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/*
* Copyright 2021 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <pass.h>
#include <wasm.h>
#include "wasm-builder.h"
#include <ir/abstract.h>
#include <ir/literal-utils.h>
#include <ir/localize.h>
#include <ir/match.h>
namespace wasm {
struct OptimizeForJSPass : public WalkerPass<PostWalker<OptimizeForJSPass>> {
bool isFunctionParallel() override { return true; }
Pass* create() override { return new OptimizeForJSPass; }
void visitBinary(Binary* curr) {
using namespace Abstract;
using namespace Match;
{
// Rewrite popcnt(x) == 1 ==> !!x & !(x & (x - 1))
Expression* x;
if (matches(curr, binary(Eq, unary(Popcnt, any(&x)), ival(1)))) {
rewritePopcntEqualOne(x);
}
}
}
void rewritePopcntEqualOne(Expression* expr) {
// popcnt(x) == 1 ==> !!x & !(x & (x - 1))
BinaryOp andOp, subOp;
UnaryOp eqzOp;
Literal litOne;
Type type = expr->type;
switch (type.getBasic()) {
case Type::i32:
eqzOp = EqZInt32;
andOp = AndInt32;
subOp = SubInt32;
litOne = Literal::makeOne(Type::i32);
break;
case Type::i64:
eqzOp = EqZInt64;
andOp = AndInt64;
subOp = SubInt64;
litOne = Literal::makeOne(Type::i64);
break;
default:
return;
}
Localizer temp(expr, getFunction(), getModule());
Builder builder(*getModule());
replaceCurrent(builder.makeBinary(
AndInt32,
builder.makeUnary(
EqZInt32,
builder.makeUnary(eqzOp, builder.makeLocalGet(temp.index, type))),
builder.makeUnary(
eqzOp,
builder.makeBinary(
andOp,
builder.makeLocalGet(temp.index, type),
builder.makeBinary(subOp,
builder.makeLocalGet(temp.index, type),
builder.makeConst(litOne))))));
}
};
Pass* createOptimizeForJSPass() { return new OptimizeForJSPass(); }
} // namespace wasm
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