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Factor out removal of write only stores from execute_fixup_cfg

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To make it easier to fix PR 102703, factoring this code out
to its own function makes it easier to read and less indentions
too.

gcc/ChangeLog:

	* tree-cfg.c (maybe_remove_writeonly_store): New function
	factored out from ...
	(execute_fixup_cfg): Here. Call maybe_remove_writeonly_store.
This commit is contained in:
Andrew Pinski 2021-10-16 03:09:05 +00:00
parent 0a717f1335
commit 36ec4a3c92
1 changed files with 37 additions and 25 deletions
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62
gcc/tree-cfg.c
View file

@ -9666,6 +9666,38 @@ make_pass_warn_unused_result (gcc::context *ctxt)
return new pass_warn_unused_result (ctxt);
}
/* Maybe Remove stores to variables we marked write-only.
Return true if a store was removed. */
static bool
maybe_remove_writeonly_store (gimple_stmt_iterator &gsi, gimple *stmt)
{
/* Keep access when store has side effect, i.e. in case when source
is volatile. */
if (!gimple_store_p (stmt)
|| gimple_has_side_effects (stmt)
|| optimize_debug)
return false;
tree lhs = get_base_address (gimple_get_lhs (stmt));
if (!VAR_P (lhs)
|| (!TREE_STATIC (lhs) && !DECL_EXTERNAL (lhs))
|| !varpool_node::get (lhs)->writeonly)
return false;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Removing statement, writes"
" to write only var:\n");
print_gimple_stmt (dump_file, stmt, 0,
TDF_VOPS|TDF_MEMSYMS);
}
unlink_stmt_vdef (stmt);
gsi_remove (&gsi, true);
release_defs (stmt);
return true;
}
/* IPA passes, compilation of earlier functions or inlining
might have changed some properties, such as marked functions nothrow,
pure, const or noreturn.
@ -9721,33 +9753,13 @@ execute_fixup_cfg (void)
todo |= TODO_cleanup_cfg;
}
/* Remove stores to variables we marked write-only.
Keep access when store has side effect, i.e. in case when source
is volatile. */
if (gimple_store_p (stmt)
&& !gimple_has_side_effects (stmt)
&& !optimize_debug)
/* Remove stores to variables we marked write-only. */
if (maybe_remove_writeonly_store (gsi, stmt))
{
tree lhs = get_base_address (gimple_get_lhs (stmt));
if (VAR_P (lhs)
&& (TREE_STATIC (lhs) || DECL_EXTERNAL (lhs))
&& varpool_node::get (lhs)->writeonly)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Removing statement, writes"
" to write only var:\n");
print_gimple_stmt (dump_file, stmt, 0,
TDF_VOPS|TDF_MEMSYMS);
}
unlink_stmt_vdef (stmt);
gsi_remove (&gsi, true);
release_defs (stmt);
todo |= TODO_update_ssa | TODO_cleanup_cfg;
continue;
}
todo |= TODO_update_ssa | TODO_cleanup_cfg;
continue;
}
/* For calls we can simply remove LHS when it is known
to be write-only. */
if (is_gimple_call (stmt)