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Re: PATCH: PR rtl-optimization/54157: [x32] -maddress-mode=long failures
On Sun, Aug 5, 2012 at 12:47 AM, Richard Sandiford
<rdsandiford@googlemail.com> wrote:
> For the record, I can't approve this, but...
>
> "H.J. Lu" <hjl.tools@gmail.com> writes:
>> i386,md has
>>
>> (define_expand "extzv"
>> [(set (match_operand:SI 0 "register_operand")
>> (zero_extract:SI (match_operand 1 "ext_register_operand")
>> (match_operand:SI 2 "const8_operand")
>> (match_operand:SI 3 "const8_operand")))]
>> ""
>>
>> and mode_for_extraction picks word_mode for operand 1 since
>> its mode is VOIDmode. This patch changes mode_for_extraction
>> to return the mode of operand 1 if the pattern accepts any mode.
>> I added *jcc_btsi_mask_2 since combine now tries a different
>> pattern, which leads to test failures on gcc.target/i386/bt-mask-1.c
>> and gcc.target/i386/bt-mask-2. I didn't update *jcc_btsi_mask_1
>> instead since I am not sure if it is used elsewhere. Tested on
>> Linux/x86-64 and Linux/x32. OK for trunk?
>
> the mode of the extraction operand is defined to be word_mode
> for registers (see md.texi), so that at least would need to
> be updated. But I'm not convinced that the wanted_inner_mode here:
>
> if (! in_dest && unsignedp
> - && mode_for_extraction (EP_extzv, -1) != MAX_MACHINE_MODE)
> + && mode_for_extraction (EP_extzv, -1, VOIDmode) != MAX_MACHINE_MODE)
> {
> - wanted_inner_reg_mode = mode_for_extraction (EP_extzv, 1);
> - pos_mode = mode_for_extraction (EP_extzv, 3);
> - extraction_mode = mode_for_extraction (EP_extzv, 0);
> + wanted_inner_reg_mode = mode_for_extraction (EP_extzv, 1,
> + inner_mode);
> + pos_mode = mode_for_extraction (EP_extzv, 3, VOIDmode);
> + extraction_mode = mode_for_extraction (EP_extzv, 0, VOIDmode);
> }
>
> is right. inner_mode is the mode of the thing we're extracting,
> which doesn't ncessarily have anything to do with what the ext*
> patterns support.
>
> FWIW, in reply to your force_to_mode message, gen_lowpart_for_combine
> looks a bit odd:
>
> if (omode == imode)
> return x;
>
> /* Return identity if this is a CONST or symbolic reference. */
> if (omode == Pmode
> && (GET_CODE (x) == CONST
> || GET_CODE (x) == SYMBOL_REF
> || GET_CODE (x) == LABEL_REF))
> return x;
>
> So if we know the modes are different, we nevertheless return the
> original mode for CONST, SYMBOL_REF or LABEL_REF. Surely the caller
> isn't going to be expecting that? If we're not prepared to change
> the mode to the one that the caller asked for then I think we should
> goto fail instead.
>
> I don't know if you're hitting that or not.
>
> Richard
Yes, I did
Breakpoint 5, gen_lowpart_for_combine (omode=DImode, x=0x7ffff1b03440)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:10778
10778 {
(const:SI (plus:SI (symbol_ref:SI ("tmp2") <var_decl 0x7ffff1997140 tmp2>)
(const_int 99452 [0x1847c])))
(gdb) c
Continuing.
