RFR: 8361494: [IR Framework] Escape too much in replacement of placeholder [v3]

[Marc Chevalier]

On Fri, 11 Jul 2025 07:30:55 GMT, Marc Chevalier <mchevalier at openjdk.org> wrote:

>> In `RawIRNode::regex`, the call to `String::replaceAll` doesn't quote the replace string.
>> 
>> Meaning that in the IR rule
>> 
>> @IR(failOn = {IRNode.ALLOC_OF, "\\w+"})
>> 
>> The interpreted `\w` is interpreted as a group reference, and we get
>> 
>> java.lang.IllegalArgumentException: Illegal group reference
>> 
>> so we should write instead
>> 
>> @IR(failOn = {IRNode.ALLOC_OF, "\\\\w+"})
>> 
>> To mean the interpreted string `\\w`, to mean an escaped single backslash. Same goes with `$` (used for nested classes).
>> 
>> Since we don't want to refer to groups (and anyway, there are not in `IRNode.IS_REPLACED`), we just quote the replacement string with `java.util.regex.Matcher.quoteReplacement` to make it more usable.
>> 
>> Note that you would still need to write `\$` since the `$` is the end of string regex, and needs to be escaped at the regex level (and not at the string, so it's not `$`, since `$` is not a special character). Before the fix, it should be `\\\$`. Phew! Regexes are bad enough, let's not escape them manually twice!
>> 
>> In `test/hotspot/jtreg/compiler/c2/TestMergeStores.java`, that makes us save 1344 backslashes.
>> 
>> Thanks,
>> Marc
>
> Marc Chevalier has updated the pull request incrementally with one additional commit since the last revision:
> 
>   i

Thanks @mhaessig  and @chhagedorn!

-------------

PR Comment: https://git.openjdk.org/jdk/pull/26243#issuecomment-3061701499