v8/src/ast/source-range-ast-visitor.cc
Jakob Gruber 9365d0904e [coverage] Rework continuation counter handling
This changes a few bits about how continuation counters are handled.

It introduces a new mechanism that allows removal of a continuation
range after it has been created. If coverage is enabled, we run a first
post-processing pass on the AST immediately after parsing, which
removes problematic continuation ranges in two situations:

1. nested continuation counters - only the outermost stays alive.
2. trailing continuation counters within a block-like structure are
   removed if the containing structure itself has a continuation.

R=bmeurer@chromium.org, jgruber@chromium.org, yangguo@chromium.org

Bug: v8:8381, v8:8539
Change-Id: I6bcaea5060d8c481d7bae099f6db9f993cc30ee3
Reviewed-on: https://chromium-review.googlesource.com/c/1339119
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58443}
2018-12-21 15:29:48 +00:00

69 lines
2.3 KiB
C++

// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/ast/source-range-ast-visitor.h"
#include "src/ast/ast-source-ranges.h"
namespace v8 {
namespace internal {
SourceRangeAstVisitor::SourceRangeAstVisitor(uintptr_t stack_limit,
Expression* root,
SourceRangeMap* source_range_map)
: AstTraversalVisitor(stack_limit, root),
source_range_map_(source_range_map) {}
void SourceRangeAstVisitor::VisitBlock(Block* stmt) {
AstTraversalVisitor::VisitBlock(stmt);
ZonePtrList<Statement>* stmts = stmt->statements();
AstNodeSourceRanges* enclosingSourceRanges = source_range_map_->Find(stmt);
if (enclosingSourceRanges != nullptr) {
CHECK(enclosingSourceRanges->HasRange(SourceRangeKind::kContinuation));
MaybeRemoveLastContinuationRange(stmts);
}
}
void SourceRangeAstVisitor::VisitFunctionLiteral(FunctionLiteral* expr) {
AstTraversalVisitor::VisitFunctionLiteral(expr);
ZonePtrList<Statement>* stmts = expr->body();
MaybeRemoveLastContinuationRange(stmts);
}
bool SourceRangeAstVisitor::VisitNode(AstNode* node) {
AstNodeSourceRanges* range = source_range_map_->Find(node);
if (range == nullptr) return true;
if (!range->HasRange(SourceRangeKind::kContinuation)) return true;
// Called in pre-order. In case of conflicting continuation ranges, only the
// outermost range may survive.
SourceRange continuation = range->GetRange(SourceRangeKind::kContinuation);
if (continuation_positions_.find(continuation.start) !=
continuation_positions_.end()) {
range->RemoveContinuationRange();
} else {
continuation_positions_.emplace(continuation.start);
}
return true;
}
void SourceRangeAstVisitor::MaybeRemoveLastContinuationRange(
ZonePtrList<Statement>* statements) {
if (statements->is_empty()) return;
Statement* last_statement = statements->last();
AstNodeSourceRanges* last_range = source_range_map_->Find(last_statement);
if (last_range == nullptr) return;
if (last_range->HasRange(SourceRangeKind::kContinuation)) {
last_range->RemoveContinuationRange();
}
}
} // namespace internal
} // namespace v8