[Bug rtl-optimization/116600] [12/13/14/15/16 Regression] shrink wrapping vs asm goto, ICE: in maybe_record_trace_start, at dwarf2cfi.cc:2584 since r7-5127-g827ab47ab1f

[chenglulu at loongson dot cn via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116600

--- Comment #9 from chenglulu <chenglulu at loongson dot cn> ---
I found that there are two edges, 6->13 and 12->13, as shown in
https://gcc.gnu.org/bugzilla/attachment.cgi?id=61211. When shrink-wrap
optimizes 6->13, it finds that bb12 fall-through bb13. So it needs to split
12->13 first. There is an error in the split process.
I tried to modify this part of the code and it solved the problem, but I'm not
sure if the logic is correct.
```
diff --git a/gcc/cfgrtl.cc b/gcc/cfgrtl.cc
index d206c0d53a7..57bb4699c6a 100644
--- a/gcc/cfgrtl.cc
+++ b/gcc/cfgrtl.cc
@@ -1593,6 +1593,7 @@ force_nonfallthru_and_redirect (edge e, basic_block
target, rtx jump_label)
        }
     }

+      bool adjust_jump_target = false;
   /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs
      don't point to the target or fallthru label.  */
   if (JUMP_P (BB_END (e->src))
@@ -1601,7 +1602,6 @@ force_nonfallthru_and_redirect (edge e, basic_block
target, rtx jump_label)
       && (note = extract_asm_operands (PATTERN (BB_END (e->src)))))
     {
       int i, n = ASM_OPERANDS_LABEL_LENGTH (note);
-      bool adjust_jump_target = false;

       for (i = 0; i < n; ++i)
        {
@@ -1615,33 +1615,6 @@ force_nonfallthru_and_redirect (edge e, basic_block
target, rtx jump_label)
          if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target))
            asm_goto_edge = true;
        }
-      if (adjust_jump_target)
-       {
-         rtx_insn *insn = BB_END (e->src);
-         rtx note;
-         rtx_insn *old_label = BB_HEAD (e->dest);
-         rtx_insn *new_label = BB_HEAD (target);
-
-         if (JUMP_LABEL (insn) == old_label)
-           {
-             JUMP_LABEL (insn) = new_label;
-             note = find_reg_note (insn, REG_LABEL_TARGET, new_label);
-             if (note)
-               remove_note (insn, note);
-           }
-         else
-           {
-             note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
-             if (note)
-               remove_note (insn, note);
-             if (JUMP_LABEL (insn) != new_label
-                 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
-               add_reg_note (insn, REG_LABEL_TARGET, new_label);
-           }
-         while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
-                != NULL_RTX)
-           XEXP (note, 0) = new_label;
-       }
     }

   if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge)
@@ -1692,6 +1665,42 @@ force_nonfallthru_and_redirect (edge e, basic_block
target, rtx jump_label)
        }

       new_bb = jump_block;
+
+      if (adjust_jump_target)
+       {
+         rtx_insn *insn = BB_END (new_edge->src);
+         rtx note;
+         rtx_insn *old_label = BB_HEAD (e->dest);
+         rtx_insn *new_label = BB_HEAD (jump_block);
+
+         if (JUMP_LABEL (insn) == old_label)
+           {
+             rtx tmp = extract_asm_operands (PATTERN (insn));
+             rtx_code_label *new_label = block_label (new_edge->dest);
+             rtx old_ref = ASM_OPERANDS_LABEL (tmp, 0);
+             gcc_assert (GET_CODE(old_ref) == LABEL_REF);
+             ASM_OPERANDS_LABEL (tmp, 0) = gen_rtx_LABEL_REF (Pmode,
new_label);
+             JUMP_LABEL (insn) = new_label;
+             --LABEL_NUSES (old_label);
+             ++LABEL_NUSES (new_label);
+             note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
+             if (note)
+               remove_note (insn, note);
+
+           }
+         else
+           {
+             note = find_reg_note (insn, REG_LABEL_TARGET, old_label);
+             if (note)
+               remove_note (insn, note);
+             if (JUMP_LABEL (insn) != new_label
+                 && !find_reg_note (insn, REG_LABEL_TARGET, new_label))
+               add_reg_note (insn, REG_LABEL_TARGET, new_label);
+           }
+         while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label))
+                != NULL_RTX)
+           XEXP (note, 0) = new_label;
+       }
     }
   else
     jump_block = e->src;

```