Re: PING: PATCH [4/n]: Prepare x32: Permute the conversion and addition if one operand is a constant

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Sun, Jul 10, 2011 at 2:04 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Sun, Jul 10, 2011 at 9:36 AM, Paolo Bonzini <bonzini@gnu.org> wrote:
>> On Sat, Jul 9, 2011 at 23:31, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Sat, Jul 9, 2011 at 2:18 PM, Paolo Bonzini <bonzini@gnu.org> wrote:
>>>> On 07/05/2011 04:27 PM, H.J. Lu wrote:
>>>>>>
>>>>>> ?diff --git a/gcc/explow.c b/gcc/explow.c
>>>>>> ?index 7387dad..b343bf8 100644
>>>>>> ?--- a/gcc/explow.c
>>>>>> ?+++ b/gcc/explow.c
>>>>>> ?@@ -383,18 +383,13 @@ convert_memory_address_addr_space (enum
>>>>>> machine_mode to_mode ATTRIBUTE_UNUSED,
>>>>>>
>>>>>> ? ? ?case PLUS:
>>>>>> ? ? ?case MULT:
>>>>>> ?- ? ? ?/* For addition we can safely permute the conversion and addition
>>>>>> ?- ? ? ? ?operation if one operand is a constant and converting the
>>>>>> constant
>>>>>> ?- ? ? ? ?does not change it or if one operand is a constant and we are
>>>>>> ?- ? ? ? ?using a ptr_extend instruction ?(POINTERS_EXTEND_UNSIGNED< ?0).
>>>>>> ?- ? ? ? ?We can always safely permute them if we are making the address
>>>>>> ?- ? ? ? ?narrower. ?*/
>>>>>> ?+ ? ? ?/* For addition we safely permute the conversion and addition
>>>>>> ?+ ? ? ? ?operation if one operand is a constant since we can't generate
>>>>>> ?+ ? ? ? ?new instructions. ?We can always safely permute them if we are
>>>>>> ?+ ? ? ? ?making the address narrower. ?*/
>>>>>> ? ? ? ?if (GET_MODE_SIZE (to_mode)< ?GET_MODE_SIZE (from_mode)
>>>>>> ? ? ? ? ? || (GET_CODE (x) == PLUS
>>>>>> ?-&& ?CONST_INT_P (XEXP (x, 1))
>>>>>> ?-&& ?(XEXP (x, 1) == convert_memory_address_addr_space
>>>>>> ?- ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?(to_mode, XEXP (x, 1), as)
>>>>>> ?- ? ? ? ? ? ? ? ? || POINTERS_EXTEND_UNSIGNED< ?0)))
>>>>>> ?+&& ?CONST_INT_P (XEXP (x, 1))))
>>>>>> ? ? ? ? return gen_rtx_fmt_ee (GET_CODE (x), to_mode,
>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?convert_memory_address_addr_space
>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?(to_mode, XEXP (x, 0), as),
>>>>
>>>> This does not seem safe to me.
>>>
>>> The current code is broken for x32. ?See:
>>>
>>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47727
>>>
>>> We can't generate any new instructions. ?Do you have any suggestions.
>>
>> By "safe" I mean that the new condition might be too wide and generate
>> wrong code. ?Richard is definitely right in comment 6, generating new
>> code in simplify-rtx is a no-no (see its usage of
>> gen_lowpart_no_emit).
>
> Here is a different approach. ?I added convert_memory_address_addr_space_1
> and convert_modes_1 so that simplify-rtx won't generate new insns. ?OK
> for trunk if there are no regressions on Linux/x86?
>
> Thanks.
>
> --
> H.J.
> ---
> 2011-07-10 ?H.J. Lu ?<hongjiu.lu@intel.com>
>
> ? ? ? ?* explow.c (convert_memory_address_addr_space_1): New.
> ? ? ? ?(convert_memory_address_addr_space): Use it.
>
> ? ? ? ?* expr.c (convert_modes_1): New.
> ? ? ? ?(convert_modes): Use it.
>
> ? ? ? ?* expr.h (convert_modes_1): New.
>
> ? ? ? ?* rtl.h (convert_memory_address_addr_space_1): New.
> ? ? ? ?(convert_memory_address_1): Likewise.
>
> ? ? ? ?* simplify-rtx.c (simplify_unary_operation_1): Call
> ? ? ? ?convert_memory_address_1 instead of convert_memory_address.
>

