ARM: Add support for just one string argument in the string add stub...

src/arm/code-stubs-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2943 matching lines @@
   __ bind(&call_runtime);
   GenerateCallRuntime(masm);
 }
 
 
 void TypeRecordingBinaryOpStub::GenerateAddStrings(MacroAssembler* masm) {
   ASSERT(op_ == Token::ADD);
 
   Register left = r1;
   Register right = r0;
-  Label call_runtime;
+  Label left_not_string, call_runtime;
 
-  // Check if first argument is a string.
-  __ JumpIfSmi(left, &call_runtime);
+  // Check if left argument is a string.
+  __ JumpIfSmi(left, &left_not_string);
   __ CompareObjectType(left, r2, r2, FIRST_NONSTRING_TYPE);
-  __ b(ge, &call_runtime);
+  __ b(ge, &left_not_string);
 
-  // First argument is a a string, test second.
+  StringAddStub string_add_left_stub(NO_STRING_CHECK_LEFT_IN_STUB);
+  GenerateRegisterArgsPush(masm);
+  __ TailCallStub(&string_add_left_stub);
+
+  // Left operand is not a string, test right.
+  __ bind(&left_not_string);
   __ JumpIfSmi(right, &call_runtime);
   __ CompareObjectType(right, r2, r2, FIRST_NONSTRING_TYPE);
   __ b(ge, &call_runtime);
 
-  // First and second argument are strings.
-  StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
+  StringAddStub string_add_right_stub(NO_STRING_CHECK_RIGHT_IN_STUB);
   GenerateRegisterArgsPush(masm);
-  __ TailCallStub(&string_add_stub);
+  __ TailCallStub(&string_add_right_stub);
 
   // At least one argument is not a string.
   __ bind(&call_runtime);
 }
 
 
 void TypeRecordingBinaryOpStub::GenerateCallRuntime(MacroAssembler* masm) {
   GenerateRegisterArgsPush(masm);
   switch (op_) {
     case Token::ADD:
@@ skipping 2445 matching lines @@
   GenerateCompareFlatAsciiStrings(masm, r1, r0, r2, r3, r4, r5);
 
   // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
   // tagged as a small integer.
   __ bind(&runtime);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 
 void StringAddStub::Generate(MacroAssembler* masm) {
-  Label string_add_runtime;
+  Label string_add_runtime, call_builtin;
+  Builtins::JavaScript builtin_id = Builtins::ADD;
+
   // Stack on entry:
-  // sp[0]: second argument.
-  // sp[4]: first argument.
+  // sp[0]: second argument (right).
+  // sp[4]: first argument (left).
 
   // Load the two arguments.
   __ ldr(r0, MemOperand(sp, 1 * kPointerSize));  // First argument.
   __ ldr(r1, MemOperand(sp, 0 * kPointerSize));  // Second argument.
 
   // Make sure that both arguments are strings if not known in advance.
-  if (string_check_) {
-    STATIC_ASSERT(kSmiTag == 0);
+  if (flags_ == NO_STRING_ADD_FLAGS) {
     __ JumpIfEitherSmi(r0, r1, &string_add_runtime);
     // Load instance types.
     __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
     __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
     __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
     STATIC_ASSERT(kStringTag == 0);
     // If either is not a string, go to runtime.
     __ tst(r4, Operand(kIsNotStringMask));
     __ tst(r5, Operand(kIsNotStringMask), eq);
     __ b(ne, &string_add_runtime);
+  } else {
+    // Here at least one of the arguments is definitely a string.
+    // We convert the one that is not known to be a string.
+    if ((flags_ & NO_STRING_CHECK_LEFT_IN_STUB) == 0) {
+      ASSERT((flags_ & NO_STRING_CHECK_RIGHT_IN_STUB) != 0);
+      GenerateConvertArgument(
+          masm, 1 * kPointerSize, r0, r2, r3, r4, r5, &call_builtin);
+      builtin_id = Builtins::STRING_ADD_RIGHT;
+    } else if ((flags_ & NO_STRING_CHECK_RIGHT_IN_STUB) == 0) {
+      ASSERT((flags_ & NO_STRING_CHECK_LEFT_IN_STUB) != 0);
+      GenerateConvertArgument(
+          masm, 0 * kPointerSize, r1, r2, r3, r4, r5, &call_builtin);
+      builtin_id = Builtins::STRING_ADD_LEFT;
+    }
   }
 
