RFA: replace #ifdef with if/#if for HAVE_ATTR_*

Index: doc/md.texi
===================================================================
--- doc/md.texi	(revision 192654)
+++ doc/md.texi	(working copy)
@@ -7496,7 +7496,7 @@  (define_attr "type" "branch,fp,load,stor
 the following lines will be written to the file @file{insn-attr.h}.
 
 @smallexample
-#define HAVE_ATTR_type
+#define HAVE_ATTR_type 1
 enum attr_type @{TYPE_BRANCH, TYPE_FP, TYPE_LOAD,
                  TYPE_STORE, TYPE_ARITH@};
 extern enum attr_type get_attr_type ();
@@ -7521,6 +7521,10 @@  extern enum attr_type get_attr_type ();
 generation. @xref{Disable Insn Alternatives}.
 @end table
 
+For each of these special attributes, the corresponding
+@samp{HAVE_ATTR_@var{name}} @samp{#define} is also written when the
+attribute is not defined; in that case, it is defined as @samp{0}.
+
 @findex define_enum_attr
 @anchor{define_enum_attr}
 Another way of defining an attribute is to use:
Index: final.c
===================================================================
--- final.c	(revision 192654)
+++ final.c	(working copy)
@@ -204,9 +204,7 @@  Software Foundation; either version 3, o
 /* True if printing into -fdump-final-insns= dump.  */   
 bool final_insns_dump_p;
 
-#ifdef HAVE_ATTR_length
 static int asm_insn_count (rtx);
-#endif
 static void profile_function (FILE *);
 static void profile_after_prologue (FILE *);
 static bool notice_source_line (rtx, bool *);
@@ -224,9 +222,7 @@  static int alter_cond (rtx);
 #ifndef ADDR_VEC_ALIGN
 static int final_addr_vec_align (rtx);
 #endif
-#ifdef HAVE_ATTR_length
 static int align_fuzz (rtx, rtx, int, unsigned);
-#endif
 
 /* Initialize data in final at the beginning of a compilation.  */
 
@@ -362,9 +358,8 @@  init_insn_lengths (void)
       insn_lengths = 0;
       insn_lengths_max_uid = 0;
     }
-#ifdef HAVE_ATTR_length
-  INSN_ADDRESSES_FREE ();
-#endif
+  if (HAVE_ATTR_length)
+    INSN_ADDRESSES_FREE ();
   if (uid_align)
     {
       free (uid_align);
@@ -376,14 +371,15 @@  init_insn_lengths (void)
    get its actual length.  Otherwise, use FALLBACK_FN to calculate the
    length.  */
 static inline int
-get_attr_length_1 (rtx insn ATTRIBUTE_UNUSED,
-		   int (*fallback_fn) (rtx) ATTRIBUTE_UNUSED)
+get_attr_length_1 (rtx insn, int (*fallback_fn) (rtx))
 {
-#ifdef HAVE_ATTR_length
   rtx body;
   int i;
   int length = 0;
 
+  if (!HAVE_ATTR_length)
+    return 0;
+
   if (insn_lengths_max_uid > INSN_UID (insn))
     return insn_lengths[INSN_UID (insn)];
   else
@@ -432,11 +428,6 @@  get_attr_length_1 (rtx insn ATTRIBUTE_UN
   ADJUST_INSN_LENGTH (insn, length);
 #endif
   return length;
-#else /* not HAVE_ATTR_length */
-  return 0;
-#define insn_default_length 0
-#define insn_min_length 0
-#endif /* not HAVE_ATTR_length */
 }
 
 /* Obtain the current length of an insn.  If branch shortening has been done,
@@ -583,7 +574,6 @@  label_to_max_skip (rtx label)
   return 0;
 }
 
-#ifdef HAVE_ATTR_length
 /* The differences in addresses
    between a branch and its target might grow or shrink depending on
    the alignment the start insn of the range (the branch for a forward
@@ -686,7 +676,6 @@  insn_current_reference_address (rtx bran
 	      + align_fuzz (dest, seq, length_unit_log, ~0));
     }
 }
-#endif /* HAVE_ATTR_length */
 
