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JavascriptExceptionOperators.cpp
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JavascriptExceptionOperators.cpp
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//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------
#include "RuntimeLanguagePch.h"
#include "Language/InterpreterStackFrame.h"
#ifdef _M_IX86
#ifdef _CONTROL_FLOW_GUARD
extern "C" PVOID __guard_check_icall_fptr;
#endif
#endif
namespace Js
{
void JavascriptExceptionOperators::AutoCatchHandlerExists::FetchNonUserCodeStatus(ScriptContext * scriptContext)
{
Assert(scriptContext);
bool fFound = false;
// If the outer try catch was already in the user code, no need to go any further.
if (!m_previousCatchHandlerToUserCodeStatus)
{
Js::JavascriptFunction* caller = nullptr;
if (JavascriptStackWalker::GetCaller(&caller, scriptContext))
{
Js::FunctionBody *funcBody = NULL;
if (caller != NULL && (funcBody = caller->GetFunctionBody()) != NULL)
{
m_threadContext->SetIsUserCode(funcBody->IsNonUserCode() == false);
fFound = true;
}
}
}
if (!fFound)
{
// If not successfully able to find the caller, set this catch handler belongs to the user code.
m_threadContext->SetIsUserCode(true);
}
}
JavascriptExceptionOperators::AutoCatchHandlerExists::AutoCatchHandlerExists(ScriptContext* scriptContext, bool isPromiseHandled)
{
Assert(scriptContext);
m_threadContext = scriptContext->GetThreadContext();
Assert(m_threadContext);
m_previousCatchHandlerExists = m_threadContext->HasCatchHandler();
m_threadContext->SetHasCatchHandler(TRUE);
if (!isPromiseHandled)
{
// If this is created from a promise-specific code path, and we don't have a rejection
// handler on the promise, then we want SetCatchHandler to be false so we report any
// unhandled exceptions to any detached debuggers.
m_threadContext->SetHasCatchHandler(false);
}
m_previousCatchHandlerToUserCodeStatus = m_threadContext->IsUserCode();
if (scriptContext->IsScriptContextInDebugMode())
{
FetchNonUserCodeStatus(scriptContext);
}
}
JavascriptExceptionOperators::AutoCatchHandlerExists::~AutoCatchHandlerExists()
{
m_threadContext->SetHasCatchHandler(m_previousCatchHandlerExists);
m_threadContext->SetIsUserCode(m_previousCatchHandlerToUserCodeStatus);
}
JavascriptExceptionOperators::TryHandlerAddrOfReturnAddrStack::TryHandlerAddrOfReturnAddrStack(ScriptContext* scriptContext, void *addrOfReturnAddr)
{
m_threadContext = scriptContext->GetThreadContext();
m_prevTryHandlerAddrOfReturnAddr = m_threadContext->GetTryHandlerAddrOfReturnAddr();
scriptContext->GetThreadContext()->SetTryHandlerAddrOfReturnAddr(addrOfReturnAddr);
}
JavascriptExceptionOperators::TryHandlerAddrOfReturnAddrStack::~TryHandlerAddrOfReturnAddrStack()
{
m_threadContext->SetTryHandlerAddrOfReturnAddr(m_prevTryHandlerAddrOfReturnAddr);
}
JavascriptExceptionOperators::HasBailedOutPtrStack::HasBailedOutPtrStack(ScriptContext* scriptContext, bool *hasBailedOutPtr)
{
m_threadContext = scriptContext->GetThreadContext();
m_prevHasBailedOutPtr = m_threadContext->GetHasBailedOutBitPtr();
scriptContext->GetThreadContext()->SetHasBailedOutBitPtr(hasBailedOutPtr);
}
JavascriptExceptionOperators::HasBailedOutPtrStack::~HasBailedOutPtrStack()
{
m_threadContext->SetHasBailedOutBitPtr(m_prevHasBailedOutPtr);
}
JavascriptExceptionOperators::PendingFinallyExceptionStack::PendingFinallyExceptionStack(ScriptContext* scriptContext, Js::JavascriptExceptionObject *exceptionObj)
