A64: Restore FP registers in Deoptimizer::EntryGenerator::Generate

A64: Restore FP registers in Deoptimizer::EntryGenerator::Generate

BUG=none
R=rodolph.perfetta@arm.com, ulan@chromium.org
LOG=y

Committed: https://code.google.com/p/v8/source/detail?r=18998

[jochen (gone - plz use gerrit), 2014-01-31 14:36:22]

ptal

[ulan, 2014-01-31 14:38:21]

lgtm

[Rodolph Perfetta (ARM), 2014-01-31 14:50:28]

https://codereview.chromium.org/151373004/diff/1/src/a64/deoptimizer-a64.cc
File src/a64/deoptimizer-a64.cc (right):

https://codereview.chromium.org/151373004/diff/1/src/a64/deoptimizer-a64.cc#n...
src/a64/deoptimizer-a64.cc:489: __ Mov(x4, x0);
Pop directly into x4 and update the two loads below accordingly.

https://codereview.chromium.org/151373004/diff/1/src/a64/deoptimizer-a64.cc#n...
src/a64/deoptimizer-a64.cc:520: for (unsigned i = 0; i < kNumberOfFPRegisters;
++i) {
This loop could be rewritten with CPURegList:

CPURegList fpreg_to_restore = CPURegList(CPURegister:kFPRegister, 64, 0x1f);
fpreg_to_restore.Remove(fp_scratch); // or initialise without them directly
// ditto for crankshaft_fp_scratch and fp_zero

while (!fp_reg_to_restore.Empty()) {
  __ Ldr(fpreg_to_restore.PopLowestIndex(), MemOperand(x1, src_offset));
  src_offset += kDoubleSize;
}

up to you.

https://codereview.chromium.org/151373004/diff/1/src/a64/deoptimizer-a64.cc#n...
src/a64/deoptimizer-a64.cc:525: const FPRegister reg = FPRegister::from_code(i);
const FPRegister&

https://codereview.chromium.org/151373004/diff/1/src/a64/deoptimizer-a64.cc#n...
src/a64/deoptimizer-a64.cc:526: __ Ldr(reg, MemOperand(x1, src_offset));
maybe add a todo to insider ldp later on.

[jochen (gone - plz use gerrit), 2014-01-31 15:11:48]

ptal

[Rodolph Perfetta (ARM), 2014-01-31 15:35:47]

LGTM with nit addressed.

https://codereview.chromium.org/151373004/diff/100001/src/a64/deoptimizer-a64.cc
File src/a64/deoptimizer-a64.cc (right):

https://codereview.chromium.org/151373004/diff/100001/src/a64/deoptimizer-a64...
src/a64/deoptimizer-a64.cc:523: const FPRegister reg =
saved_fp_registers.PopLowestIndex().D();
no need for D(), Ldr can handle CPURegister directly.

[jochen (gone - plz use gerrit), 2014-01-31 15:40:33]

Committed patchset #5 manually as r18998 (presubmit successful).