 /* Compute branch alignments based on frequency information in the
    CFG.  */
@@ -850,14 +839,13 @@  struct rtl_opt_pass pass_compute_alignme
    slots.  */
 
 void
-shorten_branches (rtx first ATTRIBUTE_UNUSED)
+shorten_branches (rtx first)
 {
   rtx insn;
   int max_uid;
   int i;
   int max_log;
   int max_skip;
-#ifdef HAVE_ATTR_length
 #define MAX_CODE_ALIGN 16
   rtx seq;
   int something_changed = 1;
@@ -866,8 +854,6 @@  shorten_branches (rtx first ATTRIBUTE_UN
   int uid;
   rtx align_tab[MAX_CODE_ALIGN];
 
-#endif
-
   /* Compute maximum UID and allocate label_align / uid_shuid.  */
   max_uid = get_max_uid ();
 
@@ -974,7 +960,8 @@  shorten_branches (rtx first ATTRIBUTE_UN
 	      }
 	}
     }
-#ifdef HAVE_ATTR_length
+  if (!HAVE_ATTR_length)
+    return;
 
   /* Allocate the rest of the arrays.  */
   insn_lengths = XNEWVEC (int, max_uid);
@@ -1420,11 +1407,8 @@  shorten_branches (rtx first ATTRIBUTE_UN
     }
 
   free (varying_length);
-
-#endif /* HAVE_ATTR_length */
 }
 
-#ifdef HAVE_ATTR_length
 /* Given the body of an INSN known to be generated by an ASM statement, return
    the number of machine instructions likely to be generated for this insn.
    This is used to compute its length.  */
@@ -1441,7 +1425,6 @@  asm_insn_count (rtx body)
 
   return asm_str_count (templ);
 }
-#endif
 
 /* Return the number of machine instructions likely to be generated for the
    inline-asm template. */
@@ -1902,17 +1885,18 @@  final (rtx first, FILE *file, int optimi
   /* Output the insns.  */
   for (insn = first; insn;)
     {
-#ifdef HAVE_ATTR_length
-      if ((unsigned) INSN_UID (insn) >= INSN_ADDRESSES_SIZE ())
+      if (HAVE_ATTR_length)
 	{
-	  /* This can be triggered by bugs elsewhere in the compiler if
-	     new insns are created after init_insn_lengths is called.  */
-	  gcc_assert (NOTE_P (insn));
-	  insn_current_address = -1;
+	  if ((unsigned) INSN_UID (insn) >= INSN_ADDRESSES_SIZE ())
+	    {
+	      /* This can be triggered by bugs elsewhere in the compiler if
+		 new insns are created after init_insn_lengths is called.  */
+	      gcc_assert (NOTE_P (insn));
+	      insn_current_address = -1;
+	    }
+	  else
+	    insn_current_address = INSN_ADDRESSES (INSN_UID (insn));
 	}
-      else
-	insn_current_address = INSN_ADDRESSES (INSN_UID (insn));
-#endif /* HAVE_ATTR_length */
 
       dump_basic_block_info (file, insn, start_to_bb, end_to_bb,
                              bb_map_size, &bb_seqn);
@@ -2853,12 +2837,13 @@  final_scan_insn (rtx insn, FILE *file, i
 	    if (new_rtx == insn && PATTERN (new_rtx) == body)
 	      fatal_insn ("could not split insn", insn);
 
-#ifdef HAVE_ATTR_length
-	    /* This instruction should have been split in shorten_branches,
-	       to ensure that we would have valid length info for the
-	       splitees.  */
-	    gcc_unreachable ();
-#endif
+	    if (HAVE_ATTR_length)
+	      {
+		/* This instruction should have been split in shorten_branches,
+		   to ensure that we would have valid length info for the
+		   splitees.  */
+		gcc_unreachable ();
+	      }
 
 	    return new_rtx;
 	  }
@@ -3289,10 +3274,11 @@  output_asm_name (void)
 	       insn_data[num].name);
       if (insn_data[num].n_alternatives > 1)
 	fprintf (asm_out_file, "/%d", which_alternative + 1);
-#ifdef HAVE_ATTR_length
-      fprintf (asm_out_file, "\t[length = %d]",
-	       get_attr_length (debug_insn));
-#endif
+
+      if (HAVE_ATTR_length)
+	fprintf (asm_out_file, "\t[length = %d]",
+		 get_attr_length (debug_insn));
+
       /* Clear this so only the first assembler insn
 	 of any rtl insn will get the special comment for -dp.  */
       debug_insn = 0;
Index: genattr.c
===================================================================
--- genattr.c	(revision 192654)
+++ genattr.c	(working copy)
@@ -44,7 +44,7 @@  gen_attr (rtx attr)
   if (is_const)
     VEC_safe_push (rtx, heap, const_attrs, attr);
 