   // Both arguments are strings.
   // r0: first string
   // r1: second string
-  // r4: first string instance type (if string_check_)
-  // r5: second string instance type (if string_check_)
+  // r4: first string instance type (if flags_ == NO_STRING_ADD_FLAGS)
+  // r5: second string instance type (if flags_ == NO_STRING_ADD_FLAGS)
   {
     Label strings_not_empty;
     // Check if either of the strings are empty. In that case return the other.
     __ ldr(r2, FieldMemOperand(r0, String::kLengthOffset));
     __ ldr(r3, FieldMemOperand(r1, String::kLengthOffset));
     STATIC_ASSERT(kSmiTag == 0);
     __ cmp(r2, Operand(Smi::FromInt(0)));  // Test if first string is empty.
     __ mov(r0, Operand(r1), LeaveCC, eq);  // If first is empty, return second.
     STATIC_ASSERT(kSmiTag == 0);
      // Else test if second string is empty.
     __ cmp(r3, Operand(Smi::FromInt(0)), ne);
     __ b(ne, &strings_not_empty);  // If either string was empty, return r0.
 
     __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
     __ add(sp, sp, Operand(2 * kPointerSize));
     __ Ret();
 
     __ bind(&strings_not_empty);
   }
 
   __ mov(r2, Operand(r2, ASR, kSmiTagSize));
   __ mov(r3, Operand(r3, ASR, kSmiTagSize));
   // Both strings are non-empty.
   // r0: first string
   // r1: second string
   // r2: length of first string
   // r3: length of second string
-  // r4: first string instance type (if string_check_)
-  // r5: second string instance type (if string_check_)
+  // r4: first string instance type (if flags_ == NO_STRING_ADD_FLAGS)
+  // r5: second string instance type (if flags_ == NO_STRING_ADD_FLAGS)
   // Look at the length of the result of adding the two strings.
   Label string_add_flat_result, longer_than_two;
   // Adding two lengths can't overflow.
   STATIC_ASSERT(String::kMaxLength < String::kMaxLength * 2);
   __ add(r6, r2, Operand(r3));
   // Use the runtime system when adding two one character strings, as it
   // contains optimizations for this specific case using the symbol table.
   __ cmp(r6, Operand(2));
   __ b(ne, &longer_than_two);
 
   // Check that both strings are non-external ascii strings.
-  if (!string_check_) {
+  if (flags_ != NO_STRING_ADD_FLAGS) {
     __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
     __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
     __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
   }
   __ JumpIfBothInstanceTypesAreNotSequentialAscii(r4, r5, r6, r7,
                                                   &string_add_runtime);
 
   // Get the two characters forming the sub string.
   __ ldrb(r2, FieldMemOperand(r0, SeqAsciiString::kHeaderSize));
@@ skipping 27 matching lines @@
   __ b(lt, &string_add_flat_result);
   // Handle exceptionally long strings in the runtime system.
   STATIC_ASSERT((String::kMaxLength & 0x80000000) == 0);
   ASSERT(IsPowerOf2(String::kMaxLength + 1));
   // kMaxLength + 1 is representable as shifted literal, kMaxLength is not.
   __ cmp(r6, Operand(String::kMaxLength + 1));
   __ b(hs, &string_add_runtime);
 
   // If result is not supposed to be flat, allocate a cons string object.
   // If both strings are ascii the result is an ascii cons string.
-  if (!string_check_) {
+  if (flags_ != NO_STRING_ADD_FLAGS) {
     __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
     __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
     __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
   }
   Label non_ascii, allocated, ascii_data;
   STATIC_ASSERT(kTwoByteStringTag == 0);
   __ tst(r4, Operand(kStringEncodingMask));
   __ tst(r5, Operand(kStringEncodingMask), ne);
   __ b(eq, &non_ascii);
@@ skipping 27 matching lines @@
   // Allocate a two byte cons string.
   __ AllocateTwoByteConsString(r7, r6, r4, r5, &string_add_runtime);
   __ jmp(&allocated);
 
