Hi, I tested this patch with gcc 4.8.2 32 bit, Visual C++ 2013 32 bit, Visual C++ 2013 64 bits.
Without the patch (current svn), gcc passes, VC/32 fails to compile, VC/64 compiles but fails the bit tests. With the patch, all compile and pass the tests. So the patch LGTM. Can it be committed ? bittests.cpp tests several clang/gcc compiler intrinsics missing from Visual C++ which are required by libcxx. Can we put it into libcxx tests ? Yaron 2013/12/23 G M <[email protected]> > Here's a revised version of my recent patch that implements yaron's > suggestion to remove DWORD use. I've also made it more explicitly > Win32/msvc specific which I think it practically was anyway and being > explicit may be easier to manage. On Tue, Dec 24, 2013 at 8:45 AM, G M <[email protected]> wrote: > Hi Yaron > > > On Tue, Dec 24, 2013 at 2:07 AM, Yaron Keren <[email protected]>wrote: > >> Hi G M, >> >> The DWORDs should not have been there at all as _BitScanReverse64 and >> _BitScanForward formally take unsigned long* and not DWORD* (although they >> are the same thing). >> >> http://msdn.microsoft.com/en-us/library/wfd9z0bb(v=vs.90).aspx >> >> Use unsigned long instead of DWORD and wtypes.h will not be needed. >> >> Yes I find this confusing because I'm pretty sure other documentation > (which I now conveniently can't find) had the types using DWORD etc. and I, > and I'm sure the original author of these functions that I'm fixing, based > their code after that and not the documentation you are linking too. That's > how I think the DWORD stuff got in to begin with. > > In an earlier version of this patch that I posted, but seemed to get lost > I removed the DWORD types etc. due to the documentation you linked to. > > What caused me to put it back was that some headers like Winnt.h still > refer to DWORD etc. But now looking at intrin.h which I can see is the one > to follow doesn't use DWORD anymore if it ever did. > > So I can see you are right, I'll re-submit another patch shortly that > again removes DWORD. > > Thanks. > >> >> >> >> 2013/12/23 G M <[email protected]> >> >>> Hello Win32 libcxx watchers. >>> support.h implements the functions clz, clzl, clzll, ctz, ctzl, and >>> ctzll functions (I hate those names) for Win32 when the compiler does not >>> support them. So ms's cl.exe uses the implementations in support.h >>> but clang and gcc compilers provide these implementations themselves, not >>> support.h. >>> >>> Currently these support.h implementations have a few problems. >>> >>> With the removal of windows.h from support.h they no longer compile. >>> Even when they did compile, they were incorrect at runtime. In more detail: >>> >>> 1. support.h now fails to compile for msvc (cl.exe) because it depended >>> on things like DWORD from windows.h which was removed in a prior commit >>> and no lighter weight replacement for windows.h was provided. This patch >>> supplies that with wtypes.h >>> >>> 2. These functions aren't implemented for 32 bit targets of cl.exe but >>> they should be as they are available in the 32 bit and 64 bit gcc and clang >>> targets. This is because the current implementations use BitScanForward64 >>> etc. which aren't available to 32 bit targets. This patch provides 32 bit >>> implementations of the clt/l/ll and clz/l/ll functions to fix that >>> . >>> 3. The above named functions current implementation in support.h is >>> incorrect. The return values of the support.h versions don't match the gcc >>> or clang return values when given the same inputs. >>> >>> The attached support.h.diff patch fixes these problems. >>> >>> Anyone wanting to verify the above statements: compile the attached test >>> case bittests.cpp with MS's 32 bit compiler cl.exe against the SVN version >>> of libcxx and it's support.h (i.e. before applying the support.h.diff >>> patch), you will see: >>> cl bittest.cpp -I/libcxx/include >>> c:\libcxx\include\support/win32/support.h(85) : error C2065: 'DWORD' : >>> undeclared identifier >>> <etc...> This is demonstrates problem 1 above. >>> >>> If you edit that svn version of support.h and add wtypes.h and compile >>> again, you will see the first errors vanish. but then you then you will see >>> these errors: >>> c:\libcxx\include\support\win32\support.h(97) : error C3861: >>> '_BitScanReverse64': identifier not found >>> c:\libcxx\include\support\win32\support.h(112) : error C3861: >>> '_BitScanForward64': identifier not found >>> This demonstrates problem 2 above. >>> >>> Switching to the 64 bit cl.exe compiler, if you compile with that, you >>> should be able to run it but get these runtime errors: >>> Test ctz failed. line 23, expected value: 32, actual value: 0 >>> Test ctzl failed. line 33, expected value: 32, actual value: 0 >>> Test ctzll failed. line 44, expected value: 64, actual value: 0 >>> Test clz failed. line 57, expected value: 32, actual value: 0 >>> <snip> >>> 134 tests failed >>> This demonstrates problem number 3. >>> >>> If you try compiling and runing this file with g++ or clang, you should >>> see no errors. This shows gcc and clang's implementations of the clt/clz >>> functions are ok yet support.h's version are not. >>> If you delete support.h and re get (assuming you modified it to add >>> wtypes.h) and then apply the support.h.diff patch and then re-compile with >>> g++, clang++ or cl.exe in 32 bit or 64 bit mode, the test case should then >>> run with no errors or output for all of those compilers, hopefully >>> indicating success with no regressions and proving that all the issues >>> stated were real and that this patch has fixed all the stated problems. >>> >>> I am going on holiday the day after tomorrow and won't have access to >>> email unfortunately so I won't be able to reply to any questions after >>> tomorrow for about a week, but I thought I'd make this patch available in >>> the mean time for review and anyone who wants to play with it. I'll try to >>> reply to any early responses that come in to this patch before I go though. >>> >>> Thanks >>> >> >
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