        while (count-- > 0)
> --- a/gas/testsuite/gas/macros/macros.exp
> +++ b/gas/testsuite/gas/macros/macros.exp
> @@ -105,3 +105,4 @@ run_list_test altmacro
>  run_list_test count
>  run_list_test irp-count
>  run_list_test irpc-quote
> +run_list_test rept-count
> --- /dev/null
> +++ b/gas/testsuite/gas/macros/rept-count.l
> @@ -0,0 +1,15 @@
> +#...
> +>0<
> +>1<
> +>2<
> +>3<
> +>4<
> +>0<
> +>0:0<
> +>0:1<
> +>1<
> +>1:0<
> +>1:1<
> +>2<
> +>2:0<
> +>2:1<
> --- /dev/null
> +++ b/gas/testsuite/gas/macros/rept-count.s
> @@ -0,0 +1,10 @@
> +       .rept 5
> +       .print ">\+<"
> +       .endr

LGTM.

Perhaps this .print directive can be changed to print \+ \+
to show that the \+ expanded value is identical within one iteration.

> +
> +       .rept 3
> +       .print ">\+<"
> +       .rept 2
> +       .print ">\+:\\+<"
> +       .endr
> +       .endr

Re: [PATCH] gas: extend \+ support to .rept

[Fangrui Song]

On Tue, May 28, 2024 at 10:21 PM Fangrui Song <i@maskray.me> wrote:
>
> On Mon, May 27, 2024 at 4:51 AM Jan Beulich <jbeulich@suse.com> wrote:
> >
> > PR gas/31752
> >
> > While not quite as macro-like as .irp / .irpc, this perhaps benefits from
> > supporting \+ even more than those: It allows, where desired, to get away
> > without maintaining an explicit count variable in source code.
> >
> > Keep .rep (and custom per-arch uses of s_rept() / do_repeat()) behavior
> > unaltered.
> >
> > --- a/gas/NEWS
> > +++ b/gas/NEWS
> > @@ -1,7 +1,7 @@
> >  -*- text -*-
> >
> > -* Assembler macros as well as the bodies of .irp / .irpc can now use the
> > -  syntax \+ to access the number of times a given macro has been executed.
> > +* Assembler macros as well as the bodies of .irp / .irpc / .rept can now use
> > +  the syntax \+ to access the number of times a given macro has been executed.
> >    This is similar to the already existing \@ syntax, except that the count is
> >    maintained on a per-macro basis.
> >
> > --- a/gas/doc/as.texi
> > +++ b/gas/doc/as.texi
> > @@ -6739,6 +6739,13 @@ is equivalent to assembling
> >  A count of zero is allowed, but nothing is generated.  Negative counts are not
> >  allowed and if encountered will be treated as if they were zero.
> >
> > +Much like for macros, @code{.irp}, and @code{.irpc} the @samp{\+} sequence can
> > +be used to substitute in the number of iterations done so far.  In such cases,
> > +i.e. when any @samp{\+} character sequence is present between @code{.rept} and
> > +the corresponding @code{.endr}, other backslashes also need escaping by
> > +backslashes.  Naturally the amount of escaping necessary may increase when
> > +using nested constructs.
> > +
> >  @node Sbttl
> >  @section @code{.sbttl "@var{subheading}"}
> >
> > --- a/gas/read.c
> > +++ b/gas/read.c
> > @@ -482,7 +482,7 @@ static const pseudo_typeS potable[] = {
> >    {"quad", cons, 8},
> >    {"reloc", s_reloc, 0},
> >    {"rep", s_rept, 0},
> > -  {"rept", s_rept, 0},
> > +  {"rept", s_rept, 1},
> >    {"rva", s_rva, 4},
> >    {"sbttl", listing_title, 1}, /* Subtitle of listing.  */
> >  /* scl  */
> > @@ -3066,19 +3066,21 @@ s_bad_end (int endr)
> >  /* Handle the .rept pseudo-op.  */
> >
> >  void
> > -s_rept (int ignore ATTRIBUTE_UNUSED)
> > +s_rept (int expand_count)
> >  {
> >    size_t count;
> >
> >    count = (size_t) get_absolute_expression ();
> >
> > -  do_repeat (count, "REPT", "ENDR", NULL);
> > +  do_repeat (count, "REPT", "ENDR", expand_count ? "" : NULL);
> >  }
> >
> >  /* This function provides a generic repeat block implementation.   It allows
> >     different directives to be used as the start/end keys.  Any text matching
> >     the optional EXPANDER in the block is replaced by the remaining iteration
> > -   count.  */
> > +   count.  Except when EXPANDER is the empty string, in which case \+ will
> > +   be looked for (as also recognized in macros as well as .irp and .irpc),
> > +   where the replacement will be the number of iterations done so far.  */
> >
> >  void
> >  do_repeat (size_t count, const char *start, const char *end,
> > @@ -3101,7 +3103,58 @@ do_repeat (size_t count, const char *sta
> >        return;
> >      }
> >
> > -  if (expander == NULL || strstr (one.ptr, expander) == NULL)
> > +  if (expander != NULL && !*expander && strstr (one.ptr, "\\+") != NULL)
> > +    {
> > +      /* The 3 here and below are arbitrary, added in an attempt to limit
> > +        re-allocation needs in sb_add_...() for moderate repeat counts.  */
> > +      sb_build (&many, count * (one.len + 3));
> > +
> > +      for (size_t done = 0; count-- > 0; ++done)

