[Bug tree-optimization/61203] [4.7/4.8/4.9/4.10 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[Bug tree-optimization/61203] [4.7/4.8/4.9/4.10 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.4

[Bug tree-optimization/61203] [4.7/4.8/4.9/4.10 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.4                       |4.8.4

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The 4.7 branch is being closed, moving target milestone to 4.8.4.

[Bug tree-optimization/61203] [4.8/4.9/4.10 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |matz at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This started with r181332.  forwprop3 moves the comparison after the CLOBBER
stmt and IPA opts change the method so that it doesn't take the argument that
it doesn't use, so there are no references to a anymore before the temporary
goes out of scope and expansion decides to allocate them at the same spot.  No
idea what to do against this though, treating a CLOBBER as a barrier for
propagation of addresses to other local variables would penalize stuff way too
much.  And giving up on stack slot sharing because of such an artificial
testcase is not useful either.

[Bug tree-optimization/61203] [4.8/4.9/5 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2014-12-01
                 CC|                            |jason at gcc dot gnu.org
     Ever confirmed|0                           |1
      Known to fail|4.10.0                      |5.0

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Michael Matz from comment #3)
> (In reply to Jakub Jelinek from comment #2)
> > same spot.  No idea what to do against this though, treating a CLOBBER as a
> > barrier for propagation of addresses to other local variables would penalize
> > stuff way too much.
> 
> Conceptually this should be the right thing.  The clobber says
> the object doesn't exist anymore, so also forming its address should be
> invalid/implementation defined.  Either the clobber should move or it should
> be a barrier also for addresses of the clobbered object.  I'm not sure if
> that
> really would penalize much.

But I don't see how it could be easily implemented.

> > And giving up on stack slot sharing because of such an
> > artificial testcase is not useful either.
> 
> Perhaps expansion could detect the situation (address of clobbered object
> leaked after the clobber) and disable sharing just for such problematic
> objects.

Likewise.  (it would be whether the address escaped the function before
the clobber)

I'd rather say that optimization is permitted to make &a and A(a).get_this ()
equal.

Btw, there is also the missed optimization that get_this, discovered as
'const', passed &decl can only return either NULL or an address based on
&decl and thus the result cannot compare equal to &a.  So even without
inlining we could statically compute the comparison.

[Bug tree-optimization/61203] [4.8/4.9/5 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.4                       |4.8.5

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.8.4 has been released.

[Bug tree-optimization/61203] [4.8/4.9/5/6 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.5                       |4.9.3

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
The gcc-4_8-branch is being closed, re-targeting regressions to 4.9.3.

[Bug tree-optimization/61203] [4.9/5/6 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.9.3 has been released.

[Bug tree-optimization/61203] [4.9/5/6 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.9.3                       |4.9.4

[Bug tree-optimization/61203] [5/6/7/8 Regression] g++.old-deja/g++.jason/rvalue2.C FAILs with -O2 -fno-inline

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61203
Bug 61203 depends on bug 90348, which changed state.

Bug 90348 Summary: [11 Regression] Partition of char arrays is incorrect in some cases
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90348

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED