Bug 1017428 part 1. Store information in jitinfo about [Cached] attribute slots in addition to [StoreInSlot] ones. r=peterv,efaust

dom/bindings/Codegen.py

@@ -7483,7 +7483,8 @@ class CGMemberJITInfo(CGThing):
         return ""
 
     def defineJitInfo(self, infoName, opName, opType, infallible, movable,
-                      aliasSet, hasSlot, slotIndex, returnTypes, args):
+                      aliasSet, alwaysInSlot, lazilyInSlot, slotIndex,
+                      returnTypes, args):
         """
         aliasSet is a JSJitInfo::AliasSet value, without the "JSJitInfo::" bit.
 
@@ -7492,7 +7493,7 @@ class CGMemberJITInfo(CGThing):
         otherwise an iterable of the arguments for this method.
         """
         assert(not movable or aliasSet != "AliasEverything")  # Can't move write-aliasing things
-        assert(not hasSlot or movable)  # Things with slots had better be movable
+        assert(not alwaysInSlot or movable)  # Things always in slots had better be movable
 
         def jitInfoInitializer(isTypedMethod):
             initializer = fill(
@@ -7506,7 +7507,8 @@ class CGMemberJITInfo(CGThing):
                   ${returnType},  /* returnType.  Not relevant for setters. */
                   ${isInfallible},  /* isInfallible. False in setters. */
                   ${isMovable},  /* isMovable.  Not relevant for setters. */
-                  ${isInSlot},  /* isInSlot.  Only relevant for getters. */
+                  ${isAlwaysInSlot}, /* isAlwaysInSlot.  Only relevant for getters. */
+                  ${isLazilyCachedInSlot}, /* isLazilyCachedInSlot.  Only relevant for getters. */
                   ${isTypedMethod},  /* isTypedMethod.  Only relevant for methods. */
                   ${slotIndex}   /* Reserved slot index, if we're stored in a slot, else 0. */
                 }
@@ -7519,7 +7521,8 @@ class CGMemberJITInfo(CGThing):
                                   ""),
                 isInfallible=toStringBool(infallible),
                 isMovable=toStringBool(movable),
-                isInSlot=toStringBool(hasSlot),
+                isAlwaysInSlot=toStringBool(alwaysInSlot),
+                isLazilyCachedInSlot=toStringBool(lazilyInSlot),
                 isTypedMethod=toStringBool(isTypedMethod),
                 slotIndex=slotIndex)
             return initializer.rstrip()
@@ -7568,17 +7571,22 @@ class CGMemberJITInfo(CGThing):
             movable = getterpure and getterinfal
 
             getterinfal = getterinfal and infallibleForMember(self.member, self.member.type, self.descriptor)
-            isInSlot = self.member.getExtendedAttribute("StoreInSlot")
-            if isInSlot:
+            isAlwaysInSlot = self.member.getExtendedAttribute("StoreInSlot")
+            if self.member.slotIndex is not None:
+                assert isAlwaysInSlot or self.member.getExtendedAttribute("Cached")
+                isLazilyCachedInSlot = not isAlwaysInSlot
                 slotIndex = memberReservedSlot(self.member)
                 # We'll statically assert that this is not too big in
-                # CGUpdateMemberSlotsMethod
+                # CGUpdateMemberSlotsMethod, in the case when
+                # isAlwaysInSlot is true.
             else:
+                isLazilyCachedInSlot = False
                 slotIndex = "0"
 
             result = self.defineJitInfo(getterinfo, getter, "Getter",
                                         getterinfal, movable, aliasSet,
-                                        isInSlot, slotIndex,
+                                        isAlwaysInSlot, isLazilyCachedInSlot,
+                                        slotIndex,
                                         [self.member.type], None)
             if (not self.member.readonly or
                 self.member.getExtendedAttribute("PutForwards") is not None or
@@ -7590,7 +7598,7 @@ class CGMemberJITInfo(CGThing):
                 # Setters are always fallible, since they have to do a typed unwrap.
                 result += self.defineJitInfo(setterinfo, setter, "Setter",
                                              False, False, "AliasEverything",
-                                             False, "0",
+                                             False, False, "0",
                                              [BuiltinTypes[IDLBuiltinType.Types.void]],
                                              None)
             return result
@@ -7641,7 +7649,8 @@ class CGMemberJITInfo(CGThing):
             else:
                 aliasSet = "AliasEverything"
             result = self.defineJitInfo(methodinfo, method, "Method",
-                                        methodInfal, movable, aliasSet, False, "0",
+                                        methodInfal, movable, aliasSet,
+                                        False, False, "0",
                                         [s[0] for s in sigs], args)
             return result
         raise TypeError("Illegal member type to CGPropertyJITInfo")

