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[vm/compiler] Choose correct unboxed float representation for phi instructions.

Browse source 
BUG=https://github.com/dart-lang/sdk/issues/50622
TEST=FlowGraph_UnboxedFloatPhi

Change-Id: Ie7bfbb6c4028907a18243d44be8128999c1efcae
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/275180
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
This commit is contained in:
Alexander Aprelev 2022-12-15 15:24:12 +00:00 committed by Commit Queue
parent ca03588d2b
commit ff2d661d5b
2 changed files with 91 additions and 4 deletions
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37
runtime/vm/compiler/backend/flow_graph.cc
View file

@ -2053,7 +2053,16 @@ class PhiUnboxingHeuristic : public ValueObject {
switch (phi->Type()->ToCid()) {
case kDoubleCid:
if (CanUnboxDouble()) {
unboxed = kUnboxedDouble;
// Could be UnboxedDouble or UnboxedFloat
unboxed = DetermineIfAnyIncomingUnboxedFloats(phi) ? kUnboxedFloat
: kUnboxedDouble;
#if defined(DEBUG)
if (unboxed == kUnboxedFloat) {
for (auto input : phi->inputs()) {
ASSERT(input->representation() != kUnboxedDouble);
}
}
#endif
}
break;
case kFloat32x4Cid:
@ -2117,10 +2126,10 @@ class PhiUnboxingHeuristic : public ValueObject {
// unboxed operation prefer to keep it unboxed.
// We use this heuristic instead of eagerly unboxing all the phis
// because we are concerned about the code size and register pressure.
const bool has_unboxed_incomming_value = HasUnboxedIncommingValue(phi);
const bool has_unboxed_incoming_value = HasUnboxedIncomingValue(phi);
const bool flows_into_unboxed_use = FlowsIntoUnboxedUse(phi);
if (has_unboxed_incomming_value && flows_into_unboxed_use) {
if (has_unboxed_incoming_value && flows_into_unboxed_use) {
unboxed =
RangeUtils::Fits(phi->range(), RangeBoundary::kRangeBoundaryInt32)
? kUnboxedInt32
@ -2133,10 +2142,30 @@ class PhiUnboxingHeuristic : public ValueObject {
}
private:
// Returns [true] if there are UnboxedFloats representation flowing into
// the |phi|.
// This function looks through phis.
bool DetermineIfAnyIncomingUnboxedFloats(PhiInstr* phi) {
worklist_.Clear();
worklist_.Add(phi);
for (intptr_t i = 0; i < worklist_.definitions().length(); i++) {
const auto defn = worklist_.definitions()[i];
for (auto input : defn->inputs()) {
if (input->representation() == kUnboxedFloat) {
return true;
}
if (input->IsPhi()) {
worklist_.Add(input);
}
}
}
return false;
}
// Returns |true| iff there is an unboxed definition among all potential
// definitions that can flow into the |phi|.
// This function looks through phis.
bool HasUnboxedIncommingValue(PhiInstr* phi) {
bool HasUnboxedIncomingValue(PhiInstr* phi) {
worklist_.Clear();
worklist_.Add(phi);
for (intptr_t i = 0; i < worklist_.definitions().length(); i++) {

58
runtime/vm/compiler/backend/flow_graph_test.cc
View file

@ -140,6 +140,64 @@ ISOLATE_UNIT_TEST_CASE(FlowGraph_LateVariablePhiUnboxing) {
EXPECT_PROPERTY(late_var, it.representation() == kTagged);
}
ISOLATE_UNIT_TEST_CASE(FlowGraph_UnboxedFloatPhi) {
using compiler::BlockBuilder;
CompilerState S(thread, /*is_aot=*/true, /*is_optimizing=*/true);
FlowGraphBuilderHelper H;
auto normal_entry = H.flow_graph()->graph_entry()->normal_entry();
auto then_body = H.TargetEntry();
auto else_body = H.TargetEntry();
auto join_exit = H.JoinEntry();
PhiInstr* phi;
Definition* double_to_float_1;
Definition* double_to_float_2;
{
BlockBuilder builder(H.flow_graph(), normal_entry);
builder.AddBranch(
new StrictCompareInstr(
InstructionSource(), Token::kEQ_STRICT, new Value(H.IntConstant(1)),
new Value(H.IntConstant(1)),
/*needs_number_check=*/false, S.GetNextDeoptId()),
then_body, else_body);
}
{
BlockBuilder builder(H.flow_graph(), then_body);
double_to_float_1 = builder.AddDefinition(new DoubleToFloatInstr(
new Value(H.DoubleConstant(1)), S.GetNextDeoptId(),
Instruction::kNotSpeculative));
builder.AddInstruction(new GotoInstr(join_exit, S.GetNextDeoptId()));
}
{
BlockBuilder builder(H.flow_graph(), else_body);
double_to_float_2 = builder.AddDefinition(new DoubleToFloatInstr(
new Value(H.DoubleConstant(2)), S.GetNextDeoptId(),
Instruction::kNotSpeculative));
builder.AddInstruction(new GotoInstr(join_exit, S.GetNextDeoptId()));
}
{
BlockBuilder builder(H.flow_graph(), join_exit);
phi = new PhiInstr(join_exit, 3);
phi->SetInputAt(0, new Value(double_to_float_1));
phi->SetInputAt(1, new Value(double_to_float_2));
phi->SetInputAt(2, new Value(phi));
builder.AddPhi(phi);
builder.AddReturn(new Value(phi));
}
H.FinishGraph();
FlowGraphTypePropagator::Propagate(H.flow_graph());
H.flow_graph()->SelectRepresentations();
EXPECT_PROPERTY(phi, it.representation() == kUnboxedFloat);
}
void TestLargeFrame(const char* type,
const char* zero,
const char* one,