[Bug tree-optimization/19831] Missing DSE/malloc/free optimization

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19831

--- Comment #10 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-09-08 13:00:32 UTC ---
Author: rguenth
Date: Thu Sep  8 13:00:23 2011
New Revision: 178687

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178687
Log:
2011-09-08  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/19831
    * tree-ssa-dce.c (mark_all_reaching_defs_necessary_1): Also
    skip builtins with vdefs that do not really store something.
    (propagate_necessity): For calls to free that we can associate
    with an allocation function do not mark the freed pointer
    definition necessary.
    (eliminate_unnecessary_stmts): Remove a call to free if
    the associated call to an allocation function is not necessary.

    * gcc.dg/tree-ssa/pr19831-1.c: New testcase.
    * gcc.dg/tree-ssa/pr19831-2.c: Likewise.
    * gcc.dg/tree-ssa/pr19831-3.c: Likewise.
    * gcc.dg/errno-1.c: Adjust.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr19831-1.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr19831-2.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr19831-3.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/errno-1.c
    trunk/gcc/tree-ssa-dce.c