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The earliest published JIT compiler is generally attributed to work on LISP by John McCarthy in 1960. [4] In his seminal paper Recursive functions of symbolic expressions and their computation by machine, Part I, he mentions functions that are translated during runtime, thereby sparing the need to save the compiler output to punch cards [5] (although this would be more accurately known as a ...
As of 21 January 2025 (two months after PHP 8.4's release), PHP is used as the server-side programming language on 75.0% of websites where the language could be determined; PHP 7 is the most used version of the language with 47.1% of websites using PHP being on that version, while 40.6% use PHP 8, 12.2% use PHP 5 and 0.1% use PHP 4. [19]
Whereas method-based JIT compilers translate one method at a time to machine code, tracing JITs use frequently executed loops as their unit of compilation. Tracing JITs are based on the assumptions that programs spend most of their time in some loops of the program ("hot loops") and subsequent loop iterations often take similar paths.
Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter.Unlike human-readable [1] source code, bytecodes are compact numeric codes, constants, and references (normally numeric addresses) that encode the result of compiler parsing and performing semantic analysis of things like type, scope, and nesting depths of ...
Further, JIT compilers can speculatively optimize hot code by making assumptions on the code. The generated code can be deoptimized if a speculative assumption later proves wrong. Such operation slows the performance of the running software until code is optimized again by adaptive optimization. An AOT compiler cannot make such assumptions and ...
In computer science, dynamic recompilation is a feature of some emulators and virtual machines, where the system may recompile some part of a program during execution. By compiling during execution, the system can tailor the generated code to reflect the program's run-time environment, and potentially produce more efficient code by exploiting information that is not available to a traditional ...
HHVM was created as the successor to the HipHop for PHP (HPHPc) PHP execution engine, which is a PHP-to-C++ transpiler also created by Facebook. [ 11 ] [ 12 ] Based on the gained experience and aiming to solve issues introduced by HPHPc, Meta decided in early 2010 to create a JIT-based PHP virtual machine .
JIT then will transform bytecode to native x86 code like: 0: b8 44 33 22 11 mov $0x11223344, %eax mov eax, 0x11223344 5: 35 11 22 33 44 xor $0x44332211, %eax xor eax, 0x44332211 a: 35 11 22 33 44 xor $0x44332211, %eax xor eax, 0x44332211. The attacker then uses a suitable bug to redirect code execution into the newly generated code.