[PATCH 02/11] Handle epilogues that contain jumps

[Szabolcs Nagy via Gcc-patches]

From: Richard Sandiford <richard.sandif...@arm.com>

The prologue/epilogue pass allows the prologue sequence
to contain jumps.  The sequence is then partitioned into
basic blocks using find_many_sub_basic_blocks.

This patch treats epilogues in the same way.  It's needed for
a follow-on aarch64 patch that adds conditional code to both
the prologue and the epilogue.

Tested on aarch64-linux-gnu (including with a follow-on patch)
and x86_64-linux-gnu.  OK to install?

Richard

gcc/
        * function.cc (thread_prologue_and_epilogue_insns): Handle
        epilogues that contain jumps.
---

This is a previously approved patch that was not committed
because it was not needed at the time, but i'd like to commit
it as it is needed for the followup aarch64 eh_return changes:

https://gcc.gnu.org/pipermail/gcc-patches/2022-November/605769.html

---
 gcc/function.cc | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gcc/function.cc b/gcc/function.cc
index dd2c1136e07..70d1cd65303 100644
--- a/gcc/function.cc
+++ b/gcc/function.cc
@@ -6120,6 +6120,11 @@ thread_prologue_and_epilogue_insns (void)
                  && returnjump_p (BB_END (e->src)))
                e->flags &= ~EDGE_FALLTHRU;
            }
+
+         auto_sbitmap blocks (last_basic_block_for_fn (cfun));
+         bitmap_clear (blocks);
+           bitmap_set_bit (blocks, BLOCK_FOR_INSN (epilogue_seq)->index);
+         find_many_sub_basic_blocks (blocks);
        }
       else if (next_active_insn (BB_END (exit_fallthru_edge->src)))
        {
@@ -6218,6 +6223,11 @@ thread_prologue_and_epilogue_insns (void)
          set_insn_locations (seq, epilogue_location);
 
          emit_insn_before (seq, insn);
+
+         auto_sbitmap blocks (last_basic_block_for_fn (cfun));
+         bitmap_clear (blocks);
+         bitmap_set_bit (blocks, BLOCK_FOR_INSN (insn)->index);
+         find_many_sub_basic_blocks (blocks);
        }
     }
 
-- 
2.25.1