[vm/jit/unboxed] Remove heuristic that transitions unboxed fields back to boxed.
The heuristic was introduced in b870dafa4f04a117366292b5824739d8f1806fb0, but gets in the way of maintaining Slot(extended with field guard information) immutable during compilation.
Existing set of benchmarks doesn't seem to show any reasonable regression with this heuristic removed.
Bug: https://github.com/dart-lang/sdk/issues/47722
Change-Id: Ie94050d96852b7ffef2dc81248cda23e84d41f4b
TEST=ci
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/221544
Reviewed-by: Slava Egorov <vegorov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
diff --git a/runtime/vm/compiler/jit/jit_call_specializer.cc b/runtime/vm/compiler/jit/jit_call_specializer.cc
index 191e6bb..3afc611 100644
--- a/runtime/vm/compiler/jit/jit_call_specializer.cc
+++ b/runtime/vm/compiler/jit/jit_call_specializer.cc
@@ -162,57 +162,6 @@
}
}
-void JitCallSpecializer::VisitStoreInstanceField(
- StoreInstanceFieldInstr* instr) {
- if (instr->IsUnboxedDartFieldStore()) {
- // Determine if this field should be unboxed based on the usage of getter
- // and setter functions: The heuristic requires that the setter has a
- // usage count of at least 1/kGetterSetterRatio of the getter usage count.
- // This is to avoid unboxing fields where the setter is never or rarely
- // executed.
- const Field& field = instr->slot().field();
- const String& field_name = String::Handle(Z, field.name());
- const Class& owner = Class::Handle(Z, field.Owner());
- const Function& getter =
- Function::Handle(Z, owner.LookupGetterFunction(field_name));
- const Function& setter =
- Function::Handle(Z, owner.LookupSetterFunction(field_name));
- bool unboxed_field = false;
- if (!getter.IsNull() && !setter.IsNull()) {
- if (field.is_double_initialized()) {
- unboxed_field = true;
- } else if ((setter.usage_counter() > 0) &&
- ((FLAG_getter_setter_ratio * setter.usage_counter()) >=
- getter.usage_counter())) {
- unboxed_field = true;
- }
- }
- if (!unboxed_field) {
- if (FLAG_trace_optimization || FLAG_trace_field_guards) {
- THR_Print("Disabling unboxing of %s\n", field.ToCString());
- if (!setter.IsNull()) {
- THR_Print(" setter usage count: %" Pd "\n", setter.usage_counter());
- }
- if (!getter.IsNull()) {
- THR_Print(" getter usage count: %" Pd "\n", getter.usage_counter());
- }
- }
- // We determined it's not beneficial for performance to unbox the
- // field, therefore we mark it as boxed here.
- //
- // Calling `DisableFieldUnboxing` will cause transition the field to
- // boxed and deoptimize dependent code.
- //
- // NOTE: It will also, as a side-effect, change our field clone's
- // `is_unboxing_candidate()` bit. So we assume the compiler has so far
- // not relied on this bit.
- field.DisableFieldUnboxing();
- } else {
- flow_graph()->parsed_function().AddToGuardedFields(&field);
- }
- }
-}
-
// Replace generic context allocation or cloning with a sequence of inlined
// allocation and explicit initializing stores.
// If context_value is not NULL then newly allocated context is a populated
diff --git a/runtime/vm/compiler/jit/jit_call_specializer.h b/runtime/vm/compiler/jit/jit_call_specializer.h
index 8c743ed..ecbee73 100644
--- a/runtime/vm/compiler/jit/jit_call_specializer.h
+++ b/runtime/vm/compiler/jit/jit_call_specializer.h
@@ -27,7 +27,6 @@
// Find a better place for them.
virtual void VisitAllocateContext(AllocateContextInstr* instr);
virtual void VisitCloneContext(CloneContextInstr* instr);
- virtual void VisitStoreInstanceField(StoreInstanceFieldInstr* instr);
private:
virtual bool IsAllowedForInlining(intptr_t deopt_id) const;
diff --git a/runtime/vm/flag_list.h b/runtime/vm/flag_list.h
index 679bf26..edf42f7 100644
--- a/runtime/vm/flag_list.h
+++ b/runtime/vm/flag_list.h
@@ -125,8 +125,6 @@
P(enable_ffi, bool, true, "Disable to make importing dart:ffi an error.") \
P(force_clone_compiler_objects, bool, false, \
"Force cloning of objects needed in compiler (ICData and Field).") \
- P(getter_setter_ratio, int, 13, \
- "Ratio of getter/setter usage used for double field unboxing heuristics") \
P(guess_icdata_cid, bool, true, \
"Artificially create type feedback for arithmetic etc. operations") \
P(huge_method_cutoff_in_tokens, int, 20000, \
