Changeset 214384 in webkit for trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h

Timestamp:

Mar 24, 2017, 4:25:16 PM (8 years ago)

Author:

[email protected]

Message:

WebAssembly: store state in TLS instead of on VM
​https://bugs.webkit.org/show_bug.cgi?id=169611

Reviewed by Filip Pizlo.

Source/JavaScriptCore:

Using thread-local storage instead of VM makes code more position
independent. We used to store the WebAssembly top Instance (the
latest one in the call stack) on VM, now we instead store it in
TLS. This top Instance is used to access a bunch of state such as
Memory location, size, table (for call_indirect), etc.

Instead of calling it "top", which is confusing, we now just call
it WasmContext.

Making the code PIC means future patches will be able to
postMessage and structured clone into IDB without having to
recompile the code. This wasn't possible before because we
hard-coded the address of VM at compilation time. That doesn't
work between workers, and doesn't work across reloads (which IDB
is intended to do).

It'll also potentially make code faster once we start tuning
what's in TLS, what's in which of the 4 free slots, and what's in
pinned registers. I'm leaving this tuning for later because
there's lower lying fruit for us to pick.

• CMakeLists.txt:
• JavaScriptCore.xcodeproj/project.pbxproj:
• assembler/AbstractMacroAssembler.h:
• assembler/AllowMacroScratchRegisterUsageIf.h: Copied from assembler/AllowMacroScratchRegisterUsage.h.

(JSC::AllowMacroScratchRegisterUsageIf::AllowMacroScratchRegisterUsageIf):
(JSC::AllowMacroScratchRegisterUsageIf::~AllowMacroScratchRegisterUsageIf):

• assembler/MacroAssembler.h:

(JSC::MacroAssembler::storeToTLSPtr): we previously didn't have
the code required to store to TLS, only to load

• assembler/MacroAssemblerARM64.h:

(JSC::MacroAssemblerARM64::loadFromTLSPtrNeedsMacroScratchRegister):
(JSC::MacroAssemblerARM64::storeToTLS32):
(JSC::MacroAssemblerARM64::storeToTLS64):
(JSC::MacroAssemblerARM64::storeToTLSPtrNeedsMacroScratchRegister):

• assembler/MacroAssemblerX86Common.h:

(JSC::MacroAssemblerX86Common::loadFromTLSPtrNeedsMacroScratchRegister):
(JSC::MacroAssemblerX86Common::storeToTLS32):
(JSC::MacroAssemblerX86Common::storeToTLSPtrNeedsMacroScratchRegister):

• assembler/MacroAssemblerX86_64.h:

(JSC::MacroAssemblerX86_64::loadFromTLS64): was loading 32-bit instead of 64-bit
(JSC::MacroAssemblerX86_64::storeToTLS64):

• assembler/X86Assembler.h:

(JSC::X86Assembler::movl_rm):
(JSC::X86Assembler::movq_rm):

• b3/testb3.cpp:

(JSC::B3::testFastTLSLoad):
(JSC::B3::testFastTLSStore):
(JSC::B3::run):

• jit/AssemblyHelpers.h:

(JSC::AssemblyHelpers::loadWasmContext):
(JSC::AssemblyHelpers::storeWasmContext):
(JSC::AssemblyHelpers::loadWasmContextNeedsMacroScratchRegister):
(JSC::AssemblyHelpers::storeWasmContextNeedsMacroScratchRegister):

• jit/Repatch.cpp:

(JSC::webAssemblyOwner):

• jit/ThunkGenerators.cpp:

(JSC::throwExceptionFromWasmThunkGenerator):

• runtime/Options.h:
• runtime/VM.cpp:

(JSC::VM::VM):

• runtime/VM.h:
• wasm/WasmB3IRGenerator.cpp:

(JSC::Wasm::loadWasmContext):
(JSC::Wasm::storeWasmContext):
(JSC::Wasm::B3IRGenerator::B3IRGenerator):
(JSC::Wasm::getMemoryBaseAndSize):
(JSC::Wasm::restoreWebAssemblyGlobalState):
(JSC::Wasm::createJSToWasmWrapper):
(JSC::Wasm::parseAndCompile):

• wasm/WasmBinding.cpp:

(JSC::Wasm::materializeImportJSCell):
(JSC::Wasm::wasmToJs):
(JSC::Wasm::wasmToWasm):

• wasm/WasmContext.cpp: Added.

(JSC::loadWasmContext):
(JSC::storeWasmContext):

• wasm/WasmContext.h: Added. Replaces "top" JSWebAssemblyInstance.
• wasm/js/WebAssemblyFunction.cpp:

(JSC::callWebAssemblyFunction):

• wasm/js/WebAssemblyInstanceConstructor.h:

Source/WTF:

• wtf/FastTLS.h: reserve one key for WebAssembly, delete a bunch

of dead code which clang couldn't compile (it's valid GCC assembly
which LLVM dislikes).

File:

• trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h (modified) (1 diff)

trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h

@@ -3864 +3864 @@
         m_assembler.gs();
         m_assembler.movl_mr(offset, dst);
+    }
+
+
+    static bool loadFromTLSPtrNeedsMacroScratchRegister()
+    {
+        return false;
+    }
+
+    void storeToTLS32(RegisterID src, uint32_t offset)
+    {
+        m_assembler.gs();
+        m_assembler.movl_rm(src, offset);
+    }
+
+    static bool storeToTLSPtrNeedsMacroScratchRegister()
+    {
+        return false;
     }
 #endif