{
m_threadContext = scriptContext->GetThreadContext();
m_threadContext->SetPendingFinallyException(exceptionObj);
}
JavascriptExceptionOperators::PendingFinallyExceptionStack::~PendingFinallyExceptionStack()
{
m_threadContext->SetPendingFinallyException(nullptr);
}
bool JavascriptExceptionOperators::CrawlStackForWER(Js::ScriptContext& scriptContext)
{
return Js::Configuration::Global.flags.WERExceptionSupport && !scriptContext.GetThreadContext()->HasCatchHandler();
}
uint64 JavascriptExceptionOperators::StackCrawlLimitOnThrow(Var thrownObject, ScriptContext& scriptContext)
{
return CrawlStackForWER(scriptContext) ? MaxStackTraceLimit : GetStackTraceLimit(thrownObject, &scriptContext);
}
#ifdef _M_X64
void *JavascriptExceptionOperators::OP_TryCatch(void *tryAddr,
void *catchAddr,
void *frame,
size_t spillSize,
size_t argsSize,
int hasBailedOutOffset,
ScriptContext *scriptContext)
{
void *continuation = nullptr;
JavascriptExceptionObject *exception = nullptr;
void *tryHandlerAddrOfReturnAddr = nullptr;
Js::JavascriptExceptionOperators::HasBailedOutPtrStack hasBailedOutPtrStack(scriptContext, (bool*)((char*)frame + hasBailedOutOffset));
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout + spillSize + argsSize);
{
void * addrOfReturnAddr = (void*)((char*)frame + sizeof(char*));
Js::JavascriptExceptionOperators::TryHandlerAddrOfReturnAddrStack tryHandlerAddrOfReturnAddrStack(scriptContext, addrOfReturnAddr);
try
{
Js::JavascriptExceptionOperators::AutoCatchHandlerExists autoCatchHandlerExists(scriptContext);
continuation = amd64_CallWithFakeFrame(tryAddr, frame, spillSize, argsSize);
}
catch (const Js::JavascriptException& err)
{
exception = err.GetAndClear();
tryHandlerAddrOfReturnAddr = scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr();
}
}
if (exception)
{
// We need to clear callinfo on inlinee virtual frames on an exception.
// We now allow inlining of functions into callers that have try-catch/try-finally.
// When there is an exception inside the inlinee with caller having a try-catch, clear the inlinee callinfo by walking the stack.
// If not, we might have the try-catch inside a loop, and when we execute the loop next time in the interpreter on BailOnException,
// we will see inlined frames as being present even though they are not, because we depend on FrameInfo's callinfo to tell if an inlinee is on the stack,
// and we haven't cleared those bits due to the exception
// When we start inlining functions with try, we have to track the try addresses of the inlined functions as well.
#if ENABLE_NATIVE_CODEGEN
if (exception->GetExceptionContext() && exception->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, tryHandlerAddrOfReturnAddr);
}
#endif
exception = exception->CloneIfStaticExceptionObject(scriptContext);
bool hasBailedOut = *(bool*)((char*)frame + hasBailedOutOffset); // stack offsets are negative
// If an inlinee bailed out due to some reason, the execution of the current function enclosing the try catch will also continue in the interpreter
// During execution in the interpreter, if we throw outside the region enclosed in try/catch, this catch ends up catching that exception because its present on the call stack
if (hasBailedOut)
{
// If we have bailed out, this exception is coming from the interpreter. It should not have been caught;
// it so happens that this catch was on the stack and caught the exception.
// Re-throw!
JavascriptExceptionOperators::DoThrow(exception, scriptContext);
}
Var exceptionObject = exception->GetThrownObject(scriptContext);
AssertMsg(exceptionObject, "Caught object is null.");
continuation = amd64_CallWithFakeFrame(catchAddr, frame, spillSize, argsSize, exceptionObject);
}
return continuation;
}
void *JavascriptExceptionOperators::OP_TryFinally(void *tryAddr,
void *finallyAddr,
void *frame,
size_t spillSize,
size_t argsSize,
int hasBailedOutOffset,
ScriptContext *scriptContext)
{
void *tryContinuation = nullptr;
JavascriptExceptionObject *exception = nullptr;
Js::JavascriptExceptionOperators::HasBailedOutPtrStack hasBailedOutPtrStack(scriptContext, (bool*)((char*)frame + hasBailedOutOffset));
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout + spillSize + argsSize);
try
{
tryContinuation = amd64_CallWithFakeFrame(tryAddr, frame, spillSize, argsSize);
}
catch (const Js::JavascriptException& err)
{
exception = err.GetAndClear();
}
if (exception)
{
// Clone static exception object early in case finally block overwrites it
exception = exception->CloneIfStaticExceptionObject(scriptContext);
}
if (exception)
{
#if ENABLE_NATIVE_CODEGEN
if (scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr() != nullptr)
{
if (exception->GetExceptionContext() && exception->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr());
}
}
else
{
if (exception->GetExceptionContext() && exception->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, frame);
}
}
#endif
bool hasBailedOut = *(bool*)((char*)frame + hasBailedOutOffset); // stack offsets are negative
if (hasBailedOut)
{
// If we have bailed out, this exception is coming from the interpreter. It should not have been caught;
// it so happens that this catch was on the stack and caught the exception.
// Re-throw!
JavascriptExceptionOperators::DoThrow(exception, scriptContext);
}
{
Js::JavascriptExceptionOperators::PendingFinallyExceptionStack pendingFinallyExceptionStack(scriptContext, exception);
void *continuation = amd64_CallWithFakeFrame(finallyAddr, frame, spillSize, argsSize, exception);
return continuation;
}
}
return tryContinuation;
}
void * JavascriptExceptionOperators::OP_TryFinallyNoOpt(void * tryAddr, void * finallyAddr, void * frame, size_t spillSize, size_t argsSize, ScriptContext * scriptContext)
{
void *tryContinuation = nullptr;
void *finallyContinuation = nullptr;
JavascriptExceptionObject *exception = nullptr;
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout + spillSize + argsSize);
try
{
tryContinuation = amd64_CallWithFakeFrame(tryAddr, frame, spillSize, argsSize);
}
catch (const Js::JavascriptException& err)
{
exception = err.GetAndClear();
}
if (exception)
{
// Clone static exception object early in case finally block overwrites it
exception = exception->CloneIfStaticExceptionObject(scriptContext);
}
finallyContinuation = amd64_CallWithFakeFrame(finallyAddr, frame, spillSize, argsSize);
if (finallyContinuation)
{
return finallyContinuation;
}
if (exception)
{
JavascriptExceptionOperators::DoThrow(exception, scriptContext);
}
return tryContinuation;
}
#elif defined(_M_ARM32_OR_ARM64)
void *JavascriptExceptionOperators::OP_TryCatch(
void *tryAddr,
void *catchAddr,
void *framePtr,
void *localsPtr,
size_t argsSize,
int hasBailedOutOffset,
ScriptContext *scriptContext)
{
void *continuation = nullptr;
JavascriptExceptionObject *exception = nullptr;
void * tryHandlerAddrOfReturnAddr = nullptr;
Js::JavascriptExceptionOperators::HasBailedOutPtrStack hasBailedOutPtrStack(scriptContext, (bool*)((char*)localsPtr + hasBailedOutOffset));
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout + argsSize);
{
void * addrOfReturnAddr = (void*)((char*)framePtr + sizeof(char*));
Js::JavascriptExceptionOperators::TryHandlerAddrOfReturnAddrStack tryHandlerAddrOfReturnAddrStack(scriptContext, addrOfReturnAddr);
try
{
Js::JavascriptExceptionOperators::AutoCatchHandlerExists autoCatchHandlerExists(scriptContext);
#if defined(_M_ARM)
continuation = arm_CallEhFrame(tryAddr, framePtr, localsPtr, argsSize);
#elif defined(_M_ARM64)
continuation = arm64_CallEhFrame(tryAddr, framePtr, localsPtr, argsSize);
#endif
}
catch (const Js::JavascriptException& err)
{
exception = err.GetAndClear();
tryHandlerAddrOfReturnAddr = scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr();
}
}
if (exception)
{
// We need to clear callinfo on inlinee virtual frames on an exception.
