[LLVMdev] Possible change to ExecutionEngine::create()

[Rob Grapes]

Hi Daniel,

In my case ExecutionEngine::create() loads 40 modules, then each time I try to resolve a symbol that I know is in a DLL that I supply, it looks through all 40 modules first.  This is on Windows, so I get the following modules loaded:

ntdll.dll, kernel32.dll, USER32.dll, GDI32.dll, SHELL32.dll, ADVAPI32.dll, RPCRT4.dll,
Secur32.dll, msvcrt.dll, SHLWAPI.dll, ole32.dll, OLEAUT32.dll, WS2_32.dll, WS2HELP.dll,
PSAPI.DLL, VERSION.dll, MSACM32.dll, WINMM.dll, WININET.dll, Normaliz.dll, urlmon.dll,
iertutil.dll, IPHLPAPI.DLL, IMM32.dll, HID.DLL, SETUPAPI.dll, OPENGL32.dll, GLU32.dll,
DDRAW.dll, DCIMAN32.dll, dbghelp.dll, LPK.DLL, USP10.dll, comctl32.dll, comctl32.dll,
rsaenh.dll, uxtheme.dll, MSCTF.dll, USERENV.dll, as well as the exe.

It wouldn't be so bad if it looked through the modules in reverse order, so mine were searched
first.

So, as an alternative can the order be changed, or, can it be set up so that the user must explicitly enumerate and add modules.

Rob.

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Daniel Dunbar
Sent: Thursday, 23 July 2009 6:35 p.m.
To: LLVM Developers Mailing List
Subject: Re: [LLVMdev] Possible change to ExecutionEngine::create()

Hi Rob,

Can you comment on exactly what the problem is you want to solve? Is
it a performance issue with LoadLibraryPermanently, or do you simply
not want the external symbols to be resolved from within the JIT?

 - Daniel

On Wed, Jul 22, 2009 at 11:22 PM, Evan Cheng<evan.cheng at apple.com> wrote:
>
> On Jul 22, 2009, at 9:43 PM, Rob Grapes wrote:
>
>> Hi,
>>
>> Would it be possible to make the following slight change to
>> ExecutionEngine::create()?
>>
>> I would like to be able to disable the automatic enumeration of
>> loaded modules, and the subsequent searching for undefined symbols
>> (using SearchForAddressOfSymbol).
>>
>> I propose adding an extra parameter to the function definition,
>> defaulting to true.
>
> I'd rather not. The current API is messy enough already. Is there not
> another way to solve the problem?
>
> Evan
>
>>
>>  static ExecutionEngine *create(ModuleProvider *MP,
>>                                 bool ForceInterpreter = false,
>>                                 std::string *ErrorStr = 0,
>>                                 bool Fast = false,
>>                                 bool EnumModules = true);
>>
>> And corresponding change to the function.
>>
>> ExecutionEngine *ExecutionEngine::create(ModuleProvider *MP,
>>                                         bool ForceInterpreter,
>>                                         std::string *ErrorStr,
>>                                         bool Fast,
>>                                         bool EnumModules) {
>>  ExecutionEngine *EE = 0;
>>  if (EnumModules) {
>>    // Make sure we can resolve symbols in the program as well. The
>> zero arg
>>    // to the function tells DynamicLibrary to load the program, not
>> a library.
>>    if (sys::DynamicLibrary::LoadLibraryPermanently(0, ErrorStr))
>>      return 0;
>>  }
>>  ...
>>
>> Your help would be appreciated.
>>
>> Rob.
>>
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