http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50628
Richard Guenther <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2011-10-06 Ever Confirmed|0 |1 --- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-10-06 13:34:38 UTC --- PRE now changes -<bb 6>: D.2317 = VIEW_CONVERT_EXPR<union munion.1.f2>(__complex__ (4.5e+1, 0.0)); D.2317.e2 = 0; - D.2329_19 = REALPART_EXPR <VIEW_CONVERT_EXPR<complex(kind=4)>(D.2317)>; + D.2329_19 = 0.0; D.2330_20 = IMAGPART_EXPR <VIEW_CONVERT_EXPR<complex(kind=4)>(D.2317)>; - D.2331_21 = D.2329_19 != 4.5e+1; + D.2331_21 = 1; D.2332_22 = D.2330_20 != 0.0; - D.2333_23 = D.2332_22 | D.2331_21; - if (D.2333_23 == 1) but you can see that the transform is correct - __complex__ (4.5e+1, 0.0) is stored to D.2317 but then the realpart is overwritten by a boolean(kind=4) false. Which is interpreted as 0.0 by REALPART_EXPR <VIEW_CONVERT_EXPR<complex(kind=4)>(D.2317)>; thus the D.2329_19 != 4.5e+1 is always true. that's the e1 (7) test. Without PRE it fails at the g4 (2) test (via FRE). I suppose the frontend eventually fails foul of aliasing issues here? Reduced testcase: complex function f2 (a) integer a logical e2 entry e2 (a) if (a .gt. 0) then e2 = a .lt. 46 else f2 = 45 endif end function program entrytest complex f2 if (f2 (0) .ne. 45) call abort () end