[Bug rtl-optimization/35281] [4.3/4.4 Regression] multiply with 0 generated for 64*32->64

[bonzini at gnu dot org]

------- Comment #8 from bonzini at gnu dot org  2008-03-05 13:21 -------
Should be handled by this code in simplify_subreg:

      /* A SUBREG resulting from a zero extension may fold to zero if
         it extracts higher bits that the ZERO_EXTEND's source bits.  */
      if (GET_CODE (op) == ZERO_EXTEND
          && bitpos >= GET_MODE_BITSIZE (GET_MODE (XEXP (op, 0))))
        return CONST0_RTX (outermode);

fwprop does not because the memory is written to.  Can anyone run spec moving
fwprop *before* CSE instead of after?


-- 

bonzini at gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |13724


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35281