Hi,

this is the new version of the patch.

I have bootstrapped it on both aarch64 and x86,  no regression.

please take a look.

Okay for commit?

thanks.

Qing

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gcc/ChangeLog:

2018-11-15  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_optimizations_for_live_patching): New function.
	(finish_options): Make flag_live_patching incompatible with flag_lto.
	(common_handle_option): Handle flive-patching flag.

gcc/testsuite/ChangeLog:

2018-11-15  qing zhao  <qing.zhao@oracle.com>

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