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

src/a64/deoptimizer-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
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 //
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@@ skipping 468 matching lines @@
   // Compute the output frame in the deoptimizer.
   __ Push(x0);  // Preserve deoptimizer object across call.
 
   {
     // Call Deoptimizer::ComputeOutputFrames().
     AllowExternalCallThatCantCauseGC scope(masm());
     __ CallCFunction(
         ExternalReference::compute_output_frames_function(isolate()), 1);
   }
   __ Pop(x0);  // Restore deoptimizer object (class Deoptimizer).
+  __ Mov(x4, x0);

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

Pop directly into x4 and update the two loads below accordingly.

 
   // Replace the current (input) frame with the output frames.
   Label outer_push_loop, inner_push_loop,
       outer_loop_header, inner_loop_header;
   __ Ldrsw(x1, MemOperand(x0, Deoptimizer::output_count_offset()));
   __ Ldr(x0, MemOperand(x0, Deoptimizer::output_offset()));
   __ Add(x1, x0, Operand(x1, LSL, kPointerSizeLog2));
   __ B(&outer_loop_header);
 
   __ Bind(&outer_push_loop);
   Register current_frame = x2;
   __ Ldr(current_frame, MemOperand(x0, 0));
   __ Ldr(x3, MemOperand(current_frame, FrameDescription::frame_size_offset()));
   __ B(&inner_loop_header);
 
   __ Bind(&inner_push_loop);
   __ Sub(x3, x3, kPointerSize);
   __ Add(x6, current_frame, x3);
   __ Ldr(x7, MemOperand(x6, FrameDescription::frame_content_offset()));
   __ Push(x7);
   __ Bind(&inner_loop_header);
   __ Cbnz(x3, &inner_push_loop);
 
   __ Add(x0, x0, kPointerSize);
   __ Bind(&outer_loop_header);
   __ Cmp(x0, x1);
   __ B(lt, &outer_push_loop);
 
-  // TODO(jbramley): The ARM code restores FP registers here.
-  TODO_UNIMPLEMENTED("EntryGenerator::Generate: Restore FP registers.");
+  __ Ldr(x1, MemOperand(x4, Deoptimizer::input_offset()));
+  int src_offset = FrameDescription::double_registers_offset();
+  for (unsigned i = 0; i < kNumberOfFPRegisters; ++i) {

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

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.

+    if (i == crankshaft_fp_scratch.code()) continue;
+    if (i == fp_zero.code()) continue;
+    if (i == fp_scratch.code()) continue;
+
+    const FPRegister reg = FPRegister::from_code(i);

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

const FPRegister&

+    __ Ldr(reg, MemOperand(x1, src_offset));

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

maybe add a todo to insider ldp later on.

+    src_offset += kDoubleSize;
+  }
 
   // Push state, pc, and continuation from the last output frame.
   if (type() != OSR) {
     __ Ldr(x6, MemOperand(current_frame, FrameDescription::state_offset()));
     __ Push(x6);
   }
 
   // TODO(all): This code needs to be revisited, We probably don't need to
   // restore all the registers as fullcodegen does not keep live values in
   // registers (note that at least fp must be restored though).
@@ skipping 65 matching lines @@
 
 
 void FrameDescription::SetCallerFp(unsigned offset, intptr_t value) {
   SetFrameSlot(offset, value);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal