[Bug rtl-optimization/47299] [4.6 Regression] Widening multiply optimization generates bad code

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47299

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-01-18 
07:45:17 UTC ---
Author: jakub
Date: Tue Jan 18 07:45:12 2011
New Revision: 168944

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=168944
Log:
    PR rtl-optimization/47299
    * expr.c (expand_expr_real_2) <case WIDEN_MULT_EXPR>: Don't use
    subtarget.  Use normal multiplication if both operands are
    constants.
    * expmed.c (expand_widening_mult): Don't try to optimize constant
    multiplication if op0 has VOIDmode.  Convert op1 constant to mode
    before using it.

    * gcc.c-torture/execute/pr47299.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr47299.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/expmed.c
    trunk/gcc/expr.c
    trunk/gcc/testsuite/ChangeLog