https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67490
--- Comment #2 from Alexandre Oliva ---
Author: aoliva
Date: Sun Sep 27 09:02:00 2015
New Revision: 228175
URL: https://gcc.gnu.org/viewcvs?rev=228175&root=gcc&view=rev
Log:
revert to assign_parms assignments using default defs
Revert the fragile and complicated changes to assign_parms designed to
enable it to use RTL assigments chosen by cfgexpand, and instead have
cfgexpand use the RTL assignments by assign_parms, keying them off of
the default defs that are now necessarily introduced for each parm and
result. The possible lack of a default def was already a problem, and
the fallbacks in place were not enough, as shown by PR67312. We now
have checking asserts in set_rtl that verify that we're assigning to
each var a piece of RTL that matches the expectations set forth by
use_register_for_decl.
for gcc/ChangeLog
PR rtl-optimization/64164
PR tree-optimization/67312
PR middle-end/67340
PR middle-end/67490
PR bootstrap/67597
* cfgexpand.c (parm_in_stack_slot_p): Remove.
(ssa_default_def_partition): Remove.
(get_rtl_for_parm_ssa_default_def): Remove.
(set_rtl): Check that RTL assignments match expectations.
Loop on SUBREGs, CONCATs and PARALLELs subexprs. Set only the
default def location for params and results. Record SSA names
or types in REG and MEM attrs, respectively.
(set_parm_rtl): New.
(expand_one_ssa_partition): Drop logic that assigned MEMs with
unassigned addresses.
(adjust_one_expanded_partition_var): Don't accept NULL RTL on
deferred stack alloc vars.
(expand_used_vars): Skip partitions holding parm default defs.
Move adjust_one_expanded_partition_var loop...
(pass_expand::execute): ... here. Drop redundant assert.
Adjust comments before the final loop over all ssa names.
Require assigned rtl of parms and results to match exactly.
Reset its attributes to match them, not any other variables in
the same partition.
(expand_debug_expr): Use entry value for PARM's default defs
only iff they have zero nondebug uses.
* cfgexpand.h (parm_in_stack_slot_p): Remove.
(get_rtl_for_parm_ssa_default_def): Remove.
(set_parm_rtl): Declare.
* doc/invoke.texi: Improve wording.
* explow.c (promote_decl_mode): Fix promote_function_mode for
result decls not by reference.
(promote_ssa_mode): Disregard BLKmode from promote_decl, and
bypass TYPE_MODE to get the actual vector mode.
* function.c: Include tree-dfa.h. Revert 2015-08-14's and
2015-08-19's changes as follows. Drop include of
basic-block.h and df.h.
(rtl_for_parm): Remove.
(maybe_reset_rtl_for_parm): Remove.
(parm_in_unassigned_mem_p): Remove.
(use_register_for_decl): Add logic for RESULT_DECLs matching
assign_parms' behavior.
(split_complex_args): Revert.
(assign_parms_augmented_arg_list): Revert. Add comment
referencing the logic above.
(assign_parm_adjust_stack_rtl): Revert.
(assign_parm_setup_block): Revert. Use set_parm_rtl instead
of SET_DECL_RTL. Set up a REG if the parm demands so.
(assign_parm_setup_reg): Revert. Consolidated SET_DECL_RTL
calls into a single set_parm_rtl. Set up a temporary RTL
temporarily for expand_assignment.
(assign_parm_setup_stack): Revert. Use set_parm_rtl.
(assign_parms_unsplit_complex): Revert. Use set_parm_rtl.
(assign_bounds): Revert.
(assign_parms): Revert. Use set_parm_rtl.
(allocate_struct_function): Relayout result and parms of
non-abstruct functions.
(expand_function_start): Revert. Use set_parm_rtl. If the
result is not a hard reg, create a pseudo from the promoted
mode of the default def. Promote static chain mode.
* tree-outof-ssa.c (remove_ssa_form): Drop unused
partition_has_default_def. Set up
partitions_for_parm_default_defs.
(finish_out_of_ssa): Remove partition_has_default_def.
Release partitions_for_parm_default_defs.
* tree-outof-ssa.h (struct ssaexpand): Remove
partition_has_default_def. Add
partitions_for_parm_default_defs.
* tree-ssa-coalesce.c: Include tree-dfa.h, tm_p.h and
stor-layout.h.
(build_ssa_conflict_graph): Fix conflict-detection of default
defs of even unused default defs of params and results.
(for_all_parms): New.
(create_default_def): New.
(register_default_def): New.
(coalesce_with_default): New.
(create_outofssa_var_map): Create default defs for all parms
and results, and register their partitions. Add GIMPLE_RETURN
operands as coalesce candidates with results. Add default
defs of ea
