On Tue, Mar 5, 2024 at 1:45 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> We can't instrument an IFUNC resolver nor its callees as it may require
> 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. Update tree_profiling to skip
> functions called by IFUNC resolver.
>
> 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 (tree_profiling): Do not instrument an IFUNC
> resolver nor its callees.
>
> gcc/testsuite/ChangeLog:
>
> PR tree-optimization/114115
> * gcc.dg/pr114115.c: New test.
> ---
> gcc/cgraph.h | 6 +++
> gcc/cgraphunit.cc | 2 +
> gcc/symtab.cc | 89 +++++++++++++++++++++++++++++++++
> gcc/testsuite/gcc.dg/pr114115.c | 24 +++++++++
> gcc/tree-profile.cc | 4 ++
> 5 files changed, 125 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/pr114115.c
>
> diff --git a/gcc/cgraph.h b/gcc/cgraph.h
> index 47f35e8078d..a8c3224802c 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)
> {}
>
> @@ -1495,6 +1499,8 @@ 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 d200166f7e9..2bd0289ffba 100644
> --- a/gcc/cgraphunit.cc
> +++ b/gcc/cgraphunit.cc
> @@ -2317,6 +2317,8 @@ 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 4c7e3c135ca..3256133891d 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 aed13e2b1bc..2e55a5d8402 100644
> --- a/gcc/tree-profile.cc
> +++ b/gcc/tree-profile.cc
> @@ -848,6 +848,10 @@ tree_profiling (void)
> }
> }
>
> + /* Do not instrument an IFUNC resolver nor its callees. */
> + if (node->called_by_ifunc_resolver)
> + continue;
> +
> push_cfun (DECL_STRUCT_FUNCTION (node->decl));
>
> if (dump_file)
> --
> 2.44.0
>
PING.
--
H.J.
