Thumb32 assembler (6/69)

[Zack Weinberg <zack at codesourcery dot com>]

Part of this patch has already been submitted.  It introduces a new
interface to hash.c, hash_find_n, which takes the length of the key as
an explicit argument; this is convenient when the key is part of the
string passed to md_assemble, as it then does not have to munge that
string.  In subsequent patches, tc-arm.c will make extensive use of
this feature.

Note that there is a bug in this edition of hash_find_n; the fix shows
up several patches later.

zw

	* hash.c (hash_lookup): Delete unnecessary forward declaration.
	Add 'len' parameter.  Take this as length of key; do not look for
	a NUL terminator; use strncmp when searching collision chains.
	All callers changed to match.
	(hash_find_n): New function.
	* hash.h: Declare hash_find_n.
	* config/tc-arm.c (md_assemble): Use hash_find_n; no need to
	mutate the string.

===================================================================
Index: gas/hash.c
--- gas/hash.c	(revision 6)
+++ gas/hash.c	(revision 8)
@@ -120,19 +120,13 @@
    Each time we look up a string, we move it to the start of the list
    for its hash code, to take advantage of referential locality.  */
 
-static struct hash_entry *hash_lookup (struct hash_control *,
-				       const char *,
-				       struct hash_entry ***,
-				       unsigned long *);
-
 static struct hash_entry *
-hash_lookup (struct hash_control *table, const char *key,
+hash_lookup (struct hash_control *table, const char *key, size_t len,
 	     struct hash_entry ***plist, unsigned long *phash)
 {
-  register unsigned long hash;
-  unsigned int len;
-  register const unsigned char *s;
-  register unsigned int c;
+  unsigned long hash;
+  size_t n;
+  unsigned int c;
   unsigned int index;
   struct hash_entry **list;
   struct hash_entry *p;
@@ -143,13 +137,11 @@
 #endif
 
   hash = 0;
-  len = 0;
-  s = (const unsigned char *) key;
-  while ((c = *s++) != '\0')
+  for (n = 0; n < len; n++)
     {
+      c = key[n];
       hash += c + (c << 17);
       hash ^= hash >> 2;
-      ++len;
     }
   hash += len + (len << 17);
   hash ^= hash >> 2;
@@ -176,7 +168,7 @@
 	  ++table->string_compares;
 #endif
 
-	  if (strcmp (p->string, key) == 0)
+	  if (p->string[len] == '\0' && strncmp (p->string, key, len) == 0)
 	    {
 	      if (prev != NULL)
 		{
@@ -207,7 +199,7 @@
   struct hash_entry **list;
   unsigned long hash;
 
-  p = hash_lookup (table, key, &list, &hash);
+  p = hash_lookup (table, key, strlen (key), &list, &hash);
   if (p != NULL)
     return "exists";
 
@@ -237,7 +229,7 @@
   struct hash_entry **list;
   unsigned long hash;
 
-  p = hash_lookup (table, key, &list, &hash);
+  p = hash_lookup (table, key, strlen (key), &list, &hash);
   if (p != NULL)
     {
 #ifdef HASH_STATISTICS
@@ -274,7 +266,7 @@
   struct hash_entry *p;
   PTR ret;
 
-  p = hash_lookup (table, key, NULL, NULL);
+  p = hash_lookup (table, key, strlen (key), NULL, NULL);
   if (p == NULL)
     return NULL;
 
@@ -297,13 +289,28 @@
 {
   struct hash_entry *p;
 
-  p = hash_lookup (table, key, NULL, NULL);
+  p = hash_lookup (table, key, strlen (key), NULL, NULL);
   if (p == NULL)
     return NULL;
 
   return p->data;
 }
 
+/* As hash_find, but KEY is of length LEN and is not guaranteed to be
+   NUL-terminated.  */
+
+PTR
+hash_find_n (struct hash_control *table, const char *key, size_t len)
+{
+  struct hash_entry *p;
+
+  p = hash_lookup (table, key, len, NULL, NULL);
+  if (p == NULL)
+    return NULL;
+
+  return p->data;
+}
+
 /* Delete an entry from a hash table.  This returns the value stored
    for that entry, or NULL if there is no such entry.  */
 
@@ -313,7 +320,7 @@
   struct hash_entry *p;
   struct hash_entry **list;
 
-  p = hash_lookup (table, key, &list, NULL);
+  p = hash_lookup (table, key, strlen (key), &list, NULL);
   if (p == NULL)
     return NULL;
 
===================================================================
Index: gas/hash.h
--- gas/hash.h	(revision 6)
+++ gas/hash.h	(revision 8)
@@ -59,6 +59,11 @@
 
 extern PTR hash_find (struct hash_control *, const char *key);
 
+/* As hash_find, but KEY is of length LEN and is not guaranteed to be
+   NUL-terminated.  */
+
+extern PTR hash_find_n (struct hash_control *, const char *key, size_t len);
+
 /* Delete an entry from a hash table.  This returns the value stored
    for that entry, or NULL if there is no such entry.  */
 
===================================================================
Index: gas/config/tc-arm.c
--- gas/config/tc-arm.c	(revision 6)
+++ gas/config/tc-arm.c	(revision 8)
@@ -9985,9 +9985,7 @@
 void
 md_assemble (char * str)
 {
-  char  c;
   char *p;
-  char *start;
 
   /* Align the previous label if needed.  */
   if (last_label_seen != NULL)
@@ -10004,7 +10002,7 @@
 
   /* Scan up to the end of the op-code, which must end in white space or
      end of string.  */
-  for (start = p = str; *p != '\0'; p++)
+  for (p = str; *p != '\0'; p++)
     if (*p == ' ')
       break;
 
@@ -10018,10 +10016,7 @@
     {
       const struct thumb_opcode * opcode;
 
-      c = *p;
-      *p = '\0';
-      opcode = (const struct thumb_opcode *) hash_find (arm_tops_hsh, str);
-      *p = c;
+      opcode = hash_find_n (arm_tops_hsh, str, p - str);
 
       if (opcode)
 	{
@@ -10044,10 +10039,7 @@
     {
       const struct asm_opcode * opcode;
 
-      c = *p;
-      *p = '\0';
-      opcode = (const struct asm_opcode *) hash_find (arm_ops_hsh, str);
-      *p = c;
+      opcode = hash_find_n (arm_ops_hsh, str, p - str);
 
       if (opcode)
 	{
@@ -10072,7 +10064,7 @@
   if (create_register_alias (str, p))
     return;
 
-  as_bad (_("bad instruction `%s'"), start);
+  as_bad (_("bad instruction `%s'"), str);
 }
 
 /* Various frobbings of labels and their addresses.  */