RISC-V: Remove vsetvl_pre bogus instructions in VSETVL PASS

I realize there is a RTL regression between GCC-14 and GCC-13.
https://godbolt.org/z/Ga7K6MqaT

GCC-14:
(insn 9 13 31 2 (set (reg:DI 15 a5 [138])
        (unspec:DI [
                (const_int 64 [0x40])
            ] UNSPEC_VLMAX)) "/app/example.c":5:15 2566 {vlmax_avldi}
     (expr_list:REG_EQUIV (unspec:DI [
                (const_int 64 [0x40])
            ] UNSPEC_VLMAX)
        (nil)))
(insn 31 9 10 2 (parallel [
            (set (reg:DI 15 a5 [138])
                (unspec:DI [
                        (reg:DI 0 zero)
                        (const_int 32 [0x20])
                        (const_int 7 [0x7])
                        (const_int 1 [0x1]) repeated x2
                    ] UNSPEC_VSETVL))
            (set (reg:SI 66 vl)
                (unspec:SI [
                        (reg:DI 0 zero)
                        (const_int 32 [0x20])
                        (const_int 7 [0x7])
                    ] UNSPEC_VSETVL))
            (set (reg:SI 67 vtype)
                (unspec:SI [
                        (const_int 32 [0x20])
                        (const_int 7 [0x7])
                        (const_int 1 [0x1]) repeated x2
                    ] UNSPEC_VSETVL))
        ]) "/app/example.c":5:15 3281 {vsetvldi}
     (nil))

GCC-13:
(insn 10 7 26 2 (set (reg/f:DI 11 a1 [139])
        (plus:DI (reg:DI 11 a1 [142])
            (const_int 800 [0x320]))) "/app/example.c":6:32 5 {adddi3}
     (nil))
(insn 26 10 9 2 (parallel [
            (set (reg:DI 15 a5)
                (unspec:DI [
                        (reg:DI 0 zero)
                        (const_int 32 [0x20])
                        (const_int 7 [0x7])
                        (const_int 1 [0x1]) repeated x2
                    ] UNSPEC_VSETVL))
            (set (reg:SI 66 vl)
                (unspec:SI [
                        (reg:DI 0 zero)
                        (const_int 32 [0x20])
                        (const_int 7 [0x7])
                    ] UNSPEC_VSETVL))
            (set (reg:SI 67 vtype)
                (unspec:SI [
                        (const_int 32 [0x20])
                        (const_int 7 [0x7])
                        (const_int 1 [0x1]) repeated x2
                    ] UNSPEC_VSETVL))
        ]) "/app/example.c":5:15 792 {vsetvldi}
     (nil))

GCC-13 doesn't have:
(insn 9 13 31 2 (set (reg:DI 15 a5 [138])
        (unspec:DI [
                (const_int 64 [0x40])
            ] UNSPEC_VLMAX)) "/app/example.c":5:15 2566 {vlmax_avldi}
     (expr_list:REG_EQUIV (unspec:DI [
                (const_int 64 [0x40])
            ] UNSPEC_VLMAX)
        (nil)))

vsetvl_pre doesn't emit any assembler which is just used for occupying scalar register.
It should be removed in VSETVL PASS.

Tested on both RV32 and RV64 no regression.

gcc/ChangeLog:

	* config/riscv/riscv-vsetvl.cc (vsetvl_pre_insn_p): New function.
	(pre_vsetvl::cleaup): Remove vsetvl_pre.
	(pre_vsetvl::remove_vsetvl_pre_insns): New function.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/vsetvl/vsetvl_pre-1.c: New test.

0 files changed, 0 insertions, 0 deletions