Re: [PATCH] rs6000: Disable generation of lwa in 32-bit mode

2012-10-27 Thread Alan Modra 
On Sat, Oct 27, 2012 at 06:33:34AM +0200, Segher Boessenkool wrote:
 some (20040709-2.c, etc.) fail with a linker error now, instead of

Hmm, packed structs.  If gcc is generating mis-aligned accesses using
lwa or ld, that would be another TARGET_64BIT vs TARGET_POWERPC64
bug, wouldn't it?

-- 
Alan Modra
Australia Development Lab, IBM

Re: [PATCH] rs6000: Disable generation of lwa in 32-bit mode

2012-10-27 Thread Segher Boessenkool 

some (20040709-2.c, etc.) fail with a linker error now, instead of


Hmm, packed structs.  If gcc is generating mis-aligned accesses using
lwa or ld, that would be another TARGET_64BIT vs TARGET_POWERPC64
bug, wouldn't it?


I have analysed it, patch on the way.  The problem is LO_SUMs of
misaligned symbols; we never get those in practice on 64-bit
because things go via the TOC, but the problem is there in theory
for 64-bit as well.


Segher

Re: [PATCH] rs6000: Disable generation of lwa in 32-bit mode

2012-10-26 Thread Peter Bergner 
On Fri, 2012-10-26 at 15:00 +1030, Alan Modra wrote:
 On Thu, Oct 25, 2012 at 03:57:38PM -0700, Segher Boessenkool wrote:
  for most others.  This patch disables all lwa insns in 32-bit mode.
  We can later re-enable it if the assembler used handles it properly,
 
 Well, you can now do that.  Mainline gas and ld are now fixed.

Now that gas and ld are fixed, can we use a configure time check to
see whether we're using a fixed gas/ld or not before we disable them?

Peter

Re: [PATCH] rs6000: Disable generation of lwa in 32-bit mode

2012-10-26 Thread Segher Boessenkool 

for most others.  This patch disables all lwa insns in 32-bit mode.
We can later re-enable it if the assembler used handles it properly,


Well, you can now do that.  Mainline gas and ld are now fixed.


Yes, you are much too quick for me to keep up.  Thank you!


Now that gas and ld are fixed, can we use a configure time check to
see whether we're using a fixed gas/ld or not before we disable them?


When I wrote this patch, I thought the Darwin assembler had the same
problem.  No idea how I got that in my mind; it doesn't.  And AIX does
not support -m32 -mpowerpc64 at all (the compiler disallows it), so
that is out of the picture as well.

I now bootstrapped and tested with the new binutils.  Most of the
testcases that were fixed with my patch are fixed there as well; and
some (20040709-2.c, etc.) fail with a linker error now, instead of
the runtime error.  Some fail that passed without either patch, but
failing is correct -- wrong code sometimes runs fine :-)

So I'm not applying this patch.  I don't think we need a configure
check: we have had many releases with these bugs already, one more
won't hurt.  People generally use a recent version of binutils as well.


Segher

Re: [PATCH] rs6000: Disable generation of lwa in 32-bit mode

2012-10-25 Thread David Edelsohn 
On Thu, Oct 25, 2012 at 6:57 PM, Segher Boessenkool
seg...@kernel.crashing.org wrote:

 2012-10-25  Segher Boessenkool  seg...@kernel.crashing.org

 gcc/
 * config/rs6000/rs6000.md (sign_extend:SI patterns): Split
 the memory case off.  Merge the two register cases.  Change
 the condition for the memory case to require 64-bit mode.

This is okay.

Thanks, David

Re: [PATCH] rs6000: Disable generation of lwa in 32-bit mode

2012-10-25 Thread Alan Modra 
On Thu, Oct 25, 2012 at 03:57:38PM -0700, Segher Boessenkool wrote:
 for most others.  This patch disables all lwa insns in 32-bit mode.
 We can later re-enable it if the assembler used handles it properly,

Well, you can now do that.  Mainline gas and ld are now fixed.

-- 
Alan Modra
Australia Development Lab, IBM