[gcc r14-3826] Darwin: Partial reversion of r14-3648 (Inits Section).

[Iain D Sandoe]

https://gcc.gnu.org/g:5b33b364652866165431aef1810af1e890229c5e

commit r14-3826-g5b33b364652866165431aef1810af1e890229c5e
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Sun Sep 10 14:48:42 2023 +0100

    Darwin: Partial reversion of r14-3648 (Inits Section).
    
    Although the Darwin ABI places both hot and cold partitions in the same
    section (the linker can partition by name), this does not work with the
    current dwarf2out implementation.
    
    Since we do see global initialization code getting hot/cold splits, this
    patch places the cold parts into text_cold, and keeps the hot part in
    the correct Init section per ABI.
    
    TODO: figure out a way to allow us to match the ABI fully.
    
    gcc/ChangeLog:
    
            * config/darwin.cc (darwin_function_section): Place unlikely
            executed global init code into the standard cold section.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

Diff:
---
 gcc/config/darwin.cc | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/gcc/config/darwin.cc b/gcc/config/darwin.cc
index 95d6194cf22d..154a2b2755a8 100644
--- a/gcc/config/darwin.cc
+++ b/gcc/config/darwin.cc
@@ -3893,19 +3893,22 @@ darwin_function_section (tree decl, enum node_frequency freq,
   if (decl && DECL_SECTION_NAME (decl) != NULL)
     return get_named_section (decl, NULL, 0);
 
+  /* We always put unlikely executed stuff in the cold section; we have to put
+     this ahead of the global init section, since partitioning within a section
+     breaks some assumptions made in the DWARF handling.  */
+  if (freq == NODE_FREQUENCY_UNLIKELY_EXECUTED)
+    return (use_coal) ? darwin_sections[text_cold_coal_section]
+		      : darwin_sections[text_cold_section];
+
   /* Intercept functions in global init; these are placed in separate sections.
-     FIXME: there should be some neater way to do this.  */
+     FIXME: there should be some neater way to do this, FIXME we should be able
+     to partition within a section.  */
   if (DECL_NAME (decl)
       && (startswith (IDENTIFIER_POINTER (DECL_NAME (decl)), "_GLOBAL__sub_I")
 	  || startswith (IDENTIFIER_POINTER (DECL_NAME (decl)),
 			 "__static_initialization_and_destruction")))
     return  darwin_sections[static_init_section];
 
-  /* We always put unlikely executed stuff in the cold section.  */
-  if (freq == NODE_FREQUENCY_UNLIKELY_EXECUTED)
-    return (use_coal) ? darwin_sections[text_cold_coal_section]
-		      : darwin_sections[text_cold_section];
-
   /* If we have LTO *and* feedback information, then let LTO handle
      the function ordering, it makes a better job (for normal, hot,
      startup and exit - hence the bailout for cold above).  */