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Reland "[vm/compiler] Remove unnecessary type check from optimized switches"

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This is a reland of commit 43ce5487c1

In addition to removing type check, switch range checks are adjusted
in order to avoid call to 'int.operator<=', which can be removed by
tree shaker in AOT/product mode, causing NoSuchMethodError at runtime.

Original change's description:
> [vm/compiler] Remove unnecessary type check from optimized switches
>
> Switch optimization now relies on static type of the tested value,
> so it is safe to omit the type check (with sound null safety) or
> reduce it to a null check (without sound null safety).
>
> TEST=co19/LanguageFeatures/Patterns/Exhaustiveness/exhaustiveness_enum_A01_t01
> Fixes https://github.com/dart-lang/sdk/issues/52422
>
> Change-Id: Ic93f4f212bee9ed3bfe5035f3c8d7535274c2f63
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/304102
> Commit-Queue: Alexander Markov <alexmarkov@google.com>
> Reviewed-by: Alexander Aprelev <aam@google.com>

TEST=co19/LanguageFeatures/Patterns/Exhaustiveness/exhaustiveness_enum_A01_t01
TEST=language/async/switch_test

Change-Id: I70bf480bf376f946d66caa504120c8f85093ea8d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/304322
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
This commit is contained in:
Alexander Markov 2023-05-18 18:33:37 +00:00 committed by Commit Queue
parent 34a21f5691
commit 0bff5652ba
3 changed files with 58 additions and 35 deletions
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57
runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
View file

@ -5072,30 +5072,23 @@ Fragment StreamingFlowGraphBuilder::BuildOptimizedSwitchPrelude(
SwitchHelper* helper,
JoinEntryInstr* join) {
const TokenPosition pos = helper->position();
// We need to check that the switch variable is of the correct type.
// If it is not, we go to [join] which is either the default case or
// the exit of the switch statement.
TargetEntryInstr* then_entry;
TargetEntryInstr* otherwise_entry;
const AbstractType& expression_type = helper->expression_type();
ASSERT(dart::SimpleInstanceOfType(expression_type));
Fragment instructions;
instructions += LoadLocal(scopes()->switch_variable);
instructions += Constant(expression_type);
instructions += InstanceCall(
pos, Library::PrivateCoreLibName(Symbols::_simpleInstanceOf()),
Token::kIS, /*argument_count=*/2,
/*checked_argument_count=*/2);
instructions += BranchIfTrue(&then_entry, &otherwise_entry, /*negate=*/false);
Fragment otherwise_instructions(otherwise_entry);
otherwise_instructions += Goto(join);
if (!IG->null_safety()) {
// Without sound null safety we need to check that the switch variable is
// not null. If it is null, we go to [join] which is either the default
// case or the exit of the switch statement.
TargetEntryInstr* null_entry;
TargetEntryInstr* non_null_entry;
instructions = Fragment(instructions.entry, then_entry);
instructions += LoadLocal(scopes()->switch_variable);
instructions += BranchIfNull(&null_entry, &non_null_entry);
Fragment null_instructions(null_entry);
null_instructions += Goto(join);
instructions = Fragment(instructions.entry, non_null_entry);
}
if (helper->is_enum_switch()) {
// For an enum switch, we need to load the enum index from the switch
@ -5224,10 +5217,7 @@ Fragment StreamingFlowGraphBuilder::BuildBinarySearchSwitch(
branch_instructions += LoadLocal(scopes()->switch_variable);
branch_instructions += Constant(middle_expression.integer());
branch_instructions +=
InstanceCall(middle_expression.position(),
Symbols::LessEqualOperator(), Token::kLTE,
/*argument_count=*/2,
/*checked_argument_count=*/2);
B->IntRelationalOp(middle_expression.position(), Token::kLTE);
branch_instructions +=
BranchIfTrue(&then_entry, &otherwise_entry, /*negate=*/false);
@ -5242,10 +5232,7 @@ Fragment StreamingFlowGraphBuilder::BuildBinarySearchSwitch(
upper_branch_instructions += LoadLocal(scopes()->switch_variable);
upper_branch_instructions += Constant(next_expression.integer());
upper_branch_instructions +=
InstanceCall(next_expression.position(),
Symbols::GreaterEqualOperator(), Token::kGTE,
/*argument_count=*/2,
/*checked_argument_count=*/2);
B->IntRelationalOp(next_expression.position(), Token::kGTE);
upper_branch_instructions +=
BranchIfTrue(&then_entry, &otherwise_entry, /*negate=*/false);
@ -5260,6 +5247,10 @@ Fragment StreamingFlowGraphBuilder::BuildBinarySearchSwitch(
stack.Add(
SwitchRange::Branch(range.min(), middle, lower_branch_instructions));
}
if (current_instructions.is_empty()) {
current_instructions = branch_instructions;
}
}
return Fragment(current_instructions.entry, join_instructions.current);
@ -5302,9 +5293,7 @@ Fragment StreamingFlowGraphBuilder::BuildJumpTableSwitch(SwitchHelper* helper) {
if (helper->RequiresLowerBoundCheck()) {
current_instructions += LoadLocal(scopes()->switch_variable);
current_instructions += Constant(expression_min);
current_instructions += InstanceCall(pos, Symbols::GreaterEqualOperator(),
Token::kGTE, /*argument_count=*/2,
/*checked_argument_count=*/2);
current_instructions += B->IntRelationalOp(pos, Token::kGTE);
current_instructions += BranchIfTrue(&then_entry, &otherwise_entry,
/*negate=*/false);
Fragment otherwise_instructions(otherwise_entry);
@ -5316,9 +5305,7 @@ Fragment StreamingFlowGraphBuilder::BuildJumpTableSwitch(SwitchHelper* helper) {
if (helper->RequiresUpperBoundCheck()) {
current_instructions += LoadLocal(scopes()->switch_variable);
current_instructions += Constant(expression_max);
current_instructions += InstanceCall(pos, Symbols::LessEqualOperator(),
Token::kLTE, /*argument_count=*/2,
/*checked_argument_count=*/2);
current_instructions += B->IntRelationalOp(pos, Token::kLTE);
current_instructions += BranchIfTrue(&then_entry, &otherwise_entry,
/*negate=*/false);
Fragment otherwise_instructions(otherwise_entry);

