[gcc r16-1693] x86: Handle REG_EH_REGION note in DEF_INSN

[H.J. Lu]

https://gcc.gnu.org/g:62a80185db84f20f3efb05c81598bffa95bcd63d

commit r16-1693-g62a80185db84f20f3efb05c81598bffa95bcd63d
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Jun 25 12:50:53 2025 +0800

    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>

Diff:
---
 gcc/config/i386/i386-features.cc | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index be2ce3103dde..d942bf08b56f 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -3820,6 +3820,8 @@ remove_redundant_vector_load (void)
 
   if (replaced)
     {
+      auto_vec<rtx_insn *> control_flow_insns;
+
       /* (Re-)discover loops so that bb->loop_father can be used in the
 	 analysis below.  */
       calculate_dominance_info (CDI_DOMINATORS);
@@ -3835,6 +3837,20 @@ remove_redundant_vector_load (void)
 		rtx set = gen_rtx_SET (load->broadcast_reg,
 				       load->broadcast_source);
 		insn = emit_insn_after (set, load->def_insn);
+
+		if (cfun->can_throw_non_call_exceptions)
+		  {
+		    /* Handle REG_EH_REGION note in DEF_INSN.  */
+		    rtx note = find_reg_note (load->def_insn,
+					      REG_EH_REGION, nullptr);
+		    if (note)
+		      {
+			control_flow_insns.safe_push (load->def_insn);
+			add_reg_note (insn, REG_EH_REGION,
+				      XEXP (note, 0));
+		      }
+		  }
+
 		if (dump_file)
 		  {
 		    fprintf (dump_file, "\nAdd:\n\n");
@@ -3855,6 +3871,22 @@ remove_redundant_vector_load (void)
 
       loop_optimizer_finalize ();
 
+      if (!control_flow_insns.is_empty ())
+	{
+	  free_dominance_info (CDI_DOMINATORS);
+
+	  FOR_EACH_VEC_ELT (control_flow_insns, i, insn)
+	    if (control_flow_insn_p (insn))
+	      {
+		/* Split the block after insn.  There will be a fallthru
+		   edge, which is OK so we keep it.  We have to create
+		   the exception edges ourselves.  */
+		bb = BLOCK_FOR_INSN (insn);
+		split_block (bb, insn);
+		rtl_make_eh_edge (NULL, bb, BB_END (bb));
+	      }
+	}
+
       df_process_deferred_rescans ();
     }