Re: TLS on windows (was: Re: Gfortran on Windows (mingw32) with OpenMP)
On Sun, Jun 04, 2006 at 02:03:05PM +0200, Piotr Wyderski wrote: > fs:[0x14] is a per-thread 32-bit word available for applications, > so you can store a pointer to your own TLS array there. I don't think we can hijack this. > fs:[0x2c] points to a Windows-specific TLS array, so you can > make use of it, too, but you must conform to the limitations of > the WinAPI constraints related with TLS management. Given that microsoft's openmp implementation is also limited in this way, I don't think that's a real problem. > >Now, for an idea of how much work it represents... perhaps someone > >here can tell us? The biggest piece of work is in the linker, noticing the existance of the .tls section and setting up the IMAGE_TLS_DIRECTORY structure, and related activities. There's a value I'll name "tls_handle" that is created as part of this; ideally that would use whatever name vc++ does in its object files. There's also arranging for tls symbol references to resolve to the offset of the symbol in the .tls section, rather than some sort of absolute address. On the compiler side, you'd need to replace legitimize_tls_address with a windows implementation. You'd need some new patterns, since you'll be wanting to generate something akin to movl %fs:0x2c, %eax// global array base movl tls_handle, %edx // value from TlsAlloc movl (%eax, %edx, 4), %eax // local array base addl $variable, %eax // compute address movl variable(%eax), %ecx // when loading/storing a value r~
Re: TLS on windows (was: Re: Gfortran on Windows (mingw32) with OpenMP)
Hi, all, After I refer to the Intel paper titled "Threading Methodology : Principles and Practices" versin 2.0 published in 2003, I note the following message in the article mentioning:(from page 22, web site : http://cache-www.intel.com/cd/00/00/21/93/219349_threadingmethodology.pdf) _ OpenMP and thread libraries have mechanisms to create thread-local storage. Threads can safely access this storage without synchronization. Use the following declarations to create thread-local storage in different threading models: In OpenMP use threadprivate In Win32, use the TlsAlloc() function In Pthreads, use the pthread_key_create function __ >From the above description, I think that "gfortran with OpenMP" compiler can also implemented the TLS using Win32 threads or Pthreads. Please comment on the above implementation methods. Thanks. Best regards, Henry Kar Ming Chan --- FX Coudert <[EMAIL PROTECTED]> wrote: > [First, a warning: I'm neither an expert in TLS, nor > in Windows nor > in GCC guts > > > can we have chance to solve the > > problem of threadprivate by adding the TLS support > to > > mingw32? > > The support for TLS (Thread Local Storage) would > probably come from > the compiler itself. Windows has TLS (see for > example http:// > dotnet.di.unipi.it/Content/sscli/docs/doxygen/pal/localstorage_8c- > > source.html and > http://www.ddj.com/dept/cpp/184403874, or the MSDN > documentation at > http://msdn.microsoft.com/library/default.asp?url=/ > library/en-us/dllproc/base/tlsalloc.asp), so you'd > "only" need to > teach GCC how to call that. > > Now, I don't have competence, time and motivation to > do that. So, if > my analysis above is correct, there are three things > you can do: ask > around here if someone is interested in this and is > planning to do > it; do it yourself, if you have the competence; find > someone you > know, that you have leverage on, to do it :) > > Now, for an idea of how much work it represents... > perhaps someone > here can tell us? > > FX > Send instant messages to your online friends http://uk.messenger.yahoo.com
Re: TLS on windows (was: Re: Gfortran on Windows (mingw32) with OpenMP)
FX Coudert wrote: The support for TLS (Thread Local Storage) would probably come from the compiler itself. Windows has TLS (see for example http:// dotnet.di.unipi.it/Content/sscli/docs/doxygen/pal/localstorage_8c- source.html and http://www.ddj.com/dept/cpp/184403874, or the MSDN documentation at http://msdn.microsoft.com/library/default.asp?url=/ library/en-us/dllproc/base/tlsalloc.asp), so you'd "only" need to teach GCC how to call that. fs:[0x14] is a per-thread 32-bit word available for applications, so you can store a pointer to your own TLS array there. fs:[0x2c] points to a Windows-specific TLS array, so you can make use of it, too, but you must conform to the limitations of the WinAPI constraints related with TLS management. IMO the best would be the offset 0x14 + a custom design of TLSes (BTW, it must be extremely fast! Many applications get their TLS values very often). Now, for an idea of how much work it represents... perhaps someone here can tell us? I don't know much about GCC internals, but I use my own implementation based on inline assembly and the implementation took, hm, 20 minutes? Best regards Piotr Wyderski
TLS on windows (was: Re: Gfortran on Windows (mingw32) with OpenMP)
[First, a warning: I'm neither an expert in TLS, nor in Windows nor in GCC guts can we have chance to solve the problem of threadprivate by adding the TLS support to mingw32? The support for TLS (Thread Local Storage) would probably come from the compiler itself. Windows has TLS (see for example http:// dotnet.di.unipi.it/Content/sscli/docs/doxygen/pal/localstorage_8c- source.html and http://www.ddj.com/dept/cpp/184403874, or the MSDN documentation at http://msdn.microsoft.com/library/default.asp?url=/ library/en-us/dllproc/base/tlsalloc.asp), so you'd "only" need to teach GCC how to call that. Now, I don't have competence, time and motivation to do that. So, if my analysis above is correct, there are three things you can do: ask around here if someone is interested in this and is planning to do it; do it yourself, if you have the competence; find someone you know, that you have leverage on, to do it :) Now, for an idea of how much work it represents... perhaps someone here can tell us? FX
