Re: Re: [PATCH V2] RISC-V: Fix bug of pre-calculated const vector mask

["juzhe.zhong@rivai.ai" <juzhe.zhong@rivai.ai>]

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The difference between v1 and v2 is the compact mask generation:

v1 : 
+rtx
+rvv_builder::compact_mask () const
+{
+  /* Use the container mode with SEW = 8 and LMUL = 1.  */
+  unsigned container_size
+    = MAX (CEIL (npatterns (), 8), BYTES_PER_RISCV_VECTOR.to_constant () / 8);
+  machine_mode container_mode
+    = get_vector_mode (QImode, container_size).require ();...

v2:
+rtx
+rvv_builder::get_compact_mask () const
+{
+  /* If TARGET_MIN_VLEN == 32, the minimum LMUL = 1/4.
+     Otherwise, the minimum LMUL = 1/8.  */
+  unsigned min_lmul = TARGET_MIN_VLEN == 32 ? 4 : 8;
+  unsigned min_container_size
+    = BYTES_PER_RISCV_VECTOR.to_constant () / min_lmul;
+  unsigned container_size = MAX (CEIL (npatterns (), 8), min_container_size);
+  machine_mode container_mode
+    = get_vector_mode (QImode, container_size).require ();...

The difference is that v1:
unsigned container_size = MAX (CEIL (npatterns (), 8), BYTES_PER_RISCV_VECTOR.to_constant () / 8);


v2: 

+  /* If TARGET_MIN_VLEN == 32, the minimum LMUL = 1/4.
+     Otherwise, the minimum LMUL = 1/8.  */
+  unsigned min_lmul = TARGET_MIN_VLEN == 32 ? 4 : 8;
+  unsigned min_container_size
+    = BYTES_PER_RISCV_VECTOR.to_constant () / min_lmul;
+  unsigned container_size = MAX (CEIL (npatterns (), 8), min_container_size);




juzhe.zhong@rivai.ai
 
From: Kito Cheng
Date: 2023-06-28 14:01
To: Jeff Law
CC: juzhe.zhong@rivai.ai; gcc-patches; kito.cheng; palmer; palmer; Robin Dapp
Subject: Re: [PATCH V2] RISC-V: Fix bug of pre-calculated const vector mask
I mean the difference between v1 and v2 patch
 
On Wed, Jun 28, 2023 at 12:09 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
>
>
>
> On 6/27/23 21:16, Kito Cheng wrote:
> > Do you mind giving some comments about what the difference between the
> > two versions?
> And I'd like a before/after assembly code with the example in the commit
> message.  I didn't see the same behavior when I tried it earlier today
> and ran out of time to dig into it further.
>
> Juzhe -- most folks wait ~1wk to ping patches, even codegen bugfixes.
> Pinging this fast runs the risk of irritating others.  Please be patient.
>
> Jeff