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Commit 93599534 authored by Yedidya Feldblum's avatar Yedidya Feldblum Committed by Facebook GitHub Bot
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notes for FOLLY_UNLIKELY 

Summary: A note describing some ways compilers infer unlikeliness.

Reviewed By: iahs

Differential Revision: D27298067

fbshipit-source-id: c2e0409aa6f0e95f6e68724f56a0e53a47d9a19e
parent fa02762b
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folly/Likely.h
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...@@ -31,6 +31,12 @@ ...@@ -31,6 +31,12 @@
// paths are designed as the fast path and which are designed as the slow path, // paths are designed as the fast path and which are designed as the slow path,
// and to force the compiler to optimize for the fast path, even when it is not // and to force the compiler to optimize for the fast path, even when it is not
// overwhelmingly likely. // overwhelmingly likely.
//
// Notes:
// * All supported compilers treat unconditionally-noreturn blocks as unlikely.
// This is true for blocks which unconditionally throw exceptions and for
// blocks which unconditionally call [[noreturn]]-annotated functions. Such
// cases do not require likeliness annotations.
#define FOLLY_LIKELY(x) FOLLY_DETAIL_BUILTIN_EXPECT((x), 1) #define FOLLY_LIKELY(x) FOLLY_DETAIL_BUILTIN_EXPECT((x), 1)
#define FOLLY_UNLIKELY(x) FOLLY_DETAIL_BUILTIN_EXPECT((x), 0) #define FOLLY_UNLIKELY(x) FOLLY_DETAIL_BUILTIN_EXPECT((x), 0)
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