4 files changed, 29 insertions, 24 deletions

diff --git a/ChangeLog b/ChangeLog
index 5a20c09b..eced4196 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2019-08-15         Andrew J. Schorr      <aschorr@telemetry-investments.com>
+
+	Reduce memory usage by only compiling the IGNORECASE version of
+	regexp when it's actually needed.
+
+	* awkgram.y (make_regnode): Only compile the regular version.
+	* re.c (re_cache_get): New function.
+	(re_update): Use it as appropriate.
+
 2019-07-23         Koichi Murase         <myoga.murase@gmail.com>
 
 	* builtin.c (do_xor): Remove unneeded local variable `i'. Simplify
diff --git a/awkgram.c b/awkgram.c
index 19a11827..b923f191 100644
--- a/awkgram.c
+++ b/awkgram.c
@@ -7764,12 +7764,6 @@ make_regnode(int type, NODE *exp)
 			freenode(n);
 			return NULL;
 		}
-		n->re_reg[1] = make_regexp(exp->stptr, exp->stlen, true, true, false);
-		if (n->re_reg[1] == NULL) {
-			refree(n->re_reg[0]);
-			freenode(n);
-			return NULL;
-		}
 		n->re_exp = exp;
 		n->re_flags = CONSTANT;
 	}
diff --git a/awkgram.y b/awkgram.y
index aa8ccb1d..62865e1b 100644
--- a/awkgram.y
+++ b/awkgram.y
@@ -5267,12 +5267,6 @@ make_regnode(int type, NODE *exp)
 			freenode(n);
 			return NULL;
 		}
-		n->re_reg[1] = make_regexp(exp->stptr, exp->stlen, true, true, false);
-		if (n->re_reg[1] == NULL) {
-			refree(n->re_reg[0]);
-			freenode(n);
-			return NULL;
-		}
 		n->re_exp = exp;
 		n->re_flags = CONSTANT;
 	}
diff --git a/re.c b/re.c
index 32d03341..91cff4d6 100644
--- a/re.c
+++ b/re.c
@@ -391,6 +391,16 @@ dfaerror(const char *s)
 	exit(EXIT_FATAL);	/* for DJGPP */
 }
 
+/* re_cache_get --- populate regexp cache if empty */
+
+static inline Regexp *
+re_cache_get(NODE *t)
+{
+	if (t->re_reg[IGNORECASE] == NULL)
+		t->re_reg[IGNORECASE] = make_regexp(t->re_exp->stptr, t->re_exp->stlen, IGNORECASE, t->re_cnt, true);
+	return t->re_reg[IGNORECASE];
+}
+
 /* re_update --- recompile a dynamic regexp */
 
 Regexp *
@@ -399,18 +409,18 @@ re_update(NODE *t)
 	NODE *t1;
 
 	if (t->type == Node_val && (t->flags & REGEX) != 0)
-		return t->typed_re->re_reg[IGNORECASE];
+		return re_cache_get(t->typed_re);
 
 	if ((t->re_flags & CONSTANT) != 0) {
 		/* it's a constant, so just return it as is */
 		assert(t->type == Node_regex);
-		return t->re_reg[IGNORECASE];
+		return re_cache_get(t);
 	}
 	t1 = t->re_exp;
 	if (t->re_text != NULL) {
 		/* if contents haven't changed, just return it */
 		if (cmp_nodes(t->re_text, t1, true) == 0)
-			return t->re_reg[IGNORECASE];
+			return re_cache_get(t);
 		/* things changed, fall through to recompile */
 		unref(t->re_text);
 	}
@@ -420,10 +430,14 @@ re_update(NODE *t)
 	/* text changed */
 
 	/* free old */
-	if (t->re_reg[0] != NULL)
+	if (t->re_reg[0] != NULL) {
 		refree(t->re_reg[0]);
-	if (t->re_reg[1] != NULL)
+		t->re_reg[0] = NULL;
+	}
+	if (t->re_reg[1] != NULL) {
 		refree(t->re_reg[1]);
+		t->re_reg[1] = NULL;
+	}
 	if (t->re_cnt > 0)
 		t->re_cnt++;
 	if (t->re_cnt > 10)
@@ -434,13 +448,7 @@ re_update(NODE *t)
 		unref(t->re_text);
 		t->re_text = dupnode(t1);
 	}
-	/* compile it */
-	t->re_reg[0] = make_regexp(t->re_text->stptr, t->re_text->stlen,
-				false, t->re_cnt, true);
-	t->re_reg[1] = make_regexp(t->re_text->stptr, t->re_text->stlen,
-				true, t->re_cnt, true);
-
-	return t->re_reg[IGNORECASE];
+	return re_cache_get(t);
 }
 
 /* resetup --- choose what kind of regexps we match */