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Target dependent modes (3/3) Runtime adjustable mode properties


This patch gives the ability to adjust the byte size, alignment, and
floating point format of machine modes at compiler runtime.  Rather
than add target hooks to do the adjustment on the fly, I created a
declarative notation for the ARCH-modes.def file.  This gets processed
into a generated init_adjust_machine_modes function that is called
once at the beginning of backend_init() - safely after processing
command line options, but it does mean that you can't adjust these
things in the middle of a run.  It is inspired by the runtime
adjustments to real_format_for_mode that are currently done ad-hoc in
OVERRIDE_OPTIONS.  I anticipate migrating all of that to this new
notation, but I have other fish to fry right now.

I also incorporated the fix for the argument typing bug pointed out
yesterday.  The fix for the undeclared snprintf bug will be a little
finickier so I am doing it separately.

This patch does not use the new functionality for anything.  The next
patch from me will use it.

Bootstrapped ia64-hp-hpux11.23.

zw

        * genmodes.c: Include hashtab.h.
        (modes_by_name, hash_mode, eq_mode, struct mode_adjust)
        (adj_bytesize, adj_alignment, adj_format, new_adjust)
        (_ADD_ADJUST, ADJUST_BYTESIZE, ADJUST_ALIGNMENT, ADJUST_FORMAT)
        (print_maybe_const_decl, emit_mode_adjustments): New.
        (known_modes): Rename to modes.
        (find_mode): Kill class argument; look up in hash table.
        (new_mode): Insert into hash table also.
        (new_adjust): New.
        (reset_float_format, make_partial_integer_mode)
        (make_vector_mode): Tweak error reporting.
        (reset_float_format): Correct type of fourth argument.
        (emit_insn_modes_h): Add #defines to help make mode_size,
        mode_base_align, and real_format_for_mode conditionally const.
        (emit_mode_size, emit_mode_base_align): Use print_maybe_const_decl.
        (emit_real_format_for_mode): Likewise, but temporarily disabled.
        (emit_insn_modes_c): Call emit_mode_adjustments.
        (main): Initialize modes_by_name.
        * Makefile.in: Update dependencies.
        * machmode.def: Document EXPR arguments and new ADJUST_* statements.
        * machmode.h: Use CONST_MODE_SIZE and CONST_MODE_BASE_ALIGN in
        declarations of mode_size and mode_base_align.  Declare
        init_adjust_machine_modes.
        * toplev.c (backend_init): Call init_adjust_machine_modes.

===================================================================
Index: Makefile.in
--- Makefile.in	14 Oct 2003 03:41:41 -0000	1.1172
+++ Makefile.in	15 Oct 2003 21:48:29 -0000
@@ -2198,8 +2198,8 @@ genmodes$(build_exeext) : genmodes.o $(B
 	$(CC_FOR_BUILD) $(BUILD_CFLAGS) $(BUILD_LDFLAGS) -o $@ \
 	 genmodes.o $(BUILD_ERRORS) $(BUILD_LIBS)
 
-genmodes.o : genmodes.c $(BCONFIG_H) $(SYSTEM_H) errors.h machmode.def \
-	     $(extra_modes_file)
+genmodes.o : genmodes.c $(BCONFIG_H) $(SYSTEM_H) errors.h $(HASHTAB_H) \
+	     machmode.def $(extra_modes_file)
 
 genpreds$(build_exeext) : genpreds.o $(BUILD_LIBDEPS)
 	$(CC_FOR_BUILD) $(BUILD_CFLAGS) $(BUILD_LDFLAGS) -o $@ \
===================================================================
Index: genmodes.c
--- genmodes.c	15 Oct 2003 17:24:44 -0000	1.4
+++ genmodes.c	15 Oct 2003 20:54:17 -0000
@@ -22,6 +22,7 @@ Software Foundation, 59 Temple Place - S
 #include "bconfig.h"
 #include "system.h"
 #include "errors.h"
+#include "hashtab.h"
 
