X87: [turbofan] Remove the no-context hack for JSToNumber.

port d211608a

original commit message:
  [turbofan] Remove the no-context hack for JSToNumber.

  The ToNumberStub is now able to handle all plain primitives (Numbers,
  Booleans, Null, Undefined and Strings) without context access.

BUG=

Review URL: https://codereview.chromium.org/810683002

Cr-Commit-Position: refs/heads/master@{#25833}

src/x87/code-stubs-x87.cc

@@ -2917,18 +2917,45 @@ void SubStringStub::Generate(MacroAssembler* masm) {
 
 void ToNumberStub::Generate(MacroAssembler* masm) {
   // The ToNumber stub takes one argument in eax.
-  Label check_heap_number, call_builtin;
-  __ JumpIfNotSmi(eax, &check_heap_number, Label::kNear);
+  Label not_smi;
+  __ JumpIfNotSmi(eax, &not_smi, Label::kNear);
   __ Ret();
+  __ bind(&not_smi);
 
-  __ bind(&check_heap_number);
+  Label not_heap_number;
   __ CompareMap(eax, masm->isolate()->factory()->heap_number_map());
-  __ j(not_equal, &call_builtin, Label::kNear);
+  __ j(not_equal, &not_heap_number, Label::kNear);
   __ Ret();
+  __ bind(&not_heap_number);
+
+  Label not_string, slow_string;
+  __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, edi);
+  // eax: object
+  // edi: object map
+  __ j(above_equal, &not_string, Label::kNear);
+  // Check if string has a cached array index.
+  __ test(FieldOperand(eax, String::kHashFieldOffset),
+          Immediate(String::kContainsCachedArrayIndexMask));
+  __ j(not_zero, &slow_string, Label::kNear);
+  __ mov(eax, FieldOperand(eax, String::kHashFieldOffset));
+  __ IndexFromHash(eax, eax);
+  __ Ret();
+  __ bind(&slow_string);
+  __ pop(ecx);   // Pop return address.
+  __ push(eax);  // Push argument.
+  __ push(ecx);  // Push return address.
+  __ TailCallRuntime(Runtime::kStringToNumber, 1, 1);
+  __ bind(&not_string);
 
-  __ bind(&call_builtin);
-  __ pop(ecx);  // Pop return address.
-  __ push(eax);
+  Label not_oddball;
+  __ CmpInstanceType(edi, ODDBALL_TYPE);
+  __ j(not_equal, &not_oddball, Label::kNear);
+  __ mov(eax, FieldOperand(eax, Oddball::kToNumberOffset));
+  __ Ret();
+  __ bind(&not_oddball);
+
+  __ pop(ecx);   // Pop return address.
+  __ push(eax);  // Push argument.
   __ push(ecx);  // Push return address.
   __ InvokeBuiltin(Builtins::TO_NUMBER, JUMP_FUNCTION);
 }