Re: GNU toolchain with RVV intrinsic support


Bruce Hoult
 

On Tue, Aug 25, 2020 at 5:34 AM David Horner <ds2horner@...> wrote:
Thank you very much for this advancement.
I have two concerns, in the body is a response.
.

On 2020-08-21 9:34 a.m., Kito Cheng wrote:
I am pleased to announce that our/SiFive's RVV intrinsic enabled GCC are open-sourced now.

We put the sources on riscv's github, and the RVV intrinsics have been integrated in the riscv-gnu-toolchain, so you can build the RVV intrinsic enabled GNU toolchain as usual.

 $ git clone git@...:riscv/riscv-gnu-toolchain.git -b rvv-intrinsic
 $ <path-to-riscv-gnu-toolchain>/configure --with-arch=rv64gcv_zfh --prefix=<INSTALL-PATH>
 $ make newlib build-qemu
 $ cat rvv_vadd.c
>
> #include <riscv_vector.h>
> #include <stdio.h>
>
> void vec_add_rvv
Shouldn't this be vec_add32_rvv ? It is not a generalized vector add.

The user can call functions anything they want. The example might be better if this was clear by calling it foo() or demo_vector_add() or something.
 
(int *a, int *b, int *c, size_t n) {
>   size_t vl;
>   vint32m2_t va, vb, vc;
>   for (;vl = vsetvl_e32m2 (n);n -= vl) {
>     vb = vle32_v_i32m2 (b);
>     vc = vle32_v_i32m2 (c);
>     va = vadd_vv_i32m2 (vb, vc);
>     vse32_v_i32m2 (a, va);
>     a += vl;
The vector pointer should be advanced by vl * 32.

The variable "a" in an "int *" pointer. When you add an integer to it C automatically scales the integer (vl) by sizeof(int).

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