[gcc r13-8606] tree-profile: Disable indirect call profiling for IFUNC resolvers

[gcc r13-8606] tree-profile: Disable indirect call profiling for IFUNC resolvers

[H.J. Lu]

https://gcc.gnu.org/g:abe3a80aa2d6d53cc9b8c9f7c531e065451d5b6e

commit r13-8606-gabe3a80aa2d6d53cc9b8c9f7c531e065451d5b6e
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Sun Apr 14 12:57:39 2024 -0700

    tree-profile: Disable indirect call profiling for IFUNC resolvers
    
    We can't profile indirect calls to IFUNC resolvers nor their callees as
    it requires TLS which hasn't been set up yet when the dynamic linker is
    resolving IFUNC symbols.
    
    Add an IFUNC resolver caller marker to cgraph_node and set it if the
    function is called by an IFUNC resolver.  Disable indirect call profiling
    for IFUNC resolvers and their callees.
    
    Tested with profiledbootstrap on Fedora 39/x86-64.
    
    gcc/ChangeLog:
    
            PR tree-optimization/114115
            * cgraph.h (symtab_node): Add check_ifunc_callee_symtab_nodes.
            (cgraph_node): Add called_by_ifunc_resolver.
            * cgraphunit.cc (symbol_table::compile): Call
            symtab_node::check_ifunc_callee_symtab_nodes.
            * symtab.cc (check_ifunc_resolver): New.
            (ifunc_ref_map): Likewise.
            (is_caller_ifunc_resolver): Likewise.
            (symtab_node::check_ifunc_callee_symtab_nodes): Likewise.
            * tree-profile.cc (gimple_gen_ic_func_profiler): Disable indirect
            call profiling for IFUNC resolvers and their callees.
    
    gcc/testsuite/ChangeLog:
    
            PR tree-optimization/114115
            * gcc.dg/pr114115.c: New test.
    
    (cherry picked from commit cab32bacaea268ec062b1fb4fc662d90c9d1cfce)

Diff:
---
 gcc/cgraph.h                    |  6 +++
 gcc/cgraphunit.cc               |  2 +
 gcc/symtab.cc                   | 89 +++++++++++++++++++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/pr114115.c | 24 +++++++++++
 gcc/tree-profile.cc             |  8 +++-
 5 files changed, 128 insertions(+), 1 deletion(-)

diff --git a/gcc/cgraph.h b/gcc/cgraph.h
index c1a3691b6f5..430c87d8bb7 100644
--- a/gcc/cgraph.h
+++ b/gcc/cgraph.h
@@ -479,6 +479,9 @@ public:
      Return NULL if there's no such node.  */
   static symtab_node *get_for_asmname (const_tree asmname);
 
+  /* Check symbol table for callees of IFUNC resolvers.  */
+  static void check_ifunc_callee_symtab_nodes (void);
+
   /* Verify symbol table for internal consistency.  */
   static DEBUG_FUNCTION void verify_symtab_nodes (void);
 
@@ -896,6 +899,7 @@ struct GTY((tag ("SYMTAB_FUNCTION"))) cgraph_node : public symtab_node
       redefined_extern_inline (false), tm_may_enter_irr (false),
       ipcp_clone (false), declare_variant_alt (false),
       calls_declare_variant_alt (false), gc_candidate (false),
+      called_by_ifunc_resolver (false),
       m_uid (uid), m_summary_id (-1)
   {}
 
@@ -1491,6 +1495,8 @@ struct GTY((tag ("SYMTAB_FUNCTION"))) cgraph_node : public symtab_node
      is set for local SIMD clones when they are created and cleared if the
      vectorizer uses them.  */
   unsigned gc_candidate : 1;
+  /* Set if the function is called by an IFUNC resolver.  */
+  unsigned called_by_ifunc_resolver : 1;
 
 private:
   /* Unique id of the node.  */
diff --git a/gcc/cgraphunit.cc b/gcc/cgraphunit.cc
index bccd2f2abb5..40dcceccca5 100644
--- a/gcc/cgraphunit.cc
+++ b/gcc/cgraphunit.cc
@@ -2313,6 +2313,8 @@ symbol_table::compile (void)
 
   symtab_node::checking_verify_symtab_nodes ();
 
+  symtab_node::check_ifunc_callee_symtab_nodes ();
+
   timevar_push (TV_CGRAPHOPT);
   if (pre_ipa_mem_report)
     dump_memory_report ("Memory consumption before IPA");
diff --git a/gcc/symtab.cc b/gcc/symtab.cc
index 0470509a98d..df09def81e9 100644
--- a/gcc/symtab.cc
+++ b/gcc/symtab.cc
@@ -1369,6 +1369,95 @@ symtab_node::verify (void)
   timevar_pop (TV_CGRAPH_VERIFY);
 }
 