   // Handle creating a flat result. First check that both strings are
   // sequential and that they have the same encoding.
   // r0: first string
   // r1: second string
   // r2: length of first string
   // r3: length of second string
-  // r4: first string instance type (if string_check_)
-  // r5: second string instance type (if string_check_)
+  // r4: first string instance type (if flags_ == NO_STRING_ADD_FLAGS)
+  // r5: second string instance type (if flags_ == NO_STRING_ADD_FLAGS)
   // r6: sum of lengths.
   __ bind(&string_add_flat_result);
-  if (!string_check_) {
+  if (flags_ != NO_STRING_ADD_FLAGS) {
     __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
     __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
     __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
   }
   // Check that both strings are sequential.
   STATIC_ASSERT(kSeqStringTag == 0);
   __ tst(r4, Operand(kStringRepresentationMask));
   __ tst(r5, Operand(kStringRepresentationMask), eq);
   __ b(ne, &string_add_runtime);
@@ skipping 77 matching lines @@
   StringHelper::GenerateCopyCharacters(masm, r6, r1, r3, r4, false);
 
   __ mov(r0, Operand(r7));
   __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
   __ add(sp, sp, Operand(2 * kPointerSize));
   __ Ret();
 
   // Just jump to runtime to add the two strings.
   __ bind(&string_add_runtime);
   __ TailCallRuntime(Runtime::kStringAdd, 2, 1);
+
+  if (call_builtin.is_linked()) {
+    __ bind(&call_builtin);
+    __ InvokeBuiltin(builtin_id, JUMP_JS);
+  }
+}
+
+
+void StringAddStub::GenerateConvertArgument(MacroAssembler* masm,
+                                            int stack_offset,
+                                            Register arg,
+                                            Register scratch1,
+                                            Register scratch2,
+                                            Register scratch3,
+                                            Register scratch4,
+                                            Label* slow) {
+  // First check if the argument is already a string.
+  Label not_string, done;
+  __ JumpIfSmi(arg, &not_string);
+  __ CompareObjectType(arg, scratch1, scratch1, FIRST_NONSTRING_TYPE);
+  __ b(lt, &done);
+
+  // Check the number to string cache.
+  Label not_cached;
+  __ bind(&not_string);
+  // Puts the cached result into scratch1.
+  NumberToStringStub::GenerateLookupNumberStringCache(masm,
+                                                      arg,
+                                                      scratch1,
+                                                      scratch2,
+                                                      scratch3,
+                                                      scratch4,
+                                                      false,
+                                                      &not_cached);
+  __ mov(arg, scratch1);
+  __ str(arg, MemOperand(sp, stack_offset));
+  __ jmp(&done);
+
+  // Check if the argument is a safe string wrapper.
+  __ bind(&not_cached);
+  __ JumpIfSmi(arg, slow);
+  __ CompareObjectType(
+      arg, scratch1, scratch2, JS_VALUE_TYPE);  // map -> scratch1.
+  __ b(ne, slow);
+  __ ldrb(scratch2, FieldMemOperand(scratch1, Map::kBitField2Offset));
+  __ and_(scratch2,
+          scratch2, Operand(1 << Map::kStringWrapperSafeForDefaultValueOf));
+  __ cmp(scratch2,
+         Operand(1 << Map::kStringWrapperSafeForDefaultValueOf));
+  __ b(ne, slow);
+  __ ldr(arg, FieldMemOperand(arg, JSValue::kValueOffset));
+  __ str(arg, MemOperand(sp, stack_offset));
+
+  __ bind(&done);
 }
 
 
 void StringCharAtStub::Generate(MacroAssembler* masm) {
   // Expects two arguments (object, index) on the stack:
   //  lr: return address
   //  sp[0]: index
   //  sp[4]: object
   Register object = r1;
   Register index = r0;
@@ skipping 332 matching lines @@
   __ strb(untagged_value, MemOperand(external_pointer, untagged_key));
   __ Ret();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM