* rtl.h (traverse_md_constants): Declare.

	(struct md_constant): Define.
	* Makefile.in (HOST_RTL): Add hashtab.o .
	(OBJS): Add hashtab.o .
	(hashtab.o): New rule.
	(rtl.o): Depends on HASHTAB_H.
	* rtl.c (hashtab.h): #include.
	(md_constants): New static variable.
	(def_hash, def_name_eq_p, read_constants): New static functions.
	(traverse_md_constants): New function.
	(read_name): Do constant expansion.
	(read_rtx): Recognize define_constants.
	* gencodes.c (print_md_constant): New function.
	(main): Emit #defines for all constant definitions encountered.
	* md.texi (Constant Definitions): New node.
	* gensupport.c (xcalloc): New function.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@37635 138bc75d-0d04-0410-961f-82ee72b054a4

7 files changed, 242 insertions, 5 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f95b9ba1849..a60a7e9ae70 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,22 @@
+Wed Nov 22 00:52:55 2000  J"orn Rennecke <amylaar@redhat.com>
+
+	* rtl.h (traverse_md_constants): Declare.
+	(struct md_constant): Define.
+	* Makefile.in (HOST_RTL): Add hashtab.o .
+	(OBJS): Add hashtab.o .
+	(hashtab.o): New rule.
+	(rtl.o): Depends on HASHTAB_H.
+	* rtl.c (hashtab.h): #include.
+	(md_constants): New static variable.
+	(def_hash, def_name_eq_p, read_constants): New static functions.
+	(traverse_md_constants): New function.
+	(read_name): Do constant expansion.
+	(read_rtx): Recognize define_constants.
+	* gencodes.c (print_md_constant): New function.
+	(main): Emit #defines for all constant definitions encountered.
+	* md.texi (Constant Definitions): New node.
+	* gensupport.c (xcalloc): New function.
+
 2000-11-21  Richard Henderson  <rth@redhat.com>
 
 	* config/alpha/alpha.c (alpha_split_tfmode_frobsign): New.
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 219b3df6209..a80b6af99e1 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -633,7 +633,7 @@ HOST_LIBS = $(USE_HOST_OBSTACK) $(USE_HOST_ALLOCA) $(USE_HOST_MALLOC)  \
 	    $(USE_HOST_VFPRINTF) $(USE_HOST_DOPRINT) $(HOST_CLIB)
 
 HOST_RTL = $(HOST_PREFIX)rtl.o $(HOST_PREFIX)bitmap.o \
-		$(HOST_PREFIX)ggc-none.o gensupport.o
+		$(HOST_PREFIX)ggc-none.o gensupport.o hashtab.o
 
 HOST_PRINT = $(HOST_PREFIX)print-rtl.o
 HOST_ERRORS = $(HOST_PREFIX)errors.o
@@ -735,7 +735,8 @@ OBJS = diagnostic.o version.o tree.o print-tree.o stor-layout.o fold-const.o  \
  profile.o insn-attrtab.o $(out_object_file) $(EXTRA_OBJS) convert.o	      \
  mbchar.o splay-tree.o graph.o sbitmap.o resource.o hash.o predict.o	      \
  lists.o ggc-common.o $(GGC) stringpool.o simplify-rtx.o ssa.o bb-reorder.o   \
- sibcall.o conflict.o timevar.o ifcvt.o dominance.o dependence.o dce.o
+ sibcall.o conflict.o timevar.o ifcvt.o dominance.o dependence.o dce.o \
+ hashtab.o
 
 BACKEND = toplev.o libbackend.a
 
@@ -1653,6 +1654,11 @@ $(MD_FILE): $(MD_DEPS)
 gensupport.o: gensupport.c $(RTL_H) $(OBSTACK_H) system.h errors.h gensupport.h
 	$(HOST_CC) -c $(HOST_CFLAGS) $(HOST_CPPFLAGS) $(INCLUDES) $(srcdir)/gensupport.c
 
+hashtab.o: $(srcdir)/../libiberty/hashtab.c $(CONFIG_H)
+	rm -f hashtab.c
+	$(LN_S) $(srcdir)/../libiberty/hashtab.c hashtab.c
+	$(HOST_CC) -c $(HOST_CFLAGS) $(HOST_CPPFLAGS) $(INCLUDES) hashtab.c
+
 genconfig : genconfig.o $(HOST_RTL) $(HOST_PRINT) $(HOST_ERRORS) $(HOST_LIBDEPS)
 	$(HOST_CC) $(HOST_CFLAGS) $(HOST_LDFLAGS) -o $@ \
 	  genconfig.o $(HOST_RTL) $(HOST_PRINT) $(HOST_ERRORS) $(HOST_LIBS)
@@ -1749,7 +1755,7 @@ gengenrtl.o : gengenrtl.c $(RTL_BASE_H) system.h real.h
 # and HOST_PREFIX_1 is `foobar', just to ensure these rules don't conflict
 # with the rules for rtl.o, alloca.o, etc.
 $(HOST_PREFIX_1)rtl.o: $(srcdir)/rtl.c $(CONFIG_H) system.h $(RTL_H) \
-  bitmap.h $(GGC_H) toplev.h
+  bitmap.h $(GGC_H) toplev.h $(HASHTAB_H)
 	rm -f $(HOST_PREFIX)rtl.c
 	sed -e 's/config[.]h/hconfig.h/' $(srcdir)/rtl.c > $(HOST_PREFIX)rtl.c
 	$(HOST_CC) -c $(HOST_CFLAGS) $(HOST_CPPFLAGS) $(INCLUDES) $(HOST_PREFIX)rtl.c
diff --git a/gcc/gencodes.c b/gcc/gencodes.c
index 3c9bf9cc20c..04d6b45961c 100644
--- a/gcc/gencodes.c
+++ b/gcc/gencodes.c
@@ -32,6 +32,7 @@ Boston, MA 02111-1307, USA.  */
 static int insn_code_number;
 
 static void gen_insn PARAMS ((rtx));
+static int print_md_constant PARAMS ((void **, void *));
 
 static void
 gen_insn (insn)
@@ -86,9 +87,11 @@ from the machine description file `md'.  */\n\n");
 
   printf ("  CODE_FOR_nothing = %d };\n", insn_code_number + 1);
 
-  printf ("\n#define MAX_INSN_CODE ((int) CODE_FOR_nothing)\n");
+  printf ("\n#define MAX_INSN_CODE ((int) CODE_FOR_nothing)\n\n");
 
-  printf ("#endif /* MAX_INSN_CODE */\n");
+  traverse_md_constants (print_md_constant, stdout);
+
+  printf ("\n#endif /* MAX_INSN_CODE */\n");
 
   fflush (stdout);
   return (ferror (stdout) != 0 ? FATAL_EXIT_CODE : SUCCESS_EXIT_CODE);
@@ -101,3 +104,17 @@ get_insn_name (code)
 {
   return NULL;
 }
+
+/* Called via traverse_md_constants; emit a #define for
+   the current constant definition.  */
+static int
+print_md_constant (slot, info)
+     void **slot;
+     void *info;
+{
+  struct md_constant *def = *slot;
+  FILE *file = info;
+
+  fprintf (file, "#define %s %s\n", def->name, def->value);
+  return 1;
+}
diff --git a/gcc/gensupport.c b/gcc/gensupport.c
index ce4869bccbe..cde2a220b4e 100644
--- a/gcc/gensupport.c
+++ b/gcc/gensupport.c
@@ -863,6 +863,21 @@ xstrdup (input)
 }
 
 PTR
+xcalloc (nelem, elsize)
+  size_t nelem, elsize;
+{
+  PTR newmem;
+
+  if (nelem == 0 || elsize == 0)
+    nelem = elsize = 1;
+
+  newmem = calloc (nelem, elsize);
+  if (!newmem)
+    fatal ("virtual memory exhausted");
+  return (newmem);
+}
+
+PTR
 xrealloc (old, size)
   PTR old;
   size_t size;
diff --git a/gcc/md.texi b/gcc/md.texi
index 3b77c4b4020..82271596bb4 100644
--- a/gcc/md.texi
+++ b/gcc/md.texi
@@ -39,6 +39,8 @@ See the next chapter for information on the C header file.
 * Insn Attributes::     Specifying the value of attributes for generated insns.
 * Conditional Execution::Generating @code{define_insn} patterns for
                            predication.
+* Constant Definitions::Defining symbolic constants that can be used in the
+                        md file.
 @end menu
 
 @node Patterns
@@ -4690,3 +4692,55 @@ generates a new pattern
   "(@var{test2}) && (@var{test1})"
   "(%3) add %2,%1,%0")
 @end smallexample
+
+@node Constant Definitions
+@section Constant Definitions
+@cindex constant definitions
+@findex define_constants
+
+Using literal constants inside instruction patterns reduces legibility and
+can be a maintenance problem.
+
+To overcome this problem, you may use the @code{define_constants}
+expression.  It contains a vector of name-value pairs.  From that
+point on, wherever any of the names appears in the MD file, it is as
+if the corresponding value had been written instead.  You may use
+@code{define_constants} multiple times; each appearance adds more
+constants to the table.  It is an error to redefine a constant with
+a different value.
+
+To come back to the a29k load multiple example, instead of
+
+@smallexample
+(define_insn ""
+  [(match_parallel 0 "load_multiple_operation"
+     [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
+           (match_operand:SI 2 "memory_operand" "m"))
+      (use (reg:SI 179))
+      (clobber (reg:SI 179))])]
+  ""
+  "loadm 0,0,%1,%2")
+@end smallexample
+
+You could write:
+
+@smallexample
+(define_constants [
+    (R_BP 177)
+    (R_FC 178)
+    (R_CR 179)
+    (R_Q  180)
+])
+
+(define_insn ""
+  [(match_parallel 0 "load_multiple_operation"
+     [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
+           (match_operand:SI 2 "memory_operand" "m"))
+      (use (reg:SI R_CR))
+      (clobber (reg:SI R_CR))])]
+  ""
+  "loadm 0,0,%1,%2")
+@end smallexample
+
+The constants that are defined with a define_constant are also output
+in the insn-codes.h header file as #defines.
diff --git a/gcc/rtl.c b/gcc/rtl.c
index 7cc339d4c6a..48efc2640c9 100644
--- a/gcc/rtl.c
+++ b/gcc/rtl.c
@@ -28,6 +28,7 @@ Boston, MA 02111-1307, USA.  */
 #include "ggc.h"
 #include "obstack.h"
 #include "toplev.h"
+#include "hashtab.h"
 
 #define	obstack_chunk_alloc	xmalloc
 #define	obstack_chunk_free	free
@@ -290,10 +291,15 @@ const char * const reg_note_name[] =
   "REG_EH_RETHROW", "REG_SAVE_NOTE", "REG_MAYBE_DEAD", "REG_NORETURN"
 };
 
+static htab_t md_constants;
+
 static void fatal_with_file_and_line PARAMS ((FILE *, const char *, ...))
   ATTRIBUTE_PRINTF_2 ATTRIBUTE_NORETURN;
 static void fatal_expected_char PARAMS ((FILE *, int, int)) ATTRIBUTE_NORETURN;
 static void read_name		PARAMS ((char *, FILE *));
+static unsigned def_hash PARAMS ((const void *));
+static int def_name_eq_p PARAMS ((const void *, const void *));
+static void read_constants PARAMS ((FILE *infile, char *tmp_char));
 
 
 /* Allocate an rtx vector of N elements.
@@ -829,6 +835,25 @@ read_name (str, infile)
     read_rtx_lineno++;
 
   *p = 0;
+
+  if (md_constants)
+    {
+      /* Do constant expansion.  */
+      struct md_constant *def;
+
+      p = str;
+      do
+	{
+	  struct md_constant tmp_def;
+
+	  tmp_def.name = p;
+	  def = htab_find (md_constants, &tmp_def);
+	  if (def)
+	    p = def->value;
+	} while (def);
+      if (p != str)
+	strcpy (str, p);
+    }
 }
 
 /* Provide a version of a function to read a long long if the system does
@@ -868,6 +893,98 @@ atoll(p)
 }
 #endif
 
