Hal —
Am I understanding this correctly:
vector4float x;
vector4int16 y = (vector4int16)x; // this is a conversion
vector4int32 z = (vector4int32)x; // this is a bitcast
This seems confusing in the extreme.
Thanks,
– Steve
On Sep 11, 2013, at 12:04 PM, Hal Finkel <[email protected]> wrote:
> Hello,
>
> Please review the attached patch which adds support for casting between
> vector types with different sizes (but the same number of vector elements).
> LLVM supports these conversions for the underlying LLVM vector types (just as
> for the scalar types), and this adds support in Clang, requiring minor
> modifications in Sema and CodeGen.
>
> For example, this patch allows the following to work:
>
> typedef double vector4double __attribute__((__vector_size__(32)));
> typedef float vector4float __attribute__((__vector_size__(16)));
>
> vector4float flt_trunc(vector4double x) {
> return (vector4float) x;
> }
>
> On some targets the code generation for these conversions has been optimized
> (autovectorization can produce these conversions), and accessing these
> capabilities from Clang is important, for example, when writing intrinsics
> headers (which, when possible, we prefer to implement in terms of generic IR).
>
> Thanks in advance,
> Hal
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
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