Setup, STR, etc, exactly as with bug 1361372. DHAT says we allocate 9138 blocks via gfxHarfBuzzShaper::ShapeText hb_buffer_add_utf16 hb_buffer_add_utf ensure hb_buffer_t::enlarge realloc malloc always of size 640. Averaged over all allocations, each byte is written 0.40 times and read only 0.18 times. From the log (see attachment) there are no uses at offset 560 or after in any block, and almost no uses after the halfway point (offset 320).

This sounds pretty reasonable, actually, given that we're normally shaping an individual (fairly short) word, but harfbuzz can't know this; so it allocates space for glyph details and position data in 32-char increments (IIRC). Usually, we only use the first few characters' worth of that space. I suppose we could optimize slightly, though, by caching the hb_buffer record in gfxHarfBuzzShaper and just clearing its contents, instead of discarding the buffer and creating a new one for each ShapeText call.

This should eliminate three malloc/free operations (the buffer itself, and its internal 'info' and 'pos' arrays) per ShapeText call, in general.

https://hg.mozilla.org/integration/mozilla-inbound/rev/eee394a4575b6caf23b820c930059bf994ea228d Bug 1361392 - Re-use the hb_buffer in gfxHarfBuzzShaper instead of creating/destroying it on each call to ShapeText. r=jrmuizel

Backed out for causing asan mochitests to leak like https://treeherder.mozilla.org/logviewer.html#?job_id=97011198&repo=mozilla-inbound

Also in valgrind builds https://treeherder.mozilla.org/logviewer.html#?job_id=97012345&repo=mozilla-inbound

Backout by kwierso@gmail.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/21a512c16cf8 Backed out changeset eee394a4575b for leaksanitizer failures in pretty much all ASAN mochitests a=backout

Sorry -- I messed up when rebasing the patch to inbound tip. :( Fixed version coming....

https://hg.mozilla.org/integration/mozilla-inbound/rev/22c2c450b41e59198d38aa9936072de43ab77703 Bug 1361392 - Re-use the hb_buffer in gfxHarfBuzzShaper instead of creating/destroying it on each call to ShapeText. r=jrmuizel

Pushed by jkew@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/22c2c450b41e Re-use the hb_buffer in gfxHarfBuzzShaper instead of creating/destroying it on each call to ShapeText. r=jrmuizel