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Merge branch 'master' into nvptx

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Evghenii
2014-04-01 09:10:10 +02:00
parent 4c837d94a9 5a16b3eb10
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docs/ispc.rst
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@@ -2938,23 +2938,28 @@ Function Overloading
--------------------
Functions can be overloaded by parameter type. Given multiple definitions
of a function, ``ispc`` uses the following methods to try to find a match.
If a single match of a given type is found, it is used; if multiple matches
of a given type are found, an error is issued.
of a function, ``ispc`` uses the following model to choose the best function:
each conversion of two types has its cost. ``ispc`` tries to find conversion
with the smallest cost. When ``ispc`` can't find any conversion it means that
this function is not suitable. Then ``ispc`` sums costs for all arguments and
chooses the function with the smallest final cost. If the chosen function
has some arguments which costs are bigger than their costs in other function
this treats as ambiguous.
Costs of type conversions placed from small to big:
* All parameter types match exactly.
* All parameter types match exactly, where any reference-type
parameters are considered equivalent to their underlying type.
* Parameters match with only type conversions that don't risk losing any
information (for example, converting an ``int16`` value to an ``int32``
parameter value.)
* Parameters match with only promotions from ``uniform`` to ``varying``
types.
* Parameters match using arbitrary type conversion, without changing
variability from ``uniform`` to ``varying`` (e.g., ``int`` to ``float``,
``float`` to ``int``.)
* Parameters match using arbitrary type conversion, including also changing
variability from ``uniform`` to ``varying`` as needed.
1. Parameter types match exactly.
2. Function parameter type is reference and parameters match when any reference-type parameter are considered equivalent to their underlying type.
3. Function parameter type is const-reference and parameters match when any reference-type parameter are considered equivalent to their underlying type ignoring const attributes.
4. Parameters match exactly, except constant attributes. [NO CONSTANT ATTRIBUTES LATER]
5. Parameters match exactly, except reference attributes. [NO REFERENCES ATTRIBUTES LATER]
6. Parameters match with only type conversions that don't risk losing any information (for example, converting an int16 value to an int32 parameter value.)
7. Parameters match with only promotions from uniform to varying types.
8. Parameters match using arbitrary type conversion, without changing variability from uniform to varying (e.g., int to float, float to int.)
9. Parameters match with widening and promotions from uniform to varying types. (combination of "6" and "7")
10. Parameters match using arbitrary type conversion, including also changing variability from uniform to varying.
* If function parameter type is reference and neither "2" nor "3" aren't suitable, function is not suitable
* If "10" isn't suitable, function is not suitable
Re-establishing The Execution Mask