// We now allow inlining of functions into callers that have try-catch/try-finally.
// When there is an exception inside the inlinee with caller having a try-catch, clear the inlinee callinfo by walking the stack.
// If not, we might have the try-catch inside a loop, and when we execute the loop next time in the interpreter on BailOnException,
// we will see inlined frames as being present even though they are not, because we depend on FrameInfo's callinfo to tell if an inlinee is on the stack,
// and we haven't cleared those bits due to the exception
// When we start inlining functions with try, we have to track the try addresses of the inlined functions as well.
#if ENABLE_NATIVE_CODEGEN
if (exception->GetExceptionContext() && exception->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, tryHandlerAddrOfReturnAddr);
}
#endif
exception = exception->CloneIfStaticExceptionObject(scriptContext);
bool hasBailedOut = *(bool*)((char*)localsPtr + hasBailedOutOffset); // stack offsets are sp relative
if (hasBailedOut)
{
// If we have bailed out, this exception is coming from the interpreter. It should not have been caught;
// it so happens that this catch was on the stack and caught the exception.
// Re-throw!
JavascriptExceptionOperators::DoThrow(exception, scriptContext);
}
Var exceptionObject = exception->GetThrownObject(scriptContext);
AssertMsg(exceptionObject, "Caught object is null.");
#if defined(_M_ARM)
continuation = arm_CallCatch(catchAddr, framePtr, localsPtr, argsSize, exceptionObject);
#elif defined(_M_ARM64)
continuation = arm64_CallCatch(catchAddr, framePtr, localsPtr, argsSize, exceptionObject);
#endif
}
return continuation;
}
void *JavascriptExceptionOperators::OP_TryFinally(
void *tryAddr,
void *finallyAddr,
void *framePtr,
void *localsPtr,
size_t argsSize,
int hasBailedOutOffset,
ScriptContext *scriptContext)
{
void *tryContinuation = nullptr;
JavascriptExceptionObject *exception = nullptr;
Js::JavascriptExceptionOperators::HasBailedOutPtrStack hasBailedOutPtrStack(scriptContext, (bool*)((char*)localsPtr + hasBailedOutOffset));
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout + argsSize);
try
{
#if defined(_M_ARM)
tryContinuation = arm_CallEhFrame(tryAddr, framePtr, localsPtr, argsSize);
#elif defined(_M_ARM64)
tryContinuation = arm64_CallEhFrame(tryAddr, framePtr, localsPtr, argsSize);
#endif
}
catch (const Js::JavascriptException& err)
{
exception = err.GetAndClear();
}
if (exception)
{
#if ENABLE_NATIVE_CODEGEN
if (scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr() != nullptr)
{
if (exception->GetExceptionContext() && exception->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr());
}
}
else
{
if (exception->GetExceptionContext() && exception->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, framePtr);
}
}
#endif
// Clone static exception object early in case finally block overwrites it
exception = exception->CloneIfStaticExceptionObject(scriptContext);
bool hasBailedOut = *(bool*)((char*)localsPtr + hasBailedOutOffset); // stack offsets are sp relative
if (hasBailedOut)
{
// If we have bailed out, this exception is coming from the interpreter. It should not have been caught;
// it so happens that this catch was on the stack and caught the exception.
// Re-throw!
