diff options
Diffstat (limited to 'docs/Atomics.html')
| -rw-r--r-- | docs/Atomics.html | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/docs/Atomics.html b/docs/Atomics.html index 357f43167b..d4a3795b9d 100644 --- a/docs/Atomics.html +++ b/docs/Atomics.html @@ -121,9 +121,10 @@ void f(int* a) { </pre> <p>However, LLVM is not allowed to transform the former to the latter: it could - introduce undefined behavior if another thread can access x at the same time. - (This example is particularly of interest because before the concurrency model - was implemented, LLVM would perform this transformation.)</p> + indirectly introduce undefined behavior if another thread can access x at + the same time. (This example is particularly of interest because before the + concurrency model was implemented, LLVM would perform this + transformation.)</p> <p>Note that speculative loads are allowed; a load which is part of a race returns <code>undef</code>, but does not have undefined @@ -177,7 +178,7 @@ void f(int* a) { <p>In order to achieve a balance between performance and necessary guarantees, there are six levels of atomicity. They are listed in order of strength; each level includes all the guarantees of the previous level except for - Acquire/Release.</p> + Acquire/Release. (See also <a href="LangRef.html#ordering">LangRef</a>.)</p> <!-- ======================================================================= --> <h3> @@ -188,15 +189,15 @@ void f(int* a) { <p>NotAtomic is the obvious, a load or store which is not atomic. (This isn't really a level of atomicity, but is listed here for comparison.) This is - essentially a regular load or store. If code accesses a memory location - from multiple threads at the same time, the resulting loads return - 'undef'.</p> + essentially a regular load or store. If there is a race on a given memory + location, loads from that location return undef.</p> <dl> <dt>Relevant standard</dt> <dd>This is intended to match shared variables in C/C++, and to be used in any other context where memory access is necessary, and - a race is impossible. + a race is impossible. (The precise definition is in + <a href="LangRef.html#memmodel">LangRef</a>.) <dt>Notes for frontends</dt> <dd>The rule is essentially that all memory accessed with basic loads and stores by multiple threads should be protected by a lock or other |