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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /js/src/wasm/WasmInitExpr.h | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/src/wasm/WasmInitExpr.h')
-rw-r--r-- | js/src/wasm/WasmInitExpr.h | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/js/src/wasm/WasmInitExpr.h b/js/src/wasm/WasmInitExpr.h new file mode 100644 index 0000000000..adb30cbeb3 --- /dev/null +++ b/js/src/wasm/WasmInitExpr.h @@ -0,0 +1,119 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * + * Copyright 2021 Mozilla Foundation + * + * 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. + */ + +#ifndef wasm_initexpr_h +#define wasm_initexpr_h + +#include "wasm/WasmConstants.h" +#include "wasm/WasmSerialize.h" +#include "wasm/WasmTypeDecls.h" +#include "wasm/WasmValType.h" +#include "wasm/WasmValue.h" + +namespace js { +namespace wasm { + +class Decoder; +struct ModuleEnvironment; + +// Validates a constant expression. Returns an optional literal value if the +// final value was from a simple instruction such as i32.const. +[[nodiscard]] bool DecodeConstantExpression(Decoder& d, ModuleEnvironment* env, + ValType expected, + Maybe<LitVal>* literal); + +enum class InitExprKind { + None, + Literal, + Variable, +}; + +// A InitExpr describes a WebAssembly constant expression, such as those used to +// initialize a global, specify memory offsets in data segments, or populate +// element segments. Such expressions are created during decoding and actually +// executed on module instantiation. +// +// An InitExpr can only contain constant instructions, which are defined here in +// the spec: +// +// https://webassembly.github.io/spec/core/valid/instructions.html#constant-expressions + +class InitExpr { + InitExprKind kind_; + // The bytecode for this constant expression if this is not a literal. + Bytes bytecode_; + // The value if this is a literal. + LitVal literal_; + // The value type of this constant expression in either case. + ValType type_; + + public: + InitExpr() : kind_(InitExprKind::None) {} + + explicit InitExpr(LitVal literal) + : kind_(InitExprKind::Literal), + literal_(literal), + type_(literal.type()) {} + + // Decode and validate a constant expression given at the current + // position of the decoder. Upon failure, the decoder contains the failure + // message or else the failure was an OOM. + static bool decodeAndValidate(Decoder& d, ModuleEnvironment* env, + ValType expected, InitExpr* expr); + + // Decode and evaluate a constant expression at the current position of the + // decoder. Does not validate the expression first, since all InitExprs are + // required to have been validated. Failure conditions are the same as + // InitExpr::evaluate, i.e. failing only on OOM. + [[nodiscard]] static bool decodeAndEvaluate( + JSContext* cx, Handle<WasmInstanceObject*> instanceObj, Decoder& d, + ValType expectedType, MutableHandleVal result); + + // Evaluate the constant expresssion with the given context. This may only + // fail due to an OOM, as all InitExpr's are required to have been validated. + bool evaluate(JSContext* cx, Handle<WasmInstanceObject*> instanceObj, + MutableHandleVal result) const; + + bool isLiteral() const { return kind_ == InitExprKind::Literal; } + + // Gets the result of this expression if it was determined to be a literal. + LitVal literal() const { + MOZ_ASSERT(isLiteral()); + return literal_; + } + + // Get the type of the resulting value of this expression. + ValType type() const { return type_; } + + // Allow moving, but not implicit copying + InitExpr(const InitExpr&) = delete; + InitExpr& operator=(const InitExpr&) = delete; + InitExpr(InitExpr&&) = default; + InitExpr& operator=(InitExpr&&) = default; + + // Allow explicit cloning + [[nodiscard]] bool clone(const InitExpr& src); + + size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const; + WASM_DECLARE_FRIEND_SERIALIZE(InitExpr); +}; + +} // namespace wasm +} // namespace js + +#endif // wasm_initexpr_h |