Re: [PATCH v2 2/2] LoongArch: When the code model is extreme, the symbol address is obtained through macro instructions regardless of the value of -mexplicit-relocs.

[chenglulu <chenglulu@loongson.cn>]

在 2024/1/17 下午5:50, Xi Ruoyao 写道:
> On Wed, 2024-01-17 at 17:38 +0800, chenglulu wrote:
>> 在 2024/1/13 下午9:05, Xi Ruoyao 写道:
>>> 在 2024-01-13星期六的 15:01 +0800，chenglulu写道：
>>>> 在 2024/1/12 下午7:42, Xi Ruoyao 写道:
>>>>> 在 2024-01-12星期五的 09:46 +0800，chenglulu写道：
>>>>>
>>>>>>> I found an issue bootstrapping GCC with -mcmodel=extreme in BOOT_CFLAGS:
>>>>>>> we need a target hook to tell the generic code
>>>>>>> UNSPEC_LA_PCREL_64_PART{1,2} are just a wrapper around symbols, or we'll
>>>>>>> see millions lines of messages like
>>>>>>>
>>>>>>> ../../gcc/gcc/tree.h:4171:1: note: non-delegitimized UNSPEC
>>>>>>> UNSPEC_LA_PCREL_64_PART1 (42) found in variable location
>>>>>> I build GCC with -mcmodel=extreme in BOOT_CFLAGS, but I haven't reproduced the problem you mentioned.
>>>>>>
>>>>>>        $ ../configure --host=loongarch64-linux-gnu --target=loongarch64-linux-gnu --build=loongarch64-linux-gnu \
>>>>>>            --with-arch=loongarch64 --with-abi=lp64d --enable-tls --enable-languages=c,c++,fortran,lto --enable-plugin \
>>>>>>            --disable-multilib --disable-host-shared --enable-bootstrap --enable-checking=release
>>>>>>        $ make BOOT_FLAGS="-mcmodel=extreme"
>>>>>>
>>>>>> What did I do wrong?:-(
>>>>> BOOT_CFLAGS, not BOOT_FLAGS :).
>>>>>
>>>> This is so strange. My compilation here stopped due to syntax problems,
>>>>
>>>> and I still haven't reproduced the information you mentioned about
>>>> UNSPEC_LA_PCREL_64_PART1.
>>> I used:
>>>
>>> ../gcc/configure --with-system-zlib --disable-fixincludes \
>>>                    --enable-default-ssp --enable-default-pie \
>>>                    --disable-werror --disable-multilib \
>>>                    --prefix=/home/xry111/gcc-dev
>>>
>>> and then
>>>
>>> make STAGE1_{C,CXX}FLAGS="-O2 -g" -j8 \
>>>        BOOT_{C,CXX}FLAGS="-O2 -g -mcmodel=extreme" &| tee gcc-build.log
>>>
>>> I guess "-g" is needed to reproduce the issue as well as the messages
>>> were produced in dwarf generation.
>>>
>> I have reproduced this problem, and it can be solved by adding a hook.
>>
>> But unfortunately, when using '-mcmodel=extreme -mexplicit-relocs=always'
>>
>> to test spec2006 403.gcc, an error will occur. Others have not been
>> tested yet.
>>
>> I roughly debugged it, and the problem should be this:
>>
>> The problem is that the address of the instruction ‘ldx.d $r12, $r25,
>> $r6’ is wrong.
>>
>> Wrong assembly:
>>
>>      5826         pcalau12i       $r13,%got_pc_hi20(recog_data)
>>    5827         addi.d  $r12,$r0,%got_pc_lo12(recog_data)
>>    5828         lu32i.d $r12,%got64_pc_lo20(recog_data)
>>    5829         lu52i.d $r12,$r12,%got64_pc_hi12(recog_data)
>>    5830         ldx.d   $r12,$r13,$r12
>>    5831         ld.b    $r8,$r12,997
>>    5832         .loc 1 829 18 discriminator 1 view .LVU1527
>>    5833         ble     $r8,$r0,.L476
>>    5834         ld.d    $r6,$r3,16
>>    5835         ld.d    $r9,$r3,88
>>    5836 .LBB189 = .
