[Interpreter] Save and restore dispatch table pointer during calls.

src/mips64/builtins-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS64
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 952 matching lines @@
 void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   // Open a frame scope to indicate that there is a frame on the stack.  The
   // MANUAL indicates that the scope shouldn't actually generate code to set up
   // the frame (that is done below).
   FrameScope frame_scope(masm, StackFrame::MANUAL);
 
   __ Push(ra, fp, cp, a1);
   __ Daddu(fp, sp, Operand(StandardFrameConstants::kFixedFrameSizeFromFp));
   __ Push(a3);
 
+  // Push dispatch table pointer.
+  __ li(a0, Operand(ExternalReference::interpreter_dispatch_table_address(
+                masm->isolate())));
+  __ Push(a0);

[balazs.kilvady, 2016/02/11 10:44:01]

You could use __ Push(a0, zero_reg); to save one daddu(sp, ...); instruction.

[rmcilroy, 2016/02/11 12:30:12]

Done.

   // Push zero for bytecode array offset.
   __ Push(zero_reg);
 
   // Get the bytecode array from the function object and load the pointer to the
   // first entry into kInterpreterBytecodeRegister.
   __ ld(a0, FieldMemOperand(a1, JSFunction::kSharedFunctionInfoOffset));
   __ ld(kInterpreterBytecodeArrayRegister,
         FieldMemOperand(a0, SharedFunctionInfo::kFunctionDataOffset));
 
   if (FLAG_debug_code) {
@@ skipping 39 matching lines @@
   //  - Support profiler (specifically profiling_counter).
   //  - Call ProfileEntryHookStub when isolate has a function_entry_hook.
   //  - Code aging of the BytecodeArray object.
 
   // Load bytecode offset and dispatch table into registers.
   __ LoadRoot(kInterpreterAccumulatorRegister, Heap::kUndefinedValueRootIndex);
   __ Daddu(kInterpreterRegisterFileRegister, fp,
            Operand(InterpreterFrameConstants::kRegisterFilePointerFromFp));
   __ li(kInterpreterBytecodeOffsetRegister,
         Operand(BytecodeArray::kHeaderSize - kHeapObjectTag));
-  __ li(kInterpreterDispatchTableRegister,
-        Operand(ExternalReference::interpreter_dispatch_table_address(
-            masm->isolate())));
+  __ lw(kInterpreterDispatchTableRegister,
+        MemOperand(fp, InterpreterFrameConstants::kDispatchTableFromFp));
 
   // Dispatch to the first bytecode handler for the function.
   __ Daddu(a0, kInterpreterBytecodeArrayRegister,
            kInterpreterBytecodeOffsetRegister);
   __ lbu(a0, MemOperand(a0));
   __ Dlsa(at, kInterpreterDispatchTableRegister, a0, kPointerSizeLog2);
   __ ld(at, MemOperand(at));
   // TODO(rmcilroy): Make dispatch table point to code entrys to avoid untagging
   // and header removal.
   __ Daddu(at, at, Operand(Code::kHeaderSize - kHeapObjectTag));
@@ skipping 1711 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64