[Openexr-devel] update for ImathPlatform.h for Win32 (MSVC): 'restrict' support for VC

[Ger Hobbelt]

Here's the addition of 'restrict' support for MSVC(2005 at least), as
that compiler also supports 'restrict', but there's a cinch. Which is
taken care of in this fix, though in a rather 'hackish' way. I've a
few other possbile slutions, but nothing else worked out. See the
comment in the diff/source code below.

Passes all OpenEXR tests on Win32 (compiled with MSVC2005SP1 on XP
32-bit, running on AMD XP (no! SSE2 support, so the project files are
tweaked; no other change for that). Will test on 64-bit Win platforms
later on, when I've migrated the project files.

diff included below (note that line numbers will be off, due to
M_PI/M_PI_2 fix up there in the same file).

Ger


--- \\Debbie\ger\prj\1original\OpenEXR\src\IlmBase\Imath\ImathPlatform.h        
2006-12-09
00:23:08.000000000 +-0200
+++ \\Debbie\ger\prj\3actual\OpenEXR\IlmBase\Imath\ImathPlatform.h      
2008-06-17
22:15:23.000000000 +-0200
@@ -81,12 +159,70 @@
 #elif defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC)
|| defined(__ECC)
     // supports restrict, do nothing.

 #elif defined __sgi
     // supports restrict, do nothing.

+#elif defined _MSC_VER
+       // supports restrict as __restrict.
+       //
+       // Unfortunately MSVC also knows 'restrict' in this context:
+       //   __declspec(restrict)
+       // which leads to very 'funny' (not!) error reports in stdlib.h when it 
is
+       // loaded AFTER this. And it often is... Sigh.
+       //
+       // So we do the hack thing and load <stdlib.h> anyway here, so the
preprocessor
+       // will prevent it from loading again after we coerce 'restrict' to 
something
+       // meaningful for this compiler, e.g. '__restrict'.
+       //
+       // Update for the above:
+       //
+       // Microsoft encapsulates the 'restrict' in the define '_CRTRESTRICT',
+       // (Code based on the crtdefs.h definitions by Microsoft.)
+       // There are multiple system header files using this macro and we don't 
want
+       // them to load here all, but we have to if we don't want the compiler 
to barf
+       // as there's no simple way to use '__declspec(restrict)' in code
following this
+       // section where 'restict' is defined as '__restrict'.
+       // 'Best' (yech) thing I can think of now is #undef restrict at those 
spots
+       // where you want to use __declspec(restrict) yourself. :-((
+       //
+       #if (defined(_M_IA64) && (_MSC_FULL_VER >= 13102050)) || (_MSC_VER >= 
1400)
+               /* these compiler versions have __declspec(restrict); load the
header files which are affected */
+               #include <stdlib.h>
+               #include <malloc.h>
+       #endif
+
+    #if !defined(restrict)
+               /*
+                       Microsoft says:
+
+                       Like the restrict __declspec modifier, the __restrict 
keyword
indicates that
+                       a symbol is not aliased in the current scope. The 
__restrict
keyword differs
+                       from the restrict __declspec modifier in the following 
ways:
+
+                       - The __restrict keyword is valid only on variables, and
__declspec(restrict)
+                         is only valid on function declarations and 
definitions.
+
+                       - When __restrict is used, the compiler will not 
propagate the no-alias
+                         property of a variable. That is, if you assign a 
__restrict variable to
+                         a non-__restrict variable, the compiler will not 
imply that the
+                         non-__restrict variable is not aliased.
+
+                       Generally, if you affect the behavior of an entire 
function, it is
better to
+                       use the __declspec than the keyword.
+
+                       __restrict is similar to restrict from the C99 spec, 
but __restrict can be
+                       used in C++ or C programs.
+
+                       ----
+
+                       Given the use of 'restrict' in OpenEXR, it should be 
defined as
'__restrict'.
+               */
+       #define restrict __restrict
+    #endif
+
 #else
     #define restrict

 #endif

 #endif // INCLUDED_IMATHPLATFORM_H


-- 
Met vriendelijke groeten / Best regards,

Ger Hobbelt

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