[PATCH][Version 3]Come up with -flive-patching master option.

[Qing Zhao <qing dot zhao at oracle dot com>]

Hi,

this is the newest version of the patch. 
major changes:
	1. format fixes raised by Martin;
	2. output error when disabled IPA optimizations are turned on explicitly by the user 
	with -flive-patching at the same time. based on Honza’s suggestions. 

the new changes have been bootstrapped and tested on both aarch64 and x86, no regressions.

Okay for commit?

thanks.

Qing.

===========
gcc/ChangeLog:

2018-11-20  qing zhao  <qing.zhao@oracle.com>

	* cif-code.def (EXTERN_LIVE_ONLY_STATIC): New CIF code.
	* common.opt: Add -flive-patching flag.
	* doc/invoke.texi: Document -flive-patching.
	* flag-types.h (enum live_patching_level): New enum.
	* ipa-inline.c (can_inline_edge_p): Disable external functions from
	inlining when flag_live_patching is LIVE_PATCHING_INLINE_ONLY_STATIC.
	* opts.c (control_options_for_live_patching): New function.
	(finish_options): Make flag_live_patching incompatible with flag_lto.
	Control IPA optimizations based on different levels of 
	flag_live_patching.

gcc/testsuite/ChangeLog:

2018-11-20  qing zhao  <qing.zhao@oracle.com>

	* gcc.dg/live-patching-1.c: New test.
	* gcc.dg/live-patching-2.c: New test.
	* gcc.dg/live-patching-3.c: New test.
	* gcc.dg/tree-ssa/writeonly-3.c: New test.
	* gcc.target/i386/ipa-stack-alignment-2.c: New test.

Attachment: flive-patching-new.patch
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