5c2d703e6d
Add attributes to the accessors for the global memory resource objects, to allow the compiler to eliminate redundant calls to them. For example, multiple calls to std::pmr::new_delete_resource() will always return the same object, and so the compiler can replace them with a single call. Ideally we would like adjacent calls to std::pmr::get_default_resource() to be combined into a single call by the CSE pass. The 'pure' attribute would permit that. However, the standard requires that calls to std::pmr::set_default_resource() synchronize with subsequent calls to std::pmr::get_default_resource(). With 'pure' the DCE pass might eliminate seemingly redundant calls to std::pmr::get_default_resource(). That might be unsafe, because the caller might be relying on the associated synchronization. We could use a hypothetical attribute that allows CSE but not DCE, but we don't have one. So it can't be 'pure'. Also add [[nodiscard]] to equality operators. libstdc++-v3/ChangeLog: * include/std/memory_resource (new_delete_resource): Add nodiscard, returns_nonnull and const attributes. (null_memory_resource): Likewise. (set_default_resource, get_default_resource): Add returns_nonnull attribute. (memory_resource::is_equal): Add nodiscard attribute. (operator==, operator!=): Likewise. |
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| .. | ||
| backward | ||
| bits | ||
| c | ||
| c_compatibility | ||
| c_global | ||
| c_std | ||
| debug | ||
| decimal | ||
| experimental | ||
| ext | ||
| parallel | ||
| precompiled | ||
| pstl | ||
| std | ||
| tr1 | ||
| tr2 | ||
| Makefile.am | ||
| Makefile.in | ||