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Improve documentation of -fallow-store-data-races

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2020-10-08  John Henning  <john.henning@oracle.com>

gcc/

	PR other/97309
	* doc/invoke.texi: Improve documentation of
	-fallow-store-data-races.
This commit is contained in:
qing zhao 2020-10-08 17:01:07 +02:00
parent b2a96bf9dc
commit baf4750fea
1 changed files with 12 additions and 1 deletions
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gcc/doc/invoke.texi
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@ -11622,7 +11622,18 @@ Do not remove unused C++ allocations in dead code elimination.
@item -fallow-store-data-races
@opindex fallow-store-data-races
Allow the compiler to introduce new data races on stores.
Allow the compiler to perform optimizations that may introduce new data races
on stores, without proving that the variable cannot be concurrently accessed
by other threads. Does not affect optimization of local data. It is safe to
use this option if it is known that global data will not be accessed by
multiple threads.
Examples of optimizations enabled by @option{-fallow-store-data-races} include
hoisting or if-conversions that may cause a value that was already in memory
to be re-written with that same value. Such re-writing is safe in a single
threaded context but may be unsafe in a multi-threaded context. Note that on
some processors, if-conversions may be required in order to enable
vectorization.
Enabled at level @option{-Ofast}.