Allow bailing out of the register allocator when running out of virtual registers.

Allow bailing out of the register allocator when running out of virtual registers.

1. Instead of checking upfront and estimating a limit for the number, we
now are able to stop register allocation and bailout when we don't
have enough virtual registers.

2. GCed some out-dated flags from flag-definition.h

3. Simplified the interface from the Lithium builder to the
register allocator in lithium-*.cc: For uses and definitions, we
just record the virtual register number given by the Hydrogen value id.
For temporaries, we request a new virtual register from the allocator.
For fixed temps, we don't need to do anything.

4. Increased number of deoptimization entries to 16K. Eventually we
probably want to make this array grow dynamically.

Committed as r10597.

[Sven Panne, 2012-02-03 09:01:20]

http://codereview.chromium.org/9325019/diff/1/src/arm/lithium-arm.cc
File src/arm/lithium-arm.cc (right):

http://codereview.chromium.org/9325019/diff/1/src/arm/lithium-arm.cc#newcode795
src/arm/lithium-arm.cc:795: if (!allocator_->AllocationOk()) Abort("Not enough
virtual registers.");
I am a little bit concerned about this 'Abort' (and the corresponding ones in
other lithium-*.cc files): I don't think we aborted before if we somehow ran out
of virtual registers, now we do. Either a comment is missing why this will never
happen ;-) or this has to be handled differently, I think (bailing out?).

[fschneider, 2012-02-03 09:17:41]

http://codereview.chromium.org/9325019/diff/1/src/arm/lithium-arm.cc
File src/arm/lithium-arm.cc (right):

http://codereview.chromium.org/9325019/diff/1/src/arm/lithium-arm.cc#newcode795
src/arm/lithium-arm.cc:795: if (!allocator_->AllocationOk()) Abort("Not enough
virtual registers.");
Abort in this case is doing exactly that, namely bailing out of the lithium
construction by setting the is_aborted flag which is checked in
LChunkBuilder::DoBasicBlock.

On 2012/02/03 09:01:20, Sven wrote:
> I am a little bit concerned about this 'Abort' (and the corresponding ones in
> other lithium-*.cc files): I don't think we aborted before if we somehow ran
out
> of virtual registers, now we do. Either a comment is missing why this will
never
> happen ;-) or this has to be handled differently, I think (bailing out?).

[Sven Panne, 2012-02-03 09:46:50]

lgtm

http://codereview.chromium.org/9325019/diff/1/src/arm/lithium-arm.cc
File src/arm/lithium-arm.cc (right):

http://codereview.chromium.org/9325019/diff/1/src/arm/lithium-arm.cc#newcode795
src/arm/lithium-arm.cc:795: if (!allocator_->AllocationOk()) Abort("Not enough
virtual registers.");
On 2012/02/03 09:17:41, fschneider wrote:
> Abort in this case is doing exactly that, namely bailing out of the lithium
> construction by setting the is_aborted flag which is checked in
> LChunkBuilder::DoBasicBlock.

Ooops, I've missed the Abort method in LChunkBuilder, sorry... %-}