[gasm] Trigger IfBuilder0 graph generation in destructor

To improve ergonomics, graph generation is now triggered by the
IfBuilder0 destructor instead of requiring an implicit call to
Build().  This will be more expected for gasm users, since no other
builders require such a Build() call.

Drive-by: Rename 'ForSmiZeroUntil' methods to 'ForZeroUntil' since
'Smi' doesn't make sense in this context (TF only knows the Number
type here).

Bug: v8:9972
Change-Id: I365805e8428b35f19760e6ff155423463194b0f1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2011107
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65877}

src/compiler/js-call-reducer.cc

@@ -85,33 +85,41 @@ class JSCallReducerAssembler : public JSGraphAssembler {
   // separate classes. If, in the future, we encounter additional use cases that
   // return more than 1 value, we should merge these back into a single variadic
   // implementation.
-  class IfBuilder0 {
+  class IfBuilder0 final {
    public:
     IfBuilder0(JSGraphAssembler* gasm, TNode<Boolean> cond, bool negate_cond)
-        : gasm_(gasm), cond_(cond), negate_cond_(negate_cond) {}
+        : gasm_(gasm),
+          cond_(cond),
+          negate_cond_(negate_cond),
+          initial_effect_(gasm->effect()),
+          initial_control_(gasm->control()) {}
 
-    V8_WARN_UNUSED_RESULT IfBuilder0& ExpectTrue() {
+    IfBuilder0& ExpectTrue() {
       DCHECK_EQ(hint_, BranchHint::kNone);
       hint_ = BranchHint::kTrue;
       return *this;
     }
-
-    V8_WARN_UNUSED_RESULT IfBuilder0& ExpectFalse() {
+    IfBuilder0& ExpectFalse() {
       DCHECK_EQ(hint_, BranchHint::kNone);
       hint_ = BranchHint::kFalse;
       return *this;
     }
 
-    V8_WARN_UNUSED_RESULT IfBuilder0& Then(const VoidGenerator0& body) {
+    IfBuilder0& Then(const VoidGenerator0& body) {
       then_body_ = body;
       return *this;
     }
-    V8_WARN_UNUSED_RESULT IfBuilder0& Else(const VoidGenerator0& body) {
+    IfBuilder0& Else(const VoidGenerator0& body) {
       else_body_ = body;
       return *this;
     }
 
-    void Build() {
+    ~IfBuilder0() {
+      // Ensure correct usage: effect/control must not have been modified while
+      // the IfBuilder0 instance is alive.
+      DCHECK_EQ(gasm_->effect(), initial_effect_);
+      DCHECK_EQ(gasm_->control(), initial_control_);
+
       // Unlike IfBuilder1, this supports an empty then or else body. This is
       // possible since the merge does not take any value inputs.
       DCHECK(then_body_ || else_body_);
@@ -140,9 +148,13 @@ class JSCallReducerAssembler : public JSGraphAssembler {
     JSGraphAssembler* const gasm_;
     const TNode<Boolean> cond_;
     const bool negate_cond_;
+    const Effect initial_effect_;
+    const Control initial_control_;
     BranchHint hint_ = BranchHint::kNone;
     VoidGenerator0 then_body_;
     VoidGenerator0 else_body_;
+
+    DISALLOW_COPY_AND_ASSIGN(IfBuilder0);
   };
 
   IfBuilder0 If(TNode<Boolean> cond) { return {this, cond, false}; }
@@ -473,7 +485,7 @@ class JSCallReducerAssembler : public JSGraphAssembler {
     const StepFunction1 step_;
   };
 
-  ForBuilder0 ForSmiZeroUntil(TNode<Number> excluded_limit) {
+  ForBuilder0 ForZeroUntil(TNode<Number> excluded_limit) {
     TNode<Number> initial_value = ZeroConstant();
     auto cond = [=](TNode<Number> i) {
       return NumberLessThan(i, excluded_limit);
@@ -555,7 +567,7 @@ class JSCallReducerAssembler : public JSGraphAssembler {
     return {this, initial_value, cond, step, initial_arg0};
   }
 
