[gcc r15-9035] IRA+LRA: Let the backend request to split basic blocks

[Maciej W. Rozycki via Gcc-cvs]

https://gcc.gnu.org/g:89f03fd59fbe151b2efee354c616862a9b194ed9

commit r15-9035-g89f03fd59fbe151b2efee354c616862a9b194ed9
Author: Maciej W. Rozycki <ma...@orcam.me.uk>
Date:   Sun Mar 30 15:24:50 2025 +0100

    IRA+LRA: Let the backend request to split basic blocks
    
    The next change for Alpha will produce extra labels and branches in
    reload, which in turn requires basic blocks to be split at completion.
    We do this already for functions that can trap, so just extend the
    arrangement with a flag for the backend to use whenever it finds it
    necessary.
    
            gcc/
            * function.h (struct function): Add
            `split_basic_blocks_after_reload' member.
            * lra.cc (lra): Handle it.
            * reload1.cc (reload): Likewise.

Diff:
---
 gcc/function.h | 3 +++
 gcc/lra.cc     | 6 ++++--
 gcc/reload1.cc | 6 ++++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/gcc/function.h b/gcc/function.h
index e8aa52fc780a..2260d6704ecc 100644
--- a/gcc/function.h
+++ b/gcc/function.h
@@ -449,6 +449,9 @@ struct GTY(()) function {
   /* Set for artificial function created for [[assume (cond)]].
      These should be GIMPLE optimized, but not expanded to RTL.  */
   unsigned int assume_function : 1;
+
+  /* Nonzero if reload will have to split basic blocks.  */
+  unsigned int split_basic_blocks_after_reload : 1;
 };
 
 /* Add the decl D to the local_decls list of FUN.  */
diff --git a/gcc/lra.cc b/gcc/lra.cc
index 8c6991751e5c..2b3014f160cf 100644
--- a/gcc/lra.cc
+++ b/gcc/lra.cc
@@ -2615,8 +2615,10 @@ lra (FILE *f, int verbose)
 
   inserted_p = fixup_abnormal_edges ();
 
-  /* We've possibly turned single trapping insn into multiple ones.  */
-  if (cfun->can_throw_non_call_exceptions)
+  /* Split basic blocks if we've possibly turned single trapping insn
+     into multiple ones or otherwise the backend requested to do so.  */
+  if (cfun->can_throw_non_call_exceptions
+      || cfun->split_basic_blocks_after_reload)
     {
       auto_sbitmap blocks (last_basic_block_for_fn (cfun));
       bitmap_ones (blocks);
diff --git a/gcc/reload1.cc b/gcc/reload1.cc
index fe4fe58981c9..64ec74e2bf5f 100644
--- a/gcc/reload1.cc
+++ b/gcc/reload1.cc
@@ -1272,8 +1272,10 @@ reload (rtx_insn *first, int global)
 
   inserted = fixup_abnormal_edges ();
 
-  /* We've possibly turned single trapping insn into multiple ones.  */
-  if (cfun->can_throw_non_call_exceptions)
+  /* Split basic blocks if we've possibly turned single trapping insn
+     into multiple ones or otherwise the backend requested to do so.  */
+  if (cfun->can_throw_non_call_exceptions
+      || cfun->split_basic_blocks_after_reload)
     {
       auto_sbitmap blocks (last_basic_block_for_fn (cfun));
       bitmap_ones (blocks);