ia32: Fuse map and type checks in call ICs for API functions.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 19a380b029bd8055a5db70b68b52be382b35e4f1..49fc88b9101031727a18fcdc044821a75d258052 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -538,6 +538,7 @@ void MacroAssembler::PopTryHandler() {
 Register MacroAssembler::CheckMaps(JSObject* object, Register object_reg,
                                    JSObject* holder, Register holder_reg,
                                    Register scratch,
+                                   int save_at_depth,
                                    Label* miss) {
   // Make sure there's no overlap between scratch and the other
   // registers.
@@ -545,7 +546,11 @@ Register MacroAssembler::CheckMaps(JSObject* object, Register object_reg,
 
   // Keep track of the current object in register reg.
   Register reg = object_reg;
-  int depth = 1;
+  int depth = 0;
+
+  if (save_at_depth == depth) {
+    mov(Operand(esp, kPointerSize), object_reg);
+  }
 
   // Check the maps in the prototype chain.
   // Traverse the prototype chain from the object and do map checks.
@@ -577,7 +582,6 @@ Register MacroAssembler::CheckMaps(JSObject* object, Register object_reg,
       // to it in the code. Load it from the map.
       reg = holder_reg;  // from now the object is in holder_reg
       mov(reg, FieldOperand(scratch, Map::kPrototypeOffset));
-
     } else {
       // Check the map of the current object.
       cmp(FieldOperand(reg, HeapObject::kMapOffset),
@@ -595,6 +599,10 @@ Register MacroAssembler::CheckMaps(JSObject* object, Register object_reg,
       mov(reg, Handle<JSObject>(prototype));
     }
 
+    if (save_at_depth == depth) {
+      mov(Operand(esp, kPointerSize), reg);
+    }
+
     // Go to the next object in the prototype chain.
     object = prototype;
   }
@@ -605,7 +613,7 @@ Register MacroAssembler::CheckMaps(JSObject* object, Register object_reg,
   j(not_equal, miss, not_taken);
 
   // Log the check depth.
-  LOG(IntEvent("check-maps-depth", depth));
+  LOG(IntEvent("check-maps-depth", depth + 1));
 
   // Perform security check for access to the global object and return
   // the holder register.