According to MSVC manual (*1), cl.exe can skip including a header file
when that:
- contains #pragma once, or
- starts with #ifndef, or
- starts with #if ! defined.
GCC has a similar trick (*2), but it acts more stricter (e. g. there
must be _no tokens_ outside of #ifndef...#endif).
Sun C lacked #pragma once for a looong time. Oracle Developer Studio
12.5 finally implemented it, but we cannot assume such recent version.
This changeset modifies header files so that each of them include
strictly one #ifndef...#endif. I believe this is the most portable way
to trigger compiler optimizations. [Bug #16770]
*1: https://docs.microsoft.com/en-us/cpp/preprocessor/once
*2: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html
debug utility macro rp() (rp_m()) and bp() are introduced.
* rp(obj) shows obj information w/o any side-effect to STDERR.
* rp_m(m, obj) is similar to rp(obj), but show m before.
* bp() is alias of ruby_debug_breakpoint(), which is registered
as a breakpoint in run.gdb (used by `make gdb` or make gdb-ruby`).
Debugging/profiling features will be located.
* vm_trace.c: expose C-level TracePoint APIs.
Note that they are experimental.
* vm_trace.c, include/ruby/debug.h: rename `rb_hook_flag_t'
to `rb_event_hook_flag_t'.
Macro names `RUBY_HOOK_FLAG_*' are also renamed to
`RUBY_EVENT_HOOK_FLAG_*'.
* debug.h, vm_debug.h: rename debug.h to vm_debug.h.
* common.mk: ditto.
* debug.c, main.c, vm_core.h: ditto.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37765 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
