[Bug fortran/54522] New: Using "g77 -O -fno-automatic", reassignment of a variable in an if statement in a function triggers a compiler bug.

[aap1 at psu dot edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54522

             Bug #: 54522
           Summary: Using "g77 -O -fno-automatic", reassignment of a
                    variable in an if statement in a function triggers a
                    compiler bug.
    Classification: Unclassified
           Product: gcc
           Version: 3.4.6
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: aap1@psu.edu


C g77 bug found 9/7/2012.
C When command "g77 -c -O -fno-automatic reasssignment_bug.for" is
C used on the included code, the following is produced:
C
C   reassignment_bug.for: In function `dum':
C   In file included from reassignment_bug.for:0:
C   reassignment_bug.for:7: internal compiler error: in gen_reg_rtx, at
C   emit-rtl.c:819
C   Please submit a full bug report,
C   with preprocessed source if appropriate.
C   See <URL:http://bugzilla.redhat.com/bugzilla> for instructions.
C
C The code is non-sensical but valid and should not crash the compiler.
C The logic was found in a larger more complex piece of code where the
C cause was hard to find.
C
C Compiler version from "g77 -v":
C Reading specs from /usr/lib/gcc/x86_64-redhat-linux/3.4.6/specs
C Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
C --infodir=/usr/share/info --enable-shared --enable-threads=posix
C --disable-checking --with-system-zlib --enable-__cxa_atexit
C --disable-libunwind-exceptions --enable-languages=c,c++,f77
C --disable-libgcj --host=x86_64-redhat-linux
C Thread model: posix
C gcc version 3.4.6 20060404 (Red Hat 3.4.6-19.el6)
C
      FUNCTION DUM(A)
      B=A
      IF (B.EQ.1) B=A
      DUM=B
      RETURN
      END