Implement specialized IC code stubs for pixel array stores.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 7d70ac343cd0ef368e5959fcfd9db8e746774904..af18404970483b822f589a923d0e5c4ae02ad4d8 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -6559,9 +6559,19 @@ void GenerateFastPixelArrayLoad(MacroAssembler* masm,
   __ mov(untagged_key, key);
   __ SmiUntag(untagged_key);
 
-  // Verify that the receiver has pixel array elements.
   __ mov(elements, FieldOperand(receiver, JSObject::kElementsOffset));
-  __ CheckMap(elements, Factory::pixel_array_map(), not_pixel_array, true);
+  // By passing NULL as not_pixel_array, callers signal that they have already
+  // verified that the receiver has pixel array elements.
+  if (not_pixel_array != NULL) {
+    __ CheckMap(elements, Factory::pixel_array_map(), not_pixel_array, true);
+  } else {
+    if (FLAG_debug_code) {
+      // Map check should have already made sure that elements is a pixel array.
+      __ cmp(FieldOperand(elements, HeapObject::kMapOffset),
+             Immediate(Factory::pixel_array_map()));
+      __ Assert(equal, "Elements isn't a pixel array");
+    }
+  }
 
   // Key must be in range.
   __ cmp(untagged_key, FieldOperand(elements, PixelArray::kLengthOffset));
@@ -6575,6 +6585,90 @@ void GenerateFastPixelArrayLoad(MacroAssembler* masm,
 }
 
 
+// Stores an indexed element into a pixel array, clamping the stored value.
+void GenerateFastPixelArrayStore(MacroAssembler* masm,
+                                 Register receiver,
+                                 Register key,
+                                 Register value,
+                                 Register elements,
+                                 Register scratch1,
+                                 bool load_elements_from_receiver,
+                                 Label* key_not_smi,
+                                 Label* value_not_smi,
+                                 Label* not_pixel_array,
+                                 Label* out_of_range) {
+  // Register use:
+  //   receiver - holds the receiver and is unchanged unless the
+  //              store succeeds.
+  //   key - holds the key (must be a smi) and is unchanged.
+  //   value - holds the value (must be a smi) and is unchanged.
+  //   elements - holds the element object of the receiver on entry if
+  //              load_elements_from_receiver is false, otherwise used
+  //              internally to store the pixel arrays elements and
+  //              external array pointer.
+  //
+  // receiver, key and value remain unmodified until it's guaranteed that the
+  // store will succeed.
+  Register external_pointer = elements;
+  Register untagged_key = scratch1;
+  Register untagged_value = receiver;  // Only set once success guaranteed.
+
+  // Fetch the receiver's elements if the caller hasn't already done so.
+  if (load_elements_from_receiver) {
+    __ mov(elements, FieldOperand(receiver, JSObject::kElementsOffset));
+  }
+
+  // By passing NULL as not_pixel_array, callers signal that they have already
+  // verified that the receiver has pixel array elements.
+  if (not_pixel_array != NULL) {
+    __ CheckMap(elements, Factory::pixel_array_map(), not_pixel_array, true);
+  } else {
+    if (FLAG_debug_code) {
+      // Map check should have already made sure that elements is a pixel array.
+      __ cmp(FieldOperand(elements, HeapObject::kMapOffset),
+             Immediate(Factory::pixel_array_map()));
+      __ Assert(equal, "Elements isn't a pixel array");
+    }
+  }
+
+  // Some callers already have verified that the key is a smi.  key_not_smi is
+  // set to NULL as a sentinel for that case.  Otherwise, add an explicit check
+  // to ensure the key is a smi must be added.
+  if (key_not_smi != NULL) {
+    __ JumpIfNotSmi(key, key_not_smi);
+  } else {
+    if (FLAG_debug_code) {
+      __ AbortIfNotSmi(key);
+    }
+  }
+
+  // Key must be a smi and it must be in range.
+  __ mov(untagged_key, key);
+  __ SmiUntag(untagged_key);
+  __ cmp(untagged_key, FieldOperand(elements, PixelArray::kLengthOffset));
+  __ j(above_equal, out_of_range);  // unsigned check handles negative keys.
+
+  // Value must be a smi.
+  __ JumpIfNotSmi(value, value_not_smi);
+  __ mov(untagged_value, value);
+  __ SmiUntag(untagged_value);
+
+  {  // Clamp the value to [0..255].
+    NearLabel done;
+    __ test(untagged_value, Immediate(0xFFFFFF00));
+    __ j(zero, &done);
+    __ setcc(negative, untagged_value);  // 1 if negative, 0 if positive.
+    __ dec_b(untagged_value);  // 0 if negative, 255 if positive.
+    __ bind(&done);
+  }
+
+  __ mov(external_pointer,
+         FieldOperand(elements, PixelArray::kExternalPointerOffset));
+  __ mov_b(Operand(external_pointer, untagged_key, times_1, 0), untagged_value);
+  __ ret(0);  // Return value in eax.
+}
+
+
 #undef __
 
 } }  // namespace v8::internal