Arrange for RE engine workspace to be held in TSD. This is safe, less

C-stack-hungry than before, and faster than just using heap allocation.

4 files changed, 49 insertions, 8 deletions

diff --git a/generic/regcomp.c b/generic/regcomp.c
index 0d6f066..049ad69 100644
--- a/generic/regcomp.c
+++ b/generic/regcomp.c
@@ -287,8 +287,7 @@ compile(
     size_t len,
     int flags)
 {
-    struct vars var;
-    struct vars *v = &var;
+    AllocVars(v);
     struct guts *g;
     int i;
     size_t j;
@@ -300,12 +299,15 @@ compile(
      */
 
     if (re == NULL || string == NULL) {
+	FreeVars(v);
 	return REG_INVARG;
     }
     if ((flags&REG_QUOTE) && (flags&(REG_ADVANCED|REG_EXPANDED|REG_NEWLINE))) {
+	FreeVars(v);
 	return REG_INVARG;
     }
     if (!(flags&REG_EXTENDED) && (flags&REG_ADVF)) {
+	FreeVars(v);
 	return REG_INVARG;
     }
 
@@ -525,6 +527,8 @@ freev(
     struct vars *v,
     int err)
 {
+    register int ret;
+
     if (v->re != NULL) {
 	rfree(v->re);
     }
@@ -554,7 +558,9 @@ freev(
     }
     ERR(err);			/* nop if err==0 */
 
-    return v->err;
+    ret = v->err;
+    FreeVars(v);
+    return ret;
 }
 
 /*
diff --git a/generic/regcustom.h b/generic/regcustom.h
index 6abd24c..6b6b38c 100644
--- a/generic/regcustom.h
+++ b/generic/regcustom.h
@@ -11,12 +11,12 @@
  * redistributions in source form retain this entire copyright notice and
  * indicate the origin and nature of any modifications.
  *
- * I'd appreciate being given credit for this package in the documentation
- * of software which uses it, but that is not a requirement.
+ * I'd appreciate being given credit for this package in the documentation of
+ * software which uses it, but that is not a requirement.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
@@ -116,5 +116,21 @@ typedef int celt;		/* type to hold chr, MCCE number, or NOCELT */
 #define	REG_DEBUG	/* */
 #endif
 
+/* method of allocating a local workspace */
+#if 1
+#define AllocVars(vPtr) \
+    static Tcl_ThreadDataKey varsKey; \
+    register struct vars *vPtr = (struct vars *) \
+	Tcl_GetThreadData(&varsKey, sizeof(struct vars))
+#else
+/* This strategy for allocating workspace is "more proper" in some sense, but
+ * quite a bit slower. Using TSD (as above) leads to code that is quite a bit
+ * faster in practice. */
+#define AllocVars(vPtr) \
+    register struct vars *vPtr = (struct vars *) MALLOC(sizeof(struct vars))
+#define FreeVars(vPtr) \
+    FREE(vPtr)
+#endif
+
 /* and pick up the standard header */
 #include "regex.h"
diff --git a/generic/regexec.c b/generic/regexec.c
index 6862ef9..d39685c 100644
--- a/generic/regexec.c
+++ b/generic/regexec.c
@@ -170,8 +170,7 @@ exec(
     regmatch_t pmatch[],
     int flags)
 {
-    struct vars var;
-    register struct vars *v = &var;
+    AllocVars(v);
     int st;
     size_t n;
     int backref;
@@ -185,9 +184,11 @@ exec(
      */
 
     if (re == NULL || string == NULL || re->re_magic != REMAGIC) {
+	FreeVars(v);
 	return REG_INVARG;
     }
     if (re->re_csize != sizeof(chr)) {
+	FreeVars(v);
 	return REG_MIXED;
     }
 
@@ -198,9 +199,11 @@ exec(
     v->re = re;
     v->g = (struct guts *)re->re_guts;
     if ((v->g->cflags&REG_EXPECT) && details == NULL) {
+	FreeVars(v);
 	return REG_INVARG;
     }
     if (v->g->info&REG_UIMPOSSIBLE) {
+	FreeVars(v);
 	return REG_NOMATCH;
     }
     backref = (v->g->info&REG_UBACKREF) ? 1 : 0;
@@ -221,6 +224,7 @@ exec(
 		    MALLOC((v->g->nsub + 1) * sizeof(regmatch_t));
 	}
 	if (v->pmatch == NULL) {
+	    FreeVars(v);
 	    return REG_ESPACE;
 	}
 	v->nmatch = v->g->nsub + 1;
@@ -247,6 +251,7 @@ exec(
 	    if (v->pmatch != pmatch && v->pmatch != mat) {
 		FREE(v->pmatch);
 	    }
+	    FreeVars(v);
 	    return REG_ESPACE;
 	}
     } else {
@@ -284,6 +289,7 @@ exec(
     if (v->mem != NULL && v->mem != mem) {
 	FREE(v->mem);
     }
+    FreeVars(v);
     return st;
 }
 
diff --git a/generic/regguts.h b/generic/regguts.h
index 190d40b..991979e 100644
--- a/generic/regguts.h
+++ b/generic/regguts.h
@@ -399,6 +399,19 @@ struct guts {
     struct subre *lacons;	/* lookahead-constraint vector */
     int nlacons;		/* size of lacons */
 };
+
+/*
+ * Magic for allocating a variable workspace.
+ */
+
+#ifndef AllocVars
+#define AllocVars(vPtr) \
+    struct vars var; \
+    register struct vars *vPtr = &var
+#endif
+#ifndef FreeVars
+#define FreeVars(vPtr) ((void) 0)
+#endif
 
 /*
  * Local Variables: