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r242139 - /branches/ARM/sve-branch/gcc/combine.c

Author: rsandifo
Date: Fri Nov 11 17:06:56 2016
New Revision: 242139

Use scalar_int_mode in simplify_comparison

The main loop of simplify_comparison starts with:

      if (GET_MODE_CLASS (mode) != MODE_INT
          && ! (mode == VOIDmode
                && (GET_CODE (op0) == COMPARE || COMPARISON_P (op0))))

So VOIDmode is only acceptable when comparing a COMPARE,
EQ, NE, etc. operand against a constant.  After this, the loop
calls simplify_compare_const to:

  (a) bring the constant op1 closer to 0 where possible and
  (b) use nonzero_bits and num_sign_bit_copies to get a simpler

(a) works for both integer and VOID modes, (b) is specific
to integer modes.

The loop then has a big switch statement that handles further
simplifications.  This switch statement checks for COMPARISON_P
codes but not for COMPARE.

This patch uses scalar_int_mode to make the split between
(a) and (b) more explicit.  It also takes the COMPARISON_P
handling out of the switch statement and does it first,
so that the rest of the loop can treat the mode as a


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