Commit 4d926435b91a820bfd5c831948c8d1228cedb50a
2019-05-19T22:40:08
md_analyze_line: Disallow the strcspn() optiomization path... for other platforms then Linux. glibc has well-optimized implementation which provides good boost, but (as measured one Windows), it can be also relatively small to our own path below. We can always enable that path for more platforms, if we get some data showing it has good impact.
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diff --git a/md4c/md4c.c b/md4c/md4c.c
index fd9d9f0..ff483b3 100644
--- a/md4c/md4c.c
+++ b/md4c/md4c.c
@@ -5834,23 +5834,28 @@ md_analyze_line(MD_CTX* ctx, OFF beg, OFF* p_end,
break;
}
- /* Scan for end of the line. */
+ /* Scan for end of the line.
+ *
+ * Note this is quite a bottleneck of the parsing as we here iterate almost
+ * over compete document.
+ */
+#if defined __linux__ && !defined MD4C_USE_UTF16
+ /* Recent glibc versions have superbly optimized strcspn(), even using
+ * vectorization if available. */
if(ctx->doc_ends_with_newline && off < ctx->size) {
- /* There is a good chance libc provides well optimized code for these. */
while(TRUE) {
-#ifdef MD4C_USE_UTF16
- off += (OFF) wcscspn(STR(off), _T("\r\n"));
-#else
off += (OFF) strcspn(STR(off), "\r\n");
-#endif
- /* strcspn()/wcscspn() also stops on zero terminator (which we
- * need to ignore here.) */
+
+ /* strcspn() can stop on zero terminator; but that can appear
+ * anywhere in the Markfown input... */
if(CH(off) == _T('\0'))
off++;
else
break;
}
- } else {
+ } else
+#endif
+ {
/* Optimization: Use some loop unrolling. */
while(off + 3 < ctx->size && !ISNEWLINE(off+0) && !ISNEWLINE(off+1)
&& !ISNEWLINE(off+2) && !ISNEWLINE(off+3))