[Bug tree-optimization/61576] [4.10 Regression] wrong code at -O3 on x86_64-linux-gnu

[ysrumyan at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61576

--- Comment #4 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
There is an issue with phi-node and reduction stmt - after r211302 new hammock
was inserted between reduction stmt and bb containing phi:

  <bb 6>:
  d.6_12 = d_lsm.14_17 + 1;
  if (c.8_13 != 0)
    goto <bb 7>;
  else
    goto <bb 8>;

  <bb 7>:

  <bb 8>:
  # iftmp.7_15 = PHI <1(7), _19(6)>

  <bb 9>:
  # d_lsm.14_16 = PHI <d_lsm.14_17(5), d.6_12(8)>

but algorithm for converting conditional scalar reduction assumes that basic
block containing reduction is one of predecessors of phi-block. I added check
on it and test is passed.

BTW I wonder why such code motion has been done - in fact, redundant
computations were introduced in loop, before this fix all computations related
to hammock were hoisted out off loop:

  <bb 4>:
  d_lsm.14_25 = d;
  c.8_13 = c;
  f.9_14 = f;
  _18 = f.9_14 != 0;
  _19 = (int) _18;
  iftmp.7_15 = c.8_13 != 0 ? 1 : _19;
  e_lsm.15_26 = e;

  <bb 5>:
  # d_lsm.14_17 = PHI <d_lsm.14_25(4), d_lsm.14_16(9)>
  # e_lsm.15_1 = PHI <e_lsm.15_26(4), e_lsm.15_24(9)>
  b.4_10 ={v} b;
  if (b.4_10 != 0)
    goto <bb 6>;
  else
    goto <bb 7>;

  <bb 6>:
  d.6_12 = d_lsm.14_17 + 1;

  <bb 7>:
  # d_lsm.14_16 = PHI <d_lsm.14_17(5), d.6_12(6)>
  # e_lsm.15_24 = PHI <e_lsm.15_1(5), iftmp.7_15(6)>

I will send for review patch after required testing completion.