[PATCH] RISC-V: Change VSETVL PASS always call split_all_insns

[PATCH] RISC-V: Change VSETVL PASS always call split_all_insns

[juzhe.zhong]

From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>

Since LCM will destroy CFG, we are going to reorder the location of VSETVL PASS
at least before bbro (block-reorder PASS) which is before split3 PASS. We need
to call it in VSETVL PASS to get final RVV instructions patterns.

gcc/ChangeLog:

        * config/riscv/riscv-vsetvl.cc (pass_vsetvl::execute): Always call split_all_insns.

---
 gcc/config/riscv/riscv-vsetvl.cc | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index 0245124e28f..d494369a603 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -3092,12 +3092,10 @@ pass_vsetvl::execute (function *)
   if (n_basic_blocks_for_fn (cfun) <= 0)
     return 0;
 
-  /* The reason we have this since we didn't finish splitting yet
-     when optimize == 0. In this case, we should conservatively
-     split all instructions here to make sure we don't miss any
-     RVV instruction.  */
-  if (!optimize)
-    split_all_insns ();
+  /* The RVV instruction may change after split which is not a stable
+     instruction. We need to split it here to avoid potential issue
+     since the VSETVL PASS is insert before split PASS.  */
+  split_all_insns ();
 
   /* Early return for there is no vector instructions.  */
   if (!has_vector_insn (cfun))
-- 
2.36.3

Re: [PATCH] RISC-V: Change VSETVL PASS always call split_all_insns

[Jeff Law]

On 1/17/23 19:50, juzhe.zhong@rivai.ai wrote:
> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
> 
> Since LCM will destroy CFG, we are going to reorder the location of VSETVL PASS
> at least before bbro (block-reorder PASS) which is before split3 PASS. We need
> to call it in VSETVL PASS to get final RVV instructions patterns.
Just for the record.  LCM does not destroy the CFG, it just splits 
critical edges.

> 
> gcc/ChangeLog:
> 
>          * config/riscv/riscv-vsetvl.cc (pass_vsetvl::execute): Always call split_all_insns.
OK.
jeff

Re: [PATCH] RISC-V: Change VSETVL PASS always call split_all_insns

[Kito Cheng]

[-- Attachment #1: Type: text/plain, Size: 684 bytes --]

committed, thanks

On Mon, Jan 23, 2023 at 3:39 AM Jeff Law via Gcc-patches <
gcc-patches@gcc.gnu.org> wrote:

>
>
> On 1/17/23 19:50, juzhe.zhong@rivai.ai wrote:
> > From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
> >
> > Since LCM will destroy CFG, we are going to reorder the location of
> VSETVL PASS
> > at least before bbro (block-reorder PASS) which is before split3 PASS.
> We need
> > to call it in VSETVL PASS to get final RVV instructions patterns.
> Just for the record.  LCM does not destroy the CFG, it just splits
> critical edges.
>
> >
> > gcc/ChangeLog:
> >
> >          * config/riscv/riscv-vsetvl.cc (pass_vsetvl::execute): Always
> call split_all_insns.
> OK.
> jeff
>