This is a major update, which switches virtually every allocated-but-not-freed

string into the strcache.  As a side-effect, many more structure members and
function arguments can/should be declared const.

As mentioned in the changelog, unfortunately measurement shows that this
change does not yet reduce memory.  The problem is with secondary expansion:
because of this we store all the prerequisites in the string cache twice.
First we store the prerequisite string after initial expansion but before
secondary expansion, then we store each individual file after secondary
expansion and expand_deps().  I plan to change expand_deps() to be callable
in either context (eval or snap_deps) then have non-second-expansion
targets call expand_deps() during eval, so that we only need to store that
dependency list once.

1 files changed, 47 insertions, 72 deletions

diff --git a/implicit.c b/implicit.c
index d239952..7255bc7 100644
--- a/implicit.c
+++ b/implicit.c
@@ -68,9 +68,9 @@ try_implicit_rule (struct file *file, unsigned int depth)
 struct idep
 {
   struct idep *next;              /* struct dep -compatible interface */
-  char *name;                     /* name of the prerequisite */
+  const char *name;               /* name of the prerequisite */
   struct file *intermediate_file; /* intermediate file, 0 otherwise */
-  char *intermediate_pattern;     /* pattern for intermediate file */
+  const char *intermediate_pattern; /* pattern for intermediate file */
   unsigned char had_stem;         /* had % substituted with stem */
   unsigned char ignore_mtime;     /* ignore_mtime flag */
 };
@@ -83,18 +83,6 @@ free_idep_chain (struct idep *p)
   for (; p != 0; p = n)
     {
       n = p->next;
-
-      if (p->name)
-        {
-          struct file *f = p->intermediate_file;
-
-          if (f != 0
-              && (f->stem < f->name || f->stem > f->name + strlen (f->name)))
-            free (f->stem);
-
-          free (p->name);
-        }
-
       free (p);
     }
 }
@@ -105,9 +93,9 @@ free_idep_chain (struct idep *p)
    length of the word.  */
 
 static char *
-get_next_word (char *buffer, unsigned int *length)
+get_next_word (const char *buffer, unsigned int *length)
 {
-  char *p = buffer, *beg;
+  const char *p = buffer, *beg;
   char c;
 
   /* Skip any leading whitespace.  */
@@ -178,7 +166,7 @@ get_next_word (char *buffer, unsigned int *length)
   if (length)
     *length = p - beg;
 
-  return beg;
+  return (char *)beg;
 }
 
 /* Search the pattern rules for a rule with an existing dependency to make
@@ -200,7 +188,7 @@ pattern_search (struct file *file, int archive,
                 unsigned int depth, unsigned int recursions)
 {
   /* Filename we are searching for a rule for.  */
-  char *filename = archive ? strchr (file->name, '(') : file->name;
+  const char *filename = archive ? strchr (file->name, '(') : file->name;
 
   /* Length of FILENAME.  */
   unsigned int namelen = strlen (filename);
@@ -225,7 +213,7 @@ pattern_search (struct file *file, int archive,
   char *depname = alloca (namelen + max_pattern_dep_length);
 
   /* The start and length of the stem of FILENAME for the current rule.  */
-  char *stem = 0;
+  const char *stem = 0;
   unsigned int stemlen = 0;
   unsigned int fullstemlen = 0;
 
@@ -258,8 +246,6 @@ pattern_search (struct file *file, int archive,
   struct rule *rule;
   struct dep *dep, *expl_d;
 
-  char *p, *vname;
-
   struct idep *d;
   struct idep **id_ptr;
   struct dep **d_ptr;
@@ -318,10 +304,10 @@ pattern_search (struct file *file, int archive,
 	  continue;
 	}
 
-      for (ti = 0; rule->targets[ti] != 0; ++ti)
+      for (ti = 0; ti < rule->num; ++ti)
 	{
-	  char *target = rule->targets[ti];
-	  char *suffix = rule->suffixes[ti];
+	  const char *target = rule->targets[ti];
+	  const char *suffix = rule->suffixes[ti];
 	  int check_lastslash;
 
 	  /* Rules that can match any filename and are not terminal
@@ -416,11 +402,12 @@ pattern_search (struct file *file, int archive,
       if (!tryrules[ri]->terminal)
 	{
 	  unsigned int j;
-	  for (j = 0; tryrules[ri]->targets[j] != 0; ++j)
+	  for (j = 0; j < tryrules[ri]->num; ++j)
 	    if (tryrules[ri]->targets[j][1] == '\0')
-	      break;
-	  if (tryrules[ri]->targets[j] != 0)
-	    tryrules[ri] = 0;
+              {
+                tryrules[ri] = 0;
+                break;
+              }
 	}
 
   /* We are going to do second expansion so initialize file variables
@@ -486,6 +473,7 @@ pattern_search (struct file *file, int archive,
 	  for (dep = rule->deps; dep != 0; dep = dep->next)
 	    {
               unsigned int len;
+              char *p;
               char *p2;
               unsigned int order_only = 0; /* Set if '|' was seen. */
 
@@ -614,14 +602,10 @@ pattern_search (struct file *file, int archive,
 
                               if (add_dir)
                                 {
-                                  char *n = d->name;
-
-                                  d->name = xmalloc (strlen (n) + l + 1);
-
-                                  memcpy (d->name, filename, l);
-                                  memcpy (d->name + l, n, strlen (n) + 1);
-
-                                  free (n);
+                                  char *n = alloca (strlen (d->name) + l + 1);
+                                  memcpy (n, filename, l);
+                                  memcpy (n+l, d->name, strlen (d->name) + 1);
+                                  d->name = strcache_add (n);
                                 }
 
                               if (had_stem)
@@ -653,7 +637,7 @@ pattern_search (struct file *file, int archive,
 
           for (d = deps; d != 0; d = d->next)
             {
-              char *name = d->name;
+              const char *name = d->name;
 
               if (file_impossible_p (name))
                 {
@@ -701,17 +685,16 @@ pattern_search (struct file *file, int archive,
 
               /* This code, given FILENAME = "lib/foo.o", dependency name
                  "lib/foo.c", and VPATH=src, searches for "src/lib/foo.c".  */
-              vname = name;
-              if (vpath_search (&vname, (FILE_TIMESTAMP *) 0))
-                {
-                  DBS (DB_IMPLICIT,
-                       (_("Found prerequisite `%s' as VPATH `%s'\n"),
-                        name,
-                        vname));
-
-                  free (vname);
-                  continue;
-                }
+              {
+                const char *vname = vpath_search (name, 0);
+                if (vname)
+                  {
+                    DBS (DB_IMPLICIT,
+                         (_("Found prerequisite `%s' as VPATH `%s'\n"),
+                          name, vname));
+                    continue;
+                  }
+              }
 
 
               /* We could not find the file in any place we should look.  Try
@@ -734,10 +717,9 @@ pattern_search (struct file *file, int archive,
                                       depth + 1,
                                       recursions + 1))
                     {
-                      d->intermediate_file = intermediate_file;
                       d->intermediate_pattern = intermediate_file->name;
-
-                      intermediate_file->name = xstrdup (name);
+                      intermediate_file->name = strcache_add (name);
+                      d->intermediate_file = intermediate_file;
                       intermediate_file = 0;
 
                       continue;
@@ -819,7 +801,7 @@ pattern_search (struct file *file, int archive,
 
   for (d = deps; d != 0; d = d->next)
     {
-      register char *s;
+      const char *s;
 
       if (d->intermediate_file != 0)
 	{
@@ -839,7 +821,7 @@ pattern_search (struct file *file, int archive,
           if (f != 0)
             f->precious = 1;
           else
-            f = enter_file (imf->name);
+            f = enter_file (strcache_add (imf->name));
 
 	  f->deps = imf->deps;
 	  f->cmds = imf->cmds;
@@ -859,9 +841,6 @@ pattern_search (struct file *file, int archive,
 	  for (dep = f->deps; dep != 0; dep = dep->next)
 	    {
 	      dep->file = enter_file (dep->name);
-              /* enter_file uses dep->name _if_ we created a new file.  */
-              if (dep->name != dep->file->name)
-                free (dep->name);
 	      dep->name = 0;
 	      dep->file->tried_implicit |= dep->changed;
 	    }
@@ -875,17 +854,10 @@ pattern_search (struct file *file, int archive,
 	{
 	  dep->file = lookup_file (s);
 	  if (dep->file == 0)
-	    /* enter_file consumes S's storage.  */
 	    dep->file = enter_file (s);
-	  else
-	    /* A copy of S is already allocated in DEP->file->name.
-	       So we can free S.  */
-	    free (s);
 	}
       else
-	{
-	  dep->name = s;
-	}
+        dep->name = s;
 
       if (d->intermediate_file == 0 && tryrules[foundrule]->terminal)
 	{
@@ -910,20 +882,22 @@ pattern_search (struct file *file, int archive,
     {
       /* Always allocate new storage, since STEM might be
          on the stack for an intermediate file.  */
-      file->stem = savestring (stem, stemlen);
+      file->stem = strcache_add_len (stem, stemlen);
       fullstemlen = stemlen;
     }
   else
     {
       int dirlen = (lastslash + 1) - filename;
+      char *sp;
 
       /* We want to prepend the directory from
 	 the original FILENAME onto the stem.  */
       fullstemlen = dirlen + stemlen;
-      file->stem = xmalloc (fullstemlen + 1);
-      memcpy (file->stem, filename, dirlen);
-      memcpy (file->stem + dirlen, stem, stemlen);
-      file->stem[fullstemlen] = '\0';
+      sp = alloca (fullstemlen + 1);
+      memcpy (sp, filename, dirlen);
+      memcpy (sp + dirlen, stem, stemlen);
+      sp[fullstemlen] = '\0';
+      file->stem = strcache_add (sp);
     }
 
   file->cmds = rule->cmds;
@@ -939,15 +913,15 @@ pattern_search (struct file *file, int archive,
   /* If this rule builds other targets, too, put the others into FILE's
      `also_make' member.  */
 
-  if (rule->targets[1] != 0)
-    for (ri = 0; rule->targets[ri] != 0; ++ri)
+  if (rule->num > 1)
+    for (ri = 0; ri < rule->num; ++ri)
       if (ri != matches[foundrule])
 	{
+          char *p = alloca (rule->lens[ri] + fullstemlen + 1);
 	  struct file *f;
 	  struct dep *new = alloc_dep ();
 
 	  /* GKM FIMXE: handle '|' here too */
-	  new->name = p = xmalloc (rule->lens[ri] + fullstemlen + 1);
 	  memcpy (p, rule->targets[ri],
                   rule->suffixes[ri] - rule->targets[ri] - 1);
 	  p += rule->suffixes[ri] - rule->targets[ri] - 1;
@@ -955,6 +929,7 @@ pattern_search (struct file *file, int archive,
 	  p += fullstemlen;
 	  memcpy (p, rule->suffixes[ri],
                   rule->lens[ri] - (rule->suffixes[ri] - rule->targets[ri])+1);
+          new->name = strcache_add (p);
 	  new->file = enter_file (new->name);
 	  new->next = file->also_make;