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

src/a64/deoptimizer-a64.cc

Index: src/a64/deoptimizer-a64.cc
diff --git a/src/a64/deoptimizer-a64.cc b/src/a64/deoptimizer-a64.cc
index 95c5d3b1adde2fa1e50aed8b2b88b3c45a70e883..5416b669abc81133973c4b7e98753a85b06e8cb2 100644
--- a/src/a64/deoptimizer-a64.cc
+++ b/src/a64/deoptimizer-a64.cc
@@ -486,6 +486,7 @@ void Deoptimizer::EntryGenerator::Generate() {
         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,
@@ -514,8 +515,17 @@ void Deoptimizer::EntryGenerator::Generate() {
   __ 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) {