Created attachment 508659 [details] [diff] [review] patch (against TM 61287:a6d56af51d69) JITScript has several variable-length sections at its end. Currently it holds a pointer to every section and the length of every section. But only one or the other is necessary; this patch removes all the pointers. This reduces sizeof(JITScript) nicely: - 32-bits: 120 bytes -> 84 bytes - 64-bits: 200 bytes -> 128 bytes Reusing the calculation from bug 619849 comment 0: on a 20-tab cad-comics browser run this reduces peak memory use by ~800 KB on 64-bit platforms and ~400 KB on 32-bit platforms. It also reduces the cost of adding new sections, which may happen with PICs (see the last sentence of bug 629601 comment 2). The patch: - Changes all the section pointer fields (.nmap, .pics, etc) to methods. - Removes 'idReg' from PICGenInfo; it's a dead field. - Reorders the section lengths in JITScript to match the order of the sections as written by finishThisUp(). - Simplifies the writing of sections in finishThisUp(). Most of the sections had an "is this zero length?" test that wasn't necessary and just increased indentation, so I removed it. The patch is reasonably big but most of the changes are mechanical. I confirmed with Cachegrind that instruction counts were only negligibly affected by the new section-finding methods, each of which requires multiple adds and multiplies.
cdleary-bot mozilla-central merge info: http://hg.mozilla.org/mozilla-central/rev/a1a8cd4accba