The low level can be explored with a disassembler but the short answer is that it’s a bunch of if/elses where the predicate depends on the pattern case Sum(l,r) // instance of check followed by fetching the two arguments and assigning to two variables l and r but see below about custom extractors case “hello” … Read more
There are a lot of similarities between both implementations (and in my opinion: yes, they’re both “virtual machines”). For one thing, they’re both stack-based VM’s, with no notion of “registers” like we’re used to seeing in a modern CPU like the x86 or PowerPC. The evaluation of all expressions ((1 + 1) / 2) is … Read more
After working with Java byte code for quite a while and doing some additional research on this matter, here is a summary of my findings: Execute code in a constructor before calling a super constructor or auxiliary constructor In the Java programming language (JPL), a constructor’s first statement must be an invocation of a super … Read more
If you are using Android Studio, the Java 7 language should be enabled automatically without any patches. Try-with-resource requires API Level 19+, and NIO 2.0 stuff are missing. If you can’t use Java 7 features, see @Nuno’s answer on how to edit your build.gradle. The following is for historical interest only. A small part of … Read more
Basically, line numbers are kept for debugging, so if you change your source code the way you did, your method starts at a different line and the compiled class reflects the difference.
After this question was asked, Facebook launched HipHop for PHP which is probably the best-tested PHP compiler to date (seeing as it ran one of the world’s 10 biggest websites). However, Facebook discontinued it in favour of HHVM, which is a virtual machine, not a compiler. Beyond that, googling PHP compiler turns up a number … Read more
There is a slight difference in the ordering of the bytecode. 2 * (i * i): iconst_2 iload0 iload0 imul imul iadd vs 2 * i * i: iconst_2 iload0 imul iload0 imul iadd At first sight this should not make a difference; if anything the second version is more optimal since it uses one … Read more