ecbuf: Use gcc hints to indicate that buffer resizes aren't common

This provided a ~1.2 to 2 times performance improvement in the
benchmark.

1 files changed, 10 insertions, 4 deletions

diff --git a/ecbuf.h b/ecbuf.h
index deb4521..c279c0e 100644
--- a/ecbuf.h
+++ b/ecbuf.h
@@ -98,6 +98,12 @@ typedef struct {
 #define ecbuf_peek(e) ((e).a[(e).v.o])
 
 
+#if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
+#define ecbuf__unlikely(expr) (__builtin_expect(expr, 0))
+#else
+#define ecbuf__unlikely(expr) (expr)
+#endif
+
 static inline void *ecbuf__push(ecbuf_vars_t *v, void **a, size_t alen) {
 	/* The algortihm is something like:
 	 * 1. If the buffer is full, "grow" it
@@ -108,7 +114,7 @@ static inline void *ecbuf__push(ecbuf_vars_t *v, void **a, size_t alen) {
 	 */
 	int i, obn = v->bn;
 	/* 1 */
-	if(v->l == v->bn) {
+	if(ecbuf__unlikely(v->l == v->bn)) {
 		v->bn <<= 1;
 		if(v->cn == obn) {
 			if(v->o) v->b = (v->o - 1 + v->cn) & (v->cn-1);
@@ -120,8 +126,8 @@ static inline void *ecbuf__push(ecbuf_vars_t *v, void **a, size_t alen) {
 	if(v->bn == v->cn)    i &= v->cn-1;
 	else if(v->o <= v->b) i += v->cn;
 	/* 3 */
-	if(i >= v->bn) v->bn <<= 1;
-	if(v->bn != obn) *a = realloc(*a, v->bn*alen);
+	if(ecbuf__unlikely(i >= v->bn)) v->bn <<= 1;
+	if(ecbuf__unlikely(v->bn != obn)) *a = realloc(*a, v->bn*alen);
 	v->l++;
 	return ((char *)*a)+alen*i;
 }
@@ -133,7 +139,7 @@ static inline void *ecbuf__push(ecbuf_vars_t *v, void **a, size_t alen) {
 static inline int ecbuf__pop(ecbuf_vars_t *v) {
 	int l = v->o;
 	v->l--;
-	if(v->o == v->b) {
+	if(ecbuf__unlikely(v->o == v->b)) {
 		v->o = v->cn;
 		v->cn = v->bn;
 		v->b = -1;