x86: Handle REG_EH_REGION note in DEF_INSN

x86: Handle REG_EH_REGION note in DEF_INSN

For tcpsock_test.go in libgo tests,

commit aba3b9d3a48a0703fd565f7c5f0caf604f59970b
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri May 9 07:17:07 2025 +0800

    x86: Extend the remove_redundant_vector pass

added an instruction:

(insn 501 101 102 21 (set (reg:V2DI 234)
        (vec_duplicate:V2DI (reg:DI 111 [ _46 ]))) "tcpsock_test.go":691:12 discrim 1 -1
     (nil))

after

(insn 101 100 501 21 (set (reg:DI 111 [ _46 ])
        (mem:DI (reg/f:DI 110 [ _45 ]) [5 *_45+0 S8 A64])) "tcpsock_test.go":691:12 discrim 1 99 {*movdi_internal}
     (expr_list:REG_DEAD (reg/f:DI 110 [ _45 ])
        (expr_list:REG_EH_REGION (const_int 1 [0x1])
            (nil))))

which resulted in

(insn 101 100 501 21 (set (reg:DI 111 [ _46 ])
        (mem:DI (reg/f:DI 110 [ _45 ]) [5 *_45+0 S8 A64])) "tcpsock_test.go":691:12 discrim 1 99 {*movdi_internal}
     (expr_list:REG_DEAD (reg/f:DI 110 [ _45 ])
        (expr_list:REG_EH_REGION (const_int 1 [0x1])
            (nil))))
(insn 501 101 102 21 (set (reg:V2DI 234)
        (vec_duplicate:V2DI (reg:DI 111 [ _46 ]))) "tcpsock_test.go":691:12 discrim 1 -1
     (nil))

and caused:

tcpsock_test.go: In function 'net.TestTCPBig..func2':
tcpsock_test.go:684:28: error: in basic block 21:
  684 |                         go func() {
      |                            ^
tcpsock_test.go:684:28: error: flow control insn inside a basic block
(insn 101 100 501 21 (set (reg:DI 111 [ _46 ])
        (mem:DI (reg/f:DI 110 [ _45 ]) [5 *_45+0 S8 A64])) "tcpsock_test.go":691:12 discrim 1 99 {*movdi_internal}
     (expr_list:REG_DEAD (reg/f:DI 110 [ _45 ])
        (expr_list:REG_EH_REGION (const_int 1 [0x1])
            (nil))))
during RTL pass: rrvl
tcpsock_test.go:684:28: internal compiler error: in rtl_verify_bb_insns, at cfgrtl.cc:2834

Copy the REG_EH_REGION note to the newly added instruction and split the
block after the previous instruction.

	PR target/120816
	* config/i386/i386-features.cc (remove_redundant_vector_load):
	Handle REG_EH_REGION note in DEF_INSN.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>