Improve JIT TRACE coverage #16171
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Improve JIT TRACE coverage #16171
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Now it's possible that PHP tracing JIT loses some parts of the "hot" code. In case we have a root LOOP trace with an inlined call of some function, and we get a SIDE exit inside that function - we recorded a side trace, but finished it a the RETURN of the inlined function. As result the opcodes betwee RETURN from SIDE trace and LOOP exit were not covered by tracer and were executed in interpreter. This patch introduces a "ret_depth" argument that prevents stopping tracing on RETURN of such SIDE trace.
nielsdos
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Oct 2, 2024
dstogov
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* PHP-8.4: Improve JIT TRACE coverage (#16171)
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Now PHP tracing JIT may lose some parts of the "hot" code.
In case we have a root LOOP trace with an inlined call of some function, and we get a SIDE exit inside that function - we start recording a side trace, but we finish recording at the RETURN of the inlined function. As result the opcodes between RETURN from SIDE trace and root trace LOOP exit might be never traced and were always executed in interpreter.
This patch introduces a "ret_depth" argument that prevents stopping tracing on RETURN of such SIDE trace.
This is targeted to PHP-8.4, because this may disclose unrelated JIT problems and I don't like to do this in old stable releases.