 /* enum mode_class is normally defined by machmode.h but we can't
    include that header here.  */
@@ -68,7 +69,7 @@ struct mode_data
   unsigned int line;		/* for error reporting */
 };
 
-static struct mode_data *known_modes[MAX_MODE_CLASS];
+static struct mode_data *modes[MAX_MODE_CLASS];
 static unsigned int n_modes[MAX_MODE_CLASS];
 static struct mode_data *void_mode;
 
@@ -79,6 +80,25 @@ static const struct mode_data blank_mode
   "<unknown>", 0
 };
 
+static htab_t modes_by_name;
+
+/* Data structure for recording target-specified runtime adjustments
+   to a particular mode.  We support varying the byte size, the
+   alignment, and the floating point format.  */
+struct mode_adjust
+{
+  struct mode_adjust *next;
+  struct mode_data *mode;
+  const char *adjustment;
+
+  const char *file;
+  unsigned int line;
+};
+
+static struct mode_adjust *adj_bytesize;
+static struct mode_adjust *adj_alignment;
+static struct mode_adjust *adj_format;
+
 /* Mode class operations.  */
 static enum mode_class
 complex_class (enum mode_class class)
@@ -106,16 +126,14 @@ vector_class (enum mode_class class)
     }
 }
 
-static struct mode_data *
-find_mode (enum mode_class class, const char *name)
+/* Utility routines.  */
+static inline struct mode_data *
+find_mode (const char *name)
 {
-  struct mode_data *m;
-
-  for (m = known_modes[class]; m; m = m->next)
-    if (!strcmp (name, m->name))
-      return m;
+  struct mode_data key;
 
-  return 0;
+  key.name = name;
+  return htab_find (modes_by_name, &key);
 }
 
 static struct mode_data *
@@ -124,7 +142,7 @@ new_mode (enum mode_class class, const c
 {
   struct mode_data *m;
 
-  m = find_mode (class, name);
+  m = find_mode (name);
   if (m)
     {
       error ("%s:%d: duplicate definition of mode \"%s\"",
@@ -141,16 +159,79 @@ new_mode (enum mode_class class, const c
     m->file = trim_filename (file);
   m->line = line;
 
-  m->next = known_modes[class];
-  known_modes[class] = m;
+  m->next = modes[class];
+  modes[class] = m;
   n_modes[class]++;
+
+  *htab_find_slot (modes_by_name, m, INSERT) = m;
+  
   return m;
 }
 
+static hashval_t
+hash_mode (const void *p)
+{
+  const struct mode_data *m = (const struct mode_data *)p;
+  return htab_hash_string (m->name);
+}
+
+static int
+eq_mode (const void *p, const void *q)
+{
+  const struct mode_data *a = (const struct mode_data *)p;
+  const struct mode_data *b = (const struct mode_data *)q;
+
+  return !strcmp (a->name, b->name);
+}
+
 #define for_all_modes(C, M)			\
   for (C = 0; C < MAX_MODE_CLASS; C++)		\
-    for (M = known_modes[C]; M; M = M->next)
+    for (M = modes[C]; M; M = M->next)
 
+static void ATTRIBUTE_UNUSED
+new_adjust (const char *name,
+	    struct mode_adjust **category, const char *catname,
+	    const char *adjustment,
+	    enum mode_class required_class,
+	    const char *file, unsigned int line)
+{
+  struct mode_data *mode = find_mode (name);
+  struct mode_adjust *a;
+
+  file = trim_filename (file);
+
+  if (!mode)
+    {
+      error ("%s:%d: no mode \"%s\"", file, line, name);
+      return;
+    }
+
+  if (required_class != MODE_RANDOM && mode->class != required_class)
+    {
+      error ("%s:%d: mode \"%s\" is not class %s",
+	     file, line, name, mode_class_names[required_class] + 5);
+      return;
+    }
+  
+
+  for (a = *category; a; a = a->next)
+    if (a->mode == mode)
+      {
+	error ("%s:%d: mode \"%s\" already has a %s adjustment",
+	       file, line, name, catname);
+	error ("%s:%d: previous adjustment here", a->file, a->line);
+	return;
+      }
+
+  a = xmalloc (sizeof (struct mode_adjust));
+  a->mode = mode;
+  a->adjustment = adjustment;
+  a->file = file;
+  a->line = line;
+
+  a->next = *category;
+  *category = a;
+}
 
