[Bug bootstrap/16865] New: False alarm about use of uninitialized variable breaks bootstrap at -O3

[Bug bootstrap/16865] New: False alarm about use of uninitialized variable breaks bootstrap at -O3

[v dot haisman at sh dot cvut dot cz]

Bootstrap with -O3 dies with error bellow. It is false alarm about use of
uninitialized variable. With -O2 the warning doesn't trigger.


make[2]: Entering directory `/home/4/wilx/tmp/gcc-head/objdir/gcc'
stage1/xgcc -Bstage1/ -B/home/4/wilx/i386-unknown-freebsd4.10/bin/ -c   -O3 -g
-DIN_GCC   -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes
-pedantic -Wno-long-long -Wno-variadic-macros -Wold-style-definition -Werror
-fno-common   -DHAVE_CONFIG_H    -I. -I. -I../../srcdir/gcc -I../../srcdir/gcc/.
-I../../srcdir/gcc/../include -I../../srcdir/gcc/../libcpp/include
-I../../srcdir/gcc/../libbanshee/libcompat -I../../srcdir/gcc/../libbanshee
-I../../srcdir/gcc/../libbanshee/points-to  ../../srcdir/gcc/loop-iv.c -o loop-iv.o
../../srcdir/gcc/loop-iv.c: In function `simplify_using_initial_values':
../../srcdir/gcc/loop-iv.c:1360: warning: 'lhs' may be used uninitialized in
this function
make[2]: *** [loop-iv.o] Error 1
make[2]: Leaving directory `/home/4/wilx/tmp/gcc-head/objdir/gcc'
make[1]: *** [stage2_build] Error 2
make[1]: Leaving directory `/home/4/wilx/tmp/gcc-head/objdir/gcc'
make: *** [bootstrap] Error 2

I've used this to unbreak the bootstrap:
Index: gcc/loop-iv.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/loop-iv.c,v
retrieving revision 2.13
diff -c -p -r2.13 loop-iv.c
*** gcc/loop-iv.c       27 Jul 2004 07:27:12 -0000      2.13
--- gcc/loop-iv.c       3 Aug 2004 20:22:07 -0000
*************** static void
*** 1357,1363 ****
  simplify_using_assignment (rtx insn, rtx *expr, regset altered)
  {
    rtx set = single_set (insn);
!   rtx lhs, rhs;
    bool ret = false;

    if (set)
--- 1357,1363 ----
  simplify_using_assignment (rtx insn, rtx *expr, regset altered)
  {
    rtx set = single_set (insn);
!   rtx lhs = 0, rhs;
    bool ret = false;

    if (set)

-- 
           Summary: False alarm about use of uninitialized variable breaks
                    bootstrap at -O3
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: bootstrap
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: v dot haisman at sh dot cvut dot cz
                CC: gcc-bugs at gcc dot gnu dot org,v dot haisman at sh dot
                    cvut dot cz
 GCC build triplet: i386-unknown-freebsd4.10
  GCC host triplet: i386-unknown-freebsd4.10
GCC target triplet: i386-unknown-freebsd4.10


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-03 20:44 -------
Confirmed and the reason why it does not trigger at -O2 is because altered_reg_used does not get 
inlined so the variable is consided to take the address of so we cannot warn about that.

I will commit the obvious fix.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pinskia at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|                            |1
           Keywords|                            |build
   Last reconfirmed|0000-00-00 00:00:00         |2004-08-03 20:44:19
               date|                            |
   Target Milestone|---                         |3.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-03 21:13 -------
Fixed.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-08-03 21:13 -------
Subject: Bug 16865

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	pinskia@gcc.gnu.org	2004-08-03 21:13:15

Modified files:
	gcc            : ChangeLog loop-iv.c 

Log message:
	2004-08-03  Andrew Pinski  <apinski@apple.com>
	
	PR bootstrap/16865
	* loop-iv.c (simplify_using_assignment): Initialize lhs.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.4784&r2=2.4785
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/loop-iv.c.diff?cvsroot=gcc&r1=2.13&r2=2.14



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[v dot haisman at sh dot cvut dot cz]

------- Additional Comments From v dot haisman at sh dot cvut dot cz  2004-08-03 21:49 -------
I posted the PR too early. There were some more:

../../srcdir/gcc/var-tracking.c:2500: warning: 'offset' may be used
uninitialized in this function
../../srcdir/gcc/var-tracking.c:2499: warning: 'decl' may be used uninitialized
in this function
../../srcdir/gcc/cp/parser.c:6742: warning: 'token2$type' may be used
uninitialized in this function
../../srcdir/gcc/cp/parser.c:6742: warning: 'token2$keyword' may be used
uninitialized in this function



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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-03 22:00 -------
The var-tracking ones look like a real bug in the compiler code (not in this var-tracking one though):
      if (!vt_get_decl_and_offset (incoming, &decl, &offset))
        if (!vt_get_decl_and_offset (decl_rtl, &decl, &offset))
          continue;

Now the cp/parser one is really a true posiable use of the uninitialized variable.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|pinskia at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|REOPENED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[v dot haisman at sh dot cvut dot cz]

------- Additional Comments From v dot haisman at sh dot cvut dot cz  2004-08-19 09:03 -------
Bootstrap of yesterday's CVS sources showed some more of these. Worked around
with patch bellow:

Index: gcc/tree-vectorizer.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-vectorizer.c,v
retrieving revision 2.2
diff -c -p -r2.2 tree-vectorizer.c
*** gcc/tree-vectorizer.c       19 Aug 2004 07:16:55 -0000      2.2
--- gcc/tree-vectorizer.c       19 Aug 2004 08:44:21 -0000
*************** vect_create_index_for_array_ref (tree st
*** 591,597 ****
    loop_vec_info loop_info = loop->aux;
    int vectorization_factor = LOOP_VINFO_VECT_FACTOR (loop_info);
    tree vf;
!   tree array_first_index;
    tree indx_before_incr, indx_after_incr;
    int loopnum = loop->num;
    bool ok;
--- 591,597 ----
    loop_vec_info loop_info = loop->aux;
    int vectorization_factor = LOOP_VINFO_VECT_FACTOR (loop_info);
    tree vf;
!   tree array_first_index = NULL_TREE;
    tree indx_before_incr, indx_after_incr;
    int loopnum = loop->num;
    bool ok;
*************** vect_compute_data_ref_alignment (struct
*** 2248,2254 ****
    tree init;
    tree scalar_type;
    tree misalign;
!   tree array_first_index;
    tree array_base = DR_BASE_NAME (dr);
    tree base_decl = NULL_TREE;
    tree bit_offset = size_zero_node;
--- 2248,2254 ----
    tree init;
    tree scalar_type;
    tree misalign;
!   tree array_first_index = NULL_TREE;
    tree array_base = DR_BASE_NAME (dr);
    tree base_decl = NULL_TREE;
    tree bit_offset = size_zero_node;


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-10-18 00:26 -------
Here is some more with --enable-intermodule which means a huge amount more inlining:
/Users/pinskia/src/local/gcc/gcc/cfgbuild.c: In function 'make_edges':
/Users/pinskia/src/local/gcc/gcc/cfgbuild.c:289: warning: 'tmp' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/jump.c: In function 'delete_related_insns':
/Users/pinskia/src/local/gcc/gcc/jump.c:1390: warning: 'lab_next' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c: In function 'cfg_layout_delete_block':
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c:369: warning: 'tmp' may be used uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c: In function 'rtl_delete_block':
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c:369: warning: 'tmp' may be used uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-dom.c: In function 'simplify_cond_and_lookup_avail_expr':
/Users/pinskia/src/local/gcc/gcc/tree-ssa-dom.c:1912: warning: 'cond_inverted' may be used 
uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-dom.c:1911: warning: 'cond_low' may be used uninitialized 
in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-dom.c:1911: warning: 'cond_high' may be used 
uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-dom.c:2015: warning: 'tmp_low' may be used uninitialized 
in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-dom.c:2015: warning: 'tmp_high' may be used uninitialized 
in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-loop-ivopts.c: In function 'get_computation_at':
/Users/pinskia/src/local/gcc/gcc/tree-ssa-loop-ivopts.c:2158: warning: 'ratioi' may be used 
uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/var-tracking.c: In function 'vt_initialize':
/Users/pinskia/src/local/gcc/gcc/var-tracking.c:2500: warning: 'decl' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/var-tracking.c:2501: warning: 'offset' may be used uninitialized in 
this function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c: In function 'try_crossjump_to_edge':
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:1358: warning: 'table1' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:1357: warning: 'label1' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:1358: warning: 'table2' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:1357: warning: 'label2' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:1572: warning: 'label1' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:1572: warning: 'label2' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c: In function 'redirect_branch_edge':
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c:871: warning: 'tmp' may be used uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c: In function 'force_nonfallthru_and_redirect':
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c:993: warning: 'note' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c: In function 'try_redirect_by_replacing_jump':
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c:772: warning: 'table' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgrtl.c:772: warning: 'label' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c: In function 'try_optimize_cfg':
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:729: warning: 'table' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cfgcleanup.c:729: warning: 'label' may be used uninitialized in this 
function
/Users/pinskia/src/local/gcc/gcc/cse.c: In function 'fold_rtx':
/Users/pinskia/src/local/gcc/gcc/cse.c:3224: warning: 'next' may be used uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/tree-ssa-loop-ivopts.c: In function 'get_computation_cost_at':
/Users/pinskia/src/local/gcc/gcc/tree-ssa-loop-ivopts.c:2802: warning: 'ratio' may be used 
uninitialized in this function
/Users/pinskia/src/local/gcc/gcc/value-prof.c: In function 'rtl_value_profile_transformations':
/Users/pinskia/src/local/gcc/gcc/value-prof.c:929: warning: 'write' may be used uninitialized in this 
function

Most of these come from inlining tablejump_p.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-01-23 13:33 -------
What is the status on this one? 
 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-23 15:26 -------
Well it still happens.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
   Last reconfirmed|2005-01-17 00:32:43         |2005-01-23 15:26:05
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[mmitchel at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.0                       |4.0.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[mmitchel at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.1                       |4.0.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.2                       |4.0.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[v dot haisman at sh dot cvut dot cz]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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------- Comment #11 from v dot haisman at sh dot cvut dot cz  2007-06-09 08:33 -------
I guess this is now passé.


-- 

v dot haisman at sh dot cvut dot cz changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[gdr at gcc dot gnu dot org]

------- Comment #10 from gdr at gcc dot gnu dot org  2007-01-18 03:00 -------
Won't fix for GCC-4.0.x


-- 

gdr at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.4                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865

[Bug bootstrap/16865] False alarm about use of uninitialized variable breaks bootstrap at -O3

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.3                       |4.0.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16865