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| author | Max Graey <maxgraey@gmail.com> | 2021-08-02 16:30:26 +0300 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-08-02 13:30:26 +0000 |
| commit | f35f02c1ce1b3129aa83d2dddeababd414c1ca8f (patch) | |
| tree | 52b70c4193f77d63615f6571458248cf055c62a8 /src/passes/OptimizeForJS.cpp | |
| parent | 512033eed52fff82274650aca7d7374b4b305551 (diff) | |
| download | binaryen-f35f02c1ce1b3129aa83d2dddeababd414c1ca8f.tar.gz binaryen-f35f02c1ce1b3129aa83d2dddeababd414c1ca8f.tar.bz2 binaryen-f35f02c1ce1b3129aa83d2dddeababd414c1ca8f.zip | |
[JS] Add a new OptimizeForJS pass (#4033)
Add a new OptimizeForJS pass which contains rewriting rules specific to JavaScript.
LLVM usually lowers x != 0 && (x & (x - 1)) == 0 (isPowerOf2) to popcnt(x) == 1 which is ok for wasm and other targets but is quite expensive for JavaScript. In this PR we lower the popcnt pattern back to the isPowerOf2 pattern.
Diffstat (limited to 'src/passes/OptimizeForJS.cpp')
| -rw-r--r-- | src/passes/OptimizeForJS.cpp | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/src/passes/OptimizeForJS.cpp b/src/passes/OptimizeForJS.cpp new file mode 100644 index 000000000..976a16f94 --- /dev/null +++ b/src/passes/OptimizeForJS.cpp @@ -0,0 +1,92 @@ +/* + * 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 |