[Bug c++/56854] New: error: non-decl/MEM_REF LHS in clobber statement

[Bug c++/56854] New: error: non-decl/MEM_REF LHS in clobber statement

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56854

             Bug #: 56854
           Summary: error: non-decl/MEM_REF LHS in clobber statement
    Classification: Unclassified
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dcb314@hotmail.com


I just tried to compile the package openlierox-0.59-0.10
on gcc-4.9 trunk dated 20130403 on an AMD x86_64 box.

The compiler said

/home/dcb/rpmbuild/BUILD/OpenLieroX/src/game/Settings.h: In constructor
'FeatureSettingsLayer::FeatureSettingsLayer(const string&)':
/home/dcb/rpmbuild/BUILD/OpenLieroX/src/game/Settings.h:49:2: error:
non-decl/MEM_REF LHS in clobber statement
  FeatureSettingsLayer(const std::string& debug_name_) :
debug_name(debug_name_) { makeSet(false); }
  ^
MEM[(struct ScriptVar_t *)this_1(D)].settings[_32]
# .MEM_113 = VDEF <.MEM_85>
MEM[(struct ScriptVar_t *)this_1(D)].settings[_32] ={v} {CLOBBER};

/home/dcb/rpmbuild/BUILD/OpenLieroX/src/game/Settings.h:49:2: internal compiler
error: verify_gimple failed
0xab89f9 verify_gimple_in_cfg(function*)
    ../../src/trunk/gcc/tree-cfg.c:4769
0x9efe17 execute_function_todo
    ../../src/trunk/gcc/passes.c:1963
0x9f0807 execute_todo
    ../../src/trunk/gcc/passes.c:1996
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

Preprocessed source code attached. Flag -O2 required.

[Bug c++/56854] error: non-decl/MEM_REF LHS in clobber statement

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56854

--- Comment #1 from David Binderman <dcb314 at hotmail dot com> 2013-04-06 09:45:18 UTC ---
Created attachment 29813
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29813
gzipped C++ source code

[Bug tree-optimization/56854] [4.9 Regression] error: non-decl/MEM_REF LHS in clobber statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56854

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |tree-optimization
   Target Milestone|---                         |4.9.0
            Summary|error: non-decl/MEM_REF LHS |[4.9 Regression] error:
                   |in clobber statement        |non-decl/MEM_REF LHS in
                   |                            |clobber statement

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> 2013-04-08 11:09:28 UTC ---
It's very likely forwprop that does this.  We should probably disallow
any forwprop into CLOBBER lhs.  CCP will do everything that is allowed.

[Bug tree-optimization/56854] [4.9 Regression] error: non-decl/MEM_REF LHS in clobber statement

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56854

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

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

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-04-08 14:15:17 UTC ---
So like this?

Reducing testcase now...

--- tree-ssa-forwprop.c.jj12013-02-25 23:51:21.000000000 +0100
+++ tree-ssa-forwprop.c2013-04-08 16:12:37.908611768 +0200
@@ -826,7 +826,11 @@ forward_propagate_addr_expr_1 (tree name
        && integer_zerop (TREE_OPERAND (lhs, 1))
        && useless_type_conversion_p
             (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
-             TREE_TYPE (gimple_assign_rhs1 (use_stmt))))
+             TREE_TYPE (gimple_assign_rhs1 (use_stmt)))
+       /* Don't forward anything into clobber stmts if it would result
+          in the lhs no longer being a MEM_REF.  */
+       && (!gimple_clobber_p (use_stmt)
+           || TREE_CODE (TREE_OPERAND (def_rhs, 0)) == MEM_REF))
 {
   tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
   tree new_offset, new_base, saved, new_lhs;

[Bug tree-optimization/56854] [4.9 Regression] error: non-decl/MEM_REF LHS in clobber statement

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56854

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

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

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-04-09 10:16:15 UTC ---
Author: jakub
Date: Tue Apr  9 10:04:24 2013
New Revision: 197625

URL: http://gcc.gnu.org/viewcvs?rev=197625&root=gcc&view=rev
Log:
    PR tree-optimization/56854
    * tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Don't
    forward into clobber stmts if it would change MEM_REF lhs into
    non-MEM_REF.

    * g++.dg/torture/pr56854.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/torture/pr56854.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-forwprop.c