[gcc r13-4998] Avoid quadratic behaviour of LTO symbol promotion

[gcc r13-4998] Avoid quadratic behaviour of LTO symbol promotion

[Jan Hubicka]

https://gcc.gnu.org/g:edc038863d88ef0fe7c3ffb3703a9d2b3a17f0a9

commit r13-4998-gedc038863d88ef0fe7c3ffb3703a9d2b3a17f0a9
Author: Jan Hubicka <jh@suse.cz>
Date:   Wed Jan 4 18:03:53 2023 +0100

    Avoid quadratic behaviour of LTO symbol promotion
    
    LTO partitioning does renaming of symbols that ends up in same partition
    and clash with assembler name.  This is done for "ordinary" symbols (such
    as static functions) but also for symbols that are kept only as master
    clones holding bodies of functions to be specialized later.
    This is done only becuase we stream bodies to named section and clash
    in names would mean that ltrans will load wrong body and crash.
    
    Martin recently added bit to stream body for clones that are needed
    since this makes it easier to bookeep what summaries are output.  THis
    however triggers mass renaming of inline clones that is very slow
    and unnecesary since their bodies are never streamed.
    
    Bootstrapped/regtested x86_64-linux, comitted.
    
    gcc/lto/ChangeLog:
    
    2023-01-04  Jan Hubicka  <hubicka@ucw.cz>
    
            * lto-partition.cc (may_need_named_section_p): Clones with no body
            need no remaning.

Diff:
---
 gcc/lto/lto-partition.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gcc/lto/lto-partition.cc b/gcc/lto/lto-partition.cc
index 654d67f272e..b96d1dd473d 100644
--- a/gcc/lto/lto-partition.cc
+++ b/gcc/lto/lto-partition.cc
@@ -1035,15 +1035,18 @@ promote_symbol (symtab_node *node)
 /* Return true if NODE needs named section even if it won't land in
    the partition symbol table.
 
-   FIXME: we should really not use named sections for inline clones
-   and master clones.  */
+   FIXME: we should really not use named sections for master clones.  */
 
 static bool
 may_need_named_section_p (lto_symtab_encoder_t encoder, symtab_node *node)
 {
   struct cgraph_node *cnode = dyn_cast <cgraph_node *> (node);
+  /* We do not need to handle variables since we never clone them.  */
   if (!cnode)
     return false;
+  /* Only master clones will have bodies streamed.  */
+  if (cnode->clone_of)
+    return false;
   if (node->real_symbol_p ())
     return false;
   return (!encoder