Nit: done = 0; done < count; ++done)  might be more idiomatic (avoid
changing `count`).

> > +       {
> > +         const char *ptr, *bs;
> > +         sb processed;
> > +
> > +         sb_build (&processed, one.len + 3);
> > +
> > +         for (ptr = one.ptr;
> > +              (bs = memchr (ptr, '\\', one.ptr + one.len - ptr)) != NULL; )
> > +           {
> > +             sb_add_buffer (&processed, ptr, bs - ptr);
> > +             switch (bs[1])
> > +               {
> > +                 char scratch[24];
> > +
> > +               default:
> > +                 sb_add_char (&processed, '\\');
> > +                 sb_add_char (&processed, bs[1]);
> > +                 ptr = bs + 2;
> > +                 break;
> > +
> > +               case '\0':
> > +                 as_warn (_("`\\' at end of line/statement; ignored"));
> > +                 ptr = bs + 1;
> > +                 break;
> > +
> > +               case '\\':
> > +                 sb_add_char (&processed, '\\');
> > +                 ptr = bs + 2;
> > +                 break;
> > +
> > +               case '+':
> > +                 snprintf (scratch, ARRAY_SIZE (scratch), "%zu", done);
> > +                 sb_add_string (&processed, scratch);
> > +                 ptr = bs + 2;
> > +                 break;
> > +               }
> > +           }
> > +
> > +         sb_add_buffer (&processed, ptr, one.ptr + one.len - ptr);
> > +
> > +         sb_add_sb (&many, &processed);
> > +         sb_kill (&processed);
> > +       }
> > +    }
> > +  else if (expander == NULL || !*expander || strstr (one.ptr, expander) == NULL)
> >      {
> >        sb_build (&many, count * one.len);
> >        while (count-- > 0)
> > --- a/gas/testsuite/gas/macros/macros.exp
> > +++ b/gas/testsuite/gas/macros/macros.exp
> > @@ -105,3 +105,4 @@ run_list_test altmacro
> >  run_list_test count
> >  run_list_test irp-count
> >  run_list_test irpc-quote
> > +run_list_test rept-count
> > --- /dev/null
> > +++ b/gas/testsuite/gas/macros/rept-count.l
> > @@ -0,0 +1,15 @@
> > +#...
> > +>0<
> > +>1<
> > +>2<
> > +>3<
> > +>4<
> > +>0<
> > +>0:0<
> > +>0:1<
> > +>1<
> > +>1:0<
> > +>1:1<
> > +>2<
> > +>2:0<
> > +>2:1<
> > --- /dev/null
> > +++ b/gas/testsuite/gas/macros/rept-count.s
> > @@ -0,0 +1,10 @@
> > +       .rept 5
> > +       .print ">\+<"
> > +       .endr
>
> LGTM.
>
> Perhaps this .print directive can be changed to print \+ \+
> to show that the \+ expanded value is identical within one iteration.
>
> > +
> > +       .rept 3
> > +       .print ">\+<"
> > +       .rept 2
> > +       .print ">\+:\\+<"
> > +       .endr
> > +       .endr