RFR: 8274329: Fix non-portable HotSpot code in MethodMatcher::parse_method_pattern

[Jie Fu]

On Tue, 5 Oct 2021 06:38:05 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Hi all,
>> 
>> I tried to build OpenJDK on Cygwin (Windows 2016 + VS2019).
>> However, I failed with C4474 and C4778 warnings as below:
>> 
>> Compiling 100 properties into resource bundles for java.desktop
>> Compiling 3038 files for java.base
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): error C2220: the following warning is treated as an error
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4778: 'sscanf' : unterminated format string '%255[*\x01\x02\x03\x04\x05\x06\a\b\n\v\f\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f!"#$%&'*+,-0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\^_`abcdefghijklmnopqrstuvwxyz{|}~\xe2\x82\xac\xe4\xba\x97\xe5\x84\x8e\xe5\x8e\x97%n'
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4474: 'sscanf' : too many arguments passed for format string
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): note: placeholders and their parameters expect 1 variadic arguments, but 3 were provided
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(319): warning C4778: 'sscanf' : unterminated format string '%1022[[);/\x01\x02\x03\x04\x05\x06\a\b\n\v\f\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f!"#$%&'*+,-0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\^_`abcdefghijklmnopqrstuvwxyz{|}~\xe2\x82\xac\xe4\xba\x97\xe5\x84\x8e\xe5\x8e%n'
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(319): warning C4474: 'sscanf' : too many arguments passed for format string
>> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(319): note: placeholders and their parameters expect 0 variadic arguments, but 2 were provided
>> 
>> 
>> The failure is caused by non-ASCII chars in the format string of sscanf [1][2], which is non-portable on our Windows platform.
>> In fact, these non-ASCII coding also triggers C4819 warning, which had been disabled in JDK-8216154 [3].
>> And I also found an article showing that sscanf may fail with non-ASCII in the format string [4].
>> 
>> So it would be nice to remove these non-ASCII chars  (`\x80 ~ \xef`).
>> And I think it's safe to do so.
>> 
>> This is because:
>>  1) There are actually no non-ASCII chars for package/class/method/signature names.
>>  2) I don't think there is a use case, in which people will input non-ASCII for `CompileCommand`.
>> 
>> You may argue that the non-ASCII may be used by the parser itself.
>> But I didn't find that usage at all. (Please let me know if I miss something.)
>> 
>> So I suggest to remove these non-ASCII code to make HotSpot to be more portable.
>> And if we do so, we can also remove the only one `PRAGMA_DISABLE_MSVC_WARNING(4819)` [5].
>> 
>> Testing:
>>  - Build tests on Windows
>>  - tier1~3 on Linux/x64
>> 
>> Thanks.
>> Best regards,
>> Jie
>> 
>> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/methodMatcher.cpp#L269
>> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/methodMatcher.cpp#L319
>> [3] https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-January/032014.html
>> [4] https://jeffpar.github.io/kbarchive/kb/047/Q47369/
>> [5] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/methodMatcher.cpp#L246
>
> My experiments above with ` -XX:CompileCommand='compileonly,*::爪哇'` was done on Linux. I tried doing the same on Windows. On US-English Windows, the default codepage is 437 (DOS Latin US). If I change it to 65001 (UTF8) then Java is able to output CJK characters to the console.
> 
> 
> public class CJK {
>     public static void main(String args[]) {
> 	System.out.println(args[0]);
>         \u722a\u54c7();
>     }
> 
>     static void \u722a\u54c7() { // Chinese word for "Java"
>         Thread.dumpStack();
>     }
> }
> 
> 
> 
> c:\ade>chcp
> Active code page: 437
> 
> c:\ade>jdk-17\bin\java -cp . CJK 123
> 123
> java.lang.Exception: Stack trace
>         at java.base/java.lang.Thread.dumpStack(Thread.java:1380)
>         at CJK.??(CJK.java:8)
>         at CJK.main(CJK.java:4)
> 
> c:\ade>chcp 65001
> Active code page: 65001
> 
> c:\ade>jdk-17\bin\java -cp . CJK 爪哇
> ??
> java.lang.Exception: Stack trace
>         at java.base/java.lang.Thread.dumpStack(Thread.java:1380)
>         at CJK.爪哇(CJK.java:8)
>         at CJK.main(CJK.java:4)
> 
> 
> As you can see, the CJK characters in the command-line arguments can't even be correctly passed as arguments to the Java main class. If that doesn't work, I can't see how we can get `-XX:CompileCommand` to work with CJK characters.

Thanks @iklam @magicus and @vnkozlov .

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

PR: https://git.openjdk.java.net/jdk/pull/5704