Simplify handling of IC and megamorphic cache misses.

runtime/vm/stub_code_arm.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 419 matching lines @@
   __ Bind(&loop);
   __ subs(R2, R2, ShifterOperand(Smi::RawValue(1)));  // R2 is Smi.
   __ ldr(IP, Address(R1, 0), PL);
   __ str(IP, Address(R3, 0), PL);
   __ AddImmediate(R1, -kWordSize, PL);
   __ AddImmediate(R3, kWordSize, PL);
   __ b(&loop, PL);
 }
 
 
-// Input parameters:
-//   R5: ic-data.
-//   R4: arguments descriptor array.
-// Note: The receiver object is the first argument to the function being
-//       called, the stub accesses the receiver from this location directly
-//       when trying to resolve the call.
-void StubCode::GenerateInstanceFunctionLookupStub(Assembler* assembler) {
-  __ EnterStubFrame();
-
-  // Load the receiver.
-  __ ldr(R2, FieldAddress(R4, ArgumentsDescriptor::count_offset()));
-  __ add(IP, FP, ShifterOperand(R2, LSL, 1));  // R2 is Smi.
-  __ ldr(R6, Address(IP, kParamEndSlotFromFp * kWordSize));
-
-  // Push space for the return value.
-  // Push the receiver.
-  // Push IC data object.
-  // Push arguments descriptor array.
-  __ LoadImmediate(IP, reinterpret_cast<intptr_t>(Object::null()));
-  __ PushList((1 << R4) | (1 << R5) | (1 << R6) | (1 << IP));
-
-  // R2: Smi-tagged arguments array length.
-  PushArgumentsArray(assembler);
-
-  __ CallRuntime(kInstanceFunctionLookupRuntimeEntry, 4);
-
-  // Remove arguments.
-  __ Drop(4);
-  __ Pop(R0);  // Get result into R0.
-  __ LeaveStubFrame();
-  __ Ret();
-}
-
-
 DECLARE_LEAF_RUNTIME_ENTRY(intptr_t, DeoptimizeCopyFrame,
                            intptr_t deopt_reason,
                            uword saved_registers_address);
 
 DECLARE_LEAF_RUNTIME_ENTRY(void, DeoptimizeFillFrame, uword last_fp);
 
 
 // Used by eager and lazy deoptimization. Preserve result in R0 if necessary.
 // This stub translates optimized frame into unoptimized frame. The optimized
 // frame can contain values in registers and on stack, the unoptimized
@@ skipping 124 matching lines @@
 
   // Push space for the return value.
   // Push the receiver.
   // Push IC data object.
   // Push arguments descriptor array.
   __ LoadImmediate(IP, reinterpret_cast<intptr_t>(Object::null()));
   __ PushList((1 << R4) | (1 << R5) | (1 << R6) | (1 << IP));
   __ CallRuntime(kMegamorphicCacheMissHandlerRuntimeEntry, 3);
   // Remove arguments.
   __ Drop(3);
-  __ Pop(R0);  // Get result into R0.
+  __ Pop(R0);  // Get result into R0 (target function).
 
   // Restore IC data and arguments descriptor.
   __ PopList((1 << R4) | (1 << R5));
 
   __ LeaveStubFrame();
 
-  __ CompareImmediate(R0, reinterpret_cast<intptr_t>(Object::null()));
-  __ Branch(&StubCode::InstanceFunctionLookupLabel(), EQ);
-  __ AddImmediate(R0, Instructions::HeaderSize() - kHeapObjectTag);
-  __ bx(R0);
+  // Tail-call to target function.
+  __ ldr(R2, FieldAddress(R0, Function::code_offset()));
+  __ ldr(R2, FieldAddress(R2, Code::instructions_offset()));
+  __ AddImmediate(R2, Instructions::HeaderSize() - kHeapObjectTag);
+  __ bx(R2);
 }
 
 
 // Called for inline allocation of arrays.
 // Input parameters:
 //   LR: return address.
 //   R2: array length as Smi.
 //   R1: array element type (either NULL or an instantiated type).
 // NOTE: R2 cannot be clobbered here as the caller relies on it being saved.
 // The newly allocated object is returned in R0.
@@ skipping 819 matching lines @@
   // Push call arguments.
   for (intptr_t i = 0; i < num_args; i++) {
     __ LoadFromOffset(kWord, IP, R7, -i * kWordSize);
     __ Push(IP);
   }
   // Pass IC data object.
   __ Push(R5);
   __ CallRuntime(handle_ic_miss, num_args + 1);
   // Remove the call arguments pushed earlier, including the IC data object.
   __ Drop(num_args + 1);
-  // Pop returned code object into R0 (null if not found).
+  // Pop returned function object into R0.
   // Restore arguments descriptor array and IC data array.
   __ PopList((1 << R0) | (1 << R4) | (1 << R5));
   __ LeaveStubFrame();
   Label call_target_function;
-  __ CompareImmediate(R0, reinterpret_cast<intptr_t>(Object::null()));
-  __ b(&call_target_function, NE);
-  // NoSuchMethod or closure.
-  // Mark IC call that it may be a closure call that does not collect
-  // type feedback.
-  __ mov(IP, ShifterOperand(1));
-  __ strb(IP, FieldAddress(R5, ICData::is_closure_call_offset()));
-  __ Branch(&StubCode::InstanceFunctionLookupLabel());
+  __ b(&call_target_function);
 
   __ Bind(&found);
   // R6: pointer to an IC data check group.
   const intptr_t target_offset = ICData::TargetIndexFor(num_args) * kWordSize;
   const intptr_t count_offset = ICData::CountIndexFor(num_args) * kWordSize;
   __ LoadFromOffset(kWord, R0, R6, target_offset);
   __ LoadFromOffset(kWord, R1, R6, count_offset);
   __ adds(R1, R1, ShifterOperand(Smi::RawValue(1)));
   __ StoreToOffset(kWord, R1, R6, count_offset);
   __ b(&call_target_function, VC);  // No overflow.
@@ skipping 476 matching lines @@
   const Register right = R0;
   __ ldr(left, Address(SP, 1 * kWordSize));
   __ ldr(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM