[Bug debug/41616] New: Variables promoted to Gimple registers by aliasing are not getting debug statements.

[Bug debug/41616] New: Variables promoted to Gimple registers by aliasing are not getting debug statements.

[hubicka at gcc dot gnu dot org]

In the following testcase:
inline int f(int *a)
{
  return *a;
}
main()
{
  int b=1;
  return f(&b);
}
We ought to be able to track that value of "b" is 1.  However we do not:
main ()
{
<bb 2>:
  # DEBUG a => &b
  return 1;

}


-- 
           Summary: Variables promoted to Gimple registers by aliasing are
                    not getting debug statements.
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: aoliva at gcc dot gnu dot org
        ReportedBy: hubicka at gcc dot gnu dot org
  GCC host triplet: x86_64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41616

[Bug debug/41616] Variables promoted to Gimple registers by aliasing are not getting debug statements.

[hubicka at ucw dot cz]

------- Comment #1 from hubicka at ucw dot cz  2009-10-07 11:26 -------
Subject: Re:   New: Variables promoted to Gimple registers by aliasing are not
getting debug statements.

> We ought to be able to track that value of "b" is 1.  However we do not:
> main ()
> {
> <bb 2>:
>   # DEBUG a => &b

Note that Richi was mentioning that &b is invalid given that b is
register.  I think it is OK - the ADDR_EXPRs in DEBUG statements does
not count as dereferences.

However we sould be able to track here a => &1 and at dwarf2out time try
to look up 1 in constant pool if there.  For integer constants this is
unlikely going to win, but for i.e. string constants this is quite
common case we might get better debug info. The tree expansion facility
now has neccesary code to do that, I can put it into RTL expansion too.

Honza


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41616

[Bug debug/41616] Variables promoted to Gimple registers by aliasing are not getting debug statements.

[aoliva at gcc dot gnu dot org]

------- Comment #2 from aoliva at gcc dot gnu dot org  2009-10-08 21:34 -------
Yup, ADDR_EXPRs don't count as dereferences in debug stmts, but if the variable
doesn't get a memory location, we end up dropping the whole expression.  We
have to.  Finding another location holding the value of b isn't enough if the
relevant value is the address of b.  Since b did not get a memory location, its
address is non-existent.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41616

[Bug debug/41616] Variables promoted to Gimple registers by aliasing are not getting debug statements.

[aoliva at gcc dot gnu dot org]

------- Comment #3 from aoliva at gcc dot gnu dot org  2009-10-12 05:15 -------
Subject: Bug 41616

Author: aoliva
Date: Mon Oct 12 05:15:02 2009
New Revision: 152662

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=152662
Log:
gcc/ChangeLog:
PR debug/41616
* tree-into-ssa.c (insert_phi_nodes_for): Build debug bind stmts
on updates too.
(maybe_register_def): Likewise.  Take stmt iterator.
(rewrite_update_stmt): Take stmt iterator and pass it on.
(rewrite_update_enter_block): Pass stmt iterator.
gcc/testsuite/ChangeLog:
PR debug/41616
* gcc.dg/guality/pr41616-1.c: New.

Added:
    trunk/gcc/testsuite/gcc.dg/guality/pr41616-1.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-into-ssa.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41616

[Bug debug/41616] Variables promoted to Gimple registers by aliasing are not getting debug statements.

[aoliva at gcc dot gnu dot org]

------- Comment #4 from aoliva at gcc dot gnu dot org  2009-10-12 18:22 -------
Fixed.


-- 

aoliva at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aoliva at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41616