-  printf ("#define HAVE_ATTR_%s\n", XSTR (attr, 0));
+  printf ("#define HAVE_ATTR_%s 1\n", XSTR (attr, 0));
 
   /* If numeric attribute, don't need to write an enum.  */
   if (GET_CODE (attr) == DEFINE_ENUM_ATTR)
@@ -159,12 +159,6 @@  main (int argc, char **argv)
 
   puts ("#include \"insn-attr-common.h\"\n");
 
-  /* For compatibility, define the attribute `alternative', which is just
-     a reference to the variable `which_alternative'.  */
-
-  puts ("#define HAVE_ATTR_alternative");
-  puts ("#define get_attr_alternative(insn) which_alternative");
-
   /* Read the machine description.  */
 
   while (1)
@@ -342,6 +336,25 @@  main (int argc, char **argv)
       printf ("typedef void *state_t;\n\n");
     }
 
+  /* Special-purpose atributes should be tested with if, not #ifdef.  */
+  const char * const special_attrs[] = { "length", "enabled", 0 };
+  for (const char * const *p = special_attrs; *p; p++)
+    {
+      printf ("#ifndef HAVE_ATTR_%s\n"
+	      "#define HAVE_ATTR_%s 0\n"
+	      "#endif\n", *p, *p);
+    }
+  /* We make an exception here to provide stub definitions for
+     insn_*_length* functions.  */
+  puts ("#if !HAVE_ATTR_length\n"
+	"extern int hook_int_rtx_0 (rtx);\n"
+	"#define insn_default_length hook_int_rtx_0\n"
+	"#define insn_min_length hook_int_rtx_0\n"
+	"#define insn_variable_length_p hook_int_rtx_0\n"
+	"#define insn_current_length hook_int_rtx_0\n"
+	"#include \"insn-addr.h\"\n"
+	"#endif\n");
+
   /* Output flag masks for use by reorg.
 
      Flags are used to hold branch direction for use by eligible_for_...  */
Index: genattrtab.c
===================================================================
--- genattrtab.c	(revision 192654)
+++ genattrtab.c	(working copy)
@@ -1636,14 +1636,15 @@  write_length_unit_log (FILE *outf)
   unsigned int length_unit_log, length_or;
   int unknown = 0;
 
-  if (length_attr == 0)
-    return;
-  length_or = or_attr_value (length_attr->default_val->value, &unknown);
-  for (av = length_attr->first_value; av; av = av->next)
-    for (ie = av->first_insn; ie; ie = ie->next)
-      length_or |= or_attr_value (av->value, &unknown);
+  if (length_attr)
+    {
+      length_or = or_attr_value (length_attr->default_val->value, &unknown);
+      for (av = length_attr->first_value; av; av = av->next)
+	for (ie = av->first_insn; ie; ie = ie->next)
+	  length_or |= or_attr_value (av->value, &unknown);
+    }
 
-  if (unknown)
+  if (length_attr == NULL || unknown)
     length_unit_log = 0;
   else
     {
Index: recog.c
===================================================================
--- recog.c	(revision 192654)
+++ recog.c	(working copy)
@@ -57,7 +57,7 @@  Software Foundation; either version 3, o
 #endif
 #endif
 
-#ifndef HAVE_ATTR_enabled
+#if !HAVE_ATTR_enabled
 static inline bool
 get_attr_enabled (rtx insn ATTRIBUTE_UNUSED)
 {
@@ -3804,7 +3804,7 @@  struct rtl_opt_pass pass_split_after_rel
 static bool
 gate_handle_split_before_regstack (void)
 {
-#if defined (HAVE_ATTR_length) && defined (STACK_REGS)
+#if (HAVE_ATTR_length) && defined (STACK_REGS)
   /* If flow2 creates new instructions which need splitting
      and scheduling after reload is not done, they might not be
      split until final which doesn't allow splitting
@@ -3888,7 +3888,7 @@  struct rtl_opt_pass pass_split_before_sc
 static bool
 gate_do_final_split (void)
 {
-#if defined (HAVE_ATTR_length) && !defined (STACK_REGS)
+#if (HAVE_ATTR_length) && !defined (STACK_REGS)
   return 1;
 #else
   return 0;