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Failed Checking missing-syscalls for O32 #37411

Closed xiangzhai closed 3 years ago

xiangzhai commented 6 years ago
Bugzilla Link 38063
Resolution WONTFIX
Resolved on Jan 23, 2019 06:05
Version trunk
OS Linux
CC @zygoloid,@atanasyan

Extended Description

Hi LLVM developers,

I am building Linux Kernel[1] with LLVM toolchain[2] for mips64el. But it failed Checking missing-syscalls for O32:

error: ABI 'o32' is not supported on CPU 'mips64r2' Kbuild:98: recipe for target 'missing-syscalls' failed make[1]: *** [missing-syscalls] Error 1

GCC is able to work:

... Checking missing-syscalls for O32 CHK include/generated/timeconst.h CHK include/generated/bounds.h CHK include/generated/asm-offsets.h CALL scripts/checksyscalls.sh CHK include/generated/bounds.h CHK include/generated/timeconst.h CHK include/generated/asm-offsets.h ...

So ugly workaround patch:

diff --git a/lib/Basic/Targets/Mips.cpp b/lib/Basic/Targets/Mips.cpp index cbd5a01..59dd34b 100644 --- a/lib/Basic/Targets/Mips.cpp +++ b/lib/Basic/Targets/Mips.cpp @@ -207,8 +207,7 @@ bool MipsTargetInfo::validateTarget(DiagnosticsEngine &Diags) const { // FIXME: It's valid to use O32 on a 64-bit CPU but the backend can't handle // this yet. It's better to fail here than on the backend assertion. if (processorSupportsG#64 () && ABI == "o32") {

  1. Linux Kernel 4.9 branch https://github.com/loongson-community/linux-stable
  2. Loongson clang version 7.0.0 (git@github.com:llvm-mirror/clang.git ef356db5c03a0f052c09ebd0a964b9eda3852847) (git@github.com:llvm-mirror/llvm.git ab9920d16bc0acaa2a458b49a43b3aaa9bcda8e6) (based on LLVM 7.0.0svn) Target: mips64el-redhat-linux Thread model: posix InstalledDir: /opt/llvm-git/bin Found candidate GCC installation: /usr/lib/gcc/mips64el-redhat-linux/4.9.3 Selected GCC installation: /usr/lib/gcc/mips64el-redhat-linux/4.9.3 Candidate multilib: .; Selected multilib: .;

Regards, Leslie Zhai

xiangzhai commented 3 years ago

mentioned in issue llvm/llvm-bugzilla-archive#38128

atanasyan commented 5 years ago

There is no plan on support O32 for MIPS64 due to lack of resources. But I'm ready to accept and review any related patches.

xiangzhai commented 6 years ago

$ llvm-mc cpload.s -arch=mips64el -mcpu=mips64r2 -target-abi o32 -filetype=obj -o cpload-llvm-o32.o $ llvm-objdump -d -r cpload-llvm-o32.o

cpload-llvm-o32.o: file format ELF64-mips

Disassembly of section .text: .text: 0: 00 00 1c 3c lui $gp, 0 0000000000000000: R_MIPS_HI16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 4: 00 00 9c 27 addiu $gp, $gp, 0 0000000000000004: R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 8: 21 e0 99 03 addu $gp, $gp, $25

Why there is R_MIPS_NONE?

llvm-mc generates 64-bit ELF file. For 64-bit MIPS files llvm-objdump prints relocations accordingly to the N64 ABI specification. In that case each relocation record might contain up to three relocations. See p. 40 at [1].

[1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf

Sorry for my late response! So is my output correct?

It depends on what you want to geе. If you run gcc with "-mabi=32 -mips64" options, you get 32-bit binaries with MIPS64 instructions. You output from the llvm-mc shows that you get 64-bit binaries.

Thanks for your teaching!

then teach the backend to emit a correct code

llvm/llvm-project#37411 #c3

Could you give me some hint about how to support O32 ABI on 64-bit CPUs? thanks a lot!

Regards, Leslie Zhai

atanasyan commented 6 years ago

$ llvm-mc cpload.s -arch=mips64el -mcpu=mips64r2 -target-abi o32 -filetype=obj -o cpload-llvm-o32.o $ llvm-objdump -d -r cpload-llvm-o32.o

cpload-llvm-o32.o: file format ELF64-mips

Disassembly of section .text: .text: 0: 00 00 1c 3c lui $gp, 0 0000000000000000: R_MIPS_HI16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 4: 00 00 9c 27 addiu $gp, $gp, 0 0000000000000004: R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 8: 21 e0 99 03 addu $gp, $gp, $25

Why there is R_MIPS_NONE?

llvm-mc generates 64-bit ELF file. For 64-bit MIPS files llvm-objdump prints relocations accordingly to the N64 ABI specification. In that case each relocation record might contain up to three relocations. See p. 40 at [1].

