512610 - nanojit: some register allocation clean-ups

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Nicholas Nethercote [inactive]]

Attachment: patch

This patch:

- Removes copyRegisters(), because it is dead.

- Changes RegAlloc::formatRegisters() from a static function into a normal
  member function, and removes the now-unnecessary first argument, because
  why do something an unusual way if you don't have to?

- Removes the prevreg() macro, because it is dead and only defined for two
  of the five back-ends.

- Replaces a couple of '1<<REG' occurrences with 'rmask(REG)', for
  consistency.

- In RegAlloc::formatRegisters(), uses FirstReg/LastReg/nextreg() to iterate
  over the registers -- as is done everywhere else -- instead of an integer
  loop.

Comment 1

[Edwin Smith]

Comment on attachment 396637 [details] [diff] [review]
patch

one gotcha to look out for is the varous routines that do patching.  if they use asm_output indirectly, then foramtRegisters() will be called with a possibly null "this" (or _allocator) field.

Comment 2

[Nicholas Nethercote [inactive]]

(In reply to comment #1)
> one gotcha to look out for is the varous routines that do patching.  if they
> use asm_output indirectly, then foramtRegisters() will be called with a
> possibly null "this" (or _allocator) field.

I think it's safe... the only places formatRegisters() is called is within the output_asm macro, where I changed this:

   RegAlloc::formatRegisters(_allocator, outline, _thisfrag); \

to this:

   _allocator.formatRegisters(outline, _thisfrag); \

so all I really did was change _allocator from an explicit 1st argument to an implicit first argument (via 'this').  No variable scopes or uses changed otherwise.

Comment 3

[Nicholas Nethercote [inactive]]

http://hg.mozilla.org/tracemonkey/rev/c1a97865c476

Comment 4

[Blake Kaplan (:mrbkap) (inactive)]

http://hg.mozilla.org/mozilla-central/rev/c1a97865c476

Comment 5

[Robert Sayre]

http://hg.mozilla.org/releases/mozilla-1.9.2/rev/0523517082d7