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Re: ira.c update_equiv_regs patch causes gcc/testsuite/gcc.target/arm/pr43920-2.c regression


Hi, Jeff

Thanks for your advice.

can_replace_by.patch is the new patch to handle both cases.

pr43920-2.c.244r.jump2.ori is the original  jump2 rtl dump

pr43920-2.c.244r.jump2.patch_can_replace_by is the jump2 rtl dump
after patch  can_replace_by.patch

Could you help me to review the patch?

Thanks again.

Shiva

2015-04-18 0:03 GMT+08:00 Jeff Law <law@redhat.com>:
> On 04/17/2015 03:57 AM, Shiva Chen wrote:
>>
>> Hi,
>>
>> I think the rtl dump in
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64916
>> is not jump2 phase rtl dump.
>>
>> Because jump2 is after ira, the register number should be hardware
>> register number.
>>
>> the jump2 rtl dump should as follow
>>
>> ...
>>     31: NOTE_INSN_BASIC_BLOCK 5
>>     32: [r6:SI]=r4:SI
>>        REG_DEAD r6:SI
>>        REG_DEAD r4:SI
>>     33: [r5:SI]=r0:SI
>>        REG_DEAD r5:SI
>>        REG_DEAD r0:SI
>>      7: r0:SI=0
>>        REG_EQUAL 0
>>     85: use r0:SI
>>     86:
>> {return;sp:SI=sp:SI+0x18;r3:SI=[sp:SI];r4:SI=[sp:SI+0x4];r5:SI=[sp:SI+0x8];r6:SI=[sp:SI+0xc];r7:SI=[sp:SI+0x10];pc:SI=[sp:SI+0x14];}
>>        REG_UNUSED pc:SI
>>        REG_UNUSED r3:SI
>>        REG_CFA_RESTORE r7:SI
>>        REG_CFA_RESTORE r6:SI
>>        REG_CFA_RESTORE r5:SI
>>        REG_CFA_RESTORE r4:SI
>>        REG_CFA_RESTORE r3:SI
>>     77: barrier
>>     46: L46:
>>     45: NOTE_INSN_BASIC_BLOCK 6
>>      8: r0:SI=r4:SI
>>        REG_DEAD r4:SI
>>        REG_EQUAL 0xffffffffffffffff
>>     87: use r0:SI
>>     88:
>> {return;sp:SI=sp:SI+0x18;r3:SI=[sp:SI];r4:SI=[sp:SI+0x4];r5:SI=[sp:SI+0x8];r6:SI=[sp:SI+0xc];r7:SI=[sp:SI+0x10];pc:SI=[sp:SI+0x14];}
>>        REG_UNUSED pc:SI
>>        REG_UNUSED r3:SI
>>        REG_CFA_RESTORE r7:SI
>>        REG_CFA_RESTORE r6:SI
>>        REG_CFA_RESTORE r5:SI
>>        REG_CFA_RESTORE r4:SI
>>        REG_CFA_RESTORE r3:SI
>>     79: barrier
>>     54: L54:
>>     53: NOTE_INSN_BASIC_BLOCK 7
>>      9: r0:SI=0xffffffffffffffff         <== lost REG_EQUAL after patch
>>     34: L34:
>>     35: NOTE_INSN_BASIC_BLOCK 8
>>     41: use r0:SI
>>     90:
>> {return;sp:SI=sp:SI+0x18;r3:SI=[sp:SI];r4:SI=[sp:SI+0x4];r5:SI=[sp:SI+0x8];r6:SI=[sp:SI+0xc];r7:SI=[sp:SI+0x10];pc:SI=[sp:SI+0x14];}
>>        REG_UNUSED pc:SI
>>        REG_UNUSED r3:SI
>>        REG_CFA_RESTORE r7:SI
>>        REG_CFA_RESTORE r6:SI
>>        REG_CFA_RESTORE r5:SI
>>        REG_CFA_RESTORE r4:SI
>>        REG_CFA_RESTORE r3:SI
>>     89: barrier
>
> Intead of the slim dump, can you please include the full RTL dump.  I find
> those much easier to read.
>
>
>
>>
>> Possible patch for  can_replace_by in cfgcleanup.c.
>>
>> -  if (!note1 || !note2 || !rtx_equal_p (XEXP (note1, 0), XEXP (note2, 0))
>> -      || !CONST_INT_P (XEXP (note1, 0)))
>> +
>> +  if (!note1 || !CONST_INT_P (XEXP (note1, 0)))
>>       return dir_none;
>>
>> +  if (note2)
>> +    {
>> +      if (!rtx_equal_p (XEXP (note1, 0), XEXP (note2, 0)))
>> +       return dir_none;
>> +    }
>> +  else
>> +    {
>> +      if (!CONST_INT_P (SET_SRC (s2))
>> +         || !rtx_equal_p (XEXP (note1, 0), SET_SRC (s2)))
>> +       return dir_none;
>> +    }
>> +
>>
>> I'm not sure the idea is ok or it might crash something.
>> Any suggestion would be very helpful.
>
> Seems like you're on a reasonable path to me.  I suggest you stick with it.
>
> Basically what it appears you're trying to do is unify insns from different
> blocks where one looks like
>
> (set x y)  with an attached REG_EQUAL note
>
> And the other looks like
>
> (set x const_int)
>
> Where the REG_EQUAL note has the same value as the const_int in the second
> set.
>
> I think you'd want to handle both cases i1 has the note i2, no note and i1
> has no note and i2 has a note.
>
> Jeff
>
> jeff

Attachment: can_replace_by.patch
Description: Binary data

Attachment: pr43920-2.c.244r.jump2.ori
Description: Binary data

Attachment: pr43920-2.c.244r.jump2.patch_can_replace_by
Description: Binary data

Attachment: Changelog.can_replace_by
Description: Binary data


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