[1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf

Sorry for my late response! So is my output correct?

It depends on what you want to geе. If you run gcc with "-mabi=32 -mips64" options, you get 32-bit binaries with MIPS64 instructions. You output from the llvm-mc shows that you get 64-bit binaries.

xiangzhai commented 6 years ago

$ llvm-mc cpload.s -arch=mips64el -mcpu=mips64r2 -target-abi o32 -filetype=obj -o cpload-llvm-o32.o $ llvm-objdump -d -r cpload-llvm-o32.o

cpload-llvm-o32.o: file format ELF64-mips

Disassembly of section .text: .text: 0: 00 00 1c 3c lui $gp, 0 0000000000000000: R_MIPS_HI16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 4: 00 00 9c 27 addiu $gp, $gp, 0 0000000000000004: R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 8: 21 e0 99 03 addu $gp, $gp, $25

Why there is R_MIPS_NONE?

llvm-mc generates 64-bit ELF file. For 64-bit MIPS files llvm-objdump prints relocations accordingly to the N64 ABI specification. In that case each relocation record might contain up to three relocations. See p. 40 at [1].

[1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf

Sorry for my late response! So is my output correct?

Regards, Leslie Zhai

atanasyan commented 6 years ago

$ llvm-mc cpload.s -arch=mips64el -mcpu=mips64r2 -target-abi o32 -filetype=obj -o cpload-llvm-o32.o $ llvm-objdump -d -r cpload-llvm-o32.o

cpload-llvm-o32.o: file format ELF64-mips

Disassembly of section .text: .text: 0: 00 00 1c 3c lui $gp, 0 0000000000000000: R_MIPS_HI16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 4: 00 00 9c 27 addiu $gp, $gp, 0 0000000000000004: R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 8: 21 e0 99 03 addu $gp, $gp, $25

Why there is R_MIPS_NONE?

llvm-mc generates 64-bit ELF file. For 64-bit MIPS files llvm-objdump prints relocations accordingly to the N64 ABI specification. In that case each relocation record might contain up to three relocations. See p. 40 at [1].

[1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf

xiangzhai commented 6 years ago

The similar issue:

$ make CC=/opt/loong-llvm/bin/clang clang-7: warning: argument unused during compilation: '-Wa,-msoft-float' [-Wunused-command-line-argument] clang-7: warning: argument unused during compilation: '-Wa,--trap' [-Wunused-command-line-argument] clang-7: warning: argument unused during compilation: '-Wa,-mno-fix-loongson3-llsc' [-Wunused-command-line-argument] clang-7: warning: argument unused during compilation: '-mno-branch-likely' [-Wunused-command-line-argument] CHK include/config/kernel.release CHK include/generated/uapi/linux/version.h CHK include/generated/utsrelease.h Checking missing-syscalls for N32 CHK include/generated/timeconst.h CHK include/generated/bounds.h CHK include/generated/asm-offsets.h CALL scripts/checksyscalls.sh Checking missing-syscalls for O32 CHK include/generated/timeconst.h CHK include/generated/bounds.h CHK include/generated/asm-offsets.h CALL scripts/checksyscalls.sh CHK include/generated/bounds.h CHK include/generated/timeconst.h CHK include/generated/asm-offsets.h CALL scripts/checksyscalls.sh CHK include/generated/compile.h CC arch/mips/kernel/traps.o LD arch/mips/kernel/built-in.o CC arch/mips/mm/page.o CC arch/mips/mm/tlbex.o AS arch/mips/mm/tlbex-fault.o AS arch/mips/mm/tlb-funcs.o CC arch/mips/mm/uasm-mips.o CC arch/mips/mm/pgtable-64.o CC arch/mips/mm/hugetlbpage.o CC arch/mips/mm/c-r4k.o AS arch/mips/mm/cex-gen.o CC arch/mips/mm/tlb-r4k.o LD arch/mips/mm/built-in.o LD arch/mips/net/built-in.o arch/mips/vdso/Makefile:31: MIPS VDSO requires binutils >= 2.25 LDS arch/mips/vdso/vdso.lds AS arch/mips/vdso/elf.o AS arch/mips/vdso/sigreturn.o VDSO arch/mips/vdso/vdso.so.dbg.raw OBJCOPY arch/mips/vdso/vdso.so.raw HOSTCC arch/mips/vdso/genvdso GENVDSO arch/mips/vdso/vdso-image.c CC arch/mips/vdso/vdso-image.o LDS arch/mips/vdso/vdso-o32.lds error: ABI 'o32' is not supported for 'mips64el-redhat-linux' arch/mips/vdso/Makefile:122: recipe for target 'arch/mips/vdso/vdso-o32.lds' failed make[2]: *** [arch/mips/vdso/vdso-o32.lds] Error 1

