578673 - Add valgrind client requests to Nanojit's custom allocators

Status: RESOLVED WONTFIX

(Core Graveyard :: Nanojit, defect)

Description

[Edwin Smith]

nanojit::Allocator would benefit from using memchecks MEMPOOL client requests, to protect unallocated memory and add redzones around allocated chuncks.

nanojit::CodeAlloc might also benefit from redzones or protected areas, but we already have code to report freshly generated code.

Comment 1

[Edwin Smith]

Attachment: Hacky first try at nanojit::Allocator instrumentation

Comment 2

[Edwin Smith]

The patch attempts to use the MEMPOOL client request api to a) mark new arena-allocated chunks as undefined, and b) insert redzones around each arena allocation.  Each chunk of memory that the arena gets from the underlying allocator is initialized as a memory pool; nothing special is done to the Allocator instance itself.  (from my reading of the mempool docs, this might not be right; but from looking at the test code in valgrind, it looks right)

I had to add a field to track chunk sizes so that when a chunk is ultimately freed, we know the size.  Before freeing a chunk back to the underlying allocator, I mark it DEFINED; marking it undefined generates lots of spew that I didn't investigate yet.

Comment 3

[Edwin Smith]

(In reply to comment #2)
> allocator, I mark it DEFINED; marking it undefined generates lots of spew that
> I didn't investigate yet.

correction: marking it NOACCESS generated spew; undefined might be more appropriate.

Comment 4

[Nicholas Nethercote [inactive]]

Nanojit has been dead for several years. Its Bugzilla component has been moved to the graveyard (bug 984276).

I checked all the open bugs. They're all uninteresting, so I'm WONTFIXing them all. Apologies for the bugspam.