[Qemu-devel] [PATCH for-2.13] tcg: Allow wider vectors for cmp and mul

[Qemu-devel] [PATCH for-2.13] tcg: Allow wider vectors for cmp and mul

[Richard Henderson]

In db432672, we allow wide inputs for operations such as add.
However, in 212be173 and 3774030a we didn't do the same for
compare and multiply.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/tcg-op-vec.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tcg/tcg-op-vec.c b/tcg/tcg-op-vec.c
index 70ec889bc1..2ca219734d 100644
--- a/tcg/tcg-op-vec.c
+++ b/tcg/tcg-op-vec.c
@@ -355,8 +355,8 @@ void tcg_gen_cmp_vec(TCGCond cond, unsigned vece,
     TCGType type = rt->base_type;
     int can;
 
-    tcg_debug_assert(at->base_type == type);
-    tcg_debug_assert(bt->base_type == type);
+    tcg_debug_assert(at->base_type >= type);
+    tcg_debug_assert(bt->base_type >= type);
     can = tcg_can_emit_vec_op(INDEX_op_cmp_vec, type, vece);
     if (can > 0) {
         vec_gen_4(INDEX_op_cmp_vec, type, vece, ri, ai, bi, cond);
@@ -377,8 +377,8 @@ void tcg_gen_mul_vec(unsigned vece, TCGv_vec r, TCGv_vec a, TCGv_vec b)
     TCGType type = rt->base_type;
     int can;
 
-    tcg_debug_assert(at->base_type == type);
-    tcg_debug_assert(bt->base_type == type);
+    tcg_debug_assert(at->base_type >= type);
+    tcg_debug_assert(bt->base_type >= type);
     can = tcg_can_emit_vec_op(INDEX_op_mul_vec, type, vece);
     if (can > 0) {
         vec_gen_3(INDEX_op_mul_vec, type, vece, ri, ai, bi);
-- 
2.14.3

Re: [Qemu-devel] [PATCH for-2.13] tcg: Allow wider vectors for cmp and mul

[Peter Maydell]

On 17 April 2018 at 23:12, Richard Henderson
<richard.henderson@linaro.org> wrote:
> In db432672, we allow wide inputs for operations such as add.
> However, in 212be173 and 3774030a we didn't do the same for
> compare and multiply.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Can we hit these asserts in the uses of tcg_gen_mul_vec
and tcg_gen_cmp_vec currently in the aarch64 frontend, or
is this only a problem for the not-yet-landed SVE code?

I notice that do_shifti() also has a
    tcg_debug_assert(at->base_type == type);
Is that assert correct, or should it also be changed to >= ?

thanks
-- PMM

Re: [Qemu-devel] [PATCH for-2.13] tcg: Allow wider vectors for cmp and mul

[Richard Henderson]

On 04/19/2018 12:17 AM, Peter Maydell wrote:
> On 17 April 2018 at 23:12, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>> In db432672, we allow wide inputs for operations such as add.
>> However, in 212be173 and 3774030a we didn't do the same for
>> compare and multiply.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> 
> Can we hit these asserts in the uses of tcg_gen_mul_vec
> and tcg_gen_cmp_vec currently in the aarch64 frontend, or
> is this only a problem for the not-yet-landed SVE code?

Only sve code -- it requires a VQ that is not a power of 2, e.g. 3.

> I notice that do_shifti() also has a
>     tcg_debug_assert(at->base_type == type);
> Is that assert correct, or should it also be changed to >= ?

I think that one is correct.  This assert is hit for something like

	mul	z3, z2, z1[0]

where we dup the scalar to our widest host vector width and then multiply.  In
the case of VQ=3, the dup might be to v256, one v256 multiply, and one v128
multiply.


r~

Re: [Qemu-devel] [PATCH for-2.13] tcg: Allow wider vectors for cmp and mul

[Peter Maydell]

On 19 April 2018 at 18:32, Richard Henderson
<richard.henderson@linaro.org> wrote:
> On 04/19/2018 12:17 AM, Peter Maydell wrote:
>> On 17 April 2018 at 23:12, Richard Henderson
>> <richard.henderson@linaro.org> wrote:
>>> In db432672, we allow wide inputs for operations such as add.
>>> However, in 212be173 and 3774030a we didn't do the same for
>>> compare and multiply.
>>>
>>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>>
>> Can we hit these asserts in the uses of tcg_gen_mul_vec
>> and tcg_gen_cmp_vec currently in the aarch64 frontend, or
>> is this only a problem for the not-yet-landed SVE code?
>
> Only sve code -- it requires a VQ that is not a power of 2, e.g. 3.
>
>> I notice that do_shifti() also has a
>>     tcg_debug_assert(at->base_type == type);
>> Is that assert correct, or should it also be changed to >= ?
>
> I think that one is correct.  This assert is hit for something like
>
>         mul     z3, z2, z1[0]
>
> where we dup the scalar to our widest host vector width and then multiply.  In
> the case of VQ=3, the dup might be to v256, one v256 multiply, and one v128
> multiply.

Cool. In that case

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM