86 lines
3.8 KiB
Diff
86 lines
3.8 KiB
Diff
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commit 77e6311332590004c5aec82ceeb45e4d4d93f690
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Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
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Date: Thu Apr 11 08:52:22 2019 +0000
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Clarify documentation for -flive-patching
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* doc/invoke.texi (Optimize Options): Clarify -flive-patching docs.
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git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@270276 138bc75d-0d04-0410-961f-82ee72b054a4
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--- gcc/doc/invoke.texi
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+++ gcc/doc/invoke.texi
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@@ -9367,24 +9367,24 @@ This flag is enabled by default at @option{-O2} and @option{-Os}.
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@item -flive-patching=@var{level}
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@opindex flive-patching
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-Control GCC's optimizations to provide a safe compilation for live-patching.
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+Control GCC's optimizations to produce output suitable for live-patching.
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If the compiler's optimization uses a function's body or information extracted
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from its body to optimize/change another function, the latter is called an
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impacted function of the former. If a function is patched, its impacted
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functions should be patched too.
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-The impacted functions are decided by the compiler's interprocedural
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-optimizations. For example, inlining a function into its caller, cloning
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-a function and changing its caller to call this new clone, or extracting
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-a function's pureness/constness information to optimize its direct or
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-indirect callers, etc.
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+The impacted functions are determined by the compiler's interprocedural
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+optimizations. For example, a caller is impacted when inlining a function
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+into its caller,
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+cloning a function and changing its caller to call this new clone,
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+or extracting a function's pureness/constness information to optimize
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+its direct or indirect callers, etc.
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Usually, the more IPA optimizations enabled, the larger the number of
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impacted functions for each function. In order to control the number of
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-impacted functions and computed the list of impacted function easily,
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-we provide control to partially enable IPA optimizations on two different
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-levels.
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+impacted functions and more easily compute the list of impacted function,
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+IPA optimizations can be partially enabled at two different levels.
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The @var{level} argument should be one of the following:
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@@ -9395,7 +9395,7 @@ The @var{level} argument should be one of the following:
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Only enable inlining and cloning optimizations, which includes inlining,
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cloning, interprocedural scalar replacement of aggregates and partial inlining.
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As a result, when patching a function, all its callers and its clones'
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-callers need to be patched as well.
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+callers are impacted, therefore need to be patched as well.
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@option{-flive-patching=inline-clone} disables the following optimization flags:
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@gccoptlist{-fwhole-program -fipa-pta -fipa-reference -fipa-ra @gol
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@@ -9406,22 +9406,23 @@ callers need to be patched as well.
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@item inline-only-static
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Only enable inlining of static functions.
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-As a result, when patching a static function, all its callers need to be
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-patches as well.
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+As a result, when patching a static function, all its callers are impacted
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+and so need to be patched as well.
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-In addition to all the flags that -flive-patching=inline-clone disables,
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+In addition to all the flags that @option{-flive-patching=inline-clone}
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+disables,
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@option{-flive-patching=inline-only-static} disables the following additional
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optimization flags:
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@gccoptlist{-fipa-cp-clone -fipa-sra -fpartial-inlining -fipa-cp}
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@end table
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-When -flive-patching specified without any value, the default value
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-is "inline-clone".
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+When @option{-flive-patching} is specified without any value, the default value
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+is @var{inline-clone}.
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This flag is disabled by default.
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-Note that -flive-patching is not supported with link-time optimizer.
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+Note that @option{-flive-patching} is not supported with link-time optimization
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(@option{-flto}).
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@item -fisolate-erroneous-paths-dereference
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