[Bug fortran/50327] [4.7 Regression] Front-end optimization generates wrong code for BLAS's srotmg

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50327

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.0

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-09-08 
13:56:17 UTC ---
The problem is the replacement of "ABS(SD2)" by "tmp = ABS(SD2)" in the
following DO WHILE LOOP:
            DO WHILE ( (ABS(SD2).LE.RGAMSQ) .OR. (ABS(SD2).GE.GAMSQ) )
               IF (SFLAG.EQ.ZERO) THEN

While it is OK to evaluate it only once, it needs to be evaluated every time
and not once before the loop!

Working:
          while (1)
            {
              if (!(ABS_EXPR <*sd2> <= rgamsq) && !(ABS_EXPR <*sd2> >= gamsq))
                goto L.13;
              if (sflag == zero)


Failing:
            real(kind=4) __var_1;
            __var_1 = ABS_EXPR <*sd2>;

            while (1)
              {
                if (!(__var_1 <= rgamsq) && !(__var_1 >= gamsq))
                  goto L.14;
                if (sflag == zero)