[Bug bootstrap/38591] erratic comparison failures on very fast machines

[Ralf dot Wildenhues at gmx dot de]

--- Comment #10 from Ralf dot Wildenhues at gmx dot de  2009-09-17 17:40 
---
Subject: Re:  erratic comparison failures on very fast
 machines

* ebotcazou at gcc dot gnu dot org wrote on Thu, Sep 17, 2009 at 06:58:37PM
CEST:
> > No idea why the borked build does not fail but pick up auto-host.h from
> > elsewhere or so.  Or do you know for sure that auto-host.h was picked up
> > from the current directory?
> 
> Couldn't a truncated auto-host.h have been picked up?

config.status uses mv from a temporary subdirectory to the final
location of the file, thus create it created atomically.  Autoconf 2.59
did this too.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[ebotcazou at gcc dot gnu dot org]

--- Comment #9 from ebotcazou at gcc dot gnu dot org  2009-09-17 16:58 
---
> in gcc/Makefile.in, which means it was lacking $(CONFIG_H) thus lacking
> dependency on auto-host.h.  This was fixed in
> 
> and glancing at that patch, there may be quite a few other dependency issues
> in branch-4_3.

Thanks, will try to add the missing dependency.

> No idea why the borked build does not fail but pick up auto-host.h from
> elsewhere or so.  Or do you know for sure that auto-host.h was picked up
> from the current directory?

Couldn't a truncated auto-host.h have been picked up?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[rwild at gcc dot gnu dot org]

--- Comment #8 from rwild at gcc dot gnu dot org  2009-09-17 16:27 ---
Does this also happen on trunk, or with branch-4_3 only?  AFAICS 4.3.3 had
  sparseset.o: sparseset.c $(SYSTEM_H) sparseset.h

in gcc/Makefile.in, which means it was lacking $(CONFIG_H) thus lacking
dependency on auto-host.h.  This was fixed in

and glancing at that patch, there may be quite a few other dependency issues
in branch-4_3.

No idea why the borked build does not fail but pick up auto-host.h from
elsewhere or so.  Or do you know for sure that auto-host.h was picked up
from the current directory?


-- 

rwild at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||rwild at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[ebotcazou at gcc dot gnu dot org]

--- Comment #7 from ebotcazou at gcc dot gnu dot org  2009-09-06 21:18 
---
In comment #6.


-- 

ebotcazou at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
 Ever Confirmed|0   |1
   Last reconfirmed|-00-00 00:00:00 |2009-09-06 21:18:42
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[rguenth at gcc dot gnu dot org]

--- Comment #6 from rguenth at gcc dot gnu dot org  2008-12-29 22:25 ---
We also see this from time to time.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[hjl dot tools at gmail dot com]

--- Comment #5 from hjl dot tools at gmail dot com  2008-12-21 17:21 ---
Each stage has its own directory and auto-host.h should be
regenerated in each directory. I think it was regenerated
more than once in the same directory.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[ebotcazou at gcc dot gnu dot org]

--- Comment #4 from ebotcazou at gcc dot gnu dot org  2008-12-21 17:12 
---
> auto-host.h must exist when those files were compiled. I guess
> it was generated more than once.

My understanding is that it is re-generated at each stage:

auto-host.h: cstamp-h ; @true
cstamp-h: config.in config.status
CONFIG_HEADERS=auto-host.h:config.in \
CONFIG_FILES= \
LANGUAGES="$(CONFIG_LANGUAGES)" $(SHELL) config.status


In case this can make a difference, the compiler is configured as follows:
--enable-languages=c,ada,c++ --disable-libada --enable-checking=release


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[hjl dot tools at gmail dot com]

--- Comment #3 from hjl dot tools at gmail dot com  2008-12-21 16:18 ---
auto-host.h must exist when those files were compiled. I guess
it was generated more than once.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[ebotcazou at gcc dot gnu dot org]

--- Comment #2 from ebotcazou at gcc dot gnu dot org  2008-12-21 16:07 
---
> What are the differences?

This is explained in the message.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591

[Bug bootstrap/38591] erratic comparison failures on very fast machines

[hjl dot tools at gmail dot com]

--- Comment #1 from hjl dot tools at gmail dot com  2008-12-21 15:20 ---
What are the differences? While working on a patch, I had an
uninitialized stack variable, which caused random comparison
failures.


-- 

hjl dot tools at gmail dot com changed:

   What|Removed |Added

 CC||hjl dot tools at gmail dot
   ||com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38591