[gcc r13-8532] Darwin: Place global inits in the correct section.

[Iain D Sandoe]

https://gcc.gnu.org/g:be95ee81bc934d6b22e5639eb7b5f9603fa1443d

commit r13-8532-gbe95ee81bc934d6b22e5639eb7b5f9603fa1443d
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Fri Sep 1 09:04:13 2023 +0100

    Darwin: Place global inits in the correct section.
    
    This handles placement of global initializers into __TEXT,__StaticInit as used
    by other platform toolchains.
    
    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.
    
    This includes the update from 5b33b364652866165431aef1810af1e890229c5e.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    
    gcc/ChangeLog:
    
            * config/darwin-sections.def (static_init_section): Add the
            __TEXT,__StaticInit section.
            * config/darwin.cc (darwin_function_section): Use the static init
            section for global initializers, to match other platform toolchains.
            Place unlikely executed global init code into the standard cold
            section.
    
    (cherry picked from commit 68dc3e94fd6bd395a8b343533485616dff3fc796)

Diff:
---
 gcc/config/darwin-sections.def |  2 ++
 gcc/config/darwin.cc           | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/gcc/config/darwin-sections.def b/gcc/config/darwin-sections.def
index de2334f4a7a..7e1b4710bd6 100644
--- a/gcc/config/darwin-sections.def
+++ b/gcc/config/darwin-sections.def
@@ -98,6 +98,8 @@ DEF_SECTION (mod_init_section, 0, ".mod_init_func", 0)
 DEF_SECTION (mod_term_section, 0, ".mod_term_func", 0)
 DEF_SECTION (constructor_section, 0, ".constructor", 0)
 DEF_SECTION (destructor_section, 0, ".destructor", 0)
+DEF_SECTION (static_init_section, SECTION_CODE,
+	     ".section\t__TEXT,__StaticInit,regular,pure_instructions", 0)
 
 /* Objective-C ABI=0 (Original version) sections.  */
 DEF_SECTION (objc_class_section, 0, ".objc_class", 1)
diff --git a/gcc/config/darwin.cc b/gcc/config/darwin.cc
index c5c0fb034af..5e1b8ccd4eb 100644
--- a/gcc/config/darwin.cc
+++ b/gcc/config/darwin.cc
@@ -3854,11 +3854,22 @@ 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 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 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];
+
   /* 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).  */