clang 6.1 inteference

[Jim Laskey (Oracle)]

Run into an issue after upgrade to clang 6.1

/Volumes/Elephant/Projects/sandbox/hotspot/src/share/vm/opto/chaitin.cpp:2098:8:
 error: 'this' pointer cannot be null in well-defined C++ code; pointer may be 
assumed to always convert to true [-Werror,-Wundefined-bool-conversion]
  if( !this ) {                 // Not got anything?
      ~^~~~
1 error generated.



Also note

diff -r 7611110f9367 make/bsd/makefiles/gcc.make
--- a/make/bsd/makefiles/gcc.make       Mon Apr 13 10:48:47 2015 -0300
+++ b/make/bsd/makefiles/gcc.make       Mon Apr 13 11:20:15 2015 -0300
@@ -325,10 +325,13 @@
   else ifeq ($(shell expr $(CC_VER_MAJOR) = 5 \& $(CC_VER_MINOR) = 1), 1)
     OPT_CFLAGS/loopTransform.o += $(OPT_CFLAGS/NOOPT)
     OPT_CFLAGS/unsafe.o += -O1
-  # Clang 6.0 
-  else ifeq ($(shell expr $(CC_VER_MAJOR) = 6 \& $(CC_VER_MINOR) = 0), 1) 
-    OPT_CFLAGS/loopTransform.o += $(OPT_CFLAGS/NOOPT) 
-    OPT_CFLAGS/unsafe.o += -O1 
+  # Clang 6.0
+  else ifeq ($(shell expr $(CC_VER_MAJOR) = 6 \& $(CC_VER_MINOR) = 0), 1)
+    OPT_CFLAGS/loopTransform.o += $(OPT_CFLAGS/NOOPT)
+    OPT_CFLAGS/unsafe.o += -O1
+  else ifeq ($(shell expr $(CC_VER_MAJOR) = 6 \& $(CC_VER_MINOR) = 1), 1)
+    OPT_CFLAGS/loopTransform.o += $(OPT_CFLAGS/NOOPT)
+    OPT_CFLAGS/unsafe.o += -O1
   else
     $(error "Update compiler workarounds for Clang 
$(CC_VER_MAJOR).$(CC_VER_MINOR)")
   endif