JavascriptExceptionOperators::DoThrow(exception, scriptContext);
}
{
Js::JavascriptExceptionOperators::PendingFinallyExceptionStack pendingFinallyExceptionStack(scriptContext, exception);
#if defined(_M_ARM)
void * finallyContinuation = arm_CallEhFrame(finallyAddr, framePtr, localsPtr, argsSize);
#elif defined(_M_ARM64)
void * finallyContinuation = arm64_CallEhFrame(finallyAddr, framePtr, localsPtr, argsSize);
#endif
return finallyContinuation;
}
}
return tryContinuation;
}
void *JavascriptExceptionOperators::OP_TryFinallyNoOpt(
void *tryAddr,
void *finallyAddr,
void *framePtr,
void *localsPtr,
size_t argsSize,
ScriptContext *scriptContext)
{
void *tryContinuation = nullptr;
void *finallyContinuation = nullptr;
JavascriptExceptionObject *exception = nullptr;
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout + argsSize);
try
{
#if defined(_M_ARM)
tryContinuation = arm_CallEhFrame(tryAddr, framePtr, localsPtr, argsSize);
#elif defined(_M_ARM64)
tryContinuation = arm64_CallEhFrame(tryAddr, framePtr, localsPtr, argsSize);
#endif
}
catch (const Js::JavascriptException& err)
{
exception = err.GetAndClear();
}
if (exception)
{
// Clone static exception object early in case finally block overwrites it
exception = exception->CloneIfStaticExceptionObject(scriptContext);
}
#if defined(_M_ARM)
finallyContinuation = arm_CallEhFrame(finallyAddr, framePtr, localsPtr, argsSize);
#elif defined(_M_ARM64)
finallyContinuation = arm64_CallEhFrame(finallyAddr, framePtr, localsPtr, argsSize);
#endif
if (finallyContinuation)
{
return finallyContinuation;
}
if (exception)
{
JavascriptExceptionOperators::DoThrow(exception, scriptContext);
}
return tryContinuation;
}
#else
#pragma warning(push)
#pragma warning(disable:4731) // frame pointer register 'ebp' modified by inline assembly code
void* JavascriptExceptionOperators::OP_TryCatch(void* tryAddr, void* handlerAddr, void* framePtr, int hasBailedOutOffset, ScriptContext *scriptContext)
{
void* continuationAddr = NULL;
Js::JavascriptExceptionObject* pExceptionObject = NULL;
void *tryHandlerAddrOfReturnAddr = nullptr;
Js::JavascriptExceptionOperators::HasBailedOutPtrStack hasBailedOutPtrStack(scriptContext, (bool*)((char*)framePtr + hasBailedOutOffset));
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout);
{
void * addrOfReturnAddr = (void*)((char*)framePtr + sizeof(char*));
Js::JavascriptExceptionOperators::TryHandlerAddrOfReturnAddrStack tryHandlerAddrOfReturnAddrStack(scriptContext, addrOfReturnAddr);
try
{
Js::JavascriptExceptionOperators::AutoCatchHandlerExists autoCatchHandlerExists(scriptContext);
// Adjust the frame pointer and call into the try.
// If the try completes without raising an exception, it will pass back the continuation address.
// Bug in compiler optimizer: try-catch can be optimized away if the try block contains __asm calls into function
// that may throw. The current workaround is to add the following dummy throw to prevent this optimization.
if (!tryAddr)
{
Js::Throw::InternalError();
}
#ifdef _M_IX86
void *savedEsp;
__asm
{
// Save and restore the callee-saved registers around the call.
// TODO: track register kills by region and generate per-region prologs and epilogs
push esi
push edi
push ebx
// 8-byte align frame to improve floating point perf of our JIT'd code.
// Save ESP
mov ecx, esp
mov savedEsp, ecx
and esp, -8
// Set up the call target, save the current frame ptr, and adjust the frame to access
// locals in native code.
mov eax, tryAddr
#if 0 && defined(_CONTROL_FLOW_GUARD)
// verify that the call target is valid
mov ebx, eax; save call target
mov ecx, eax
call[__guard_check_icall_fptr]
mov eax, ebx; restore call target
#endif
push ebp
mov ebp, framePtr
call eax
pop ebp
// The native code gives us the address where execution should continue on exit
// from the region.
mov continuationAddr, eax
// Restore ESP
mov ecx, savedEsp
mov esp, ecx
pop ebx
pop edi
pop esi
}
#else
AssertMsg(FALSE, "Unsupported native try-catch handler");
#endif
}
catch (const Js::JavascriptException& err)
{
pExceptionObject = err.GetAndClear();
tryHandlerAddrOfReturnAddr = scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr();
}
}
// Let's run user catch handler code only after the stack has been unwound.
if(pExceptionObject)
{
// We need to clear callinfo on inlinee virtual frames on an exception.
// We now allow inlining of functions into callers that have try-catch/try-finally.
