[Bug tree-optimization/52979] [4.7/4.8 Regression] likely wrong code bug w/packed bitfields

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52979

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-25 14:27:15 UTC ---
Author: jakub
Date: Wed Apr 25 14:27:08 2012
New Revision: 186819

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186819
Log:
    PR middle-end/52979
    * stor-layout.c (get_best_mode): Don't return mode with bitsize
    larger than maxbits.  Don't compute maxbits modulo align.
    Also check that unit bytes long store at bitpos / unit * unit
    doesn't affect bits beyond bitregion_end.
    * expmed.c (store_bit_field_1): Avoid trying insv if OP_MODE MEM
    would not fit into bitregion_start ... bitregion_end + 1 bit
    region.
    (store_split_bit_field): Decrease unit close to end of bitregion_end
    if access is restricted in order to avoid mutual recursion.

    * gcc.c-torture/compile/pr52979-1.c: New test.
    * gcc.c-torture/execute/pr52979-1.c: New test.
    * gcc.c-torture/execute/pr52979-2.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/compile/pr52979-1.c
    trunk/gcc/testsuite/gcc.c-torture/execute/pr52979-1.c
    trunk/gcc/testsuite/gcc.c-torture/execute/pr52979-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/expmed.c
    trunk/gcc/stor-layout.c
    trunk/gcc/testsuite/ChangeLog