 /* Diagnose failure to meet expectations in a partially filled out
    mode structure.  */
@@ -318,7 +399,7 @@ make_complex_modes (enum mode_class clas
   if (cclass == MODE_RANDOM)
     return;
     
-  for (m = known_modes[class]; m; m = m->next)
+  for (m = modes[class]; m; m = m->next)
     {
       /* Skip BImode.  FIXME: BImode probably shouldn't be MODE_INT.  */
       if (m->bitsize == 1)
@@ -372,7 +453,7 @@ make_vector_modes (enum mode_class class
   if (vclass == MODE_RANDOM)
     return;
 
-  for (m = known_modes[class]; m; m = m->next)
+  for (m = modes[class]; m; m = m->next)
     {
       /* Do not construct vector modes with only one element, or
 	 vector modes where the element size doesn't divide the full
@@ -451,12 +532,17 @@ make_float_mode (const char *name,
   reset_float_format (#N, #F, __FILE__, __LINE__)
 static void ATTRIBUTE_UNUSED
 reset_float_format (const char *name, const char *format,
-		    const char *file, const char *line)
+		    const char *file, unsigned int line)
 {
-  struct mode_data *m = find_mode (MODE_FLOAT, name);
+  struct mode_data *m = find_mode (name);
   if (!m)
     {
-      error ("%s:%d: no mode \"%s\" in class FLOAT", file, line, name);
+      error ("%s:%d: no mode \"%s\"", file, line, name);
+      return;
+    }
+  if (m->class != MODE_FLOAT)
+    {
+      error ("%s:%d: mode \"%s\" is not class FLOAT", file, line, name);
       return;
     }
   m->format = format;
@@ -472,10 +558,15 @@ make_partial_integer_mode (const char *b
 			   const char *file, unsigned int line)
 {
   struct mode_data *m;
-  struct mode_data *component = find_mode (MODE_INT, base);
+  struct mode_data *component = find_mode (base);
   if (!component)
     {
-      error ("%s:%d: no mode \"%s\" in class INT", file, line, name);
+      error ("%s:%d: no mode \"%s\"", file, line, name);
+      return;
+    }
+  if (component->class != MODE_INT)
+    {
+      error ("%s:%d: mode \"%s\" is not class INT", file, line, name);
       return;
     }
   
@@ -496,14 +587,19 @@ make_vector_mode (enum mode_class bclass
 {
   struct mode_data *v;
   enum mode_class vclass = vector_class (bclass);
-  struct mode_data *component = find_mode (bclass, base);
+  struct mode_data *component = find_mode (base);
   char namebuf[8];
 
   if (vclass == MODE_RANDOM)
     return;
   if (component == 0)
     {
-      error ("%s:%d: no mode \"%s\" in class %s",
+      error ("%s:%d: no mode \"%s\"", file, line, base);
+      return;
+    }
+  if (component->class != bclass)
+    {
+      error ("%s:%d: mode \"%s\" is not class %s",
 	     file, line, base, mode_class_names[bclass] + 5);
       return;
     }
@@ -520,7 +616,14 @@ make_vector_mode (enum mode_class bclass
   v->ncomponents = ncomponents;
   v->component = component;
 }
-  
+
+/* Adjustability.  */
+#define _ADD_ADJUST(A, M, X, C) \
+  new_adjust (#M, &adj_##A, #A, #X, MODE_##C, __FILE__, __LINE__)
+
+#define ADJUST_BYTESIZE(M, X)  _ADD_ADJUST(bytesize, M, X, RANDOM)
+#define ADJUST_ALIGNMENT(M, X) _ADD_ADJUST(alignment, M, X, RANDOM)
+#define ADJUST_FLOAT_FORMAT(M, X)    _ADD_ADJUST(format, M, X, FLOAT)
 
 static void
 create_modes (void)
@@ -600,7 +703,7 @@ calc_wider_mode (void)
 	{
 	  struct mode_data *prev, *next;
 
