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Move misplaced assignment in num_sign_bit_copies1 

The old assignment to bitwidth was before we handled VOIDmode with:

      if (mode == VOIDmode)
        mode = GET_MODE (x);

so when VOIDmode was specified we would always use:

      if (bitwidth < GET_MODE_PRECISION (GET_MODE (x)))
        {
          num0 = cached_num_sign_bit_copies (x, GET_MODE (x),
                                             known_x, known_mode, known_ret);
          return MAX (1,
                      num0 - (int) (GET_MODE_PRECISION (GET_MODE (x)) - bitwidth));
        }

For a zero bitwidth this always returns 1 (which is the most
pessimistic result).

gcc/
2016-11-15  Richard Sandiford  <richard.sandiford@arm.com>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

	* rtlanal.c (num_sign_bit_copies1): Calculate bitwidth after
	handling VOIDmode.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r242440
This commit is contained in:
Richard Sandiford 2016-11-15 17:54:20 +00:00 committed by Richard Sandiford
parent 8e4d2ca469
commit 89e64bc030
2 changed files with 9 additions and 2 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2016-11-15 Richard Sandiford <richard.sandiford@arm.com>
Alan Hayward <alan.hayward@arm.com>
David Sherwood <david.sherwood@arm.com>
* rtlanal.c (num_sign_bit_copies1): Calculate bitwidth after
handling VOIDmode.
2016-11-15 Matthias Klose <doko@ubuntu.com>
* doc/install.texi: Remove references to gcj/libjava.

4
gcc/rtlanal.c
View File

@ -4795,7 +4795,6 @@ num_sign_bit_copies1 (const_rtx x, machine_mode mode, const_rtx known_x,
unsigned int known_ret)
{
enum rtx_code code = GET_CODE (x);
unsigned int bitwidth = GET_MODE_PRECISION (mode);
machine_mode inner_mode;
int num0, num1, result;
unsigned HOST_WIDE_INT nonzero;
@ -4811,7 +4810,8 @@ num_sign_bit_copies1 (const_rtx x, machine_mode mode, const_rtx known_x,
|| VECTOR_MODE_P (GET_MODE (x)) || VECTOR_MODE_P (mode))
return 1;
/* For a smaller object, just ignore the high bits. */
/* For a smaller mode, just ignore the high bits. */
unsigned int bitwidth = GET_MODE_PRECISION (mode);
if (bitwidth < GET_MODE_PRECISION (GET_MODE (x)))
{
num0 = cached_num_sign_bit_copies (x, GET_MODE (x),