This new pass heuristically detects symbols referenced by toplevel
assembly to prevent their optimization.
Heuristics is done by comparing identifiers in assembly to known
symbols.
The pass is split into 2 passes, in LGEN and in WPA.
There must be one pass for WPA to be able to reference any symbol.
However in WPA there may be multiple symbols with the same name,
so we handle those local symbols in LGEN.
gcc/ChangeLog:
* asm-toplevel.cc (mark_fragile_ref_by_asm):
Add marked_local to handle symbol as local.
(ipa_asm_heuristics): New.
(class pass_ipa_asm): New.
(make_pass_ipa_asm_lgen): New.
(make_pass_ipa_asm_wpa): New.
* common.opt: New flto-toplevel-asm-heuristics.
* passes.def: New asm passes.
* timevar.def (TV_IPA_LTO_ASM): New.
* tree-pass.h (make_pass_ipa_asm_lgen): New.
(make_pass_ipa_asm_wpa): New.
gcc/testsuite/ChangeLog:
* gcc.dg/lto/toplevel-simple-asm-1_0.c: New test.
* gcc.dg/lto/toplevel-simple-asm-1_1.c: New test.
* gcc.dg/lto/toplevel-simple-asm-2_0.c: New test.
* gcc.dg/lto/toplevel-simple-asm-2_1.c: New test.
---
gcc/asm-toplevel.cc | 145 +++++++++++++++++-
gcc/common.opt | 4 +
gcc/passes.def | 2 +
.../gcc.dg/lto/toplevel-simple-asm-1_0.c | 19 +++
.../gcc.dg/lto/toplevel-simple-asm-1_1.c | 12 ++
.../gcc.dg/lto/toplevel-simple-asm-2_0.c | 10 ++
.../gcc.dg/lto/toplevel-simple-asm-2_1.c | 12 ++
gcc/timevar.def | 1 +
gcc/tree-pass.h | 2 +
9 files changed, 205 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_0.c
create mode 100644 gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_1.c
create mode 100644 gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_0.c
create mode 100644 gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_1.c
diff --git a/gcc/asm-toplevel.cc b/gcc/asm-toplevel.cc
index 3f1f0f0aad5..c3fb603a180 100644
--- a/gcc/asm-toplevel.cc
+++ b/gcc/asm-toplevel.cc
@@ -29,11 +29,11 @@ along with GCC; see the file COPYING3. If not see
/* This symbol must be available and cannot be renamed.
Marks the symbol and symbols that reference it. */
static void
-mark_fragile_ref_by_asm (symtab_node* node)
+mark_fragile_ref_by_asm (symtab_node* node, bool marked_local = false)
{
node->ref_by_asm = true;
/* Local symbols must remain in the same partition with their callers. */
- if (!TREE_PUBLIC (node->decl))
+ if (!TREE_PUBLIC (node->decl) || marked_local)
{
unsigned j;
ipa_ref *ref;
@@ -112,3 +112,144 @@ analyze_toplevel_extended_asm ()
walk_tree (&l, walk_through_constraints, (void*) &data, NULL);
}
}
+
+
+/* Checks all toplevel assembly contents and compares them with known symbols.
+ Marks those symbols with relevant flags.
+ Heuristics: Detects anything in assembly that looks like an identifer.
+
+ This pass must be in WPA, otherwise we will not see all possibly referenced
+ symbols - if a symbol is only declared, it will not be in the callgraph if
+ it is only referenced from toplevel assembly.
+ However in WPA there may be multiple symbols with the same identifier.