Breakpoint 5, gen_lowpart_for_combine (omode=DImode, x=0x7ffff1b03440)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:10778
10778 {
(const:SI (plus:SI (symbol_ref:SI ("tmp2") <var_decl 0x7ffff1997140 tmp2>)
(const_int 99452 [0x1847c])))
(gdb) bt
#0 gen_lowpart_for_combine (omode=DImode, x=0x7ffff1b03440)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:10778
#1 0x0000000000c83805 in gen_lowpart_or_truncate (x=0x7ffff1b03440,
mode=DImode) at /export/gnu/import/git/gcc-misc/gcc/combine.c:8110
#2 force_to_mode (x=0x7ffff1b02cd8, mode=DImode, mask=<optimized out>,
just_select=<optimized out>)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:8389
#3 0x0000000000c8458a in make_extraction (mode=SImode, inner=0x7ffff1b02cd8,
pos=2, pos_rtx=<optimized out>, len=2, unsignedp=1,
in_dest=<optimized out>, in_compare=0)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:7480
#4 0x0000000000c86f9c in make_compound_operation (x=x@entry=0x7ffff1b02d68,
in_code=in_code@entry=SET)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:7863
#5 0x0000000000c89924 in simplify_set (x=0x7ffff1af7c78)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:6539
#6 combine_simplify_rtx (x=0x7ffff1af7c78, op0_mode=VOIDmode,
in_dest=in_dest@entry=0, in_cond=in_cond@entry=0)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:5971
#7 0x0000000000c8bd1b in subst (x=<optimized out>, from=<optimized out>,
to=<optimized out>, in_dest=0, in_cond=0, unique_copy=0)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:5301
#8 0x0000000000c8b8ab in subst (x=0x7ffff1aea870, from=0x7ffff1afc880,
---Type <return> to continue, or q <return> to quit---
to=0x7ffff1b02cd8, in_dest=0, in_cond=0, unique_copy=0)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:5165
#9 0x0000000000c8f875 in try_combine (i3=i3@entry=0x7ffff1afe5a0,
i2=i2@entry=0x7ffff1afe558, i1=<optimized out>, i0=<optimized out>,
i0@entry=0x0, new_direct_jump_p=new_direct_jump_p@entry=0x7fffffffdb64,
last_combined_insn=last_combined_insn@entry=0x7ffff1afe5a0)
at /export/gnu/import/git/gcc-misc/gcc/combine.c:3260
#10 0x0000000000c94673 in combine_instructions (nregs=<optimized out>,
f=<optimized out>) at /export/gnu/import/git/gcc-misc/gcc/combine.c:1265
#11 rest_of_handle_combine ()
at /export/gnu/import/git/gcc-misc/gcc/combine.c:13948
#12 0x0000000000824755 in execute_one_pass (
pass=pass@entry=0x135aae0 <pass_combine>)
at /export/gnu/import/git/gcc-misc/gcc/passes.c:2158
#13 0x0000000000824b15 in execute_pass_list (pass=0x135aae0 <pass_combine>)
at /export/gnu/import/git/gcc-misc/gcc/passes.c:2213
#14 0x0000000000824b27 in execute_pass_list (
pass=0x1355d20 <pass_rest_of_compilation>)
at /export/gnu/import/git/gcc-misc/gcc/passes.c:2214
#15 0x0000000000610fb8 in expand_function (node=0x7ffff1995750)
at /export/gnu/import/git/gcc-misc/gcc/cgraphunit.c:1610
#16 0x0000000000612df4 in expand_all_functions ()
at /export/gnu/import/git/gcc-misc/gcc/cgraphunit.c:1715
---Type <return> to continue, or q <return> to quit---
#17 compile () at /export/gnu/import/git/gcc-misc/gcc/cgraphunit.c:2013
#18 0x00000000006133b5 in finalize_compilation_unit ()
at /export/gnu/import/git/gcc-misc/gcc/cgraphunit.c:2090
#19 0x0000000000506b90 in c_write_global_declarations ()
at /export/gnu/import/git/gcc-misc/gcc/c/c-decl.c:10116
#20 0x00000000008c5325 in compile_file ()
at /export/gnu/import/git/gcc-misc/gcc/toplev.c:560
#21 0x00000000008c6eb8 in do_compile ()
at /export/gnu/import/git/gcc-misc/gcc/toplev.c:1863
#22 toplev_main (argc=17, argv=0x7fffffffdde8)
at /export/gnu/import/git/gcc-misc/gcc/toplev.c:1939
#23 0x0000003c88221735 in __libc_start_main () from /lib64/libc.so.6
#24 0x00000000004e9f41 in _start ()
This patch:
diff --git a/gcc/combine.c b/gcc/combine.c
index a07c046..b9a3589 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -10784,12 +10784,30 @@ gen_lowpart_for_combine (enum machine_mode omode, rtx
x)
if (omode == imode)
return x;
- /* Return identity if this is a CONST or symbolic reference. */
- if (omode == Pmode
- && (GET_CODE (x) == CONST
- || GET_CODE (x) == SYMBOL_REF
- || GET_CODE (x) == LABEL_REF))
- return x;
+ if (omode == Pmode)
+ {
+ /* Return identity if this is a symbolic reference. */
+ if (GET_CODE (x) == SYMBOL_REF || GET_CODE (x) == LABEL_REF)
+ return x;
+
+ /* Return identity for CONST unless this is a PLUS of 2 constant
+ operands. */
+ if (GET_CODE (x) == CONST)
+ {
+ rtx y = XEXP (x, 0);
+ if (GET_CODE (y) == PLUS
+ && ((CONST_INT_P (XEXP (y, 1))
+ && (GET_CODE (XEXP (y, 0)) == CONST
+ || GET_CODE (XEXP (y, 0)) == SYMBOL_REF
+ || GET_CODE (XEXP (y, 0)) == LABEL_REF))
+ || (CONST_INT_P (XEXP (y, 1))
+ && (GET_CODE (XEXP (y, 0)) == CONST
+ || GET_CODE (XEXP (y, 0)) == SYMBOL_REF
+ || GET_CODE (XEXP (y, 0)) == LABEL_REF))))
+ goto fail;
+ return x;
+ }
+ }
/* We can only support MODE being wider than a word if X is a
constant integer or has a mode the same size. */
works for the testcase.
--
H.J.