If the Intel 9.1 compilers are used to compile Python 2.6, the following
compiler error results:

/mnt/gpfs/usrpeople/jenninjl/Python-2.6-intel/Modules/_ctypes/libffi/src/x86/ffi64.c(43):
error: identifier "__int128_t" is undefined
    __int128_t sse[MAX_SSE_REGS];
    ^

Forum thread regarding lack of support for __int128_t in icc:
http://software.intel.com/en-us/forums/intel-c-compiler/topic/56652/

Intel C++ Compiler 10.1 for Linux, Intrinsic Reference:
http://softwarecommunity.intel.com/isn/downloads/softwareproducts/pdfs/347603.pdf

The Intrinsic Reference details (pp. 2-4) the __m128 type supported by
the Intel compiler, and restrictions on its use. (Note that the compiler
used was 9.1 but the documentation is from 10.1.)

Why are you reporting this as a bug in Python? Isn't it rather a bug in icc?

According to §7.1.3 of the C99 standard, the name __int128_t is reserved
for implementation-specific use because it starts with an underscore. So
if gcc defines this type and icc does not, that is not a bug in icc; and
if Python uses this type, it will only certainly build using gcc. I
doubt such a dependency was intended, because it is not documented, and
no error was thrown when the autoconf script detected that a compiler
other than GCC was being used.

C99 standard: http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1124.pdf

Exact-width integer types (e.g. int64_t) are documented in §7.18.1.1 of
the above.

Hmm. Perhaps icc shouldn't define __x86_64__ either, then?

Can you propose a patch to fix that problem?

This thread contains a feature request for __int128_t support in icc and
a workaround:

http://software.intel.com/en-us/forums/showthread.php?t=56652

Patch included for Modules/_ctyles/libffi/src/x86/ffi64.c. I've added some include guards around anything necessary to compile with the Intel compiler.
This patch is needed to compile the _ctypes module with icc on current Python releases (just successfully compiled 2.7.3, with patch)..

Can you please re-upload this as a unified diff?

I suggest to not apply additional patches for Modules/_ctypes/libffi* due to issue #12081. Patches for libffi should be sent to libffi upstream.

> I suggest to not apply additional patches for Modules/_ctypes/libffi* 
> due to issue #12081. Patches for libffi should be sent to libffi 
> upstream.

For trunk I agree.  However, it is probably worth considering this patch
for 2.7 and 3.2.

Did anyone check to see if this is already fixed in upstream libffi?

https://github.com/atgreen/libffi/blob/master/src/x86/ffi64.c contains:

#ifdef __INTEL_COMPILER
#define UINT128 __m128
#else
#define UINT128 __int128_t
#endif

Submitting a working patch upstream would make sense.. Just found, downloaded and tried compiling libffi-3.0.11. The developers have made some changes towards a solution, but compilation fails with the same error:-

libtool: compile:  icc -DHAVE_CONFIG_H -I. -I.. -I. -I../include -Iinclude -I../src -DFFI_BUILDING -g -O3 -ansi_alias -Wall -fexceptions -MT src/x86/ffi64.lo -MD -MP -MF src/x86/.deps/ffi64.Tpo -c ../src/x86/ffi64.c  -fPIC -DPIC -o src/x86/.libs/ffi64.o
../src/x86/ffi64.c(50): error: identifier "__m128" is undefined
    UINT128 sse[MAX_SSE_REGS];


__m128 is defined in Intel's xmmintrin.h though [http://software.intel.com/sites/products/documentation/hpc/compilerpro/en-us/cpp/lin/compiler_c/intref_cls/common/intref_sse_arithmetic.htm].

So I added the necessary include line, which gets a different error:-

libtool: compile:  icc -DHAVE_CONFIG_H -I. -I.. -I. -I../include -Iinclude -I../src -DFFI_BUILDING -g -O3 -ansi_alias -Wall -fexceptions -MT src/x86/ffi64.lo -MD -MP -MF src/x86/.deps/ffi64.Tpo -c ../src/x86/ffi64.c  -fPIC -DPIC -o src/x86/.libs/ffi64.o
../src/x86/ffi64.c(481): error: a value of type "UINT64={unsigned long}" cannot be assigned to an entity of type "__m128"
                  reg_args->sse[ssecount++] = *(UINT64 *) a;
                                            ^

../src/x86/ffi64.c(484): error: a value of type "UINT32={unsigned int}" cannot be assigned to an entity of type "__m128"
                  reg_args->sse[ssecount++] = *(UINT32 *) a;
                                            ^

Regarding my previous patch, I'm not convinced it works actually.. It compiles, and passes the default Python tests, but I get some dodgy behaviour. e.g. when compiling 2.7.3 with --enable-shared, I get a segfault when compiling the gdbm module against libdb4.8-dev. Any specific ways of testing the build?

