[gcc r16-1287] emit-rtl: document next_nonnote_nondebug_insn_bb () can breach into next BB

[Vineet Gupta]

https://gcc.gnu.org/g:893549330dee0281902138428929585a83899c51

commit r16-1287-g893549330dee0281902138428929585a83899c51
Author: Vineet Gupta <vineetg@rivosinc.com>
Date:   Sun Jun 8 14:44:23 2025 -0700

    emit-rtl: document next_nonnote_nondebug_insn_bb () can breach into next BB
    
    gcc/ChangeLog:
    
            * emit-rtl.cc (next_nonnote_nondebug_insn): Update comments.
    
    Signed-off-by: Vineet Gupta <vineetg@rivosinc.com>

Diff:
---
 gcc/emit-rtl.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/emit-rtl.cc b/gcc/emit-rtl.cc
index 50e3bfcb777a..e64032970d09 100644
--- a/gcc/emit-rtl.cc
+++ b/gcc/emit-rtl.cc
@@ -3690,7 +3690,11 @@ next_nonnote_nondebug_insn (rtx_insn *insn)
 
 /* Return the next insn after INSN that is not a NOTE nor DEBUG_INSN,
    but stop the search before we enter another basic block.  This
-   routine does not look inside SEQUENCEs.  */
+   routine does not look inside SEQUENCEs.
+   NOTE: This can potentially bleed into next BB. If current insn is
+	 last insn of BB, followed by a code_label before the start of
+	 the next BB, code_label will be returned. But this is the
+	 behavior rest of gcc assumes/relies on e.g. get_last_bb_insn.  */
 
 rtx_insn *
 next_nonnote_nondebug_insn_bb (rtx_insn *insn)