[Bug c/29299] New: gcc "used" attribute has no effect on local-scope static variables

[Bug c/29299] New: gcc "used" attribute has no effect on local-scope static variables

[jeremy at goop dot org]

Adding the "used" attribute to locally-scoped static variables has no effect,
and they are not emitted into the output .s file.

I am using this in combination with the "section" attribute so I can collect
the data together; it doesn't matter to me that there's no useful mapping
between the C name and the assembler name.


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           Summary: gcc "used" attribute has no effect on local-scope static
                    variables
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jeremy at goop dot org
 GCC build triplet: i386-redhat-linux
  GCC host triplet: i386-redhat-linux
GCC target triplet: i386-redhat-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug c/29299] gcc "used" attribute has no effect on local-scope static variables

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-09-30 16:04 -------
Do you have an example code?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug c/29299] gcc "used" attribute has no effect on local-scope static variables

[jeremy at goop dot org]

------- Comment #2 from jeremy at goop dot org  2006-09-30 16:46 -------
Created an attachment (id=12360)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12360&action=view)
compile with "gcc -O -S t.c"


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regresion] gcc "used" attribute has no effect on local-scope static variables

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-09-30 19:40 -------
4.1.2 works:
        .local  bar.1279
        .comm   bar.1279,4,4
        .local  bof
        .comm   bof,4,4

while 4.2.0 does not:
        .local  bof
        .comm   bof,4,4


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|c                           |middle-end
     Ever Confirmed|0                           |1
  GCC build triplet|i386-redhat-linux           |
   GCC host triplet|i386-redhat-linux           |
 GCC target triplet|i386-redhat-linux           |
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2006-09-30 19:40:21
               date|                            |
            Summary|gcc "used" attribute has no |[4.2 Regresion] gcc "used"
                   |effect on local-scope static|attribute has no effect on
                   |variables                   |local-scope static variables
   Target Milestone|---                         |4.2.0
            Version|4.1.1                       |4.2.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regresion] gcc "used" attribute has no effect on local-scope static variables

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regresion] gcc "used" attribute has no effect on local-scope static variables

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2006-10-09 13:04 -------
We have

bool
decide_is_variable_needed (struct cgraph_varpool_node *node, tree decl)
{
  /* If the user told us it is used, then it must be so.  */
  if (node->externally_visible || node->force_output)
    return true;
  if (!flag_unit_at_a_time
      && lookup_attribute ("used", DECL_ATTRIBUTES (decl)))
    return true;

with "used" set on bar...

Now, the handler for attribute "used" sets DECL_PRESERVE_P on the decl, so
we might as well check that.

Index: cgraph.c
===================================================================
*** cgraph.c    (revision 117569)
--- cgraph.c    (working copy)
*************** bool
*** 939,948 ****
  decide_is_variable_needed (struct cgraph_varpool_node *node, tree decl)
  {
    /* If the user told us it is used, then it must be so.  */
!   if (node->externally_visible || node->force_output)
!     return true;
!   if (!flag_unit_at_a_time
!       && lookup_attribute ("used", DECL_ATTRIBUTES (decl)))
      return true;

    /* ??? If the assembler name is set by hand, it is possible to assemble
--- 939,947 ----
  decide_is_variable_needed (struct cgraph_varpool_node *node, tree decl)
  {
    /* If the user told us it is used, then it must be so.  */
!   if (node->externally_visible
!       || node->force_output
!       || DECL_PRESERVE_P (decl))
      return true;

    /* ??? If the assembler name is set by hand, it is possible to assemble


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2006-09-30 19:40:21         |2006-10-09 13:04:55
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regresion] gcc "used" attribute has no effect on local-scope static variables

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2006-10-15 16:33 -------
Fixed.


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pinskia at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regresion] gcc "used" attribute has no effect on local-scope static variables

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2006-10-15 17:03 -------
Not yet for -fno-unit-at-a-time.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regresion] gcc "used" attribute has no effect on local-scope static variables

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regression] gcc "used" attribute has no effect on local-scope static variables

[hubicka at ucw dot cz]

------- Comment #9 from hubicka at ucw dot cz  2006-10-15 22:33 -------
Subject: Re:  [4.2 Regresion] gcc "used" attribute has no effect on local-scope
static variables

> Reopening because it is not fixed for non unit at a time mode (-O0 for C).
-O0 gets it right, just -O1 -fno-unit-at-a-time fails, but I am testing
patch for this already.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regression] gcc "used" attribute has no effect on local-scope static variables

[hubicka at gcc dot gnu dot org]

------- Comment #10 from hubicka at gcc dot gnu dot org  2006-10-18 21:40 -------
Subject: Bug 29299

Author: hubicka
Date: Wed Oct 18 21:39:52 2006
New Revision: 117863

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=117863
Log:
        PR middle-end/29299
        * cfgexpand.c (expand_used_vars_for_block): Vars marked used by user
        are used.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgexpand.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regression] gcc "used" attribute has no effect on local-scope static variables

[hubicka at gcc dot gnu dot org]

------- Comment #11 from hubicka at gcc dot gnu dot org  2006-10-18 21:54 -------
Patch for non-unit-at-a-time comitted now.


-- 

hubicka at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299

[Bug middle-end/29299] [4.2 Regression] gcc "used" attribute has no effect on local-scope static variables

[jakub at gcc dot gnu dot org]

------- Comment #12 from jakub at gcc dot gnu dot org  2007-06-26 11:52 -------
Subject: Bug 29299

Author: jakub
Date: Tue Jun 26 11:52:20 2007
New Revision: 126026

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=126026
Log:
2006-10-18  Jan Hubicka  <jh@suse.cz>

        PR middle-end/29299
        * cfgexpand.c (expand_used_vars_for_block): Vars marked used by user
        are used.

2006-10-15  Jan Hubicka  <jh@suse.cz>
            Richard Guenther  <rguenther@suse.de>

        PR middle-end/29299
        * cgraphunit.c (cgraph_finalize_compilation_unit): Call
        process_function_and_variable_attributes on all variables, including
        those discovered during cgraph construction phase.

        * gcc.dg/pr29299.c: New testcase.

Added:
    branches/redhat/gcc-4_1-branch/gcc/testsuite/gcc.dg/pr29299.c
Modified:
    branches/redhat/gcc-4_1-branch/gcc/ChangeLog
    branches/redhat/gcc-4_1-branch/gcc/cfgexpand.c
    branches/redhat/gcc-4_1-branch/gcc/cgraphunit.c
    branches/redhat/gcc-4_1-branch/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29299