js/src/jit/IonBuilder.cpp

@@ -8852,9 +8852,9 @@ IonBuilder::getPropTryCommonGetter(bool *emitted, MDefinition *obj, PropertyName
     if (isDOM && testShouldDOMCall(objTypes, commonGetter, JSJitInfo::Getter)) {
         const JSJitInfo *jitinfo = commonGetter->jitInfo();
         MInstruction *get;
-        if (jitinfo->isInSlot) {
+        if (jitinfo->isAlwaysInSlot) {
             // We can't use MLoadFixedSlot here because it might not have the
-            // right aliasing behavior; we want to alias DOM setters.
+            // right aliasing behavior; we want to alias DOM setters as needed.
             get = MGetDOMMember::New(alloc(), jitinfo, obj, guard);
         } else {
             get = MGetDOMProperty::New(alloc(), jitinfo, obj, guard);

js/src/jit/MIR.h

@@ -8665,7 +8665,7 @@ class MGetDOMProperty
         return info_->aliasSet();
     }
     size_t domMemberSlotIndex() const {
-        MOZ_ASSERT(info_->isInSlot);
+        MOZ_ASSERT(info_->isAlwaysInSlot || info_->isLazilyCachedInSlot);
         return info_->slotIndex;
     }
     MDefinition *object() {

js/src/jsfriendapi.h

@@ -1880,12 +1880,18 @@ struct JSJitInfo {
                                   not be enough (e.g. in cases when it can
                                   throw). */
     // XXXbz should we have a JSValueType for the type of the member?
-    uint32_t isInSlot : 1;     /* True if this is a getter that can get a member
-                                  from a slot of the "this" object directly. */
+    uint32_t isAlwaysInSlot : 1; /* True if this is a getter that can always
+                                    get the value from a slot of the "this"
+                                    object. */
+    uint32_t isLazilyCachedInSlot : 1; /* True if this is a getter that can
+                                          sometimes (if the slot doesn't contain
+                                          UndefinedValue()) get the value from a
+                                          slot of the "this" object. */
     uint32_t isTypedMethod : 1; /* True if this is an instance of
                                    JSTypedMethodJitInfo. */
-    uint32_t slotIndex : 12;   /* If isInSlot is true, the index of the slot to
-                                  get the value from.  Otherwise 0. */
+    uint32_t slotIndex : 11;   /* If isAlwaysInSlot or isSometimesInSlot is
+                                  true, the index of the slot to get the value
+                                  from.  Otherwise 0. */
 };
 
 static_assert(sizeof(JSJitInfo) == (sizeof(void*) + 2 * sizeof(uint32_t)),
@@ -1943,7 +1949,7 @@ inline int CheckIsParallelNative(JSParallelNative parallelNative);
  */
 #define JS_JITINFO_NATIVE_PARALLEL(infoName, parallelOp)                \
     const JSJitInfo infoName =                                          \
-        {{JS_CAST_PARALLEL_NATIVE_TO(parallelOp, JSJitGetterOp)},0,0,JSJitInfo::ParallelNative,JSJitInfo::AliasEverything,JSVAL_TYPE_MISSING,false,false,false,false,0}
+        {{JS_CAST_PARALLEL_NATIVE_TO(parallelOp, JSJitGetterOp)},0,0,JSJitInfo::ParallelNative,JSJitInfo::AliasEverything,JSVAL_TYPE_MISSING,false,false,false,false,false,0}
 
 #define JS_JITINFO_NATIVE_PARALLEL_THREADSAFE(infoName, wrapperName, serialOp) \
     bool wrapperName##_ParallelNativeThreadSafeWrapper(js::ForkJoinContext *cx, unsigned argc, \

js/src/shell/js.cpp

@@ -5250,7 +5250,8 @@ static const JSJitInfo dom_x_getterinfo = {
     JSVAL_TYPE_UNKNOWN, /* returnType */
     true,     /* isInfallible. False in setters. */
     true,     /* isMovable */
-    false,    /* isInSlot */
+    false,    /* isAlwaysInSlot */
+    false,    /* isLazilyCachedInSlot */
     false,    /* isTypedMethod */
     0         /* slotIndex */
 };
@@ -5264,7 +5265,8 @@ static const JSJitInfo dom_x_setterinfo = {
     JSVAL_TYPE_UNKNOWN, /* returnType */
     false,    /* isInfallible. False in setters. */
     false,    /* isMovable. */
-    false,    /* isInSlot */
+    false,    /* isAlwaysInSlot */
+    false,    /* isLazilyCachedInSlot */
     false,    /* isTypedMethod */
     0         /* slotIndex */
 };
@@ -5278,7 +5280,8 @@ static const JSJitInfo doFoo_methodinfo = {
     JSVAL_TYPE_UNKNOWN, /* returnType */
     false,    /* isInfallible. False in setters. */
     false,    /* isMovable */
-    false,    /* isInSlot */
+    false,    /* isAlwaysInSlot */
+    false,    /* isLazilyCachedInSlot */
     false,    /* isTypedMethod */
     0         /* slotIndex */
 };