-	  for (prev = 0, m = known_modes[c]; m; m = next)
+	  for (prev = 0, m = modes[c]; m; m = next)
 	    {
 	      m->wider = void_mode;
 
@@ -609,14 +712,14 @@ calc_wider_mode (void)
 	      m->next = prev;
 	      prev = m;
 	    }
-	  known_modes[c] = prev;
+	  modes[c] = prev;
 	}
       else
 	{
-	  if (!known_modes[c])
+	  if (!modes[c])
 	    continue;
 
-	  for (i = 0, m = known_modes[c]; m; i++, m = m->next)
+	  for (i = 0, m = modes[c]; m; i++, m = m->next)
 	    sortbuf[i] = m;
 
 	  qsort (sortbuf, i, sizeof (struct mode_data *), cmp_modes);
@@ -626,7 +729,7 @@ calc_wider_mode (void)
 	    sortbuf[j]->next = sortbuf[j]->wider = sortbuf[j + 1];
 
 
-	  known_modes[c] = sortbuf[0];
+	  modes[c] = sortbuf[0];
 	}
     }
 }
@@ -640,7 +743,11 @@ calc_wider_mode (void)
 } while (0)
 
 #define print_decl(TYPE, NAME, ASIZE) \
-  printf ("\nconst %s %s[%s] =\n{\n", TYPE, NAME, ASIZE);
+  puts ("\nconst " TYPE " " NAME "[" ASIZE "] =\n{");
+
+#define print_maybe_const_decl(TYPE, NAME, ASIZE, CATEGORY)	\
+  printf ("\n" TYPE " " NAME "[" ASIZE "] = \n{\n",		\
+	  adj_##CATEGORY ? "" : "const ")
 
 #define print_closer() puts ("};")
 
@@ -663,7 +770,7 @@ emit_insn_modes_h (void)
 enum machine_mode\n{");
 
   for (c = 0; c < MAX_MODE_CLASS; c++)
-    for (m = known_modes[c]; m; m = m->next)
+    for (m = modes[c]; m; m = m->next)
       {
 	int count_;
 	printf ("  %smode,%n", m->name, &count_);
@@ -675,7 +782,7 @@ enum machine_mode\n{");
 
   for (c = 0; c < MAX_MODE_CLASS; c++)
     {
-      first = known_modes[c];
+      first = modes[c];
       last = 0;
       for (m = first; m; last = m, m = m->next)
 	;
@@ -699,7 +806,15 @@ enum machine_mode\n{");
 
   puts ("\
   NUM_MACHINE_MODES = MAX_MACHINE_MODE\n\
-};\n\
+};\n");
+
+  /* I can't think of a better idea, can you?  */
+  printf ("#define CONST_MODE_SIZE%s\n", adj_bytesize ? "" : " const");
+  printf ("#define CONST_MODE_BASE_ALIGN%s\n", adj_alignment ? "" : " const");
+#if 0 /* disabled for backward compatibility, temporary */
+  printf ("#define CONST_REAL_FORMAT_FOR_MODE%s\n", adj_format ? "" :" const");
+#endif
+  puts ("\
 \n\
 #endif /* insn-modes.h */");
 }
@@ -788,7 +903,8 @@ emit_mode_size (void)
   enum mode_class c;
   struct mode_data *m;
 
-  print_decl ("unsigned char", "mode_size", "NUM_MACHINE_MODES");
+  print_maybe_const_decl ("%sunsigned char", "mode_size",
+			  "NUM_MACHINE_MODES", bytesize);
 
   for_all_modes (c, m)
     tagged_printf ("%u", m->bytesize, m->name);
@@ -875,7 +991,9 @@ emit_mode_base_align (void)
   enum mode_class c;
   struct mode_data *m;
 