+/* Return true and set *DATA to true if NODE is an ifunc resolver.  */
+
+static bool
+check_ifunc_resolver (cgraph_node *node, void *data)
+{
+  if (node->ifunc_resolver)
+    {
+      bool *is_ifunc_resolver = (bool *) data;
+      *is_ifunc_resolver = true;
+      return true;
+    }
+  return false;
+}
+
+static auto_bitmap ifunc_ref_map;
+
+/* Return true if any caller of NODE is an ifunc resolver.  */
+
+static bool
+is_caller_ifunc_resolver (cgraph_node *node)
+{
+  bool is_ifunc_resolver = false;
+
+  for (cgraph_edge *e = node->callers; e; e = e->next_caller)
+    {
+      /* Return true if caller is known to be an IFUNC resolver.  */
+      if (e->caller->called_by_ifunc_resolver)
+	return true;
+
+      /* Check for recursive call.  */
+      if (e->caller == node)
+	continue;
+
+      /* Skip if it has been visited.  */
+      unsigned int uid = e->caller->get_uid ();
+      if (bitmap_bit_p (ifunc_ref_map, uid))
+	continue;
+      bitmap_set_bit (ifunc_ref_map, uid);
+
+      if (is_caller_ifunc_resolver (e->caller))
+	{
+	  /* Return true if caller is an IFUNC resolver.  */
+	  e->caller->called_by_ifunc_resolver = true;
+	  return true;
+	}
+
+      /* Check if caller's alias is an IFUNC resolver.  */
+      e->caller->call_for_symbol_and_aliases (check_ifunc_resolver,
+					      &is_ifunc_resolver,
+					      true);
+      if (is_ifunc_resolver)
+	{
+	  /* Return true if caller's alias is an IFUNC resolver.  */
+	  e->caller->called_by_ifunc_resolver = true;
+	  return true;
+	}
+    }
+
+  return false;
+}
+
+/* Check symbol table for callees of IFUNC resolvers.  */
+
+void
+symtab_node::check_ifunc_callee_symtab_nodes (void)
+{
+  symtab_node *node;
+
+  FOR_EACH_SYMBOL (node)
+    {
+      cgraph_node *cnode = dyn_cast <cgraph_node *> (node);
+      if (!cnode)
+	continue;
+
+      unsigned int uid = cnode->get_uid ();
+      if (bitmap_bit_p (ifunc_ref_map, uid))
+	continue;
+      bitmap_set_bit (ifunc_ref_map, uid);
+
+      bool is_ifunc_resolver = false;
+      cnode->call_for_symbol_and_aliases (check_ifunc_resolver,
+					  &is_ifunc_resolver, true);
+      if (is_ifunc_resolver || is_caller_ifunc_resolver (cnode))
+	cnode->called_by_ifunc_resolver = true;
+    }
+
+  bitmap_clear (ifunc_ref_map);
+}
+
 /* Verify symbol table for internal consistency.  */
 
 DEBUG_FUNCTION void
diff --git a/gcc/testsuite/gcc.dg/pr114115.c b/gcc/testsuite/gcc.dg/pr114115.c
new file mode 100644
index 00000000000..2629f591877
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr114115.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O0 -fprofile-generate -fdump-tree-optimized" } */
+/* { dg-require-profiling "-fprofile-generate" } */
+/* { dg-require-ifunc "" } */
+
+void *foo_ifunc2() __attribute__((ifunc("foo_resolver")));
+
+void bar(void)
+{
+}
+
+static int f3()
+{
+  bar ();
+  return 5;
+}
+
+void (*foo_resolver(void))(void)
+{
+  f3();
+  return bar;
+}
+
+/* { dg-final { scan-tree-dump-not "__gcov_indirect_call_profiler_v" "optimized" } } */
diff --git a/gcc/tree-profile.cc b/gcc/tree-profile.cc
index da300d5f9e8..b5de0fb914f 100644
--- a/gcc/tree-profile.cc
+++ b/gcc/tree-profile.cc
@@ -418,7 +418,13 @@ gimple_gen_ic_func_profiler (void)
   gcall *stmt1;
   tree tree_uid, cur_func, void0;
 
-  if (c_node->only_called_directly_p ())
+  /* Disable indirect call profiling for an IFUNC resolver and its
+     callees since it requires TLS which hasn't been set up yet when
+     the dynamic linker is resolving IFUNC symbols.  See
+     https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114115
+   */
+  if (c_node->only_called_directly_p ()
+      || c_node->called_by_ifunc_resolver)
     return;
 
   gimple_init_gcov_profiler ();