[coverage] optional chaining coverage

Implement coverage tracking for optional chains.

Bug: v8:10060
Change-Id: I4f29eda64b6d859939f5f58f4fabead649905795
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2573013Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Gus Caplan <snek@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Benjamin Coe <bencoe@google.com>
Cr-Commit-Position: refs/heads/master@{#72075}

src/ast/ast-source-ranges.h

@@ -47,6 +47,7 @@ struct SourceRange {
   V(Block)                       \
   V(CaseClause)                  \
   V(Conditional)                 \
+  V(Expression)                  \
   V(FunctionLiteral)             \
   V(IfStatement)                 \
   V(IterationStatement)          \
@@ -281,6 +282,24 @@ class NaryOperationSourceRanges final : public AstNodeSourceRanges {
   ZoneVector<SourceRange> ranges_;
 };
 
+class ExpressionSourceRanges final : public AstNodeSourceRanges {
+ public:
+  explicit ExpressionSourceRanges(const SourceRange& right_range)
+      : right_range_(right_range) {}
+
+  SourceRange GetRange(SourceRangeKind kind) override {
+    DCHECK(HasRange(kind));
+    return right_range_;
+  }
+
+  bool HasRange(SourceRangeKind kind) override {
+    return kind == SourceRangeKind::kRight;
+  }
+
+ private:
+  SourceRange right_range_;
+};
+
 class SuspendSourceRanges final : public ContinuationSourceRanges {
  public:
   explicit SuspendSourceRanges(int32_t continuation_position)

src/interpreter/bytecode-generator.cc

@@ -4599,8 +4599,11 @@ void BytecodeGenerator::VisitThrow(Throw* expr) {
 void BytecodeGenerator::VisitPropertyLoad(Register obj, Property* property) {
   if (property->is_optional_chain_link()) {
     DCHECK_NOT_NULL(optional_chaining_null_labels_);
+    int right_range =
+        AllocateBlockCoverageSlotIfEnabled(property, SourceRangeKind::kRight);
     builder()->LoadAccumulatorWithRegister(obj).JumpIfUndefinedOrNull(
         optional_chaining_null_labels_->New());
+    BuildIncrementBlockCoverageCounterIfEnabled(right_range);
   }
 
   AssignType property_kind = Property::GetAssignType(property);
@@ -4940,8 +4943,11 @@ void BytecodeGenerator::VisitCall(Call* expr) {
 
   if (expr->is_optional_chain_link()) {
     DCHECK_NOT_NULL(optional_chaining_null_labels_);
+    int right_range =
+        AllocateBlockCoverageSlotIfEnabled(expr, SourceRangeKind::kRight);
     builder()->LoadAccumulatorWithRegister(callee).JumpIfUndefinedOrNull(
         optional_chaining_null_labels_->New());
+    BuildIncrementBlockCoverageCounterIfEnabled(right_range);
   }
 
   // Evaluate all arguments to the function call and store in sequential args
@@ -5220,7 +5226,10 @@ void BytecodeGenerator::VisitDelete(UnaryOperation* unary) {
       OptionalChainNullLabelScope label_scope(this);
       VisitForAccumulatorValue(property->obj());
       if (property->is_optional_chain_link()) {
+        int right_range = AllocateBlockCoverageSlotIfEnabled(
+            property, SourceRangeKind::kRight);
         builder()->JumpIfUndefinedOrNull(label_scope.labels()->New());
+        BuildIncrementBlockCoverageCounterIfEnabled(right_range);
       }
       Register object = register_allocator()->NewRegister();
       builder()->StoreAccumulatorInRegister(object);

src/parsing/parser-base.h

@@ -3297,6 +3297,7 @@ ParserBase<Impl>::ParseLeftHandSideContinuation(ExpressionT result) {
 
   bool optional_chaining = false;
   bool is_optional = false;
+  int optional_link_begin;
   do {
     switch (peek()) {
       case Token::QUESTION_PERIOD: {
@@ -3304,10 +3305,16 @@ ParserBase<Impl>::ParseLeftHandSideContinuation(ExpressionT result) {
           ReportUnexpectedToken(peek());
           return impl()->FailureExpression();
         }
+        // Include the ?. in the source range position.
+        optional_link_begin = scanner()->peek_location().beg_pos;
         Consume(Token::QUESTION_PERIOD);
         is_optional = true;
         optional_chaining = true;
-        continue;
+        if (Token::IsPropertyOrCall(peek())) continue;
+        int pos = position();
+        ExpressionT key = ParsePropertyOrPrivatePropertyName();
+        result = factory()->NewProperty(result, key, pos, is_optional);
+        break;
       }
 