33
runtime/vm/compiler/frontend/kernel_to_il.cc
View file

@ -4287,6 +4287,39 @@ Fragment FlowGraphBuilder::IntToBool() {
return body;
}
Fragment FlowGraphBuilder::IntRelationalOp(TokenPosition position,
Token::Kind kind) {
if (CompilerState::Current().is_aot()) {
Value* right = Pop();
Value* left = Pop();
RelationalOpInstr* instr = new (Z) RelationalOpInstr(
InstructionSource(position), kind, left, right, kMintCid,
GetNextDeoptId(), Instruction::SpeculativeMode::kNotSpeculative);
Push(instr);
return Fragment(instr);
}
const String* name = nullptr;
switch (kind) {
case Token::kLT:
name = &Symbols::LAngleBracket();
break;
case Token::kGT:
name = &Symbols::RAngleBracket();
break;
case Token::kLTE:
name = &Symbols::LessEqualOperator();
break;
case Token::kGTE:
name = &Symbols::GreaterEqualOperator();
break;
default:
UNREACHABLE();
}
return InstanceCall(
position, *name, kind, /*type_args_len=*/0, /*argument_count=*/2,
/*argument_names=*/Array::null_array(), /*checked_argument_count=*/2);
}
Fragment FlowGraphBuilder::NativeReturn(
const compiler::ffi::CallbackMarshaller& marshaller) {
auto* instr = new (Z)

3
runtime/vm/compiler/frontend/kernel_to_il.h
View file

@ -298,6 +298,9 @@ class FlowGraphBuilder : public BaseFlowGraphBuilder {
// Converts 0 to false and the rest to true.
Fragment IntToBool();
// Compares arbitrary integers.
Fragment IntRelationalOp(TokenPosition position, Token::Kind kind);
// Creates an ffi.Pointer holding a given address.
Fragment FfiPointerFromAddress();