On Tue, 11 Jun 2024 09:32:14 GMT, Emanuel Peter <epe...@openjdk.org> wrote:
>> @eme64 The assembly information is below, can you take a look and see if it
>> can help you diagnose the problem?
>>
>> * JavaCode
>>
>> class AbstractStringBuilder {
>> private AbstractStringBuilder appendNull() {
>> int count = this.count;
>> ensureCapacityInternal(count + 4);
>> byte[] val = this.value;
>> if (isLatin1()) {
>> val[count ] = 'n';
>> val[count + 1] = 'u';
>> val[count + 2] = 'l';
>> val[count + 3] = 'l';
>> } else {
>> StringUTF16.putCharsAt(val, count, 'n', 'u', 'l', 'l');
>> }
>> this.count = count + 4;
>> return this;
>> }
>> }
>>
>> class StringUTF16 {
>> public static void putCharsAt(byte[] value, int i, char c1, char c2,
>> char c3, char c4) {
>> putChar(value, i , c1);
>> putChar(value, i + 1, c2);
>> putChar(value, i + 2, c3);
>> putChar(value, i + 3, c4);
>> }
>> }
>>
>>
>> * Apple M1 StringBuilder.appendNull PrintAssembly
>>
>> /Users/wenshao/Work/git/jdk/build/macosx-aarch64-server-release/jdk/bin/java
>> -XX:+UnlockDiagnosticVMOptions -XX:+PrintAssembly
>> -XX:CompileCommand=compileonly,*StringBuilder.appendNull
>> -XX:-TieredCompilation -XX:TieredStopAtLevel=4
>> -javaagent:/Applications/IntelliJ
>> IDEA.app/Contents/lib/idea_rt.jar=61041:/Applications/IntelliJ
>> IDEA.app/Contents/bin -Dfile.encoding=UTF-8 -Dsun.stdout.encoding=UTF-8
>> -Dsun.stderr.encoding=UTF-8 ....
>>
>> Compiled method (n/a) 96 1 n
>> java.lang.invoke.MethodHandle::linkToStatic(LLLLLLL)L (native)
>> total in heap [0x0000000102efba08,0x0000000102efbb20] = 280
>> relocation [0x0000000102efbae0,0x0000000102efbae8] = 8
>> main code [0x0000000102efbb00,0x0000000102efbb20] = 32
>>
>> [Disassembly]
>> --------------------------------------------------------------------------------
>> [Constant Pool (empty)]
>>
>> --------------------------------------------------------------------------------
>>
>> [Verified Entry Point]
>> # {method} {0x000000011c3e1c80} 'linkToStatic'
>> '(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/invoke/MemberName;)Ljava/lang/Object;'
>> in 'java/lang/invoke/MethodHandle'
>> # parm0: c_rarg1:c_rarg1
>> = 'java/lang/Object'
>> # parm1: c_rarg2:c_rarg2
>> = 'java/lang/Object'
>> # parm2: c_rarg3:c_rarg3
>> = 'java/lang/Object'
>> # parm3: c_rarg4:c...
>
> @wenshao This is just an assembly dump. You need to have some profiling data
> that tells you where the time is spent. I'm not going to do the analysis work
> for you, I'm sorry. I gave you some pointers as how to do that. If you have
> more questions about how to do that, feel free to ask. You also have not
> provided the `TraceMergeStores` log yet, as I asked you.
>
> Can you investigate WHY there is a performance difference? Which `loads` and
> `branches` etc are generated?
@eme64 How to TraceMergeStores?
-------------
PR Comment: https://git.openjdk.org/jdk/pull/19626#issuecomment-2160275514
