Module core.builtins
To provide access to features that would be otherwise counterproductive or difficult to implement, compilers provide an interface consisting of a set of builtins (also called intrinsics) which can be called like normal functions.
This module exposes builtins both common to all D compilers
(those provided by the frontend) and specific to the host compiler i.e. those
specific to either LLVM or GCC (ldc
and gcc
are publicly imported, respectively).
Host-specific intrinsics cannot be reliably listed here, however listings can be found
at the documentation for the relevant backends, i.e.
GCC and
LLVM. It should be noted that not all
builtins listed are necessarily supported by the host compiler, please file a bug
if this is the case for your workload.
Use of this module reduces the amount of conditional compilation needed to use a given builtin. For example, to write a target independent function that uses prefetching we can write the following:
float usePrefetch(float[] x)
{
// There is only one import statement required rather than two (versioned) imports
import core .builtins;
version (GNU)
__builtin_prefetch(x .ptr);
version (LDC)
/+
For the curious: 0, 3, 1 mean `x` will only be read-from (0), it will be used
very often (3), and it should be fetched to the data-cache (1).
+/
llvm_prefetch(x .ptr, 0, 3, 1);
const doMath = blahBlahBlah;
return doMath;
}
Authors
Walter Bright