Windows breakage -- again

[Carter Schonwald]

Huh. We're not generating the atomics assembly directly ourselves?

On Wednesday, July 16, 2014, Johan Tibell <johan.tibell at gmail.com> wrote:

> I added some primops about a month ago
> (4ee4ab01c1d97845aecb7707ad2f9a80933e7a49) that call __sync_fetch_and_add,
> a gcc/llvm builtin. I'm a bit surprised to see this error. The GCC manual
> [1] says:
>
> > " Not all operations are supported by all target processors. If a
> particular operation cannot be implemented on the target processor, a
> warning will be generated and a call an external function will be
> generated. The external function will carry the same name as the builtin,
> with an additional suffix `_n' where n is the size of the data type."
>
> I'm a bit surprised by this error for two reasons:
>
>  * A call to that symbol should only be generated if the CPU doesn't
> support the atomic instructions. What CPU model does Windows report that
> you have?
>
>  * gcc should define such a symbol. For me the following test program
> compiles:
>
> #include <stdint.h>
>
> uint8_t test(uint8_t* ptr, uint8_t val) {
>   return __sync_fetch_and_add_1(ptr, val);
> }
>
> int main(void) {
>   uint8_t n;
>   return test(&n, 1);
> }
>
> Does that compile for you? Which version of GCC do we end up using on
> Windows?
>
> The reported symbol (___sync_fetch_and_add_1) has three leading
> underscores, that looks weird. Can you compile just
> libraries/ghc-prim/cbits/atomic.c and see if it's indeed GCC that generates
> a reference to that symbol?
>
> 1. http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Atomic-Builtins.html
>
>
> On Wed, Jul 16, 2014 at 12:29 AM, Simon Peyton Jones <
> simonpj at microsoft.com
> <javascript:_e(%7B%7D,'cvml','simonpj at microsoft.com');>> wrote:
>
>>  Aargh!  The Windows build has broken – again.  I can’t build GHC on my
>> laptop any more.
>>
>> A clean ‘sh validate’ finishes as below.  What on earth is
>> `___sync_fetch_and_add_1'?
>>
>> Can anyone help?  Thanks!
>>
>> Simon
>>
>> "inplace/bin/ghc-stage2.exe" -hisuf hi -osuf  o -hcsuf hc -static  -H32m
>> -O -Werror -Wall -H64m -O0    -package-name vector-0.10.9.1
>> -hide-all-packages -i -ilibraries/vector/.
>> -ilibraries/vector/dist-install/build
>> -ilibraries/vector/dist-install/build/autogen
>> -Ilibraries/vector/dist-install/build
>> -Ilibraries/vector/dist-install/build/autogen -Ilibraries/vector/include
>> -Ilibraries/vector/internal   -optP-DVECTOR_BOUNDS_CHECKS -optP-include
>> -optPlibraries/vector/dist-install/build/autogen/cabal_macros.h -package
>> base-4.7.1.0 -package deepseq-1.3.0.2 -package ghc-prim-0.3.1.0 -package
>> primitive-0.5.2.1 -O2 -XHaskell98 -XCPP -XDeriveDataTypeable -O2 -O
>> -dcore-lint -fno-warn-deprecated-flags  -no-user-package-db -rtsopts
>> -Wwarn     -odir libraries/vector/dist-install/build -hidir
>> libraries/vector/dist-install/build -stubdir
>> libraries/vector/dist-install/build   -c
>> libraries/vector/./Data/Vector/Fusion/Stream/Monadic.hs -o
>> libraries/vector/dist-install/build/Data/Vector/Fusion/Stream/Monadic.o
>>
>> Loading package ghc-prim ... linking ... ghc-stage2.exe: unable to load
>> package `ghc-prim'
>>
>> ghc-stage2.exe:
>> C:\code\HEAD\libraries\ghc-prim\dist-install\build\HSghc-prim-0.3.1.0.o:
>> unknown symbol `___sync_fetch_and_add_1'
>>
>> libraries/vector/ghc.mk:5: recipe for target
>> 'libraries/vector/dist-install/build/Data/Vector/Fusion/Stream/Monadic.o'
>> failed
>>
>> make[1]: ***
>> [libraries/vector/dist-install/build/Data/Vector/Fusion/Stream/Monadic.o]
>> Error 1
>>
>>
>>
>> I
>>
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>>
>>
>
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