Out-of-line constant pool on Arm: Stage 3 - Set Constant Pool Pointer on Function Entry

src/arm/builtins-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 604 matching lines @@
       ParameterCount actual(r0);
       __ InvokeFunction(r1, actual, CALL_FUNCTION,
                         NullCallWrapper(), CALL_AS_METHOD);
     }
 
     // Store offset of return address for deoptimizer.
     if (!is_api_function && !count_constructions) {
       masm->isolate()->heap()->SetConstructStubDeoptPCOffset(masm->pc_offset());
     }
 
-    // Restore context from the frame.
+    // Restore context and pool pointer from the frame.
     // r0: result
     // sp[0]: receiver
     // sp[1]: constructor function
     // sp[2]: number of arguments (smi-tagged)
     __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
+    __ RestoreConstantPoolPointer();
 
     // If the result is an object (in the ECMA sense), we should get rid
     // of the receiver and use the result; see ECMA-262 section 13.2.2-7
     // on page 74.
     Label use_receiver, exit;
 
     // If the result is a smi, it is *not* an object in the ECMA sense.
     // r0: result
     // sp[0]: receiver (newly allocated object)
     // sp[1]: constructor function
@@ skipping 57 matching lines @@
 
   // Clear the context before we push it when entering the internal frame.
   __ mov(cp, Operand::Zero());
 
   // Enter an internal frame.
   {
     FrameScope scope(masm, StackFrame::INTERNAL);
 
     // Set up the context from the function argument.
     __ ldr(cp, FieldMemOperand(r1, JSFunction::kContextOffset));
+    __ LoadConstantPoolPointer(r1);
 
     __ InitializeRootRegister();
 
     // Push the function and the receiver onto the stack.
     __ push(r1);
     __ push(r2);
 
     // Copy arguments to the stack in a loop.
     // r1: function
     // r3: argc
@@ skipping 118 matching lines @@
   //   r1 - isolate
   FrameScope scope(masm, StackFrame::MANUAL);
   __ stm(db_w, sp, r0.bit() | r1.bit() | fp.bit() | lr.bit());
   __ PrepareCallCFunction(1, 0, r2);
   __ mov(r1, Operand(ExternalReference::isolate_address(masm->isolate())));
   __ CallCFunction(ExternalReference::get_mark_code_as_executed_function(
         masm->isolate()), 2);
   __ ldm(ia_w, sp, r0.bit() | r1.bit() | fp.bit() | lr.bit());
 
   // Perform prologue operations usually performed by the young code stub.
-  __ stm(db_w, sp, r1.bit() | cp.bit() | fp.bit() | lr.bit());
+  __ PushFixedFrame(r1);

[JF, 2013/11/26 18:43:59]

Maybe I'm missing some context, but why is this needed?

[rmcilroy, 2013/11/27 17:33:56]

If code is pre-aged it will hit call this stub (rather than running it's
prologue).  Usually, the code-age stub will patch the prologue back in again,
and the stub will return to the start of the function and execute this prologue.
 In the case of the "MarkAsExecutedOnce" code stub however, the prologue code is
replaced with another marker, so we need to do the usual prologue operations
here, and jump to the point after the code-age marker.

   __ add(fp, sp, Operand(StandardFrameConstants::kFixedFrameSizeFromFp));
 
   // Jump to point after the code-age stub.
   __ add(r0, r0, Operand(kNoCodeAgeSequenceLength * Assembler::kInstrSize));
   __ mov(pc, r0);
 }
 
 
 void Builtins::Generate_MarkCodeAsExecutedTwice(MacroAssembler* masm) {
   GenerateMakeCodeYoungAgainCommon(masm);
@@ skipping 162 matching lines @@
   __ b(ne, &slow);
 
   // 3a. Patch the first argument if necessary when calling a function.
   // r0: actual number of arguments
   // r1: function
   Label shift_arguments;
   __ mov(r4, Operand::Zero());  // indicate regular JS_FUNCTION
   { Label convert_to_object, use_global_receiver, patch_receiver;
     // Change context eagerly in case we need the global receiver.
     __ ldr(cp, FieldMemOperand(r1, JSFunction::kContextOffset));
+    __ LoadConstantPoolPointer(r1);
 
     // Do not transform the receiver for strict mode functions.
     __ ldr(r2, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
     __ ldr(r3, FieldMemOperand(r2, SharedFunctionInfo::kCompilerHintsOffset));
     __ tst(r3, Operand(1 << (SharedFunctionInfo::kStrictModeFunction +
                              kSmiTagSize)));
     __ b(ne, &shift_arguments);
 
     // Do not transform the receiver for native (Compilerhints already in r3).
     __ tst(r3, Operand(1 << (SharedFunctionInfo::kNative + kSmiTagSize)));
@@ skipping 307 matching lines @@
     // Tear down the internal frame and remove function, receiver and args.
   }
   __ add(sp, sp, Operand(3 * kPointerSize));
   __ Jump(lr);
 }
 
 
 static void EnterArgumentsAdaptorFrame(MacroAssembler* masm) {
   __ SmiTag(r0);
   __ mov(r4, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
-  __ stm(db_w, sp, r0.bit() | r1.bit() | r4.bit() | fp.bit() | lr.bit());
+  if (FLAG_enable_ool_constant_pool) {
+    __ stm(db_w, sp, r4.bit() | fp.bit() | lr.bit());
+    __ stm(db_w, sp, r0.bit() | r1.bit() | r4.bit());

[JF, 2013/11/26 18:43:59]

Can you explain why r4 is spilled twice?

[rmcilroy, 2013/11/27 17:33:56]

The second r4 is pushed where pp would usually be in the normal FixedFrame (We
need to push something here in order to have a proper FixedFrame, but didn't
need to push pp, and doing so would have not worked using stm due to the
register order).  However, due to my change to re-order the constant pool stack
slot, I can now push everything (including the pp) in a single stm instruction. 

+  } else {
+    __ stm(db_w, sp, r0.bit() | r1.bit() | r4.bit() | fp.bit() | lr.bit());
+  }
   __ add(fp, sp,
          Operand(StandardFrameConstants::kFixedFrameSizeFromFp + kPointerSize));
 }
 
 
 static void LeaveArgumentsAdaptorFrame(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- r0 : result being passed through
   // -----------------------------------
   // Get the number of arguments passed (as a smi), tear down the frame and
@@ skipping 115 matching lines @@
   __ bind(&dont_adapt_arguments);
   __ Jump(r3);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM