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From: Lulu Cheng <>
To: Xi Ruoyao <>,
Subject: Re: [PATCH v3] LoongArch: Optimize immediate load.
Date: Fri, 4 Nov 2022 10:33:39 +0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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/ (x): New constraint.
>>          * config/loongarch/ (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 

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
>>          (LU52I_B): Likewise.
>>          (HWIT_UC_0xFFFFFFFF): New macro.
>>          (HI32_OPERAND): New macro.
>>          * config/loongarch/ (load_hi32): New template.
>>          * config/loongarch/ (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.

  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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