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/*
* Copyright (C) 2025 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "WebAssemblyBuiltinTrampoline.h"
#if ENABLE(WEBASSEMBLY) && ENABLE(JIT)
#include "JSWebAssemblyInstance.h"
#include "WasmBinding.h"
#include "WasmOperations.h"
namespace JSC {
namespace Wasm {
using JIT = CCallHelpers;
// When JIT is enabled, this generates a function that lives in the JIT arena and serves as a gateway
// into the builtin implementation. When JIT is disabled, the call path instead uses one of the static
// trampolines defined in InPlaceInterpreter.asm.
//
// IMPORTANT: Any changes to the trampoline here should be replicated in its static counterparts in InPlaceInterpreter.asm.
Expected<MacroAssemblerCodeRef<WasmEntryPtrTag>, BindingFailure> generateWasmBuiltinTrampoline(const WebAssemblyBuiltin& builtin)
{
auto scratch = GPRInfo::regT5;
size_t arity = builtin.signature().numParams();
ASSERT(arity <= 4); // r5 is scratch leaving r0-r4 for args, one of which is wasmInstance, so at most 4 for the builtin itself
auto extraArgGPR = GPRInfo::toArgumentRegister(arity);
ASSERT(scratch != GPRReg::InvalidGPRReg);
ASSERT(noOverlap(scratch, GPRInfo::wasmContextInstancePointer));
JIT jit;
jit.emitFunctionPrologue();
// IPInt stores the callee and wasmInstance into the frame but JIT tiers don't, so we must do that here.
jit.move(GPRInfo::wasmContextInstancePointer, scratch);
const size_t builtinEntryByteOffset = JSWebAssemblyInstance::offsetOfBuiltinCalleeBits() + builtin.id() * sizeof(CalleeBits);
jit.loadPtr(JIT::Address(scratch, builtinEntryByteOffset), scratch);
jit.storePairPtr(GPRInfo::wasmContextInstancePointer, scratch, GPRInfo::callFrameRegister, JIT::TrustedImm32(CallFrameSlot::codeBlock * sizeof(Register)));
// Set VM topCallFrame to null to not build an unnecessary stack trace if the function throws an exception.
jit.loadPtr(JIT::Address(GPRInfo::wasmContextInstancePointer, JSWebAssemblyInstance::offsetOfVM()), scratch);
jit.storePtr(JIT::TrustedImmPtr(nullptr), JIT::Address(scratch, VM::offsetOfTopCallFrame()));
// Add wasmInstance as the extra arg
jit.move(GPRInfo::wasmContextInstancePointer, extraArgGPR);
CodePtr<OperationPtrTag> entrypointAsOperation = builtin.wasmEntrypoint().template retagged<OperationPtrTag>();
jit.callOperation<OperationPtrTag>(entrypointAsOperation);
// Check for an exception and branch if present
jit.loadPtr(JIT::Address(GPRInfo::wasmContextInstancePointer, JSWebAssemblyInstance::offsetOfVM()), scratch);
auto handleException = jit.branchTestPtr(JIT::ResultCondition::NonZero, JIT::Address(scratch, VM::exceptionOffset()));
#if CPU(X86)
// Wasm always expects the return value in a0 which on x86 is not the same as r0
jit.move(GPRInfo::returnValueGPR, GPRInfo::argumentGPR0);
#endif
jit.emitFunctionEpilogue();
jit.ret();
// Handle the exception
handleException.link(jit);
jit.loadPtr(CCallHelpers::Address(GPRInfo::wasmContextInstancePointer, JSWebAssemblyInstance::offsetOfVM()), GPRInfo::argumentGPR0);
jit.copyCalleeSavesToVMEntryFrameCalleeSavesBuffer(GPRInfo::argumentGPR0);
jit.prepareWasmCallOperation(GPRInfo::wasmContextInstancePointer);
jit.setupArguments<decltype(operationWasmUnwind)>(GPRInfo::wasmContextInstancePointer);
jit.callOperation<OperationPtrTag>(operationWasmUnwind);
jit.farJump(GPRInfo::returnValueGPR, ExceptionHandlerPtrTag);
LinkBuffer patchBuffer(jit, GLOBAL_THUNK_ID, LinkBuffer::Profile::WasmThunk, JITCompilationMustSucceed);
if (patchBuffer.didFailToAllocate()) [[unlikely]]
return makeUnexpected(BindingFailure::OutOfMemory);
return FINALIZE_WASM_CODE(patchBuffer, WasmEntryPtrTag, nullptr, "WebAssemblyBuiltinThunk [%s]", builtin.name());
}
} // namespace Wasm
} // namespace JSC
#endif // ENABLE(WEBASSEMBLY) && ENABLE(JIT)
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