diff options
| -rw-r--r-- | lib/system.nim | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/lib/system.nim b/lib/system.nim index 41624bb05..be57ba192 100644 --- a/lib/system.nim +++ b/lib/system.nim @@ -2364,12 +2364,32 @@ when not defined(JS): #and not defined(NimrodVM): when not defined(NimrodVM): proc likely*(val: bool): bool {.importc: "likely", nodecl, nosideeffect.} - ## can be used to mark a condition to be likely. This is a hint for the - ## optimizer. + ## Hints the optimizer that `val` is likely going to be true. + ## + ## You can use this proc to decorate a branch condition. On certain + ## platforms this can help the processor predict better which branch is + ## going to be run. Example: + ## + ## .. code-block:: nimrod + ## for value in inputValues: + ## if likely(value <= 100): + ## process(value) + ## else: + ## echo "Value too big!" proc unlikely*(val: bool): bool {.importc: "unlikely", nodecl, nosideeffect.} - ## can be used to mark a condition to be unlikely. This is a hint for the - ## optimizer. + ## Hints the optimizer that `val` is likely going to be false. + ## + ## You can use this proc to decorate a branch condition. On certain + ## platforms this can help the processor predict better which branch is + ## going to be run. Example: + ## + ## .. code-block:: nimrod + ## for value in inputValues: + ## if unlikely(value > 100): + ## echo "Value too big!" + ## else: + ## process(value) proc rawProc*[T: proc](x: T): pointer {.noSideEffect, inline.} = ## retrieves the raw proc pointer of the closure `x`. This is |