[gcc r14-1891] RA: Ignore conflicts for some pseudos from insns throwing a final exception

[gcc r14-1891] RA: Ignore conflicts for some pseudos from insns throwing a final exception

[Vladimir Makarov]

https://gcc.gnu.org/g:154c69039571c66b3a6d16ecfa9e6ff22942f59f

commit r14-1891-g154c69039571c66b3a6d16ecfa9e6ff22942f59f
Author: Vladimir N. Makarov <vmakarov@redhat.com>
Date:   Fri Jun 16 11:12:32 2023 -0400

    RA: Ignore conflicts for some pseudos from insns throwing a final exception
    
    IRA adds conflicts to the pseudos from insns can throw exceptions
    internally even if the exception code is final for the function and
    the pseudo value is not used in the exception code.  This results in
    spilling a pseudo in a loop (see
    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110215).
    
    The following patch fixes the problem.
    
            PR rtl-optimization/110215
    
    gcc/ChangeLog:
    
            * ira-lives.cc: Include except.h.
            (process_bb_node_lives): Ignore conflicts from cleanup exceptions
            when the pseudo does not live at the exception landing pad.

Diff:
---
 gcc/ira-lives.cc | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/gcc/ira-lives.cc b/gcc/ira-lives.cc
index 6a3901ee234..bc8493856a4 100644
--- a/gcc/ira-lives.cc
+++ b/gcc/ira-lives.cc
@@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "ira-int.h"
 #include "sparseset.h"
 #include "function-abi.h"
+#include "except.h"
 
 /* The code in this file is similar to one in global but the code
    works on the allocno basis and creates live ranges instead of
@@ -1383,14 +1384,24 @@ process_bb_node_lives (ira_loop_tree_node_t loop_tree_node)
 		      SET_HARD_REG_SET (OBJECT_CONFLICT_HARD_REGS (obj));
 		      SET_HARD_REG_SET (OBJECT_TOTAL_CONFLICT_HARD_REGS (obj));
 		    }
-		  if (can_throw_internal (insn))
+		  eh_region r;
+		  eh_landing_pad lp;
+		  rtx_code_label *landing_label;
+		  basic_block landing_bb;
+		  if (can_throw_internal (insn)
+		      && (r = get_eh_region_from_rtx (insn)) != NULL
+		      && (lp = gen_eh_landing_pad (r)) != NULL
+		      && (landing_label = lp->landing_pad) != NULL
+		      && (landing_bb = BLOCK_FOR_INSN (landing_label)) != NULL
+		      && (r->type != ERT_CLEANUP
+			  || bitmap_bit_p (df_get_live_in (landing_bb),
+					   ALLOCNO_REGNO (a))))
 		    {
-		      OBJECT_CONFLICT_HARD_REGS (obj)
-			|= callee_abi.mode_clobbers (ALLOCNO_MODE (a));
-		      OBJECT_TOTAL_CONFLICT_HARD_REGS (obj)
-			|= callee_abi.mode_clobbers (ALLOCNO_MODE (a));
+		      HARD_REG_SET new_conflict_regs
+			= callee_abi.mode_clobbers (ALLOCNO_MODE (a));
+		      OBJECT_CONFLICT_HARD_REGS (obj) |= new_conflict_regs;
+		      OBJECT_TOTAL_CONFLICT_HARD_REGS (obj) |= new_conflict_regs;
 		    }
-
 		  if (sparseset_bit_p (allocnos_processed, num))
 		    continue;
 		  sparseset_set_bit (allocnos_processed, num);