From: Lulu Cheng <chenglulu@loongson.cn>
To: Xi Ruoyao <xry111@xry111.site>, gcc-patches@gcc.gnu.org
Cc: i@xen0n.name, xuchenghua@loongson.cn
Subject: Re: [PATCH v3] LoongArch: Optimize immediate load.
Date: Fri, 4 Nov 2022 10:33:39 +0800 [thread overview]
Message-ID: <2250cca5-a1c9-aecc-9b01-1b6e52ec5e06@loongson.cn> (raw)
In-Reply-To: <5b19fb73fc15ae68951118a96393ed2222b41190.camel@xry111.site>
在 2022/11/4 上午10:22, Xi Ruoyao 写道:
> On Tue, 2022-11-01 at 20:04 +0800, Lulu Cheng wrote:
>> gcc/ChangeLog:
>>
>> * config/loongarch/constraints.md (x): New constraint.
>> * config/loongarch/loongarch.cc (struct loongarch_address_info):
>> Adds a method to load the immediate 32 to 64 bit field.
>> (struct loongarch_integer_op): Define a new member curr_value,
>> that records the value of the number stored in the destination
>> register immediately after the current instruction has run.
>> (LARCH_MAX_INTEGER_OPS): Define this macro as 3.
>> (LU32I_B): Move to the loongarch.h.
>> (LU52I_B): Likewise.
>> (loongarch_build_integer): Adds a method to load the immediate
>> 32 to 63 bits.
>> (loongarch_move_integer): Likewise.
> We need to mention "call set_unique_reg_note" here because it seems the
> key to resolve the issue.
During debugging, I found the problem because the source register and
destination
register of the lu32i.d instruction are the same. As a result, during
loop2_invariant pass,
the destination register of lu32i.d is used twice, so the instructions
after this instruction
will not be brought out of the loop.
Therefore, I combined lu32i.d and lu52i.d into one template, which
avoids the situation
that the same register is used twice. It is not split into two
instructions until loop2_invariant has
been optimized. So I don't think "set_unique_reg_note" plays a decisive
role in this optimization.
>
> Otherwise LGTM.
>
>> (loongarch_print_operand_reloc): Modifying comment information.
>> * config/loongarch/loongarch.h (LU32I_B): Move from loongarch.cc.
>> (LU52I_B): Likewise.
>> (HWIT_UC_0xFFFFFFFF): New macro.
>> (HI32_OPERAND): New macro.
>> * config/loongarch/loongarch.md (load_hi32): New template.
>> * config/loongarch/predicates.md (const_hi32_operand): Determines
>> whether the value is an immediate number that has a value of only
>> the higher 32 bits.
>> (hi32_mask_operand): Immediately counts the mask of 32 to 61 bits.
next prev parent reply other threads:[~2022-11-04 2:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-01 12:04 Lulu Cheng
2022-11-04 2:22 ` Xi Ruoyao
2022-11-04 2:33 ` Lulu Cheng [this message]
2022-11-04 2:56 ` Xi Ruoyao
2022-11-04 3:07 ` Lulu Cheng
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