513007 - asm_restore can rematerialize stack parameters instead of spilling them

Status: VERIFIED FIXED

(Tamarin Graveyard :: Baseline JIT (CodegenLIR), defect)

Description

[Edwin Smith]

Currently on i386, we use CDECL calling convention for jit-compiled AS3 methods, which puts all the parameters on the stack.  one parameter (env) is accessed frequently and tends to spill in most functions.

asm_restore() supports rematerializing various instructions (e.g. constants) instead of spilling them.  We could rematerializing incoming stack parameters since we can load them from their stack position relative to EBP, saving a few spills and a bit of stack space.

If we switched to FASTCALL for all calls then it would obviate the need for param-spilling in tamarin's use of nanojit (but this mod still wouldn't hurt)

Comment 1

[Edwin Smith]

Attachment: rematerialize stack arguments instead of spilling

Comment 2

[Rick Reitmaier]

Comment on attachment 397390 [details] [diff] [review]
rematerialize stack arguments instead of spilling

It would be helpful to document the computation of d.

Might also be time to introduce enums for paramKind() , if you don't object to extending the bounds of this patch.

Comment 3

[Edwin Smith]

will add better docs.  bug 513468 created for the enum.  (good idea).

Comment 4

[Edwin Smith]

pushed
http://hg.mozilla.org/tamarin-redux/rev/d138e8c6e0cf

Comment 5

[Chris Peyer]

Resolved fixed engineering / work item that has been pushed.  Setting status to verified.