10468 __ctype_mask[EOF] has been working by accident
10469 GCC's -faggressive-loop-optimizations is too aggressive
10470 array over-read in has_saved_fp()
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: John Levon <john.levon@joyent.com>

*** 370,379 ****
--- 370,390 ----
  # but the application of this may move into usr/src/uts/ in future.
  CCNOREORDER=    \
          -_gcc7=-fno-reorder-functions \
          -_gcc8=-fno-reorder-functions
  
+ #
+ # gcc has a rather aggressive optimization on by default that infers loop
+ # bounds based on undefined behavior (!!).  This can lead to some VERY
+ # surprising optimizations -- ones that may be technically correct in the
+ # strictest sense but also result in incorrect program behavior.  We turn
+ # this optimization off, with extreme prejudice.
+ #
+ CCNOAGGRESSIVELOOPS= \
+         -_gcc7=-fno-aggressive-loop-optimizations \
+         -_gcc8=-fno-aggressive-loop-optimizations
+ 
  # One optimization the compiler might perform is to turn this:
  #       #pragma weak foo
  #       extern int foo;
  #       if (&foo)
  #               foo = 5;
*** 599,612 ****
--- 610,625 ----
  $(SRCDBGBLD)CCSOURCEDEBUGFLAGS  = $(CCGDEBUG) -xs
  
  CFLAGS=         $(COPTFLAG) $($(MACH)_CFLAGS) $(SPACEFLAG) $(CCMODE) \
                  $(ILDOFF) $(CERRWARN) $(CSTD) $(CCUNBOUND) $(IROPTFLAG) \
                  $(CGLOBALSTATIC) $(CCNOAUTOINLINE) $(CCNOREORDER) \
+                 $(CCNOAGGRESSIVELOOPS) \
                  $(CSOURCEDEBUGFLAGS) $(CUSERFLAGS)
  CFLAGS64=       $(COPTFLAG64) $($(MACH64)_CFLAGS) $(SPACEFLAG64) $(CCMODE64) \
                  $(ILDOFF) $(CERRWARN) $(CSTD) $(CCUNBOUND) $(IROPTFLAG64) \
                  $(CGLOBALSTATIC) $(CCNOAUTOINLINE) $(CCNOREORDER) \
+                 $(CCNOAGGRESSIVELOOPS) \
                  $(CSOURCEDEBUGFLAGS) $(CUSERFLAGS64)
  #
  # Flags that are used to build parts of the code that are subsequently
  # run on the build machine (also known as the NATIVE_BUILD).
  #