Reviewers: Yang, Description: Refactoring of snapshots. This simplifies and improves the speed of deserializing code. The current startup time improvement for V8 is around 6%, but code deserialization is speeded up disproportionately, and we will soon have more code in the snapshot. * Removed support for deserializing into large object space. The regular pages are 1Mbyte now and that is plenty. This is a big simplification. * Instead of reserving space for the snapshot we actually allocate it now. This removes some special casing from the memory management and simplifies deserialization since we are just bumping a pointer rather than calling the normal allocation routines during deserialization. * Record in the snapshot how much we need to boot up and allocate it instead of just assuming that allocations in a new VM will always be linear. * In the snapshot we always address an object as a negative offset from the current allocation point. We used to sometimes address from the start of the deserialized data, but this is less useful now that we have good support for roots and repetitions in the deserialization data. * Code objects were previously deserialized (like other objects) by alternating raw data (deserialized with memcpy) and pointers (to external references, other objects, etc.). Now we deserialize code objects with a single memcpy, followed by a series of skips and pointers that partially overwrite the code we memcopied out of the snapshot. The skips are sometimes merged into the following instruction in the deserialization data to reduce dispatch time. * Integers in the snapshot were stored in a variable length format that gives a compact representation for small positive integers. This is still the case, but the new encoding can be decoded without branches or conditional instructions, which is faster on a modern CPU.
Please review this at https://chromiumcodereview.appspot.com/10918067/ SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/ Affected files: M src/heap-inl.h M src/heap.h M src/heap.cc M src/isolate.h M src/mksnapshot.cc M src/runtime.cc M src/serialize.h M src/serialize.cc M src/snapshot-common.cc M src/snapshot-empty.cc M src/snapshot.h M src/spaces-inl.h M src/spaces.h M src/spaces.cc M test/cctest/test-heap.cc M test/cctest/test-serialize.cc -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev
