[CRuby] Optimize strscan_do_scan(): Remove unnecessary use of rb_enc_get() (#108)

naitoh · web-flow · commit ff2d7afa19f3 · 2024-10-16T09:59:44.000+09:00
- before: #106 ## Why? In `rb_strseq_index()`, the result of `rb_enc_check()` is used. - https://github.com/ruby/ruby/blob/6c7209cd3788ceec01e504d99057f9d3b396be84/string.c#L4335-L4368 > enc = rb_enc_check(str, sub); > return strseq_core(str_ptr, str_ptr_end, str_len, sub_ptr, sub_len, offset, enc); - https://github.com/ruby/ruby/blob/6c7209cd3788ceec01e504d99057f9d3b396be84/string.c#L4309-L4318 ```C strseq_core(const char *str_ptr, const char *str_ptr_end, long str_len, const char *sub_ptr, long sub_len, long offset, rb_encoding *enc) { const char *search_start = str_ptr; long pos, search_len = str_len - offset; for (;;) { const char *t; pos = rb_memsearch(sub_ptr, sub_len, search_start, search_len, enc); ``` ## Benchmark It shows String as a pattern is 1.24x faster than Regexp as a pattern. ``` $ benchmark-driver benchmark/check_until.yaml Warming up -------------------------------------- regexp 9.225M i/s - 9.328M times in 1.011068s (108.40ns/i) regexp_var 9.327M i/s - 9.413M times in 1.009214s (107.21ns/i) string 9.200M i/s - 9.355M times in 1.016840s (108.70ns/i) string_var 11.249M i/s - 11.255M times in 1.000578s (88.90ns/i) Calculating ------------------------------------- regexp 9.565M i/s - 27.676M times in 2.893476s (104.55ns/i) regexp_var 10.111M i/s - 27.982M times in 2.767496s (98.90ns/i) string 10.060M i/s - 27.600M times in 2.743465s (99.40ns/i) string_var 12.519M i/s - 33.746M times in 2.695615s (79.88ns/i) Comparison: string_var: 12518707.2 i/s regexp_var: 10111089.6 i/s - 1.24x slower string: 10060144.4 i/s - 1.24x slower regexp: 9565124.4 i/s - 1.31x slower ```
diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
@@ -709,7 +709,7 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly
     }
     else {
         StringValue(pattern);
-        rb_enc_check(p->str, pattern);
+        rb_encoding *enc = rb_enc_check(p->str, pattern);
         if (S_RESTLEN(p) < RSTRING_LEN(pattern)) {
             return Qnil;
         }
@@ -719,9 +719,10 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly
                 return Qnil;
             }
             set_registers(p, RSTRING_LEN(pattern));
-        } else {
+        }
+        else {
             long pos = rb_memsearch(RSTRING_PTR(pattern), RSTRING_LEN(pattern),
-                                    CURPTR(p), S_RESTLEN(p), rb_enc_get(pattern));
+                                    CURPTR(p), S_RESTLEN(p), enc);
             if (pos == -1) {
                 return Qnil;
             }

Original file line number	Diff line number	Diff line change
`@@ -709,7 +709,7 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly`
`709`	`709`	`}`
`710`	`710`	`else {`
`711`	`711`	`StringValue(pattern);`
`712`		`- rb_enc_check(p->str, pattern);`
	`712`	`+ rb_encoding *enc = rb_enc_check(p->str, pattern);`
`713`	`713`	`if (S_RESTLEN(p) < RSTRING_LEN(pattern)) {`
`714`	`714`	`return Qnil;`
`715`	`715`	`}`
`@@ -719,9 +719,10 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly`
`719`	`719`	`return Qnil;`
`720`	`720`	`}`
`721`	`721`	`set_registers(p, RSTRING_LEN(pattern));`
`722`		`- } else {`
	`722`	`+ }`
	`723`	`+ else {`
`723`	`724`	`long pos = rb_memsearch(RSTRING_PTR(pattern), RSTRING_LEN(pattern),`
`724`		`- CURPTR(p), S_RESTLEN(p), rb_enc_get(pattern));`
	`725`	`+ CURPTR(p), S_RESTLEN(p), enc);`
`725`	`726`	`if (pos == -1) {`
`726`	`727`	`return Qnil;`
`727`	`728`	`}`