-  print_decl ("unsigned char", "mode_base_align", "NUM_MACHINE_MODES");
+  print_maybe_const_decl ("%sunsigned char",
+			  "mode_base_align", "NUM_MACHINE_MODES",
+			  alignment);
 
   for_all_modes (c, m)
     tagged_printf ("%u", m->alignment, m->name);
@@ -893,11 +1011,11 @@ emit_class_narrowest_mode (void)
   for (c = 0; c < MAX_MODE_CLASS; c++)
     /* Bleah, all this to get the comment right for MIN_MODE_INT.  */
     tagged_printf ("MIN_%s", mode_class_names[c],
-		   known_modes[c]
-		   ? (known_modes[c]->bitsize != 1
-		      ? known_modes[c]->name
-		      : (known_modes[c]->next
-			 ? known_modes[c]->next->name
+		   modes[c]
+		   ? (modes[c]->bitsize != 1
+		      ? modes[c]->name
+		      : (modes[c]->next
+			 ? modes[c]->next->name
 			 : void_mode->name))
 		   : void_mode->name);
   
@@ -909,12 +1027,23 @@ emit_real_format_for_mode (void)
 {
   struct mode_data *m;
 
-  /* This will produce a table which is not constant, but points to
-     entities that are constant, which is what we want.  */
-  print_decl ("struct real_format *\n ", "real_format_for_mode",
+  /* The entities pointed to by this table are constant, whether
+     or not the table itself is constant.
+
+     For backward compatibility this table is always writable
+     (several targets modify it in OVERRIDE_OPTIONS).   FIXME:
+     convert all said targets to use ADJUST_FORMAT instead.  */
+#if 0
+  print_maybe_const_decl ("const struct real_format *%s",
+			  "real_format_for_mode",
+			  "MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1",
+			  format);
+#else
+  print_decl ("struct real_format *\n", "real_format_for_mode",
 	      "MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1");
+#endif
 
-  for (m = known_modes[MODE_FLOAT]; m; m = m->next)
+  for (m = modes[MODE_FLOAT]; m; m = m->next)
     if (!strcmp (m->format, "0"))
       tagged_printf ("%s", m->format, m->name);
     else
@@ -924,6 +1053,32 @@ emit_real_format_for_mode (void)
 }
 
 static void
+emit_mode_adjustments (void)
+{
+  struct mode_adjust *a;
+
+  puts ("\nvoid\ninit_adjust_machine_modes (void)\n{");
+
+  for (a = adj_bytesize; a; a = a->next)
+    printf ("  /* %s:%d */\n  mode_size[%smode] = %s;\n",
+	    a->file, a->line, a->mode->name, a->adjustment);
+  if (adj_bytesize && (adj_alignment || adj_format))
+    putchar ('\n');
+
+  for (a = adj_alignment; a; a = a->next)
+    printf ("  /* %s:%d */\n  mode_base_align[%smode] = %s;\n",
+	    a->file, a->line, a->mode->name, a->adjustment);
+  if (adj_alignment && adj_format)
+    putchar ('\n');
+
+  for (a = adj_format; a; a = a->next)
+    printf ("  /* %s:%d */\n  REAL_MODE_FORMAT (%smode) = %s;\n",
+	    a->file, a->line, a->mode->name, a->adjustment);
+
+  puts ("}");
+}
+
+static void
 emit_insn_modes_c (void)
 {
   emit_insn_modes_c_header ();
@@ -938,6 +1093,7 @@ emit_insn_modes_c (void)
   emit_mode_base_align ();
   emit_class_narrowest_mode ();
   emit_real_format_for_mode ();
+  emit_mode_adjustments ();
 }
 
 static void
@@ -968,6 +1124,8 @@ main(int argc, char **argv)
       error ("usage: %s [-h|-m] > file", progname);
       return FATAL_EXIT_CODE;
     }
+
+  modes_by_name = htab_create_alloc (64, hash_mode, eq_mode, 0, xcalloc, free);
 
   create_modes ();
   complete_all_modes ();
===================================================================
Index: machmode.def
--- machmode.def	13 Oct 2003 21:16:18 -0000	1.25
+++ machmode.def	15 Oct 2003 20:54:17 -0000
@@ -51,7 +51,13 @@ Software Foundation, 59 Temple Place - S
    constant.
 
