[Bug middle-end/80548] -Wmaybe-uninitialized false positive when an assignment is added

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80548

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-04-28
     Ever confirmed|0                           |1
      Known to fail|                            |4.8.5, 5.4.1, 6.3.1, 7.0.1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed (also with -O2).  Older compilers need -Wuninitialized to trigger it.

[WORKLIST]: add to initial list: x_22 = PHI <x_6(D)(11), x_10(3)>
[WORKLIST]: add to initial list: y_21 = PHI <y_7(D)(11), y_12(3)>
[CHECK]: examining phi: y_21 = PHI <y_7(D)(11), y_12(3)>
[CHECK]: Found unguarded use: y_18 = PHI <y_21(4), y_16(6)>
[WORKLIST]: Update worklist with phi: y_18 = PHI <y_21(4), y_16(6)>
[CHECK]: examining phi: y_18 = PHI <y_21(4), y_16(6)>

[CHECK] Found def edge 1 in y_21 = PHI <y_7(D)(11), y_12(3)>

[CHECK] Found def edge 1 in y_18 = PHI <y_21(4), y_16(6)>
[CHECK]: Found unguarded use: h (x_22, y_18);
[CHECK]: examining phi: x_22 = PHI <x_6(D)(11), x_10(3)>
[BEFORE SIMPLICATION -- [DEF]:

it's confused by the CFG structure it seems.