Regards, Leslie Zhai

xiangzhai commented 6 years ago

If you can build a N64 ABI executable, you have a N64 ABI toolchain. Why can't you use this toolchain to build Linux?

With the ugly monkey patch, LLVM is able to pass the testcase[1] Checking missing-syscalls for O32, and go forward[2]

  1. https://github.com/loongson-community/linux-stable/issues/4
  2. https://github.com/loongson-community/linux-stable/issues/5

Regards, Leslie Zhai

xiangzhai commented 6 years ago
  1. You can use mips32r2 to generate code for a MIPS64 CPU. In that case the code will not contain MIPS64 specific instructions, but will work.

Thanks for your teaching!

  1. If you can build a N64 ABI executable, you have a N64 ABI toolchain. Why can't you use this toolchain to build Linux?

It also confused me, but GCC is able to work llvm/llvm-project#37411 #c0

Take a look at test/MC/Mips test cases with the -target-abi option. For example cpload.s

$ llvm-mc cpload.s -arch=mips64el -mcpu=mips64r2 -target-abi o32 -filetype=obj -o cpload-llvm-o32.o $ llvm-objdump -d -r cpload-llvm-o32.o

cpload-llvm-o32.o: file format ELF64-mips

Disassembly of section .text: .text: 0: 00 00 1c 3c lui $gp, 0 0000000000000000: R_MIPS_HI16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 4: 00 00 9c 27 addiu $gp, $gp, 0 0000000000000004: R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE _gp_disp 8: 21 e0 99 03 addu $gp, $gp, $25

Why there is R_MIPS_NONE?

$ gcc -c cpload.s -mabi=32 -o cpload-gnu-o32.o $ llvm-objdump -d -r cpload-gnu-o32.o

cpload-gnu-o32.o: file format ELF32-mips

Disassembly of section .text: .text: 0: 00 00 1c 3c lui $gp, 0 00000000: R_MIPS_HI16 gnu_local_gp 4: 00 00 9c 27 addiu $gp, $gp, 0 00000004: R_MIPS_LO16 gnu_local_gp 8: 00 00 00 00 nop c: 00 00 00 00 nop

Regards, Leslie Zhai - an apprentice in MIPS world

atanasyan commented 6 years ago

  1. You can use mips32r2 to generate code for a MIPS64 CPU. In that case the code will not contain MIPS64 specific instructions, but will work.

  2. If you can build a N64 ABI executable, you have a N64 ABI toolchain. Why can't you use this toolchain to build Linux?

xiangzhai commented 6 years ago

In short, it's a difficult task. If you really need to support O32 ABI on 64-bit CPUs, I would recommend to start from the backend. Take a look at test/MC/Mips test cases with the -target-abi option. For example cpload.s. Add -mcpu=mips64r2 -target-abi o32 case to them, then teach the backend to emit a correct code, etc ...

Thanks for your teaching! I will try to implement it and let you to review the patch.

By the way, a) could you switch to mips32r2 option? b) could you use or build and use a toolchain with N64 ABI support?

Loongson 3A3000[1] is MIPS64r2, so I couldn't switch to mips32r2, correct? My LLVM toolchain[2] support N64 ABI, is there something wrong, please teach me, thanks a lot!

