BIAS should be:
signed char biasval
= LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
tree bias = build_int_cst (intQI_type_node, biasval);
Currently, only IBM will set LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS -1 for some
situations of len_load/len_store.
Otherwise, it is always 0.
But for consistency, I think we should use the codes as follows.
I see your patch is so big and separate into multiple sub-patches.
Do you have a patch that directly can be applied for whole support.
I want to support length and test that base your patch.
Thanks.
[email protected]
From: Tamar Christina
Date: 2023-11-30 18:58
To: [email protected]; gcc-patches
CC: Richard Biener
Subject: RE: RE: [PATCH 9/21]middle-end: implement vectorizable_early_exit for
codegen of exit code
Hi Juzhe,
I meant that “lens” is undefined, from looking around I guess that needs to be
vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
for `bias` I meant
cond = gimple_build (&cond_gsi, IFN_VCOND_MASK_LEN, truth_type,
all true mask, cond, all false mask, len, bias);
that variable `bias` isn’t defined. And I can’t find any other usage of
IFN_VCOND_MASK_LEN creation to figure out what it’s supposed to be
is it just an SImode 0?
Thanks,
Tamar
From: [email protected] <[email protected]>
Sent: Thursday, November 30, 2023 11:49 AM
To: Tamar Christina <[email protected]>; gcc-patches
<[email protected]>
Cc: Richard Biener <[email protected]>
Subject: Re: RE: [PATCH 9/21]middle-end: implement vectorizable_early_exit for
codegen of exit code
Thanks Tamar.
I am not sure whether I am not on the same page with you.
IMHO, ARM SVE will use the final mask = loop mask (generate by WHILE_ULT) &
conditional mask.
Use that final mask to do the cbranch. Am I right ?
If yes, I leverage that for length and avoid too much codes change in your
patch.
So, for RVV, the length is pretty same as loop mask in ARM SVE.
For example, suppose n = 4, in ARM SVE, WHILE_ULT (whilelo) generate mask =
0b11110000000....
Then use that mask to control the operations.
For RVV, is the same, length will be 4, then we will only process the elements
with index < 4.
For bias, I think that won't be the issue. Currently, BIAS is not used by RVV
and only used on len_load/len_store for IBM targets.
So, the bias value by default is 0 in all other situations except
len_load/len_store specifically for IBM.
[email protected]
From: Tamar Christina
Date: 2023-11-30 18:39
To: [email protected]; gcc-patches
CC: Richard Biener
Subject: RE: [PATCH 9/21]middle-end: implement vectorizable_early_exit for
codegen of exit code
Hi Juzhe,
I’m happy to take the hunks, just that I can’t test it and don’t know the
specifics of how it lens work.
I still need to read up on it.
I tried adding that chunk in, but for the first bit `lens` seems undefined, and
the second bit it seems `bias` is undefined.
I’ll also need what to do for vectorizable_live_operations how to get the first
element rather than the last.
Thanks,
Tamar
From: [email protected] <[email protected]>
Sent: Thursday, November 30, 2023 4:48 AM
To: gcc-patches <[email protected]>
Cc: Richard Biener <[email protected]>; Tamar Christina
<[email protected]>
Subject: [PATCH 9/21]middle-end: implement vectorizable_early_exit for codegen
of exit code
Hi, Richard and Tamar.
I am sorry for bothering you.
Hope you don't mind I give some comments:
Can we support partial vector for length ?
IMHO, we can do that as follows:
bool length_loop_p = LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo);
if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
{
if (direct_internal_fn_supported_p (IFN_VCOND_MASK_LEN, vectype,
OPTIMIZE_FOR_SPEED))
vect_record_loop_len (loop_vinfo, lens, ncopies, vectype, 1);
else
vect_record_loop_mask (loop_vinfo, masks, ncopies, truth_type, NULL);
}
if (length_loop_p)
{
tree len = vect_get_loop_len (loop_vinfo, gsi, loop_lens, 1, vectype, 0, 0);
/* Use VCOND_MASK_LEN (all true, cond, all false, len, bias) to generate
final mask = i < len + bias ? cond[i] : false. */
cond = gimple_build (&cond_gsi, IFN_VCOND_MASK_LEN, truth_type,
all true mask, cond, all false mask, len, bias);
}
else if (masked_loop_p)
{
tree mask
= vect_get_loop_mask (loop_vinfo, gsi, masks, ncopies, truth_type, 0);
cond
= prepare_vec_mask (loop_vinfo, TREE_TYPE (mask), mask, cond, &cond_gsi);
}
This is a prototype. Is this idea reasonable to Richi ?
Thanks.
[email protected]