+/* Given a constant definition, return a hash code for its name.  */
+static unsigned
+def_hash (def)
+     const void *def;
+{
+  unsigned result, i;
+  const char *string = ((const struct md_constant *)def)->name;
+
+  for (result = i = 0;*string++ != '\0'; i++)
+    result += ((unsigned char) *string << (i % CHAR_BIT));
+  return result;
+}
+
+/* Given two constant definitions, return true if they have the same name.  */
+static int
+def_name_eq_p (def1, def2)
+     const void *def1, *def2;
+{
+  return ! strcmp (((const struct md_constant *)def1)->name,
+		   ((const struct md_constant *)def2)->name);
+}
+
+/* INFILE is a FILE pointer to read text from.  TMP_CHAR is a buffer suitable
+   to read a name or number into.  Process a define_constants directive,
+   starting with the optional space after the "define_constants".  */
+static void
+read_constants (infile, tmp_char)
+     FILE *infile;
+     char *tmp_char;
+{
+  int c;
+  htab_t defs;
+
+  c = read_skip_spaces (infile);
+  if (c != '[')
+    fatal_expected_char (infile, '[', c);
+  defs = md_constants;
+  if (! defs)
+    defs = htab_create (32, def_hash, def_name_eq_p, (htab_del) 0);
+  /* Disable constant expansion during definition processing.  */
+  md_constants = 0;
+  while ( (c = read_skip_spaces (infile)) != ']')
+    {
+      struct md_constant *def;
+      void **entry_ptr;
+
+      if (c != '(')
+	fatal_expected_char (infile, '(', c);
+      def = xmalloc (sizeof (struct md_constant));
+      def->name = tmp_char;
+      read_name (tmp_char, infile);
+      entry_ptr = htab_find_slot (defs, def, TRUE);
+      if (! *entry_ptr)
+	def->name = xstrdup (tmp_char);
+      c = read_skip_spaces (infile);
+      ungetc (c, infile);
+      read_name (tmp_char, infile);
+      if (! *entry_ptr)
+	{
+	  def->value = xstrdup (tmp_char);
+	  *entry_ptr = def;
+	}
+      else
+	{
+	  def = *entry_ptr;
+	  if (strcmp (def->value, tmp_char))
+	    fatal_with_file_and_line (infile,
+				      "redefinition of %s, was %s, now %s",
+				      def->name, def->value, tmp_char);
+	}
+      c = read_skip_spaces (infile);
+      if (c != ')')
+	fatal_expected_char (infile, ')', c);
+    }
+  md_constants = defs;
+  c = read_skip_spaces (infile);
+  if (c != ')')
+    fatal_expected_char (infile, ')', c);
+}
+
+/* For every constant definition, call CALLBACK with two arguments:
+   a pointer a pointer to the constant definition and INFO.
+   Stops when CALLBACK returns zero.  */
+void
+traverse_md_constants (callback, info)
+     htab_trav callback;
+     void *info;
+{
+  if (md_constants)
+    htab_traverse (md_constants, callback, info);
+}
+
 /* Read an rtx in printed representation from INFILE
    and return an actual rtx in core constructed accordingly.
    read_rtx is not used in the compiler proper, but rather in
@@ -907,6 +1024,7 @@ read_rtx (infile)
     initialized = 1;
   }
 
+again:
   c = read_skip_spaces (infile); /* Should be open paren.  */
   if (c != '(')
     fatal_expected_char (infile, '(', c);
@@ -915,6 +1033,11 @@ read_rtx (infile)
 
   tmp_code = UNKNOWN;
 
+  if (! strcmp (tmp_char, "define_constants"))
+    {
+      read_constants (infile, tmp_char);
+      goto again;
+    }
   for (i = 0; i < NUM_RTX_CODE; i++)
     if (! strcmp (tmp_char, GET_RTX_NAME (i)))
       {
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 762226cd3d4..c0f543d040b 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1946,6 +1946,9 @@ extern void init_varasm_once		PARAMS ((void));
 
 /* In rtl.c */
 extern void init_rtl			PARAMS ((void));
+extern void traverse_md_constants	PARAMS ((int (*) (void **, void *),
+						 void *));
+struct md_constant { char *name, *value; };
 
 #ifdef BUFSIZ
 extern int read_skip_spaces		PARAMS ((FILE *));