[Bug libgcc/77519] New: [5/6/7 Regression] complex multiply / divide excess precision handling inverted

[jsm28 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77519

            Bug ID: 77519
           Summary: [5/6/7 Regression] complex multiply / divide excess
                    precision handling inverted
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgcc
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jsm28 at gcc dot gnu.org
  Target Milestone: ---

libgcc complex multiply and divide are meant to eliminate excess precision from
certain internal values by forcing them to memory in exactly those cases where
the type has excess precision.  But in
https://gcc.gnu.org/ml/gcc-patches/2014-09/msg01894.html I accidentally
inverted the logic so that values get forced to memory in exactly the cases
where it's not needed.  (This is a pessimization in the no-excess-precision
case, in principle could lead to bad results depending on code generation in
the excess-precision case.)