-  ForBuilder1 For1SmiZeroUntil(TNode<Number> excluded_limit,
+  ForBuilder1 For1ZeroUntil(TNode<Number> excluded_limit,
                             TNode<Object> initial_arg0) {
     TNode<Number> initial_value = ZeroConstant();
     auto cond = [=](TNode<Number> i) {
@@ -573,11 +585,9 @@ class JSCallReducerAssembler : public JSGraphAssembler {
                          NumberConstant(static_cast<double>(
                              MessageTemplate::kCalledNonCallable)),
                          maybe_callable, frame_state);
-
           Unreachable();  // The runtime call throws unconditionally.
         })
-        .ExpectTrue()
-        .Build();
+        .ExpectTrue();
   }
 
   const FeedbackSource& feedback() const {
@@ -1119,7 +1129,7 @@ IteratingArrayBuiltinReducerAssembler::ReduceArrayPrototypeForEach(
   ThrowIfNotCallable(fncallback, ForEachLoopLazyFrameState(frame_state_params,
                                                            ZeroConstant()));
 
-  ForSmiZeroUntil(original_length).Do([&](TNode<Number> k) {
+  ForZeroUntil(original_length).Do([&](TNode<Number> k) {
     Checkpoint(ForEachLoopEagerFrameState(frame_state_params, k));
 
     // Deopt if the map has changed during the iteration.
@@ -1394,7 +1404,7 @@ TNode<JSArray> IteratingArrayBuiltinReducerAssembler::ReduceArrayPrototypeMap(
   ThrowIfNotCallable(fncallback,
                      MapLoopLazyFrameState(frame_state_params, ZeroConstant()));
 
-  ForSmiZeroUntil(original_length).Do([&](TNode<Number> k) {
+  ForZeroUntil(original_length).Do([&](TNode<Number> k) {
     Checkpoint(MapLoopEagerFrameState(frame_state_params, k));
     MaybeInsertMapChecks(inference, has_stability_dependency);
 
@@ -1528,7 +1538,7 @@ IteratingArrayBuiltinReducerAssembler::ReduceArrayPrototypeFilter(
                                                           zero, zero, zero));
 
   TNode<Number> initial_a_length = zero;
-  For1SmiZeroUntil(original_length, initial_a_length)
+  For1ZeroUntil(original_length, initial_a_length)
       .Do([&](TNode<Number> k, TNode<Object>* a_length_object) {
         TNode<Number> a_length = TNode<Number>::UncheckedCast(*a_length_object);
         Checkpoint(FilterLoopEagerFrameState(frame_state_params, k, a_length));
@@ -1659,7 +1669,7 @@ TNode<Object> IteratingArrayBuiltinReducerAssembler::ReduceArrayPrototypeFind(
   const bool is_find_variant = (variant == ArrayFindVariant::kFind);
   auto out = MakeLabel(MachineRepresentation::kTagged);
 
-  ForSmiZeroUntil(original_length).Do([&](TNode<Number> k) {
+  ForZeroUntil(original_length).Do([&](TNode<Number> k) {
     Checkpoint(FindLoopEagerFrameState(frame_state_params, k, variant));
     MaybeInsertMapChecks(inference, has_stability_dependency);
 
@@ -1760,7 +1770,7 @@ IteratingArrayBuiltinReducerAssembler::ReduceArrayPrototypeEverySome(
 
   auto out = MakeLabel(MachineRepresentation::kTagged);
 
-  ForSmiZeroUntil(original_length).Do([&](TNode<Number> k) {
+  ForZeroUntil(original_length).Do([&](TNode<Number> k) {
     Checkpoint(EverySomeLoopEagerFrameState(frame_state_params, k, variant));
     MaybeInsertMapChecks(inference, has_stability_dependency);