[turbofan] Make inlining heuristic less greedy.

src/compiler/js-inlining-heuristic.cc

 // Copyright 2015 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/compiler/js-inlining-heuristic.h"
 
 #include "src/compiler.h"
 #include "src/compiler/node-matchers.h"
 #include "src/objects-inl.h"
 
@@ skipping 80 matching lines @@
   // In the general case we remember the candidate for later.
   candidates_.insert({function, node, calls});
   return NoChange();
 }
 
 
 void JSInliningHeuristic::Finalize() {
   if (candidates_.empty()) return;  // Nothing to do without candidates.
   if (FLAG_trace_turbo_inlining) PrintCandidates();
 
-  while (!candidates_.empty()) {
-    if (cumulative_count_ > FLAG_max_inlined_nodes_cumulative) break;
-    auto i = candidates_.begin();
-    Candidate const& candidate = *i;
-    inliner_.ReduceJSCall(candidate.node, candidate.function);
-    cumulative_count_ += candidate.function->shared()->ast_node_count();
-    candidates_.erase(i);
-  }
+  // We inline at most one candidate in every iteration of the fixpoint.
+  // This is to ensure that we don't consume the full inlining budget
+  // on things that aren't called very often.
+  if (cumulative_count_ > FLAG_max_inlined_nodes_cumulative) return;
+  auto i = candidates_.begin();
+  Candidate const& candidate = *i;
+  inliner_.ReduceJSCall(candidate.node, candidate.function);
+  cumulative_count_ += candidate.function->shared()->ast_node_count();
+  candidates_.erase(i);
 }
 
 
 bool JSInliningHeuristic::CandidateCompare::operator()(
     const Candidate& left, const Candidate& right) const {
   return left.node != right.node && left.calls >= right.calls;
 }
 
 
 void JSInliningHeuristic::PrintCandidates() {
   PrintF("Candidates for inlining (size=%zu):\n", candidates_.size());
   for (const Candidate& candidate : candidates_) {
     PrintF("  id:%d, calls:%d, size[source]:%d, size[ast]:%d / %s\n",
            candidate.node->id(), candidate.calls,
            candidate.function->shared()->SourceSize(),
            candidate.function->shared()->ast_node_count(),
            candidate.function->shared()->DebugName()->ToCString().get());
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8