Changeset 189993 in webkit for trunk/Source/JavaScriptCore/jsc.cpp

Timestamp:

Sep 18, 2015, 4:06:47 PM (10 years ago)

Author:

[email protected]

Message:

Implement linear memory instructions in WebAssembly
​https://bugs.webkit.org/show_bug.cgi?id=149326

Patch by Sukolsak Sakshuwong <Sukolsak Sakshuwong> on 2015-09-18
Reviewed by Geoffrey Garen.

This patch implements linear memory instructions in WebAssembly.[1] To
use the linear memory, an ArrayBuffer must be passed to loadWebAssembly().

Notes:

• We limit the ArrayBuffer's byte length to 2^{31 - 1. This enables us to use only one comparison (unsigned greater than) to check for out-of-bounds access.}
• There is no consensus yet on what should happen when an out-of-bounds access occurs.[2] For now, we throw an error when that happens.
• In asm.js, a heap access looks like this: int32Array[i >> 2]. Note that ">> 2" is part of the syntax and is required. pack-asmjs will produce bytecodes that look something like "LoadI32, i" (not "LoadI32, ShiftRightI32, i, 2"). The requirement of the shift operator prevents unaligned accesses in asm.js. (There is a proposal to support unaligned accesses in the future version of asm.js using DataView.[3]) The WebAssembly spec allows unaligned accesses.[4] But since we use asm.js for testing, we follow asm.js's behaviors for now.

[1]: ​https://github.com/WebAssembly/design/blob/master/AstSemantics.md#linear-memory
[2]: ​https://github.com/WebAssembly/design/blob/master/AstSemantics.md#out-of-bounds
[3]: ​https://wiki.mozilla.org/Javascript:SpiderMonkey:OdinMonkey#Possible_asm.js_extensions_that_don.27t_require_new_JS_features
[4]: ​https://github.com/WebAssembly/design/blob/master/AstSemantics.md#alignment

• jit/JITOperations.cpp:
• jit/JITOperations.h:
• jsc.cpp:

(GlobalObject::finishCreation):
(functionLoadWebAssembly):

• tests/stress/wasm-linear-memory.js: Added.

(shouldBe):
(shouldThrow):

• tests/stress/wasm/linear-memory.wasm: Added.
• wasm/JSWASMModule.cpp:

(JSC::JSWASMModule::JSWASMModule):
(JSC::JSWASMModule::visitChildren):

• wasm/JSWASMModule.h:

(JSC::JSWASMModule::create):
(JSC::JSWASMModule::arrayBuffer):
(JSC::JSWASMModule::JSWASMModule): Deleted.

• wasm/WASMConstants.h:
• wasm/WASMFunctionCompiler.h:

(JSC::sizeOfMemoryType):
(JSC::WASMFunctionCompiler::MemoryAddress::MemoryAddress):
(JSC::WASMFunctionCompiler::endFunction):
(JSC::WASMFunctionCompiler::buildLoad):
(JSC::WASMFunctionCompiler::buildStore):

• wasm/WASMFunctionParser.cpp:

(JSC::WASMFunctionParser::parseStatement):
(JSC::WASMFunctionParser::parseExpressionI32):
(JSC::WASMFunctionParser::parseExpressionF32):
(JSC::WASMFunctionParser::parseExpressionF64):
(JSC::WASMFunctionParser::parseMemoryAddress):
(JSC::WASMFunctionParser::parseLoad):
(JSC::WASMFunctionParser::parseStore):

• wasm/WASMFunctionParser.h:
• wasm/WASMFunctionSyntaxChecker.h:

(JSC::WASMFunctionSyntaxChecker::MemoryAddress::MemoryAddress):
(JSC::WASMFunctionSyntaxChecker::buildLoad):
(JSC::WASMFunctionSyntaxChecker::buildStore):

• wasm/WASMModuleParser.cpp:

(JSC::WASMModuleParser::WASMModuleParser):
(JSC::WASMModuleParser::parseModule):
(JSC::parseWebAssembly):
(JSC::WASMModuleParser::parse): Deleted.

• wasm/WASMModuleParser.h:

File:

• trunk/Source/JavaScriptCore/jsc.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/jsc.cpp

@@ -678 +678 @@
 
 #if ENABLE(WEBASSEMBLY)
-        addFunction(vm, "loadWebAssembly", functionLoadWebAssembly, 2);
+        addFunction(vm, "loadWebAssembly", functionLoadWebAssembly, 3);
 #endif
         addFunction(vm, "loadModule", functionLoadModule, 1);
@@ -1451 +1451 @@
     SourceCode source(sourceProvider);
     JSObject* imports = exec->argument(1).getObject();
+    JSArrayBuffer* arrayBuffer = jsDynamicCast<JSArrayBuffer*>(exec->argument(2));
 
     String errorMessage;
-    JSWASMModule* module = parseWebAssembly(exec, source, imports, errorMessage);
+    JSWASMModule* module = parseWebAssembly(exec, source, imports, arrayBuffer, errorMessage);
     if (!module)
         return JSValue::encode(exec->vm().throwException(exec, createSyntaxError(exec, errorMessage)));