Issue #10326 has been updated by Nobuyoshi Nakada.

Description updated

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Feature #10326: [PATCH] optimize: recv << "literal string"
https://bugs.ruby-lang.org/issues/10326#change-49239

* Author: Eric Wong
* Status: Open
* Priority: Normal
* Assignee: 
* Category: core
* Target version: current: 2.2.0
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Concatenating literal strings to existing strings seems fairly common
practice, so avoid extra garbage when doing it.  I don't know if escape
analysis is coming to Ruby, but this seems easier-to-do for now:

vm2_strcat

~~~ruby
i = 0
str = ""
while i<6_000_000 # benchmark loop 2
  i += 1
  str << "const"
  str.clear
end
~~~
~~~
trunk	1.020890216
trunk	1.018797116
trunk	0.992393447
built	0.626914306
built	0.627910138
built	0.644469095
~~~
-----------------------------------------------------------
benchmark results:
minimum results in each 3 measurements.
Execution time (sec)

name	|trunk	|built
--------+-------+------
loop_whileloop2	|0.160	|0.159
vm2_strcat*	|0.833	|0.468

Speedup ratio: compare with the result of `trunk' (greater is better)

name	|built
--------+-------
loop_whileloop2	|1.006
vm2_strcat*	|1.779

Future optimizations:

* recv << "interpolated #{dstr}"
  (immediate free + force recycle)

* elide allocation for equality comparisons:
  str == "literal" and "literal" == str

* optimize << recv is IO << (str|dstr) (maybe)


---Files--------------------------------
0001-optimize-recv-literal-string.patch (3.28 KB)


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