llvm dev - Jul 2009 - [LLVMdev] Possible change to ExecutionEngine::create()

On Jul 22, 2009, at 5:23 PM, Chris Lattner wrote:
>
> On Jul 22, 2009, at 1:32 PM, Dan Gohman wrote:
>
>>>>
>>>> - A null pointer is associated with no addresses.
>>>>
>>>
>>> A null pointer in address space 0.
>>
>> I'm not fond of weird address-space semantics, but for consistency
>> with what the optimizer is currently doing, you're right.
>
> FWIW, this will be addressed when we finally get around to adding
> explicit support for trappability to load/store.
This won't free the optimizer to treat null as an invalid pointer  
though.
Some LLVM hacker thought it would be a good idea to use address
spaces 256 and 257 on x86 in a way that can require dereferences
of address 0 to be valid.

Dan

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.

  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.

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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