TlsGetValue has a semantic difference with pthread_getspecific, in that it
can return a non-error NULL value, so it always sets the LastError.
But allocator callers may not be expecting calling e.g. free() to change
the value of the last error, so preserve it.
The new "num" property lets identical blocks be aggregated in the output. This
patch only uses the "num" property for dead blocks, because that's where the
greatest potential benefit lies, but it could be used for live blocks as well.
On one test case (a complex PDF file) running with --mode=cumulative
--sample-below=1 this patch had the following effects.
- Change in running speed was negligible.
- Compressed output file size dropped from 8.8 to 5.0 MB.
- Compressed output file size dropped from 297 to 50 MB.
- dmd.py runtime (without stack fixing) dropped from 30 to 8 seconds.
The infinite loop happens if chunk_alloc_arena needs to be called when a0malloc
is called. It in turn calls chunk_alloc_default, which uses tsd, which calls
a0malloc if it's the first time the tsd is being gotten from the current thread.
tsd only uses a0malloc on platforms where there is no native thread local storage
support, which, for Mozilla, essentially means anything that is not Linux.
But the tsd is only neededto get the dss precedence setting of the given arena.
That setting has no effect when dss is disabled, which it is on Windows and Mac.
Moreover, the default setting for dss precedence is "secondary", which means
jemalloc only tries dss after it failed to get memory with mmap/VirtualAlloc.
Considering the cases where mmap/VirtualAlloc would fail essentially means
there is shortage of address space, sbrk() is not going to have much more
success, so we might as well disable dss support on all platforms, avoiding
the infinite loop problem on Android and B2G as well.
This reduces the runtime on my Linux machine for one large DMD output file from
235 seconds to 105 seconds.
--HG--
extra : rebase_source : bd567319c1207a09fa47b94571066109de1cc9e7
Now that defining $DMD is no longer necessary to run DMD, this patch does the
following.
- Removes all the places where we set DMD=1 (test harnesses, etc.)
- Still handles DMD=1, for backwards compatibility.
- Prints "$DMD is undefined" at DMD start-up if appropriate.
- Writes a |null| value for |dmdEnvVar| in the JSON if $DMD is undefined. Bumps
the DMD output version number accordingly.
- Changes a bunch of the test files accordingly, including changing the mode of
script-ignore-alloc-fns.json in order to test a case where $DMD is undefined.
--HG--
extra : rebase_source : eb1ef5722410734ce6d7658465ff6f442ee4ed49
The reason for --disable-optimize is to make debugging easier, but not many
people actually need a high level of debuggability of the allocator itself.
This works around the issue that the Android NDK's definition of ffs is
broken when compiling without optimization, while avoiding to add yet another
configure test.