+ The chosen solution is to handle local symbols in LGEN pass first. */
+
+void
+ipa_asm_heuristics ()
+{
+ hash_map<nofree_string_hash, symtab_node *> map;
+ asm_node *anode = symtab->first_asm_symbol ();
+ if (!anode)
+ return;
+
+ symtab_node* snode;
+ if (flag_wpa)
+ {
+ FOR_EACH_SYMBOL (snode)
+ if (TREE_PUBLIC (snode->decl))
+ map.put (snode->asm_name (), snode);
+ }
+ else
+ {
+ FOR_EACH_SYMBOL (snode)
+ map.put (snode->asm_name (), snode);
+ }
+
+ size_t ident_buffer_size = 128;
+ char* ident = (char*) xmalloc (ident_buffer_size);
+
+ for (; anode; anode = anode->next)
+ {
+ if (TREE_CODE (anode->asm_str) != STRING_CST)
+ continue;
+
+ const char *asm_str = TREE_STRING_POINTER (anode->asm_str);
+ int asm_len = TREE_STRING_LENGTH (anode->asm_str);
+ unsigned l = 0;
+ bool prev_is_local = false;
+
+ for (int i = 0; i < asm_len + 1; ++i)
+ {
+ char c = 0;
+ if (i < asm_len)
+ c = asm_str[i];
+
+ if ('0' <= c && c <= '9')
+ {
+ if (l)
+ ident[l++] = c;
+ }
+ else if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '_')
+ ident[l++] = c;
+ else if (l)
+ {
+ ident[l] = 0;
+ symtab_node **n_ = map.get (ident);
+ if (n_)
+ mark_fragile_ref_by_asm (*n_, prev_is_local);
+
+ prev_is_local = !strcmp (ident, "local");
+
+ l = 0;
+ }
+
+ /* Prevent overflow. */
+ if (l >= ident_buffer_size)
+ {
+ ident_buffer_size *= 2;
+ ident = (char*) xrealloc (ident, ident_buffer_size);
+ }
+ }
+ }
+ free (ident);
+}
+
+namespace {
+
+const pass_data pass_data_ipa_asm =
+{
+ IPA_PASS, /* type */
+ "ipa-asm", /* name */
+ OPTGROUP_NONE, /* optinfo_flags */
+ TV_IPA_LTO_ASM, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ 0, /* todo_flags_finish */
+};
+
+class pass_ipa_asm : public ipa_opt_pass_d
+{
+public:
+ pass_ipa_asm (gcc::context *ctxt)
+ : ipa_opt_pass_d (pass_data_ipa_asm, ctxt,
+ NULL, /* generate_summary */
+ NULL, /* write_summary */
+ NULL, /* read_summary */
+ NULL, /* write_optimization_summary */
+ NULL, /* read_optimization_summary */
+ NULL, /* stmt_fixup */
+ 0, /* function_transform_todo_flags_start */
+ NULL, /* function_transform */
+ NULL) /* variable_transform */
+ {}
+
+ /* opt_pass methods: */
+
+ bool gate (function *) final override
+ {
+ return (flag_lto || flag_wpa) && flag_toplevel_asm_heuristics;
+ }
+
+ unsigned int execute (function *) final override
+ {
+ ipa_asm_heuristics ();
+ return 0;
+ }
+
+};
+
+} // anon namespace
+
+ipa_opt_pass_d *
+make_pass_ipa_asm_lgen (gcc::context *ctxt)
+{
+ return new pass_ipa_asm (ctxt);
+}
+
+ipa_opt_pass_d *
+make_pass_ipa_asm_wpa (gcc::context *ctxt)
+{
+ return new pass_ipa_asm (ctxt);
+}
diff --git a/gcc/common.opt b/gcc/common.opt
index 9bc0c65c457..84c24f27a8b 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2352,6 +2352,10 @@ flto-partition=
Common Joined RejectNegative Enum(lto_partition_model) Var(flag_lto_partition)
Init(LTO_PARTITION_BALANCED)
Specify the algorithm to partition symbols and vars at linktime.
+flto-toplevel-asm-heuristics
+Common Var(flag_toplevel_asm_heuristics) Init(0)
+Enable heuristics to recognize symbol identifiers in toplevel (not extended)
assembly and prevent their mangling/deletion.
+
; The initial value of -1 comes from Z_DEFAULT_COMPRESSION in zlib.h.
