[TypeFeedbackVector] Root feedback vectors at function literal site.

src/builtins/arm/builtins-arm.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_ARM
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 1322 matching lines @@
   //  -- r1 : target function (preserved for callee)
   // -----------------------------------
   // First lookup code, maybe we don't need to compile!
   Label gotta_call_runtime, gotta_call_runtime_no_stack;
   Label try_shared;
   Label loop_top, loop_bottom;
 
   Register argument_count = r0;
   Register closure = r1;
   Register new_target = r3;
+  Register map = argument_count;
+  Register index = r2;
+
+  // Do we have a valid feedback vector?
+  __ ldr(index, FieldMemOperand(closure, JSFunction::kFeedbackVectorOffset));
+  __ ldr(index, FieldMemOperand(index, Cell::kValueOffset));
+  __ JumpIfRoot(index, Heap::kUndefinedValueRootIndex,
+                &gotta_call_runtime_no_stack);
+
   __ push(argument_count);
   __ push(new_target);
   __ push(closure);
 
-  Register map = argument_count;
-  Register index = r2;
   __ ldr(map, FieldMemOperand(closure, JSFunction::kSharedFunctionInfoOffset));
   __ ldr(map,
          FieldMemOperand(map, SharedFunctionInfo::kOptimizedCodeMapOffset));
   __ ldr(index, FieldMemOperand(map, FixedArray::kLengthOffset));
   __ cmp(index, Operand(Smi::FromInt(2)));
-  __ b(lt, &gotta_call_runtime);
+  __ b(lt, &try_shared);
 
-  // Find literals.
   // r3  : native context
   // r2  : length / index
   // r0  : optimized code map
   // stack[0] : new target
   // stack[4] : closure
   Register native_context = r3;
   __ ldr(native_context, NativeContextMemOperand());
 
   __ bind(&loop_top);
   Register temp = r1;
   Register array_pointer = r5;
 
   // Does the native context match?
   __ add(array_pointer, map, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(temp, FieldMemOperand(array_pointer,
                                SharedFunctionInfo::kOffsetToPreviousContext));
   __ ldr(temp, FieldMemOperand(temp, WeakCell::kValueOffset));
   __ cmp(temp, native_context);
   __ b(ne, &loop_bottom);
-  // Feedback vector available?
-  __ ldr(temp, FieldMemOperand(array_pointer,
-                               SharedFunctionInfo::kOffsetToPreviousLiterals));
-  __ ldr(temp, FieldMemOperand(temp, WeakCell::kValueOffset));
-  __ JumpIfSmi(temp, &gotta_call_runtime);
-
-  // Save the feedback vector in the closure.
-  __ ldr(r4, MemOperand(sp, 0));
-  __ str(temp, FieldMemOperand(r4, JSFunction::kFeedbackVectorOffset));
-  __ push(index);
-  __ RecordWriteField(r4, JSFunction::kFeedbackVectorOffset, temp, index,
-                      kLRHasNotBeenSaved, kDontSaveFPRegs, EMIT_REMEMBERED_SET,
-                      OMIT_SMI_CHECK);
-  __ pop(index);
 
   // Code available?
   Register entry = r4;
   __ ldr(entry,
          FieldMemOperand(array_pointer,
                          SharedFunctionInfo::kOffsetToPreviousCachedCode));
   __ ldr(entry, FieldMemOperand(entry, WeakCell::kValueOffset));
   __ JumpIfSmi(entry, &try_shared);
 
-  // Found literals and code. Get them into the closure and return.
+  // Found code. Get it into the closure and return.
   __ pop(closure);
   // Store code entry in the closure.
   __ add(entry, entry, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ str(entry, FieldMemOperand(closure, JSFunction::kCodeEntryOffset));
   __ RecordWriteCodeEntryField(closure, entry, r5);
 
   // Link the closure into the optimized function list.
   // r4 : code entry
   // r3 : native context
   // r1 : closure
@@ skipping 14 matching lines @@
   __ mov(closure, r5);
   __ pop(new_target);
   __ pop(argument_count);
   __ Jump(entry);
 
   __ bind(&loop_bottom);
   __ sub(index, index, Operand(Smi::FromInt(SharedFunctionInfo::kEntryLength)));
   __ cmp(index, Operand(Smi::FromInt(1)));
   __ b(gt, &loop_top);
 
-  // We found neither literals nor code.
-  __ jmp(&gotta_call_runtime);
-
+  // We found no code.
   __ bind(&try_shared);
   __ pop(closure);
   __ pop(new_target);
   __ pop(argument_count);
   __ ldr(entry,
          FieldMemOperand(closure, JSFunction::kSharedFunctionInfoOffset));
   // Is the shared function marked for tier up?
   __ ldrb(r5, FieldMemOperand(entry,
                               SharedFunctionInfo::kMarkedForTierUpByteOffset));
   __ tst(r5, Operand(1 << SharedFunctionInfo::kMarkedForTierUpBitWithinByte));
@@ skipping 1674 matching lines @@
     __ bkpt(0);
   }
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM