Try this:
https://godbolt.org/z/x7bM5Pr84
juzhe.zh...@rivai.ai
From: Jeff Law
Date: 2023-06-29 02:11
To: Juzhe-Zhong; gcc-patches
CC: kito.cheng; kito.cheng; palmer; palmer; rdapp.gcc
Subject: Re: [PATCH V3] RISC-V: Fix bug of pre-calculated const vector mask for
VNx1BI, VNx2BI and VNx4BI
On 6/28/23 03:47, Juzhe-Zhong wrote:
> This bug blocks the following patches.
>
> GCC doesn't know RVV is using compact mask model.
> Consider this following case:
>
> #define N 16
>
> int
> main ()
> {
> int8_t mask[N] = {0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1};
> int8_t out[N] = {0};
> for (int8_t i = 0; i < N; ++i)
> if (mask[i])
> out[i] = i;
> for (int8_t i = 0; i < N; ++i)
> {
> if (mask[i])
> assert (out[i] == i);
> else
> assert (out[i] == 0);
> }
> }
>
> Before this patch, the pre-calculated mask in constant memory pool:
> .LC1:
> .byte 68 ====> 0b01000100
>
> This is incorrect, such case failed in execution.
>
> After this patch:
> .LC1:
> .byte 10 ====> 0b1010
So I don't get anything like this in my testing. What are the precise
arguments you're using to build the testcase?
I'm compiling the test use a trunk compiler with
-O3 --param riscv-autovec-preference=fixed-vlmax -march=rv64gcv
I get the attached code both before and after your patch. Clearly I'm
doing something different/wrong. So my request is for the precise
command line you're using and the before/after resulting assembly code.
Jeff
