[Torque] Reduce code size by combining FixedArray/FixedDoubleArray paths

This CL reduces the instruction size of Array.prototype.every and some
by ~20%. Should performance allow it we could do the same for other
array builtins. We attach a boolean to the FastJSArrayWitness that
remembers if it's dealing with a FixedArray or a FixedDoubleArray.
We have to check this in the loop, but it is likely that reduced
code size more than pays for the extra check, since the loop will
be dominated by the call to the users callback function.

BUG: v8:7672
Change-Id: Id3bab2b163d7ba73424250d8bb194712909cd37e
Reviewed-on: https://chromium-review.googlesource.com/c/1484293Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59835}

src/builtins/array-every.tq

@@ -83,51 +83,30 @@ namespace array {
     return True;
   }
 
-  transitioning macro
-  EveryVisitAllElements<FixedArrayType: type>(implicit context: Context)(
-      o: FastJSArray, len: Smi, callbackfn: Callable,
-      thisArg: Object): Boolean labels Bailout(Smi) {
+  transitioning macro FastArrayEvery(implicit context: Context)(
+      o: JSReceiver, len: Number, callbackfn: Callable, thisArg: Object): Object
+      labels Bailout(Smi) {
     let k: Smi = 0;
-    let fastO = FastJSArrayWitness{o};
+    const smiLen = Cast<Smi>(len) otherwise goto Bailout(k);
+    let fastO: FastJSArray = Cast<FastJSArray>(o) otherwise goto Bailout(k);
+    let fastOW = FastJSArrayWitness{fastO};
 
     // Build a fast loop over the smi array.
-    for (; k < len; k++) {
-      fastO.Recheck() otherwise goto Bailout(k);
+    for (; k < smiLen; k++) {
+      fastOW.Recheck() otherwise goto Bailout(k);
 
       // Ensure that we haven't walked beyond a possibly updated length.
-      if (k >= fastO.Get().length) goto Bailout(k);
-
-      try {
-        const value: Object = LoadElementNoHole<FixedArrayType>(fastO.Get(), k)
-            otherwise FoundHole;
-        const result: Object =
-            Call(context, callbackfn, thisArg, value, k, fastO.Get());
-        if (!ToBoolean(result)) {
-          return False;
-        }
+      if (k >= fastOW.Get().length) goto Bailout(k);
+      const value: Object = fastOW.LoadElementNoHole(k) otherwise continue;
+      const result: Object =
+          Call(context, callbackfn, thisArg, value, k, fastOW.Get());
+      if (!ToBoolean(result)) {
+        return False;
       }
-      label FoundHole {}
     }
     return True;
   }
 
-  transitioning macro FastArrayEvery(implicit context: Context)(
-      o: JSReceiver, len: Number, callbackfn: Callable, thisArg: Object): Object
-      labels Bailout(Smi) {
-    let k: Smi = 0;
-    const smiLen = Cast<Smi>(len) otherwise goto Bailout(k);
-    let fastO = Cast<FastJSArray>(o) otherwise goto Bailout(k);
-    const elementsKind: ElementsKind = fastO.map.elements_kind;
-    if (IsElementsKindLessThanOrEqual(elementsKind, HOLEY_ELEMENTS)) {
-      return EveryVisitAllElements<FixedArray>(
-          fastO, smiLen, callbackfn, thisArg) otherwise Bailout;
-    }
-
-    assert(IsDoubleElementsKind(elementsKind));
-    return EveryVisitAllElements<FixedDoubleArray>(
-        fastO, smiLen, callbackfn, thisArg) otherwise Bailout;
-  }
-
   // https://tc39.github.io/ecma262/#sec-array.prototype.every
   transitioning javascript builtin
   ArrayEvery(implicit context: Context)(receiver: Object, ...arguments):

src/builtins/array-some.tq

@@ -83,52 +83,30 @@ namespace array {
     return False;
   }
 
-  transitioning macro
-  SomeVisitAllElements<FixedArrayType: type>(implicit context: Context)(
-      o: FastJSArray, len: Smi, callbackfn: Callable, thisArg: Object): Boolean
+  transitioning macro FastArraySome(implicit context: Context)(
+      o: JSReceiver, len: Number, callbackfn: Callable, thisArg: Object): Object
       labels Bailout(Smi) {
     let k: Smi = 0;
-    let fastO = FastJSArrayWitness{o};
+    const smiLen = Cast<Smi>(len) otherwise goto Bailout(k);
+    let fastO = Cast<FastJSArray>(o) otherwise goto Bailout(k);
+    let fastOW = FastJSArrayWitness{fastO};
 
     // Build a fast loop over the smi array.
-    for (; k < len; k++) {
-      fastO.Recheck() otherwise goto Bailout(k);
+    for (; k < smiLen; k++) {
+      fastOW.Recheck() otherwise goto Bailout(k);
 
