OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Clarify documentation for -flive-patching

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

From-SVN: r270276
This commit is contained in:
Jonathan Wakely 2019-04-11 09:52:22 +01:00 committed by Jonathan Wakely
parent 3bab738598
commit ecb3e9a46e
2 changed files with 21 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
gcc/ChangeLog
View File

@ -1,3 +1,7 @@
2019-04-11 Jonathan Wakely <jwakely@redhat.com>
* doc/invoke.texi (Optimize Options): Clarify -flive-patching docs.
2019-04-11 Richard Biener <rguenther@suse.de>
PR tree-optimization/90020

33
gcc/doc/invoke.texi
View File

@ -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