It doesn't work.  I got

(gdb) f 2
#2  0x000000000078735a in convert_memory_address_addr_space_1 (to_mode=DImode,
    x=0x7ffff05ac4e0, as=0 '\000', no_emit=1 '\001')
    at /export/gnu/import/git/gcc-x32/gcc/explow.c:410
410	  return convert_modes_1 (to_mode, from_mode, x,
(gdb) call debug_rtx (x)
(plus:SI (symbol_ref:SI ("iplane.1577") [flags 0x2] <var_decl
0x7ffff0857960 iplane>)
    (const_int -4 [0xfffffffffffffffc]))
(gdb) bt
#0  fancy_abort (file=0x13531a8 "/export/gnu/import/git/gcc-x32/gcc/expr.c",
    line=798, function=0x1354a00 "convert_modes_1")
    at /export/gnu/import/git/gcc-x32/gcc/diagnostic.c:893
#1  0x000000000079c60c in convert_modes_1 (mode=DImode, oldmode=SImode,
    x=0x7ffff05ac4e0, unsignedp=1, no_emit=1 '\001')
    at /export/gnu/import/git/gcc-x32/gcc/expr.c:798
#2  0x000000000078735a in convert_memory_address_addr_space_1 (to_mode=DImode,
    x=0x7ffff05ac4e0, as=0 '\000', no_emit=1 '\001')
    at /export/gnu/import/git/gcc-x32/gcc/explow.c:410
#3  0x0000000000787281 in convert_memory_address_addr_space_1 (to_mode=DImode,
    x=0x7ffff05616d0, as=0 '\000', no_emit=1 '\001')
    at /export/gnu/import/git/gcc-x32/gcc/explow.c:381
#4  0x0000000000b0faf4 in simplify_unary_operation_1 (code=ZERO_EXTEND,
    mode=DImode, op=0x7ffff05616d0)
    at /export/gnu/import/git/gcc-x32/gcc/simplify-rtx.c:1246
#5  0x0000000000b0d851 in simplify_unary_operation (code=ZERO_EXTEND,
    mode=DImode, op=0x7ffff05616d0, op_mode=SImode)
    at /export/gnu/import/git/gcc-x32/gcc/simplify-rtx.c:582
#6  0x0000000000b0d035 in simplify_gen_unary (code=ZERO_EXTEND, mode=DImode,
    op=0x7ffff05616d0, op_mode=SImode)
    at /export/gnu/import/git/gcc-x32/gcc/simplify-rtx.c:370
#7  0x000000000117078a in if_then_else_cond (x=0x7ffff02ebb00,
    ptrue=0x7fffffffd720, pfalse=0x7fffffffd718)
---Type <return> to continue, or q <return> to quit---
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:8649
#8  0x00000000011675b5 in combine_simplify_rtx (x=0x7ffff02ebb00,
    op0_mode=SImode, in_dest=0, in_cond=0)
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:5316
#9  0x0000000001167315 in subst (x=0x7ffff02ebb00, from=0x7ffff02f8120,
    to=0x7ffff05ac4f8, in_dest=0, in_cond=0, unique_copy=0)
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:5253
#10 0x0000000001167104 in subst (x=0x7ffff02f5558, from=0x7ffff02f8120,
    to=0x7ffff05ac4f8, in_dest=0, in_cond=0, unique_copy=0)
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:5189
#11 0x00000000011611ae in try_combine (i3=0x7ffff02f4c60, i2=0x7ffff02f4c18,
    i1=0x0, i0=0x0, new_direct_jump_p=0x7fffffffde14,
    last_combined_insn=0x7ffff02f4c60)
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:3178
#12 0x000000000115c487 in combine_instructions (f=0x7ffff07e7700, nregs=3344)
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:1223
#13 0x000000000117c64e in rest_of_handle_combine ()
    at /export/gnu/import/git/gcc-x32/gcc/combine.c:13879
#14 0x0000000000a500e7 in execute_one_pass (pass=0x190d320)
    at /export/gnu/import/git/gcc-x32/gcc/passes.c:2062
#15 0x0000000000a502cd in execute_pass_list (pass=0x190d320)
    at /export/gnu/import/git/gcc-x32/gcc/passes.c:2117
#16 0x0000000000a502ee in execute_pass_list (pass=0x1908180)
---Type <return> to continue, or q <return> to quit---
    at /export/gnu/import/git/gcc-x32/gcc/passes.c:2118
#17 0x0000000000be93e0 in tree_rest_of_compilation (fndecl=0x7ffff074c200)
    at /export/gnu/import/git/gcc-x32/gcc/tree-optimize.c:416
#18 0x00000000006d3ff7 in cgraph_expand_function (node=0x7ffff0792000)
    at /export/gnu/import/git/gcc-x32/gcc/cgraphunit.c:1804
#19 0x00000000006d41b6 in cgraph_expand_all_functions ()
    at /export/gnu/import/git/gcc-x32/gcc/cgraphunit.c:1863
#20 0x00000000006d48b2 in cgraph_optimize ()
    at /export/gnu/import/git/gcc-x32/gcc/cgraphunit.c:2133
#21 0x00000000006d1b2a in cgraph_finalize_compilation_unit ()
    at /export/gnu/import/git/gcc-x32/gcc/cgraphunit.c:1304
#22 0x00000000009cb7b0 in write_global_declarations ()
    at /export/gnu/import/git/gcc-x32/gcc/langhooks.c:303
#23 0x0000000000559cac in gfc_write_global_declarations ()
    at /export/gnu/import/git/gcc-x32/gcc/fortran/f95-lang.c:322
#24 0x0000000000b4649c in compile_file ()
    at /export/gnu/import/git/gcc-x32/gcc/toplev.c:564
#25 0x0000000000b48686 in do_compile ()
    at /export/gnu/import/git/gcc-x32/gcc/toplev.c:1886
#26 0x0000000000b487ec in toplev_main (argc=19, argv=0x7fffffffe2a8)
    at /export/gnu/import/git/gcc-x32/gcc/toplev.c:1958
#27 0x000000000060be84 in main (argc=19, argv=0x7fffffffe2a8)
    at /export/gnu/import/git/gcc-x32/gcc/main.c:36
(gdb)


H.J.