// When there is an exception inside the inlinee with caller having a try-catch, clear the inlinee callinfo by walking the stack.
// If not, we might have the try-catch inside a loop, and when we execute the loop next time in the interpreter on BailOnException,
// we will see inlined frames as being present even though they are not, because we depend on FrameInfo's callinfo to tell if an inlinee is on the stack,
// and we haven't cleared those bits due to the exception
// When we start inlining functions with try, we have to track the try addresses of the inlined functions as well.
#if ENABLE_NATIVE_CODEGEN
if (pExceptionObject->GetExceptionContext() && pExceptionObject->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, tryHandlerAddrOfReturnAddr);
}
#endif
pExceptionObject = pExceptionObject->CloneIfStaticExceptionObject(scriptContext);
bool hasBailedOut = *(bool*)((char*)framePtr + hasBailedOutOffset); // stack offsets are negative
if (hasBailedOut)
{
// If we have bailed out, this exception is coming from the interpreter. It should not have been caught;
// it so happens that this catch was on the stack and caught the exception.
// Re-throw!
JavascriptExceptionOperators::DoThrow(pExceptionObject, scriptContext);
}
Var catchObject = pExceptionObject->GetThrownObject(scriptContext);
AssertMsg(catchObject, "Caught object is NULL");
#ifdef _M_IX86
void *savedEsp;
__asm
{
// Save and restore the callee-saved registers around the call.
// TODO: track register kills by region and generate per-region prologs and epilogs
push esi
push edi
push ebx
// 8-byte align frame to improve floating point perf of our JIT'd code.
// Save ESP
mov ecx, esp
mov savedEsp, ecx
and esp, -8
// Set up the call target
mov ecx, handlerAddr
#if 0 && defined(_CONTROL_FLOW_GUARD)
// verify that the call target is valid
mov ebx, ecx ; save call target
call [__guard_check_icall_fptr]
mov ecx, ebx ; restore call target
#endif
// Set up catch object, save the current frame ptr, and adjust the frame to access
// locals in native code.
mov eax, catchObject
push ebp
mov ebp, framePtr
call ecx
pop ebp
// The native code gives us the address where execution should continue on exit
// from the region.
mov continuationAddr, eax
// Restore ESP
mov ecx, savedEsp
mov esp, ecx
pop ebx
pop edi
pop esi
}
#else
AssertMsg(FALSE, "Unsupported native try-catch handler");
#endif
}
return continuationAddr;
}
void* JavascriptExceptionOperators::OP_TryFinally(void* tryAddr, void* handlerAddr, void* framePtr, int hasBailedOutOffset, ScriptContext *scriptContext)
{
Js::JavascriptExceptionObject* pExceptionObject = NULL;
void* continuationAddr = NULL;
Js::JavascriptExceptionOperators::HasBailedOutPtrStack hasBailedOutPtrStack(scriptContext, (bool*)((char*)framePtr + hasBailedOutOffset));
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout);
try
{
// Bug in compiler optimizer: try-catch can be optimized away if the try block contains __asm calls into function
// that may throw. The current workaround is to add the following dummy throw to prevent this optimization.
// It seems like compiler got smart and still optimizes if the exception is not JavascriptExceptionObject (see catch handler below).
// In order to circumvent that we are throwing OutOfMemory.
if (!tryAddr)
{
Assert(false);
ThrowOutOfMemory(scriptContext);
}
#ifdef _M_IX86
void *savedEsp;
__asm
{
// Save and restore the callee-saved registers around the call.
// TODO: track register kills by region and generate per-region prologs and epilogs
push esi
push edi
push ebx
// 8-byte align frame to improve floating point perf of our JIT'd code.
