On Thu, Jan 14, 2021 at 8:13 PM Martin Sebor via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> One aspect of PR 98465 - Bogus warning stringop-overread for std::string
> is the inconsistency between -g and -g0 which turns out to be due to
> GCC eliminating apparently unused scope blocks from inlined functions
> that aren't explicitly declared inline and artificial. PR 98664 tracks
> just this part of PR 98465.
>
> To resolve just the PR 98664 subset the attached change has
> the tree-ssa-live.c pass preserve these blocks for all inlined
> functions, not just artificial ones. Besides avoiding the interaction
> between -g and warnings it also seems to improve the inlining context
> by including more inlined call sites. This can be seen in the adjusted
> tests. (Its effect on PR 98465 is that the false positive is issued
> consistently, regardless of -g. Avoiding the false positive is my
> next step.)
>
> Jakub, you raised a concern yesterday in PR 98465 c#13 about the memory
> footprint of this change. Can you please comment on whether it's in
> line with what you were suggesting?
{
tree ao = BLOCK_ABSTRACT_ORIGIN (block);
- if (TREE_CODE (ao) == FUNCTION_DECL)
- loc = BLOCK_SOURCE_LOCATION (block);
- else if (TREE_CODE (ao) != BLOCK)
- break;
+ if (TREE_CODE (ao) == FUNCTION_DECL)
+ loc = BLOCK_SOURCE_LOCATION (block);
+ else if (TREE_CODE (ao) != BLOCK)
+ break;
you are replacing tabs with spaces?
@@ -558,16 +558,13 @@ remove_unused_scope_block_p (tree scope, bool
in_ctor_dtor_block)
else if (!flag_auto_profile && debug_info_level == DINFO_LEVEL_NONE
&& !optinfo_wants_inlining_info_p ())
{
- /* Even for -g0 don't prune outer scopes from artificial
- functions, otherwise diagnostics using tree_nonartificial_location
- will not be emitted properly. */
+ /* Even for -g0 don't prune outer scopes from inlined functions,
+ otherwise late diagnostics from such functions will not be
+ emitted or suppressed properly. */
if (inlined_function_outer_scope_p (scope))
{
tree ao = BLOCK_ORIGIN (scope);
- if (ao
- && TREE_CODE (ao) == FUNCTION_DECL
- && DECL_DECLARED_INLINE_P (ao)
- && lookup_attribute ("artificial", DECL_ATTRIBUTES (ao)))
+ if (ao && TREE_CODE (ao) == FUNCTION_DECL)
unused = false;
}
}
so which inlined_function_outer_scope_p are you _not_ marking now?
BLOCK_ORIGIN is never NULL and all inlined scopes should have
an abstract origin - I believe always a FUNCTIN_DECL. Which means
you could have simplified it further?
And yes, the main reason for the code above is memory use for
C++ with lots of inlining. I suggest to try the patch on tramp3d
for example (there's about 10 inline instances per emitted
assembly op).
Richard.
> Martin
