llvm dev - Jul 2020 - BUILD_VECTOR disambiguation

Hey devs,
>From ISDOpcodes.h...
/// BUILD_VECTOR(ELT0, ELT1, ELT2, ELT3,...) - Return a fixed-width vector
/// with the specified, possibly variable, elements. The number of elements
/// is required to be a power of two. The types of the operands must all be
/// the same and must match the vector element type, except that integer types
/// are allowed to be larger than the element type, in which case the operands
/// are implicitly truncated.
BUILD_VECTOR,

Must the operand types always be the same? Or could we see a
BUILD_VECTOR with mixed integer types? E.g.:

BUILD_VECTOR(i32, i32, i64, i32)

Thanks,
Cam

On Tue, Jul 7, 2020 at 5:52 PM Cameron McInally via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> Hey devs,
>
> From ISDOpcodes.h...
>
> /// BUILD_VECTOR(ELT0, ELT1, ELT2, ELT3,...) - Return a fixed-width vector
> /// with the specified, possibly variable, elements. The number of elements
> /// is required to be a power of two. The types of the operands must all be
> /// the same and must match the vector element type, except that integer
types
> /// The types of the operands must all be the same and must match the
vector element type,
^ ?
> /// are allowed to be larger than the element type, in which case the
operands
> /// are implicitly truncated.
> BUILD_VECTOR,
>
> Must the operand types always be the same? Or could we see a
> BUILD_VECTOR with mixed integer types? E.g.:
>
> BUILD_VECTOR(i32, i32, i64, i32)
>
> Thanks,
> Cam
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Mixed integer types are ok, but the values will get truncated to the element
type of the output value.  It's pretty much what the comment says.

--
Krzysztof Parzyszek  kparzysz at quicinc.com   AI tools development
> -----Original Message-----
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of
Cameron
> McInally via llvm-dev
> Sent: Tuesday, July 7, 2020 9:53 AM
> To: LLVM Developers Mailing List <llvm-dev at lists.llvm.org>
> Subject: [EXT] [llvm-dev] BUILD_VECTOR disambiguation
>
> Hey devs,
>
> From ISDOpcodes.h...
>
> /// BUILD_VECTOR(ELT0, ELT1, ELT2, ELT3,...) - Return a fixed-width vector
> /// with the specified, possibly variable, elements. The number of elements
> /// is required to be a power of two. The types of the operands must all be
> /// the same and must match the vector element type, except that integer
> types /// are allowed to be larger than the element type, in which case the
> operands /// are implicitly truncated.
> BUILD_VECTOR,
>
> Must the operand types always be the same? Or could we see a BUILD_VECTOR
> with mixed integer types? E.g.:
>
> BUILD_VECTOR(i32, i32, i64, i32)
>
> Thanks,
> Cam
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Thanks for the clarification. The `except` seemed dangling to me, but
it's early here.

Just curious... how do we end up with a mixed type BUILD_VECTOR?
That's counterintuitive.

On Tue, Jul 7, 2020 at 10:58 AM Krzysztof Parzyszek via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> Mixed integer types are ok, but the values will get truncated to the
element type of the output value.  It's pretty much what the comment says.
>
> --
> Krzysztof Parzyszek  kparzysz at quicinc.com   AI tools development
>
> > -----Original Message-----
> > From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of
Cameron
> > McInally via llvm-dev
> > Sent: Tuesday, July 7, 2020 9:53 AM
> > To: LLVM Developers Mailing List <llvm-dev at lists.llvm.org>
> > Subject: [EXT] [llvm-dev] BUILD_VECTOR disambiguation
> >
> > Hey devs,
> >
> > From ISDOpcodes.h...
> >
> > /// BUILD_VECTOR(ELT0, ELT1, ELT2, ELT3,...) - Return a fixed-width
vector
> > /// with the specified, possibly variable, elements. The number of
elements
> > /// is required to be a power of two. The types of the operands must
all be
> > /// the same and must match the vector element type, except that
integer
> > types /// are allowed to be larger than the element type, in which
case the
> > operands /// are implicitly truncated.
> > BUILD_VECTOR,
> >
> > Must the operand types always be the same? Or could we see a
BUILD_VECTOR
> > with mixed integer types? E.g.:
> >
> > BUILD_VECTOR(i32, i32, i64, i32)
> >
> > Thanks,
> > Cam