Re: Windows breakage -- again

Alright, then which Make file do we need to fix to make sure GCC is called correctly? Also, I remember reading that some time during the 4.x GCC series GCC switched to auto-detecting the arch to be that of the machine being used. Could someone try to just switch GCC to a newer version and see if it automatically stops trying to use i386, leading to Simon's problem? On Thu, Jul 17, 2014 at 8:37 AM, Niklas Larsson wrote:

It certainly shouldn't be built with i386, because that is generating code for a processor that lacks all these fancy atomic instructions. The first of them appears on the 486.

i686 should be safe, it goes all the way back to Pentium Pro.

2014-07-17 8:33 GMT+02:00 Johan Tibell :

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A perhaps silly question, *should* ghc-prim be built with i386 or i686?

On Thu, Jul 17, 2014 at 8:33 AM, Niklas Larsson wrote:

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I just found exactly the same thing! Well, I used i686 instead.

Sounds like it's worthwhile to see if this is limited to ghc-prim or if there's more stuff that's built with i386.

2014-07-17 8:21 GMT+02:00 Páli Gábor János :

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2014-07-17 0:51 GMT+02:00 Páli Gábor János :

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2014-07-17 0:47 GMT+02:00 Niklas Larsson :

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I hope they can just be done away with at the source, that is to make gcc generate the assembly primitives. GHC should already be built with i686, but does that reach ghc-prim?

This depends on GCC -- if no -march=XXX is explicitly set, I guess it will take its default, which may vary platform by platform.

All right, I have finally got a Windows (x64) machine and installed the msys2 environment by the GHC wiki [1]. This has GCC 4.5.2 (as Niklas wrote earlier), where the default -march is i386. You should see this line when trying to compile Johan's test program with the -v flag set:

COLLECT_GCC_OPTIONS= ... '-v' '-mtune=i386' '-march=i386'

With the -march=i586 flag explicitly set in the command line, no __sync_fetch_and_add_n() calls are generated.

[1]

https://ghc.haskell.org/trac/ghc/wiki/Building/Preparation/Windows/MSYS2