    A FORMAT argument must be one of the real_mode_format structures
-   declared in real.h, or else a literal 0.
+   declared in real.h, or else a literal 0.  Do not put a leading &
+   on the argument.
+
+   An EXPR argument must be a syntactically valid C expression.
+   If an EXPR contains commas, you may need to write an extra pair of
+   parentheses around it, so it appears to be a single argument to the
+   statement.
 
    This file defines only those modes which are of use on almost all
    machines.  Other modes can be defined in the target-specific
@@ -119,6 +125,17 @@ Software Foundation, 59 Temple Place - S
 	replacing the 'F' in the mode name with a 'C'.  (It is an
 	error if there is no 'F'.  For INT modes, the names are
 	derived by prefixing a C to the name.
+
+     ADJUST_BYTESIZE (MODE, EXPR);
+     ADJUST_ALIGNMENT (MODE, EXPR);
+     ADJUST_FLOAT_FORMAT (MODE, EXPR);
+        Arrange for the byte size, alignment, or floating point format
+	of MODE to be adjustable at run time.  EXPR will be executed
+	once after processing all command line options, and should
+	evaluate to the desired byte size, alignment, or format.
+
+	Unlike a FORMAT argument, if you are adjusting a float format
+	you must put an & in front of the name of each format structure.
 
    Note: If a mode is ever made which is more than 255 bytes wide,
    machmode.h and genmodes.c will have to be changed to allocate
===================================================================
Index: machmode.h
--- machmode.h	11 Oct 2003 00:18:02 -0000	1.35
+++ machmode.h	15 Oct 2003 20:54:17 -0000
@@ -78,7 +78,7 @@ extern const unsigned char mode_class[NU
 
 /* Get the size in bytes of an object of mode MODE.  */
 
-extern const unsigned char mode_size[NUM_MACHINE_MODES];
+extern CONST_MODE_SIZE unsigned char mode_size[NUM_MACHINE_MODES];
 #define GET_MODE_SIZE(MODE)   mode_size[MODE]
 
 /* Get the size in bytes of the basic parts of an object of mode MODE.  */
@@ -139,7 +139,7 @@ extern enum machine_mode get_best_mode (
 
 /* Determine alignment, 1<=result<=BIGGEST_ALIGNMENT.  */
 
-extern const unsigned char mode_base_align[NUM_MACHINE_MODES];
+extern CONST_MODE_BASE_ALIGN unsigned char mode_base_align[NUM_MACHINE_MODES];
 
 extern unsigned get_mode_alignment (enum machine_mode);
 
@@ -156,5 +156,8 @@ extern const unsigned char class_narrowe
 extern enum machine_mode byte_mode;
 extern enum machine_mode word_mode;
 extern enum machine_mode ptr_mode;
+
+/* Target-dependent machine mode initialization - in insn-modes.c.  */
+extern void init_adjust_machine_modes (void);
 
 #endif /* not HAVE_MACHINE_MODES */
===================================================================
Index: toplev.c
--- toplev.c	11 Oct 2003 22:57:46 -0000	1.832
+++ toplev.c	15 Oct 2003 20:54:20 -0000
@@ -4365,6 +4365,8 @@ process_options (void)
 static void
 backend_init (void)
 {
+  init_adjust_machine_modes ();
+
   init_emit_once (debug_info_level == DINFO_LEVEL_NORMAL
 		  || debug_info_level == DINFO_LEVEL_VERBOSE
 #ifdef VMS_DEBUGGING_INFO


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