Changes to ctypes should not affect the gdbm module.

More likely, icc and python just don't work together. It may be a compiler bug in icc (it wouldn't be the first one discovered by Python), or it may be a portability defect in Python (where it wouldn't be the first case, either). In any case, the gdbm issue is likely unrelated.

Thanks for the assurance. I found it strange because compilation only fails when building shared binaries. My static build of Python-2.7.3, with icc seems to work fine, except for this libffi issue.

Turns out I needed dejagnu to run the tests in libffi's `make check`, which is why it passed before when it shouldn't have.
I'll liaise with the libffi authors to try and come up with a working solution.

This is still broken after the libffi update (issue15194).  The errors are the same as Alex mentioned when he tested libffi-3.0.11.  The right way to go is to get this fixed in upstream libffi and backport the patch.

I agree with Meador that this should be fixed upstream first.
There's a thread here on libffi-discuss, with a patch but no
conclusive answer:


http://sourceware.org/ml/libffi-discuss/2012/msg00168.html

Ah, forget that: Alex has apparently already tested that patch.

I hadn't tried the `long long` substitution before, but unfortunately I don't 
think that simple fix quite does the trick.

I just checked out libffi from git, and made the following patch:-
#$ diff -u ffi64.c ffi64.c.orig 

--- ffi64.c     2012-07-16 11:38:44.237255615 +0100
+++ ffi64.c.orig        2012-07-16 11:38:34.681045084 +0100
@@ -38,7 +38,7 @@
 #define MAX_SSE_REGS 8

 #ifdef __INTEL_COMPILER
-#define UINT128 long long
+#define UINT128 __m128
 #else
 #define UINT128 __int128_t
 #endif

It compiles fine, but `make check` returns a lot of FAIL's, and a quite a few 
of the tests timeout. e.g.
FAIL: libffi.special/unwindtest.cc  -shared-libgcc -lstdc++ execution test
WARNING: program timed out.

It's probably also worth mentioning that I'm now using icc version 12.1.4

Cheers,
Alex

On Monday 16 Jul 2012 09:53:36 Stefan Krah wrote:
 > Stefan Krah <stefan-usenet@bytereef.org> added the comment:
> 
> Ah, forget that: Alex has apparently already tested that patch.
> 
> ----------
> 
> _______________________________________
> Python tracker <report@bugs.python.org>
> <http://bugs.python.org/issue4130>
> _______________________________________

I just had a dig around my cpython build dir, and found an ffi64.c I hacked at a 
while back.
I copied the edits over to the latest libffi git revision, rebuilt, and `make 
check` (of libffi) passes all tests. So as far as I can tell the below patch 
works, but it is a hack, and I'm sure it could be improved..

Regards to submitting it upstream, I've just written to the libffi-
discuss/sourceware.org mailing list, sending them the below patch also. So it 
might work, but you know that GPL clause about coming with no warranty? ;)

HTH,
Alex

libffi-git> diff -u src/x86/ffi64.c.orig src/x86/ffi64.c

--- src/x86/ffi64.c.orig        2012-07-16 11:38:34.681045084 +0100
+++ src/x86/ffi64.c     2012-07-16 22:34:42.959552750 +0100
@@ -38,7 +38,7 @@
 #define MAX_SSE_REGS 8

 #ifdef __INTEL_COMPILER
-#define UINT128 __m128
+typedef struct { int64_t m[2]; } __int128_t;
 #else
 #define UINT128 __int128_t
 #endif
@@ -47,7 +47,7 @@
 {
   /* Registers for argument passing.  */
   UINT64 gpr[MAX_GPR_REGS];
-  UINT128 sse[MAX_SSE_REGS];
+  __int128_t sse[MAX_SSE_REGS];
 };

 extern void ffi_call_unix64 (void *args, unsigned long bytes, unsigned flags,
@@ -477,10 +477,20 @@
                  break;
                case X86_64_SSE_CLASS:
                case X86_64_SSEDF_CLASS:
+#ifdef __INTEL_COMPILER
+                 reg_args->sse[ssecount].m[0] = *(UINT64 *) a;
+                 reg_args->sse[ssecount++].m[1] = 0;
+#else
                  reg_args->sse[ssecount++] = *(UINT64 *) a;
+#endif
                  break;
                case X86_64_SSESF_CLASS:
+#ifdef __INTEL_COMPILER
+                 reg_args->sse[ssecount].m[0] = *(UINT32 *) a;
+                 reg_args->sse[ssecount++].m[1] = 0;
+#else
                  reg_args->sse[ssecount++] = *(UINT32 *) a;
+#endif
                  break;
                default:
                  abort();

It skips 55, sorry, passing 1659.

That's the same patch as I attached before actually, so sorry for the spam..