commit 77e6311332590004c5aec82ceeb45e4d4d93f690

Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>

Date:   Thu Apr 11 08:52:22 2019 +0000

    Clarify documentation for -flive-patching

            * doc/invoke.texi (Optimize Options): Clarify -flive-patching docs.

    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@270276 138bc75d-0d04-0410-961f-82ee72b054a4

--- gcc/doc/invoke.texi

+++ gcc/doc/invoke.texi

@@ -9367,24 +9367,24 @@ This flag is enabled by default at @option{-O2} and @option{-Os}.

 @item -flive-patching=@var{level}

 @opindex flive-patching

-Control GCC's optimizations to provide a safe compilation for live-patching.

+Control GCC's optimizations to produce output suitable for live-patching.

 If the compiler's optimization uses a function's body or information extracted

 from its body to optimize/change another function, the latter is called an

 impacted function of the former.  If a function is patched, its impacted

 functions should be patched too.

-The impacted functions are decided by the compiler's interprocedural

-optimizations.  For example, inlining a function into its caller, cloning

-a function and changing its caller to call this new clone, or extracting

-a function's pureness/constness information to optimize its direct or

-indirect callers, etc.

+The impacted functions are determined by the compiler's interprocedural

+optimizations.  For example, a caller is impacted when inlining a function

+into its caller,

+cloning a function and changing its caller to call this new clone,

+or extracting a function's pureness/constness information to optimize

+its direct or indirect callers, etc.

 Usually, the more IPA optimizations enabled, the larger the number of

 impacted functions for each function.  In order to control the number of

-impacted functions and computed the list of impacted function easily,

-we provide control to partially enable IPA optimizations on two different

-levels.

+impacted functions and more easily compute the list of impacted function,

+IPA optimizations can be partially enabled at two different levels.

 The @var{level} argument should be one of the following:

@@ -9395,7 +9395,7 @@ The @var{level} argument should be one of the following:

 Only enable inlining and cloning optimizations, which includes inlining,

 cloning, interprocedural scalar replacement of aggregates and partial inlining.

 As a result, when patching a function, all its callers and its clones'

-callers need to be patched as well.

+callers are impacted, therefore need to be patched as well.

 @option{-flive-patching=inline-clone} disables the following optimization flags:

 @gccoptlist{-fwhole-program  -fipa-pta  -fipa-reference  -fipa-ra @gol

@@ -9406,22 +9406,23 @@ callers need to be patched as well.

 @item inline-only-static

 Only enable inlining of static functions.

-As a result, when patching a static function, all its callers need to be

-patches as well.

+As a result, when patching a static function, all its callers are impacted

+and so need to be patched as well.

-In addition to all the flags that -flive-patching=inline-clone disables,

+In addition to all the flags that @option{-flive-patching=inline-clone}

+disables,

 @option{-flive-patching=inline-only-static} disables the following additional

 optimization flags:

 @gccoptlist{-fipa-cp-clone  -fipa-sra  -fpartial-inlining  -fipa-cp}

 @end table

-When -flive-patching specified without any value, the default value

-is "inline-clone".

+When @option{-flive-patching} is specified without any value, the default value

+is @var{inline-clone}.

 This flag is disabled by default.

-Note that -flive-patching is not supported with link-time optimizer.

+Note that @option{-flive-patching} is not supported with link-time optimization

 (@option{-flto}).

 @item -fisolate-erroneous-paths-dereference