       // Ensure that we haven't walked beyond a possibly updated length.
-      if (k >= fastO.Get().length) goto Bailout(k);
-
-      try {
-        const value: Object = LoadElementNoHole<FixedArrayType>(fastO.Get(), k)
-            otherwise FoundHole;
-        const result: Object =
-            Call(context, callbackfn, thisArg, value, k, fastO.Get());
-        if (ToBoolean(result)) {
-          return True;
-        }
+      if (k >= fastOW.Get().length) goto Bailout(k);
+      const value: Object = fastOW.LoadElementNoHole(k) otherwise continue;
+      const result: Object =
+          Call(context, callbackfn, thisArg, value, k, fastOW.Get());
+      if (ToBoolean(result)) {
+        return True;
       }
-      label FoundHole {}
     }
     return False;
   }
 
-  transitioning macro FastArraySome(implicit context: Context)(
-      o: JSReceiver, len: Number, callbackfn: Callable, thisArg: Object): Object
-      labels Bailout(Smi) {
-    let k: Smi = 0;
-    const smiLen = Cast<Smi>(len) otherwise goto Bailout(k);
-    let fastO = Cast<FastJSArray>(o) otherwise goto Bailout(k);
-    const elementsKind: ElementsKind = fastO.map.elements_kind;
-    if (IsElementsKindLessThanOrEqual(elementsKind, HOLEY_ELEMENTS)) {
-      return SomeVisitAllElements<FixedArray>(
-          fastO, smiLen, callbackfn, thisArg)
-          otherwise Bailout;
-    }
-
-    assert(IsDoubleElementsKind(elementsKind));
-    return SomeVisitAllElements<FixedDoubleArray>(
-        fastO, smiLen, callbackfn, thisArg) otherwise Bailout;
-  }
-
   // https://tc39.github.io/ecma262/#sec-array.prototype.some
   transitioning javascript builtin
   ArraySome(implicit context: Context)(receiver: Object, ...arguments): Object {

src/builtins/base.tq

@@ -935,33 +935,6 @@ Cast<FastJSArray>(implicit context: Context)(o: HeapObject): FastJSArray
   return %RawDownCast<FastJSArray>(o);
 }
 
-struct FastJSArrayWitness {
-  constructor(array: FastJSArray) {
-    this.stable = this.unstable = array;
-    this.map = array.map;
-  }
-
-  Get(): FastJSArray {
-    return this.unstable;
-  }
-
-  Recheck() labels CastError {
-    if (this.stable.map != this.map) goto CastError;
-    // We don't need to check elements kind or whether the prototype
-    // has changed away from the default JSArray prototype, because
-    // if the map remains the same then those properties hold.
-    //
-    // However, we have to make sure there are no elements in the
-    // prototype chain.
-    if (IsNoElementsProtectorCellInvalid()) goto CastError;
-    this.unstable = %RawDownCast<FastJSArray>(this.stable);
-  }
-
-  stable: JSArray;
-  unstable: FastJSArray;
-  map: Map;
-}
-
 Cast<FastJSArrayForCopy>(implicit context: Context)(o: HeapObject):
     FastJSArrayForCopy
     labels CastError {
@@ -1503,6 +1476,47 @@ LoadElementNoHole<FixedDoubleArray>(implicit context: Context)(
   }
 }
 
+struct FastJSArrayWitness {
+  constructor(array: FastJSArray) {
+    this.stable = this.unstable = array;
+    this.map = array.map;
+    let kind = array.map.elements_kind;
+    this.hasDoubles = !IsElementsKindLessThanOrEqual(kind, HOLEY_ELEMENTS);
+  }
+
+  Get(): FastJSArray {
+    return this.unstable;
+  }
+
+  Recheck() labels CastError {
+    if (this.stable.map != this.map) goto CastError;
+    // We don't need to check elements kind or whether the prototype
+    // has changed away from the default JSArray prototype, because
+    // if the map remains the same then those properties hold.
+    //
+    // However, we have to make sure there are no elements in the
+    // prototype chain.
+    if (IsNoElementsProtectorCellInvalid()) goto CastError;
+    this.unstable = %RawDownCast<FastJSArray>(this.stable);
+  }
+
+  LoadElementNoHole(implicit context: Context)(k: Smi): Object
+      labels FoundHole {
+    if (this.hasDoubles) {
+      return LoadElementNoHole<FixedDoubleArray>(this.unstable, k)
+          otherwise FoundHole;
+    } else {
+      return LoadElementNoHole<FixedArray>(this.unstable, k)
+          otherwise FoundHole;
+    }
+  }
+
+  stable: JSArray;
+  unstable: FastJSArray;
+  map: Map;
+  hasDoubles: bool;
+}
+
 extern macro TransitionElementsKind(
     JSObject, Map, constexpr ElementsKind,
     constexpr ElementsKind): void labels Bailout;