[arm][stubs] Fix d16-d31 preservation on stub failure

src/arm64/deoptimizer-arm64.cc

Index: src/arm64/deoptimizer-arm64.cc
diff --git a/src/arm64/deoptimizer-arm64.cc b/src/arm64/deoptimizer-arm64.cc
index a70104fcc28992db7656326f5e9126a7c6e4c0e3..cd2899a5e29f71562f8150275b532d7f360ecf44 100644
--- a/src/arm64/deoptimizer-arm64.cc
+++ b/src/arm64/deoptimizer-arm64.cc
@@ -167,11 +167,13 @@ void Deoptimizer::TableEntryGenerator::Generate() {
   }
 
   // Copy FP registers to the input frame.
+  CPURegList copy_fp_to_input = saved_fp_registers;
   for (int i = 0; i < saved_fp_registers.Count(); i++) {
-    int dst_offset = FrameDescription::double_registers_offset() +
-        (i * kDoubleSize);
     int src_offset = kFPRegistersOffset + (i * kDoubleSize);
     __ Peek(x2, src_offset);
+    CPURegister reg = copy_fp_to_input.PopLowestIndex();
+    int dst_offset = FrameDescription::double_registers_offset() +
+                     (reg.code() * kDoubleSize);

[Jakob Kummerow, 2016/03/09 11:07:25]

The change here is s/i/reg.code()/. We must not use compact storage; non-saved
registers must leave gaps in the FrameDescription in order for
Deoptimizer::CopyDoubleRegisters (lines 79ff above) to work correctly. This is
consistent with other platforms.

     __ Str(x2, MemOperand(x1, dst_offset));
   }
 
@@ -240,11 +242,11 @@ void Deoptimizer::TableEntryGenerator::Generate() {
   DCHECK(!saved_fp_registers.IncludesAliasOf(crankshaft_fp_scratch) &&
          !saved_fp_registers.IncludesAliasOf(fp_zero) &&
          !saved_fp_registers.IncludesAliasOf(fp_scratch));
-  int src_offset = FrameDescription::double_registers_offset();
   while (!saved_fp_registers.IsEmpty()) {
     const CPURegister reg = saved_fp_registers.PopLowestIndex();
+    int src_offset = FrameDescription::double_registers_offset() +
+                     (reg.code() * kDoubleSize);
     __ Ldr(reg, MemOperand(x1, src_offset));
-    src_offset += kDoubleSize;
   }
 
   // Push state from the last output frame.