On Tue, 18 May 2021, Richard Sandiford wrote: > Richard Biener <rguent...@suse.de> writes: > > @@ -6621,9 +6637,31 @@ pass_expand::execute (function *fun) > > (int) param_ssp_buffer_size); > > } > > > > + /* Temporarily mark PARM_DECLs and RESULT_DECLs we need to expand to > > + memory addressable so expand_function_start can emit the required > > + copies. */ > > + for (tree parm = DECL_ARGUMENTS (current_function_decl); parm; > > + parm = DECL_CHAIN (parm)) > > + if (bitmap_bit_p (forced_stack_vars, DECL_UID (parm))) > > + TREE_ADDRESSABLE (parm) = 1; > > + if (DECL_RESULT (current_function_decl) > > + && bitmap_bit_p (forced_stack_vars, > > + DECL_UID (DECL_RESULT (current_function_decl)))) > > + TREE_ADDRESSABLE (DECL_RESULT (current_function_decl)) = 1; > > + > > /* Set up parameters and prepare for return, for the function. */ > > expand_function_start (current_function_decl); > > > > + /* Clear TREE_ADDRESSABLE again. */ > > + for (tree parm = DECL_ARGUMENTS (current_function_decl); parm; > > + parm = DECL_CHAIN (parm)) > > + if (bitmap_bit_p (forced_stack_vars, DECL_UID (parm))) > > + TREE_ADDRESSABLE (parm) = 0; > > + if (DECL_RESULT (current_function_decl) > > + && bitmap_bit_p (forced_stack_vars, > > + DECL_UID (DECL_RESULT (current_function_decl)))) > > + TREE_ADDRESSABLE (DECL_RESULT (current_function_decl)) = 0; > > + > > /* If we emitted any instructions for setting up the variables, > > emit them before the FUNCTION_START note. */ > > if (var_seq) > > Is TREE_ADDRESSABLE guaranteed to be 0 for these decls before the code > is hit? I was surprised that we didn't need to protect against net > 1->0 transitions.
Yes, bits are only set for decls satisfying use_register_for_decl. Oops, now that I'm double-checking, we fail to check that in discover_nonconstant_array_refs_r - I'll fix that. I can also make the above fool-proof by recoding the decls I marked addressable in a vec and traverse that for unsetting - would that be prefered? Thanks, Richard.
