Hi.
As seen in the mentioned PR we do have issues related to modification
of global_options in context of #pragma GCC optimize/target and
the corresponding function attributes. The patch brings a sanity check
that these context related option modifications should not affect global
state. The patch lists known limitations (mentioned in the PR).
So far I bootstrapped and tested the patch on x86_64-linux-gnu and
ppc64le-linux-gnu.
I'm planning to work on the problematic options in next stage1 and this
patch will help me to catch another violations.
Ready to be installed in next stage1?
Thanks,
Martin
gcc/ChangeLog:
2020-03-17 Martin Liska <[email protected]>
PR tree-optimization/92860
* opth-gen.awk: Generate new function gcc_options_check. Include
known exceptions.
gcc/c-family/ChangeLog:
2020-03-17 Martin Liska <[email protected]>
PR tree-optimization/92860
* c-attribs.c (handle_optimize_attribute):
Save global options before parsing of an optimization attribute.
* c-pragma.c (opt_stack): Add saved_global_options field.
(handle_pragma_push_options): Save current global_options.
(handle_pragma_pop_options): Check current options.
---
gcc/c-family/c-attribs.c | 3 +++
gcc/c-family/c-pragma.c | 4 ++++
gcc/opth-gen.awk | 35 +++++++++++++++++++++++++++++++++++
3 files changed, 42 insertions(+)
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 9abf81d0248..c99b1256186 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -4448,6 +4448,7 @@ handle_optimize_attribute (tree *node, tree name, tree args,
/* If we previously had some optimization options, use them as the
default. */
+ gcc_options saved_global_options = global_options;
if (old_opts)
cl_optimization_restore (&global_options,
TREE_OPTIMIZATION (old_opts));
@@ -4459,6 +4460,8 @@ handle_optimize_attribute (tree *node, tree name, tree args,
/* Restore current options. */
cl_optimization_restore (&global_options, &cur_opts);
+ if (flag_checking)
+ gcc_assert (gcc_options_check (&saved_global_options, &global_options));
}
return NULL_TREE;
diff --git a/gcc/c-family/c-pragma.c b/gcc/c-family/c-pragma.c
index 7c35741745b..8b3b4f218ba 100644
--- a/gcc/c-family/c-pragma.c
+++ b/gcc/c-family/c-pragma.c
@@ -1003,6 +1003,7 @@ struct GTY(()) opt_stack {
tree target_strings;
tree optimize_binary;
tree optimize_strings;
+ gcc_options saved_global_options;
};
static GTY(()) struct opt_stack * options_stack;
@@ -1028,6 +1029,7 @@ handle_pragma_push_options (cpp_reader *ARG_UNUSED(dummy))
options_stack = p;
/* Save optimization and target flags in binary format. */
+ p->saved_global_options = global_options;
p->optimize_binary = build_optimization_node (&global_options);
p->target_binary = build_target_option_node (&global_options);
@@ -1079,6 +1081,8 @@ handle_pragma_pop_options (cpp_reader *ARG_UNUSED(dummy))
p->optimize_binary);
optimization_current_node = p->optimize_binary;
}
+ if (flag_checking)
+ gcc_assert (gcc_options_check (&p->saved_global_options, &global_options));
current_target_pragma = p->target_strings;
current_optimize_pragma = p->optimize_strings;
diff --git a/gcc/opth-gen.awk b/gcc/opth-gen.awk
index 856a69168a5..586213da3d3 100644
--- a/gcc/opth-gen.awk
+++ b/gcc/opth-gen.awk
@@ -119,6 +119,41 @@ print "#endif"
print "#endif"
print ""
+print "#if !defined(IN_LIBGCC2) && !defined(IN_TARGET_LIBS) && !defined(IN_RTS)"
+print "#ifndef GENERATOR_FILE"
+print "static inline bool gcc_options_check (gcc_options *ptr1, gcc_options *ptr2)"
+print "{"
+print " bool result = true;"
+
+# all these options are mentioned in PR92860
+checked_options["flag_merge_constants"]++
+checked_options["param_max_fields_for_field_sensitive"]++
+checked_options["flag_omit_frame_pointer"]++
+checked_options["unroll_only_small_loops"]++
+
+for (i = 0; i < n_opts; i++) {
+ name = var_name(flags[i]);
+ if (name == "")
+ continue;
+
+ if (name in checked_options)
+ continue;
+ checked_options[name]++
+
+ print " if (ptr1->x_" name " != ptr2->x_" name ")"
+ print " {"
+ print " if (result)"
+ print " fprintf (stderr, \"Error: global_options are modified in local context:\\n\");"
+ print " fprintf (stderr, \" " name " (%ld/%ld)\\n\", (long int)ptr1->x_" name ", (long int)ptr2->x_" name ");"
+ print " result = false;"
+ print " }"
+}
+
+print " return result;"
+print "}"
+print "#endif"
+print "#endif"
+
# All of the optimization switches gathered together so they can be saved and restored.
# This will allow attribute((cold)) to turn on space optimization.