// Save ESP
mov ecx, esp
mov savedEsp, ecx
and esp, -8
// Set up the call target, save the current frame ptr, and adjust the frame to access
// locals in native code.
mov eax, tryAddr
#if 0 && defined(_CONTROL_FLOW_GUARD)
// verify that the call target is valid
mov ebx, eax ; save call target
mov ecx, eax
call [__guard_check_icall_fptr]
mov eax, ebx ; restore call target
#endif
push ebp
mov ebp, framePtr
call eax
pop ebp
// The native code gives us the address where execution should continue on exit
// from the region.
mov continuationAddr, eax
// Restore ESP
mov ecx, savedEsp
mov esp, ecx
pop ebx
pop edi
pop esi
}
#else
AssertMsg(FALSE, "Unsupported native try-finally handler");
#endif
}
catch(const Js::JavascriptException& err)
{
pExceptionObject = err.GetAndClear();
}
if (pExceptionObject)
{
#if ENABLE_NATIVE_CODEGEN
if (scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr() != nullptr)
{
if (pExceptionObject->GetExceptionContext() && pExceptionObject->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, scriptContext->GetThreadContext()->GetTryHandlerAddrOfReturnAddr());
}
}
else
{
if (pExceptionObject->GetExceptionContext() && pExceptionObject->GetExceptionContext()->ThrowingFunction())
{
WalkStackForCleaningUpInlineeInfo(scriptContext, nullptr /* start stackwalk from the current frame */, framePtr);
}
}
#endif
// Clone static exception object early in case finally block overwrites it
pExceptionObject = pExceptionObject->CloneIfStaticExceptionObject(scriptContext);
bool hasBailedOut = *(bool*)((char*)framePtr + hasBailedOutOffset); // stack offsets are negative
if (hasBailedOut)
{
// If we have bailed out, this exception is coming from the interpreter. It should not have been caught;
// it so happens that this catch was on the stack and caught the exception.
// Re-throw!
JavascriptExceptionOperators::DoThrow(pExceptionObject, scriptContext);
}
{
Js::JavascriptExceptionOperators::PendingFinallyExceptionStack pendingFinallyExceptionStack(scriptContext, pExceptionObject);
if (!tryAddr)
{
// Bug in compiler optimizer: dtor is not called, it is a compiler bug
// The compiler thinks the asm cannot throw, so add an explicit throw to generate dtor calls
Js::Throw::InternalError();
}
void* newContinuationAddr = NULL;
#ifdef _M_IX86
void *savedEsp;
__asm
{
// Save and restore the callee-saved registers around the call.
// TODO: track register kills by region and generate per-region prologs and epilogs
push esi
push edi
push ebx
// 8-byte align frame to improve floating point perf of our JIT'd code.
// Save ESP
mov ecx, esp
mov savedEsp, ecx
and esp, -8
// Set up the call target
mov eax, handlerAddr
#if 0 && defined(_CONTROL_FLOW_GUARD)
// verify that the call target is valid
mov ebx, eax; save call target
mov ecx, eax
call[__guard_check_icall_fptr]
mov eax, ebx; restore call target
#endif
// save the current frame ptr, and adjust the frame to access
// locals in native code.
push ebp
mov ebp, framePtr
call eax
pop ebp
// The native code gives us the address where execution should continue on exit
// from the finally, but only if flow leaves the finally before it completes.
mov newContinuationAddr, eax
// Restore ESP
mov ecx, savedEsp
mov esp, ecx
pop ebx
pop edi
pop esi
}
#else
AssertMsg(FALSE, "Unsupported native try-finally handler");
#endif
return newContinuationAddr;
}
}
return continuationAddr;
}
void* JavascriptExceptionOperators::OP_TryFinallyNoOpt(void* tryAddr, void* handlerAddr, void* framePtr, ScriptContext *scriptContext)
{
Js::JavascriptExceptionObject* pExceptionObject = NULL;
void* continuationAddr = NULL;
PROBE_STACK(scriptContext, Constants::MinStackJitEHBailout);
try
{
// Bug in compiler optimizer: try-catch can be optimized away if the try block contains __asm calls into function
// that may throw. The current workaround is to add the following dummy throw to prevent this optimization.
// It seems like compiler got smart and still optimizes if the exception is not JavascriptExceptionObject (see catch handler below).
// In order to circumvent that we are throwing OutOfMemory.
if (!tryAddr)
{
Assert(false);
ThrowOutOfMemory(scriptContext);
}
#ifdef _M_IX86
void *savedEsp;
__asm
{
// Save and restore the callee-saved registers around the call.
