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

[Christian Hagedorn]

On Thu, 10 Jul 2025 14:48:10 GMT, Manuel Hässig <mhaessig 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
>
> test/hotspot/jtreg/compiler/lib/ir_framework/driver/irmatching/irrule/checkattribute/parsing/RawIRNode.java line 65:
> 
>> 63:                 nodeRegex = regexForVectorIRNode(nodeRegex, vmInfo, bound);
>> 64:             } else if (userPostfix.isValid()) {
>> 65:                 nodeRegex = nodeRegex.replaceAll(IRNode.IS_REPLACED, java.util.regex.Matcher.quoteReplacement(userPostfix.value()));
> 
> Perhaps you might want to `import java.util.regex.Matcher` to make it a bit more concise?

Yes, please import it instead.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26243#discussion_r2199760949