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[maglev] Don't check smi overflow after int32 unary/binop

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This means TurboFan might not see what Maglev did, and it might make
different decisions, but if we deopt we'll learn in Ignition anyway and
won't make the same mistake later. At the same time this avoids a lot of
unnecessary operations that impact tight loops.

Bug: v8:7700
Change-Id: I6fada2ed0218b0b97fc8c9d9ba10fb2218cd71d4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4200631
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85585}
This commit is contained in:
Toon Verwaest 2023-01-27 17:22:15 +01:00 committed by V8 LUCI CQ
parent 3ff97ec329
commit 7d8ca951ec
4 changed files with 10 additions and 30 deletions
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23
src/maglev/maglev-graph-builder.cc
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@ -494,13 +494,7 @@ void MaglevGraphBuilder::BuildInt32UnaryOperationNode() {
ValueNode* value = input_is_truncated ? GetAccumulatorTruncatedInt32()
: GetAccumulatorInt32();
using OpNodeT = Int32NodeFor<kOperation>;
OpNodeT* result = AddNewNode<OpNodeT>({value});
NodeInfo* node_info = known_node_aspects().GetOrCreateInfoFor(result);
node_info->type = NodeType::kSmi;
static_assert(OpNodeT::kProperties.value_representation() ==
ValueRepresentation::kInt32);
node_info->tagged_alternative = AddNewNode<CheckedSmiTagInt32>({result});
SetAccumulator(result);
SetAccumulator(AddNewNode<OpNodeT>({value}));
}
void MaglevGraphBuilder::BuildTruncatingInt32BitwiseNotForNumber() {
@ -567,20 +561,7 @@ void MaglevGraphBuilder::BuildInt32BinaryOperationNode() {
}
using OpNodeT = Int32NodeFor<kOperation>;
OpNodeT* result = AddNewNode<OpNodeT>({left, right});
NodeInfo* node_info = known_node_aspects().GetOrCreateInfoFor(result);
node_info->type = NodeType::kSmi;
if constexpr (OpNodeT::kProperties.value_representation() ==
ValueRepresentation::kInt32) {
// For Int32, the check is the same as a tag operation, so we may as well
// keep the tagged result as the tagged alternative.
node_info->tagged_alternative = AddNewNode<CheckedSmiTagInt32>({result});
} else {
static_assert(OpNodeT::kProperties.value_representation() ==
ValueRepresentation::kUint32);
AddNewNode<CheckUint32IsSmi>({result});
}
SetAccumulator(result);
SetAccumulator(AddNewNode<OpNodeT>({left, right}));
}
template <Operation kOperation>

5
test/mjsunit/maglev/add-smi.js
View File

@ -17,9 +17,8 @@
assertEquals(3, add(1, 2));
assertTrue(isMaglevved(add));
// We should deopt here in SmiUntag.
assertEquals(0x40000000, add(1, 0x3FFFFFFF));
assertFalse(isMaglevved(add));
assertTrue(isMaglevved(add));
})();
// Checks when we deopt due to tagging.
@ -35,7 +34,7 @@
assertEquals(3, add(1, 2));
assertTrue(isMaglevved(add));
// We should deopt here in SmiTag.
// We should deopt here in Int32Add.
assertEquals(3.2, add(1.2, 2));
assertFalse(isMaglevved(add));
})();

6
test/mjsunit/maglev/shift-right-logical-smi.js
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@ -39,10 +39,10 @@ function shrl_test_expect_deopt(lhs, rhs, expected_result) {
}
shrl_test(8, 2, 2);
shrl_test_expect_deopt(-1, 1, 2147483647);
shrl_test(-1, 1, 2147483647);
shrl_test(-8, 2, 1073741822);
shrl_test_expect_deopt(-8, 0, 4294967288);
shrl_test_expect_deopt(-892396978, 0, 3402570318);
shrl_test(-8, 0, 4294967288);
shrl_test(-892396978, 0, 3402570318);
shrl_test(8, 10, 0);
shrl_test(8, 33, 4);
shrl_test_expect_deopt(0xFFFFFFFF, 0x3FFFFFFF, 1);

6
test/mjsunit/maglev/shift-right-logical.js
View File

@ -35,10 +35,10 @@ function shrl_test_expect_deopt(lhs, rhs, expected_result) {
}
shrl_test(8, 2, 2);
shrl_test_expect_deopt(-1, 1, 2147483647);
shrl_test(-1, 1, 2147483647);
shrl_test(-8, 2, 1073741822);
shrl_test_expect_deopt(-8, 0, 4294967288);
shrl_test_expect_deopt(-892396978, 0, 3402570318);
shrl_test(-8, 0, 4294967288);
shrl_test(-892396978, 0, 3402570318);
shrl_test(8, 10, 0);
shrl_test(8, 33, 4);
shrl_test_expect_deopt(0xFFFFFFFF, 0x3FFFFFFF, 1);