// TODO: track register kills by region and generate per-region prologs and epilogs
push esi
push edi
push ebx
// 8-byte align frame to improve floating point perf of our JIT'd code.
// Save ESP
mov ecx, esp
mov savedEsp, ecx
and esp, -8
// Set up the call target, save the current frame ptr, and adjust the frame to access
// locals in native code.
mov eax, tryAddr
#if 0 && defined(_CONTROL_FLOW_GUARD)
// verify that the call target is valid
mov ebx, eax; save call target
mov ecx, eax
call[__guard_check_icall_fptr]
mov eax, ebx; restore call target
#endif
push ebp
mov ebp, framePtr
call eax
pop ebp
// The native code gives us the address where execution should continue on exit
// from the region.
mov continuationAddr, eax
// Restore ESP
mov ecx, savedEsp
mov esp, ecx
pop ebx
pop edi
pop esi
}
#else
AssertMsg(FALSE, "Unsupported native try-finally handler");
#endif
}
catch (const Js::JavascriptException& err)
{
pExceptionObject = err.GetAndClear();
}
if (pExceptionObject)
{
// Clone static exception object early in case finally block overwrites it
pExceptionObject = pExceptionObject->CloneIfStaticExceptionObject(scriptContext);
}
void* newContinuationAddr = NULL;
#ifdef _M_IX86
void *savedEsp;
__asm
{
// Save and restore the callee-saved registers around the call.
// TODO: track register kills by region and generate per-region prologs and epilogs
push esi
push edi
push ebx
// 8-byte align frame to improve floating point perf of our JIT'd code.
// Save ESP
mov ecx, esp
mov savedEsp, ecx
and esp, -8
// Set up the call target
mov eax, handlerAddr
#if 0 && defined(_CONTROL_FLOW_GUARD)
// verify that the call target is valid
mov ecx, eax
call[__guard_check_icall_fptr]
mov eax, ecx; restore call target
#endif
// save the current frame ptr, and adjust the frame to access
// locals in native code.
push ebp
mov ebp, framePtr
call eax
pop ebp
// The native code gives us the address where execution should continue on exit
// from the finally, but only if flow leaves the finally before it completes.
mov newContinuationAddr, eax
// Restore ESP
mov ecx, savedEsp
mov esp, ecx
pop ebx
pop edi
pop esi
}
#else
AssertMsg(FALSE, "Unsupported native try-finally handler");
#endif
if (newContinuationAddr != NULL)
{
// Non-null return value from the finally indicates that the finally seized the flow
// with a jump/return out of the region. Continue at that address instead of handling
// the exception.
return newContinuationAddr;
}
if (pExceptionObject)
{
JavascriptExceptionOperators::DoThrow(pExceptionObject, scriptContext);
}
return continuationAddr;
}
#endif
void __declspec(noreturn) JavascriptExceptionOperators::OP_Throw(Var object, ScriptContext* scriptContext)
{
Throw(object, scriptContext);
}
#if defined(DBG) && defined(_M_IX86)
extern "C" void * _except_handler4;
void JavascriptExceptionOperators::DbgCheckEHChain()
{
#if 0
// This debug check is disabled until we figure out how to trace a fs:0 chain if we throw from inside
// a finally.
void *currentFS0;
ThreadContext * threadContext = ThreadContext::GetContextForCurrentThread();
if (!threadContext->IsScriptActive())
{
return;
}
// Walk the FS:0 chain of exception handlers, until the FS:0 handler in CallRootFunction.
// We should only see SEH frames on the way.
// We do allow C++ EH frames as long as there is no active objects (state = -1).
// That's because we may see frames that have calls to new(). This introduces an EH frame
// to call delete if the constructor throws. Our constructors shouldn't throw, so we should be fine.
currentFS0 = (void*)__readfsdword(0);
while (currentFS0 != threadContext->callRootFS0)
{
// EH struct:
// void * next;
// void * handler;
// int state;
AssertMsg(*((void**)currentFS0 + 1) == &_except_handler4
|| *((int*)currentFS0 + 2) == -1, "Found a non SEH exception frame on stack");
currentFS0 = *(void**)currentFS0;
}