       /* Property */
@@ -3387,14 +3394,7 @@ ParserBase<Impl>::ParseLeftHandSideContinuation(ExpressionT result) {
       }
 
       default:
-        /* Optional Property */
-        if (is_optional) {
-          DCHECK_EQ(scanner()->current_token(), Token::QUESTION_PERIOD);
-          int pos = position();
-          ExpressionT key = ParsePropertyOrPrivatePropertyName();
-          result = factory()->NewProperty(result, key, pos, is_optional);
-          break;
-        }
+        // Template literals in/after an Optional Chain not supported:
         if (optional_chaining) {
           impl()->ReportMessageAt(scanner()->peek_location(),
                                   MessageTemplate::kOptionalChainingNoTemplate);
@@ -3405,8 +3405,12 @@ ParserBase<Impl>::ParseLeftHandSideContinuation(ExpressionT result) {
         result = ParseTemplateLiteral(result, position(), true);
         break;
     }
-    is_optional = false;
-  } while (is_optional || Token::IsPropertyOrCall(peek()));
+    if (is_optional) {
+      SourceRange chain_link_range(optional_link_begin, end_position());
+      impl()->RecordExpressionSourceRange(result, chain_link_range);
+      is_optional = false;
+    }
+  } while (Token::IsPropertyOrCall(peek()));
   if (optional_chaining) return factory()->NewOptionalChain(result);
   return result;
 }

src/parsing/parser.h

@@ -1002,6 +1002,14 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
         node, zone()->New<IterationStatementSourceRanges>(body_range));
   }
 
+  // Used to record source ranges of expressions associated with optional chain:
+  V8_INLINE void RecordExpressionSourceRange(Expression* node,
+                                             const SourceRange& right_range) {
+    if (source_range_map_ == nullptr) return;
+    source_range_map_->Insert(node,
+                              zone()->New<ExpressionSourceRanges>(right_range));
+  }
+
   V8_INLINE void RecordSuspendSourceRange(Expression* node,
                                           int32_t continuation_position) {
     if (source_range_map_ == nullptr) return;

test/mjsunit/code-coverage-block.js

@@ -1177,7 +1177,7 @@ a(true);                                  // 0500
  {"start":0,"end":401,"count":2},
  {"start":154,"end":254,"count":0}]);
 
- TestCoverage(
+TestCoverage(
 "https://crbug.com/v8/11231 - nullish coalescing",
 `
 const a = true                            // 0000
@@ -1195,4 +1195,41 @@ const i = c ?? b ?? 'hello'               // 0400
  {"start":262,"end":274,"count":0},
  {"start":417,"end":427,"count":0}]);
 
+TestCoverage(
+"Optional Chaining",
+`
+const a = undefined || null               // 0000
+const b = a?.b                            // 0050
+const c = a?.['b']                        // 0100
+const d = {                               // 0150
+  e: {f: 99, g: () => {return undefined}} // 0200
+}                                         // 0250
+const e = d?.e?.f                         // 0300
+const f = d?.e?.['f']                     // 0350
+const g = d?.e?.f?.g                      // 0400
+const h = d?.e?.f?.g?.h                   // 0450
+const i = d?.['d']?.['e']?.['h']          // 0500
+const k = a?.('b')                        // 0550
+const l = d?.e?.g?.()                     // 0600
+const m = d?.e?.g?.()?.a?.b               // 0650
+delete a?.b                               // 0700
+const n = d?.[d?.x?.f]                    // 0750
+if (a?.[d?.x?.f]) { const p = 99 } else {}// 0800
+const p = d?.[d?.x?.f]?.x                 // 0850
+`,
+[{"start":0,"end":899,"count":1},
+ {"start":61,"end":64,"count":0},
+ {"start":111,"end":118,"count":0},
+ {"start":470,"end":473,"count":0},
+ {"start":518,"end":532,"count":0},
+ {"start":561,"end":568,"count":0},
+ {"start":671,"end":677,"count":0},
+ {"start":708,"end":711,"count":0},
+ {"start":768,"end":771,"count":0},
+ {"start":805,"end":816,"count":0},
+ {"start":818,"end":834,"count":0},
+ {"start":868,"end":871,"count":0},
+ {"start":872,"end":875,"count":0},
+ {"start":216,"end":240,"count":2}]);
+
 %DebugToggleBlockCoverage(false);