flto-compression-level=
Common Joined RejectNegative UInteger Var(flag_lto_compression_level) Init(-1)
IntegerRange(0, 19)
diff --git a/gcc/passes.def b/gcc/passes.def
index fac04cd86c7..c97eb069bfc 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -157,10 +157,12 @@ along with GCC; see the file COPYING3. If not see
NEXT_PASS (pass_ipa_increase_alignment);
NEXT_PASS (pass_ipa_tm);
NEXT_PASS (pass_ipa_lower_emutls);
+ NEXT_PASS (pass_ipa_asm_lgen);
TERMINATE_PASS_LIST (all_small_ipa_passes)
INSERT_PASSES_AFTER (all_regular_ipa_passes)
NEXT_PASS (pass_analyzer);
+ NEXT_PASS (pass_ipa_asm_wpa);
NEXT_PASS (pass_ipa_odr);
NEXT_PASS (pass_ipa_whole_program_visibility);
NEXT_PASS (pass_ipa_profile);
diff --git a/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_0.c
b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_0.c
new file mode 100644
index 00000000000..9d653d4c7a3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_0.c
@@ -0,0 +1,19 @@
+/* { dg-lto-do link } */
+/* { dg-lto-options { {-O2 -flto -flto-toplevel-asm-heuristics
-flto-partition=1to1} {-O2 -flto -flto-toplevel-asm-heuristics
-flto-partition=max} {-O2 -flto -flto-toplevel-asm-heuristics
-flto-partition=cache}} } */
+
+void asm_fn();
+void asm_fn_used();
+
+asm(".global asm_fn\nasm_fn:");
+asm(".global asm_fn_used\nasm_fn_used:");
+
+
+__attribute__((noinline))
+int privatized_fn(int v) { return v + v;}
+
+extern void call_privatized_fn();
+
+int main() {
+ privatized_fn (0);
+ call_privatized_fn ();
+}
diff --git a/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_1.c
b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_1.c
new file mode 100644
index 00000000000..9544f69f4e5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-1_1.c
@@ -0,0 +1,12 @@
+extern void asm_fn_used();
+
+__attribute__((used))
+void local_caller() {
+ asm_fn_used();
+}
+
+__attribute__((noipa))
+static void privatized_fn() { asm volatile ("");}
+asm(".long privatized_fn");
+
+void call_privatized_fn() { privatized_fn();}
diff --git a/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_0.c
b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_0.c
new file mode 100644
index 00000000000..ffc2153f0c7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_0.c
@@ -0,0 +1,10 @@
+/* { dg-lto-do link } */
+/* { dg-lto-options { {-O2 -flto -flto-toplevel-asm-heuristics
-flto-partition=1to1} {-O2 -flto -flto-toplevel-asm-heuristics
-flto-partition=max} {-O2 -flto -flto-toplevel-asm-heuristics
-flto-partition=cache}} } */
+
+extern int use_statics ();
+
+extern int asm_var;
+
+int main() {
+ return use_statics ();
+}
diff --git a/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_1.c
b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_1.c
new file mode 100644
index 00000000000..711b9a078d1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/toplevel-simple-asm-2_1.c
@@ -0,0 +1,12 @@
+extern void static_asm_fn ();
+extern int static_asm_var;
+asm(".local static_asm_fn\nstatic_asm_fn:");
+asm(".local static_asm_var\nstatic_asm_var:");
+
+extern int asm_var;
+asm("asm_var:");
+
+int use_statics () {
+ static_asm_fn ();
+ return static_asm_var;
+}
diff --git a/gcc/timevar.def b/gcc/timevar.def
index 4f60f04baa1..f0f4521894a 100644
--- a/gcc/timevar.def
+++ b/gcc/timevar.def
@@ -81,6 +81,7 @@ DEFTIMEVAR (TV_IPA_INLINING , "ipa inlining
heuristics")
DEFTIMEVAR (TV_IPA_FNSPLIT , "ipa function splitting")
DEFTIMEVAR (TV_IPA_COMDATS , "ipa comdats")
DEFTIMEVAR (TV_IPA_OPT , "ipa various optimizations")
+DEFTIMEVAR (TV_IPA_LTO_ASM , "ipa lto asm heuristics")
DEFTIMEVAR (TV_IPA_LTO_DECOMPRESS , "lto stream decompression")
DEFTIMEVAR (TV_IPA_LTO_COMPRESS , "lto stream compression")
DEFTIMEVAR (TV_IPA_LTO_OUTPUT , "lto stream output")
diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index 410341d4711..b0f6ab4cca8 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -527,6 +527,8 @@ extern simple_ipa_opt_pass
*make_pass_local_optimization_passes (gcc::context *c
extern simple_ipa_opt_pass *make_pass_ipa_remove_symbols (gcc::context *ctxt);
extern ipa_opt_pass_d *make_pass_analyzer (gcc::context *ctxt);
+extern ipa_opt_pass_d *make_pass_ipa_asm_lgen (gcc::context *ctxt);
+extern ipa_opt_pass_d *make_pass_ipa_asm_wpa (gcc::context *ctxt);
extern ipa_opt_pass_d *make_pass_ipa_whole_program_visibility (gcc::context
*ctxt);
extern simple_ipa_opt_pass *make_pass_ipa_increase_alignment (gcc::context
--
2.51.1
