Remove -O[0123s] gcc optimization flags for gcc pass 4 speedups again.

We cannot guarantee that (un)optimized code compiles and/or generates
fully functional code, so don't tempt the user to try it out.

* session.h (struct systemtap_session): Remove gcc_flags string field.
* hash.cxx (find_script_hash): Don't add gcc_flags.
* main.cxx (usage): Remove -O[0123s] documentation.
(main): Don't use gcc_flags.
* buildrun.cxx (compile_pass): Don't add gcc_flags to EXTRA_CFLAGS.
* stap1.in: Remove -O[0123s] documentation.
* testsuite/systemtap.base/cache.exp: Remove tests for -O[0123s].

1 files changed, 6 insertions, 3 deletions

diff --git a/buildrun.cxx b/buildrun.cxx
index 9cc9d98a..7bcdcf8d 100644
--- a/buildrun.cxx
+++ b/buildrun.cxx
@@ -191,9 +191,12 @@ compile_pass (systemtap_session& s)
   // -Os, otherwise -O2 is the default.
   o << "EXTRA_CFLAGS += -freorder-blocks" << endl; // improve on -Os
 
-  // Allow user to override default optimization when so requested.
-  // Last -OX wins.
-  o << "EXTRA_CFLAGS += " << s.gcc_flags << endl; // Add -O[0123s]
+  // We used to allow the user to override default optimization when so
+  // requested by adding a -O[0123s] so they could determine the
+  // time/space/speed tradeoffs themselves, but we cannot guantantee that
+  // the (un)optimized code actually compiles and/or generates functional
+  // code, so we had to remove it.
+  // o << "EXTRA_CFLAGS += " << s.gcc_flags << endl; // Add -O[0123s]
 
   // o << "CFLAGS += -fno-unit-at-a-time" << endl;