Re: inc_for_reload improvement

[Joern Rennecke <joern dot rennecke at superh dot com>]

> In this case, it would be perfectly legal to generate
> code such as :
> 
>          mov.l   @(16,r14), r0
>          mov.l   @r0+, r1
>          mov.l   r0, @(16,r14)
... 
>
> I am investigating how to specify the point where
> this preserved insn should be emitted. That is, after
> the next instruction in the sequence is emitted.
> It may require some tweaking of the reload1.c code,
> especially in the emit_input_reload_insns function
> where the inc_for_reload function is called.

I remember I had this working a few years ago - maybe
it is still working, but not in all cases.
AFAICR, the way it is supposed to work is that the auto-increment
is recognized as an in-out reload if we can have output reloads,
and both parts are assigned to the same hard register,
merge_assigned_reloads merges them to RELOAD_OTHER, and then
we emit the input and output parts appropriately.

(just checking the source)
This works together with reload inheritance:

Mon Mar 22 22:24:30 1999  J"orn Rennecke  <amylaar@cygnus.co.uk>

        * reload1.c (reload_as_needed): Set reload_is_output_reload /
        reload_has_output_reload for auto_inc expressions that could be
        reloaded.  Call forget_old_reloads for REG_INC notes.

Fri Oct 16 20:40:50 1998  J"orn Rennecke  <amylaar@cygnus.co.uk>

        Fix consistency problems with reg_equiv_{mem,address};
        Improve reload inheritance;

        * reload.c (reload_out_reg): New variable.
        (loc_mentioned_in_p, remove_address_replacements): New functions.
        (remove_replacements): Deleted.
        (push_reload): Set reload_out_reg[i].
        When merging, also set reload_{in,out}_reg[i], and remove
        duplicate address reloads.
        (combine_reloads): Copy reload_out_reg[i].
        (find_reloads): Do make_memloc substitution also when
        reg_equiv_memory_loc[regno] and num_not_at_initial_offset
        are both nonzero.
        Include *recog_operand_loc in commutativity operand changes.
        Generate optional output reloads.
        Delete reference to n_memlocs.  Don't set *recog_operand_loc before
        processing operands.  Call make_memloc in reg_equiv_address code.
        Set *recog_operand_loc only after processing operands, and only
        if replace is true.  Return a value.
        When changing address reload types for operands that didn't get
        reloaded, use RELOAD_FOR_OPADDR_ADDRESS for
        RELOAD_FOR_INPADDR_ADDRESS / RELOAD_FOR_OUTADDR_ADDRESS reloads.
        Don't emit USEs for pseudo SUBREGs when not replacing.
        (find_reloads_address): Do make_memloc substitution also when
        reg_equiv_memory_loc[regno] and num_not_at_initial_offset
        are both nonzero.
        (find_reloads_toplev): Likewise.
        Call make_memloc in reg_equiv_address code.
        (debug_reload_to_stream): Add code to output reload_out_reg.
        (make_memloc): Delete local variable i, ifdefed out code, and
        references to memlocs and n_memlocs.
        (memlocs, n_memlocs): Delete.
        (push_secondary_reload): Clear reload_out_reg.
        (find_reloads_address_1): Provide memrefloc argument to all calls
        to find_reloads_address.
        In AUTO_INC code, handle non-directly addressable equivalences properly.
        * reload.h (reload_out_reg, num_not_at_initial_offset): Declare.
        (find_reloads): Add return type.
        (remove_address_replacements, deallocate_reload_reg): Declare.
        * reload1.c (num_not_at_initial_offset): No longer static.
        (delete_address_reloads, delete_address_reloads_1): Likewise.
        (deallocate_reload_reg): New function.
        (spill_reg_stored_to): New array.
        (eliminate_regs): Don't substitute from reg_equiv_memory_loc.
        (eliminate_regs_in_insn): Move assignments of previous_offset and
        max_offset fields, and recalculation of num_not_at_initial_offset
        into new static function:
        (update_eliminable_offsets) .
        (reload_as_needed): Call update_eliminable_offsets after calling
        find_reloads.
        Call forget_old_reloads_1 with contents of reloaded auto_inc
        expressions if the actual addressing can't be changed to match the
        auto_inc.
        (choose_reload_regs): For inheritance, replace
        reload_reg_free_before_p test with reload_reg_used_at_all test, and
        remove stand-alone reload_reg_used_at_all test.
        Use reload_out_reg to determine which reload regs have output reloads.
        Treat reload_override_in more similar to inherited reloads.
        Handle (subreg (reg... for inheritance.
        For flag_expensive_optimizations, add an extra pass to remove
        unnecessary reloads from known working inheritance.
        Delete obsolete code for pseudos replaced with MEMs.
        Handle inheritance from auto_inc expressions.
        (emit_reload_insns): If reload_in is a MEM, set OLD to
        reload_in_reg[j].
        Don't reload directly from oldequiv; if it's a pseudo with a
        stack slot, use reload_in[j].
        Check that reload_in_reg[j] is a MEM before replacing reload_in
        from reg_reloaded_contents.
        Include non-spill registers in reload inheritance processing.
        Also try to use reload_out_reg to set spill_reg_store /
        reg_last_reload_reg.
        In code to set new_spill_reg_store, use single_set to find out if
        there is a single set.
        Add code that allows to delete optional output reloads.
        Add code to allow deletion of output reloads that use no spill reg.
        At the end, set reload_override_in to oldequiv.
        Also call delete_output_reload if reload_out_reg is equal to old
        in oldequiv code.
        Add code to call delete_output_reload for stores with no matching load.
        Set / use spill_reg_stored_to.
        Handle case where secondary output reload uses a temporary, but
        actual store isn't found.
        When looking for a store of a value not loaded in order to call
        delete_output_reload, count_occurrences should return 0 for no
        loads; but discount inherited input reloadill_reg_stored_to.
        Do checks for extra uses of REG.  Changed all
        callers.
        Use delete_address_reloads.
        (reload): Take return value of find_reloads into account.
        If a no-op set needs more than one reload, delete it.
        (reload_reg_free_before_p): RELOAD_FOR_INPUT
        can ignore RELOAD_FOR_INPUT_ADDRESS / RELOAD_FOR_INPADDR_ADDRESS
        for the same operand.
        (clear_reload_reg_in_use): Check for other reloads that keep a
        register in use.
        (reload_reg_free_for_value_p): Handle RELOAD_FOR_OPERAND_ADDRESS /
        RELOAD_FOR_OPADDR_ADDR.
        Take into account when an address address reload is only needed
        for the address reload we are considering.
        (count_occurrences): Use rtx_equal_p for MEMs.
        (inc_for_reload): Return instruction that stores into RELOADREG.
        New argument two, IN, and rtx.  Changed all callers.
        (calculate_needs_all_insns, reload_as_needed):
        Don't clear after_call for a CLOBBER.
        Keep track of how many hard registers need to be copied from
        after_call, and don't clear after_call before we have seen
        that much copies, or we see a different instruction.



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