[PATCH] RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

[PATCH] RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

[Juzhe-Zhong]

This patch fixes the recent regression:

FAIL: gcc.dg/torture/float32-tg-2.c   -O1  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg-2.c   -O1  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg-2.c   -O2  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg-2.c   -O2  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg-2.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg-2.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg-2.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg-2.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg-2.c   -O3 -g  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg-2.c   -O3 -g  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg-2.c   -Os  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg-2.c   -Os  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg.c   -O1  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg.c   -O1  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg.c   -O2  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg.c   -O2  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg.c   -O3 -g  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg.c   -O3 -g  (test for excess errors)
FAIL: gcc.dg/torture/float32-tg.c   -Os  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/float32-tg.c   -Os  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -O1  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -O1  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -O2  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -O2  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -O3 -g  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -O3 -g  (test for excess errors)
FAIL: gcc.dg/torture/pr48124-4.c   -Os  (internal compiler error: in reg_or_subregno, at jump.cc:1895)
FAIL: gcc.dg/torture/pr48124-4.c   -Os  (test for excess errors)

due to commit 86de9b66480b710202a2898cf513db105d8c432f.

The root cause is register_operand and reg_or_subregno are consistent so we reach the assertion fail.

We shouldn't worry about subreg:...VL_REGNUM since it's impossible that we can have such situation,
that is, we only have (set (reg) (reg:VL_REGNUM)) which generate "csrr vl" ASM for first fault load instructions (vleff).
So, using REG_P and REGNO must be totally solid and robostic.

Since we don't allow VL_RENUM involved into register allocation and we don't have such constraint, we always use this
following pattern to generate "csrr vl" ASM:

(define_insn "read_vlsi"
  [(set (match_operand:SI 0 "register_operand" "=r")
	(reg:SI VL_REGNUM))]
  "TARGET_VECTOR"
  "csrr\t%0,vl"
  [(set_attr "type" "rdvl")
   (set_attr "mode" "SI")])

So the check in riscv.md is to disallow such situation fall into move pattern in riscv.md

Tested on both RV32/RV64 no regression.

	PR target/109092

gcc/ChangeLog:

	* config/riscv/riscv.md: Use reg instead of subreg.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/pr109092.c: New test.

---
 gcc/config/riscv/riscv.md                          | 6 ++----
 gcc/testsuite/gcc.target/riscv/rvv/base/pr109092.c | 4 ++++
 2 files changed, 6 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/base/pr109092.c

diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index f8a0f7bbfac..edcaec4a786 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -1776,8 +1776,7 @@
 	(zero_extend:DI
 	    (match_operand:SI 1 "nonimmediate_operand" " r,m")))]
   "TARGET_64BIT && !TARGET_ZBA && !TARGET_XTHEADBB && !TARGET_XTHEADMEMIDX
-   && !(register_operand (operands[1], SImode)
-        && reg_or_subregno (operands[1]) == VL_REGNUM)"
+   && !(REG_P (operands[1]) && VL_REG_P (REGNO (operands[1])))"
   "@
    #
    lwu\t%0,%1"
@@ -2214,8 +2213,7 @@
 	(match_operand:SI 1 "move_operand"         " r,T,m,rJ,*r*J,*m,*f,*f,vp"))]
   "(register_operand (operands[0], SImode)
     || reg_or_0_operand (operands[1], SImode))
-    && !(register_operand (operands[1], SImode)
-         && reg_or_subregno (operands[1]) == VL_REGNUM)"
+    && !(REG_P (operands[1]) && VL_REG_P (REGNO (operands[1])))"
   { return riscv_output_move (operands[0], operands[1]); }
   [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fpstore,rdvlenb")
    (set_attr "mode" "SI")
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/pr109092.c b/gcc/testsuite/gcc.target/riscv/rvv/base/pr109092.c
new file mode 100644
index 00000000000..4a608da61f5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/pr109092.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "-mabi=lp64d -march=rv64imafdc" } */
+
+void foo(int i) {}
-- 
2.36.3

Re: [PATCH] RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

[Robin Dapp]

Hi Juzhe,

in principle this seems ok to me but I wonder about:

> We shouldn't worry about subreg:...VL_REGNUM since it's impossible
> that we can have such situation,

I think we allow this in legitimize_move for situations like
(subreg:SI (reg:V4QI)).  That was not added for correctness but
optimization - are we sure we don't undo this optimization with
that change?

Regards
 Robin

Re: Re: [PATCH] RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

[juzhe.zhong]

[-- Attachment #1: Type: text/plain, Size: 765 bytes --]

No, we didn't undo the optimization.

We just disallow move pattern for (set (reg) (VL_REGNUM)).




juzhe.zhong@rivai.ai
 
From: Robin Dapp
Date: 2024-01-22 19:25
To: Juzhe-Zhong; gcc-patches
CC: rdapp.gcc; kito.cheng; kito.cheng; jeffreyalaw
Subject: Re: [PATCH] RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f
 
Hi Juzhe,
 
in principle this seems ok to me but I wonder about:
 
> We shouldn't worry about subreg:...VL_REGNUM since it's impossible
> that we can have such situation,
 
I think we allow this in legitimize_move for situations like
(subreg:SI (reg:V4QI)).  That was not added for correctness but
optimization - are we sure we don't undo this optimization with
that change?
 
Regards
Robin
 
 

Re: [PATCH] RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

[Robin Dapp]

> No, we didn't undo the optimization.
> 
> We just disallow move pattern for (set (reg) (VL_REGNUM)).

Ah, what I referred to was the opposite direction.  We allow
(subreg:V8QI (reg:DI ...)) which is not touched by this patch.

Then it is OK.

Regards
 Robin