>>    5837         .loc 1 839 24 view .LVU1528
>>    5838         alsl.d  $r7,$r19,$r19,2
>>    5839         ldx.d   $r12,$r25,$r6
>>    5840         addi.d  $r17,$r3,120
>>    5841 .LBE189 = .
>>    5842         .loc 1 829 18 discriminator 1 view .LVU1529
>>    5843         or      $r13,$r0,$r0
>>    5844         addi.d  $r4,$r12,992
>>
>> Assembly that works fine using macros:
>>
>> 3040         la.global       $r12,$r13,recog_data
>> 3041         ld.b    $r9,$r12,997
>> 3042         ble     $r9,$r0,.L475
>> 3043         alsl.d  $r5,$r16,$r16,2
>> 3044         la.global       $r15,$r17,recog_data
>> 3045         addi.d  $r4,$r12,992
>> 3046         addi.d  $r18,$r3,48
>> 3047         or      $r13,$r0,$r0
>>
>> Comparing the assembly, we can see that lines 5844 and 3045 have the
>> same function,
>>
>> but there is a problem with the base address register optimization at
>> line 5844.
>>
>> regrename.c.283r.loop2_init:
>>
>> (insn 6 497 2741 34 (set (reg:DI 180 [ ivtmp.713D.15724 ])
>>           (const_int 0 [0])) "regrename.c":829:18 discrim 1 156
>> {*movdi_64bit}
>> (nil))
>> (insn 2741 6 2744 34 (parallel [
>>               (set (reg:DI 1502)
>>                   (unspec:DI [
>>                           (symbol_ref:DI ("recog_data") [flags 0xc0]
>> <var_decl 0x7f8c5ffd66c0 recog_data>)
>>                       ] UNSPEC_LA_PCREL_64_PART1))
>>               (set (reg/f:DI 1479)
>>                   (unspec:DI [
>>                           (symbol_ref:DI ("recog_data") [flags 0xc0]
>> <var_decl 0x7f8c5ffd66c0 recog_data>)
>>                       ] UNSPEC_LA_PCREL_64_PART2))
>>           ]) -1
>>        (expr_list:REG_UNUSED (reg/f:DI 1479)
>> (nil)))
>> (insn 2744 2741 2745 34 (set (reg/f:DI 1503)
>>           (mem:DI (plus:DI (reg/f:DI 1479)
>>                   (reg:DI 1502)) [0  S8 A8])) 156 {*movdi_64bit}
>>        (expr_list:REG_EQUAL (symbol_ref:DI ("recog_data") [flags 0xc0]
>> <var_decl 0x7f8c5ffd66c0 recog_data>)
>> (nil)))
>>
>>
>> Virtual register 1479 will be used in insn 2744, but register 1479 was
>> assigned the REG_UNUSED attribute in the previous instruction.
>>
>> The attached file is the wrong file.
>> The compilation command is as follows:
>>
>> $ ./gcc/cc1 -fpreprocessed regrename.i -quiet -dp -dumpbase regrename.c
>> -dumpbase-ext .c -mno-relax -mabi=lp64d -march=loongarch64 -mfpu=64
>> -msimd=lasx -mcmodel=extreme -mtune=loongarch64 -g3 -O2
>> -Wno-int-conversion -Wno-implicit-int -Wno-implicit-function-declaration
>> -Wno-incompatible-pointer-types -version -o regrename.s
>> -mexplicit-relocs=always -fdump-rtl-all-all
> I've seen some "guality" test failures in GCC test suite as well.
> Normally I just ignore the guality failures but this time they look very
> suspicious.  I'll investigate these issues...
>
I've also seen this type of failed regression tests and I'll continue to 
look at this issue as well.