RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

RISC-V: Fix regressions due to 86de9b66480b710202a2898cf513db105d8c432f

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.