  1. Loongson 3A3000 https://en.wikipedia.org/wiki/Loongson#Loongson_microprocessor_specifications
  2. $ cat hello.c

    include

int main(int argc, char *argv[]) { printf("Hello Loongson\n"); return 0; }

$ /opt/llvm-git/bin/clang hello.c $ file a.out a.out: ELF 64-bit LSB executable, MIPS, MIPS64 rel2 version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.32, not stripped $ readelf -a a.out ELF Header: Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: EXEC (Executable file) Machine: MIPS R3000 Version: 0x1 Entry point address: 0x1200008e0 Start of program headers: 64 (bytes into file) Start of section headers: 4944 (bytes into file) Flags: 0x80a20007, noreorder, pic, cpic, loongson-3a, mips64r2 Size of this header: 64 (bytes) Size of program headers: 56 (bytes) Number of program headers: 10 Size of section headers: 64 (bytes) Number of section headers: 31 Section header string table index: 28

Section Headers: [Nr] Name Type Address Offset Size EntSize Flags Link Info Align [ 0] NULL 0000000000000000 00000000 0000000000000000 0000000000000000 0 0 0 [ 1] .MIPS.options MIPS_OPTIONS 0000000120000270 00000270 0000000000000168 0000000000000001 Ao 0 0 8 [ 2] .dynamic DYNAMIC 00000001200003d8 000003d8 00000000000001f0 0000000000000010 A 5 0 8 [ 3] .hash HASH 00000001200005c8 000005c8 0000000000000050 0000000000000004 A 4 0 8 [ 4] .dynsym DYNSYM 0000000120000618 00000618 0000000000000168 0000000000000018 A 5 1 8 [ 5] .dynstr STRTAB 0000000120000780 00000780 00000000000000dd 0000000000000000 A 0 0 1 [ 6] .gnu.version VERSYM 000000012000085e 0000085e 000000000000001e 0000000000000002 A 4 0 2 [ 7] .gnu.version_r VERNEED 0000000120000880 00000880 0000000000000020 0000000000000000 A 5 1 8 [ 8] .init PROGBITS 00000001200008a0 000008a0 0000000000000040 0000000000000000 AX 0 0 4 [ 9] .text PROGBITS 00000001200008e0 000008e0 00000000000002c0 0000000000000000 AX 0 0 16 [10] .MIPS.stubs PROGBITS 0000000120000ba0 00000ba0 0000000000000030 0000000000000000 AX 0 0 8 [11] .fini PROGBITS 0000000120000bd0 00000bd0 0000000000000028 0000000000000000 AX 0 0 4 [12] .rodata PROGBITS 0000000120000bf8 00000bf8 0000000000000014 0000000000000000 A 0 0 4 [13] .interp PROGBITS 0000000120000c0c 00000c0c 000000000000000f 0000000000000000 A 0 0 1 [14] .eh_frame_hdr PROGBITS 0000000120000c1c 00000c1c 000000000000001c 0000000000000000 A 0 0 4 [15] .eh_frame PROGBITS 0000000120000c38 00000c38 0000000000000074 0000000000000000 A 0 0 8 [16] .note.ABI-tag NOTE 0000000120000cac 00000cac 0000000000000020 0000000000000000 A 0 0 4 [17] .init_array INIT_ARRAY 0000000120010fe8 00000fe8 0000000000000008 0000000000000000 WA 0 0 8 [18] .fini_array FINI_ARRAY 0000000120010ff0 00000ff0 0000000000000008 0000000000000000 WA 0 0 8 [19] .jcr PROGBITS 0000000120010ff8 00000ff8 0000000000000008 0000000000000000 WA 0 0 8 [20] .data PROGBITS 0000000120011000 00001000 0000000000000010 0000000000000000 WA 0 0 16 [21] .rld_map PROGBITS 0000000120011010 00001010 0000000000000008 0000000000000000 WA 0 0 8 [22] .got PROGBITS 0000000120011020 00001020 00000000000000a0 0000000000000008 WAp 0 0 16 [23] .sdata PROGBITS 00000001200110c0 000010c0 0000000000000008 0000000000000000 WAp 0 0 8 [24] .bss NOBITS 00000001200110d0 000010c8 0000000000000010 0000000000000000 WA 0 0 16 [25] .comment PROGBITS 0000000000000000 000010c8 0000000000000101 0000000000000001 MS 0 0 1 [26] .pdr PROGBITS 0000000000000000 000011cc 0000000000000060 0000000000000000 0 0 4 [27] .gnu.attributes LOOS+ffffff5 0000000000000000 0000122c 0000000000000010 0000000000000000 0 0 1 [28] .shstrtab STRTAB 0000000000000000 0000123c 0000000000000113 0000000000000000 0 0 1 [29] .symtab SYMTAB 0000000000000000 00001b10 0000000000000708 0000000000000018 30 50 8 [30] .strtab STRTAB 0000000000000000 00002218 00000000000002bc 0000000000000000 0 0 1 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings) I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown) O (extra OS processing required) o (OS specific), p (processor specific)

There are no section groups in this file.

Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align PHDR 0x0000000000000040 0x0000000120000040 0x0000000120000040 0x0000000000000230 0x0000000000000230 R E 8 INTERP 0x0000000000000c0c 0x0000000120000c0c 0x0000000120000c0c 0x000000000000000f 0x000000000000000f R 1 [Requesting program interpreter: /lib64/ld.so.1] LOAD 0x0000000000000000 0x0000000120000000 0x0000000120000000 0x0000000000000ccc 0x0000000000000ccc R E 10000 LOAD 0x0000000000000fe8 0x0000000120010fe8 0x0000000120010fe8 0x00000000000000e0 0x00000000000000f8 RW 10000 DYNAMIC 0x00000000000003d8 0x00000001200003d8 0x00000001200003d8 0x00000000000001f0 0x00000000000001f0 RWE 8 NOTE 0x0000000000000cac 0x0000000120000cac 0x0000000120000cac 0x0000000000000020 0x0000000000000020 R 4 GNU_EH_FRAME 0x0000000000000c1c 0x0000000120000c1c 0x0000000120000c1c 0x000000000000001c 0x000000000000001c R 4 GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 RWE 10 GNU_RELRO 0x0000000000000fe8 0x0000000120010fe8 0x0000000120010fe8 0x0000000000000018 0x0000000000000018 R 1 NULL 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 8

Section to Segment mapping: Segment Sections... 00
01 .interp 02 .MIPS.options .dynamic .hash .dynsym .dynstr .gnu.version .gnu.version_r .init .text .MIPS.stubs .fini .rodata .interp .eh_frame_hdr .eh_frame .note.ABI-tag 03 .init_array .fini_array .jcr .data .rld_map .got .sdata .bss 04 .dynamic 05 .note.ABI-tag 06 .eh_frame_hdr 07
08 .init_array .fini_array .jcr 09

Dynamic section at offset 0x3d8 contains 26 entries: Tag Type Name/Value 0x0000000000000001 (NEEDED) Shared library: [libc.so.6] 0x000000000000000c (INIT) 0x1200008a0 0x000000000000000d (FINI) 0x120000bd0 0x0000000000000019 (INIT_ARRAY) 0x120010fe8 0x000000000000001b (INIT_ARRAYSZ) 8 (bytes) 0x000000000000001a (FINI_ARRAY) 0x120010ff0 0x000000000000001c (FINI_ARRAYSZ) 8 (bytes) 0x0000000000000004 (HASH) 0x1200005c8 0x0000000000000005 (STRTAB) 0x120000780 0x0000000000000006 (SYMTAB) 0x120000618 0x000000000000000a (STRSZ) 221 (bytes) 0x000000000000000b (SYMENT) 24 (bytes) 0x0000000070000016 (MIPS_RLD_MAP) 0x120011010 0x0000000000000015 (DEBUG) 0x0 0x0000000000000003 (PLTGOT) 0x120011020 0x0000000070000001 (MIPS_RLD_VERSION) 1 0x0000000070000005 (MIPS_FLAGS) NOTPOT 0x0000000070000006 (MIPS_BASE_ADDRESS) 0x120000000 0x000000007000000a (MIPS_LOCAL_GOTNO) 14 0x0000000070000011 (MIPS_SYMTABNO) 15 0x0000000070000012 (MIPS_UNREFEXTNO) 28 0x0000000070000013 (MIPS_GOTSYM) 0x9 0x000000006ffffffe (VERNEED) 0x120000880 0x000000006fffffff (VERNEEDNUM) 1 0x000000006ffffff0 (VERSYM) 0x12000085e 0x0000000000000000 (NULL) 0x0

There are no relocations in this file.

The decoding of unwind sections for machine type MIPS R3000 is not currently supported.

Symbol table '.dynsym' contains 15 entries: Num: Value Size Type Bind Vis Ndx Name 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND 1: 0000000120000b98 8 FUNC GLOBAL DEFAULT 9 libc_csu_fini 2: 0000000000000001 0 SECTION GLOBAL DEFAULT ABS _DYNAMIC_LINKING 3: 0000000120000bf8 4 OBJECT GLOBAL DEFAULT 12 _IO_stdin_used 4: 0000000120011010 0 OBJECT GLOBAL DEFAULT 21 __RLD_MAP 5: 0000000120000b00 148 FUNC GLOBAL DEFAULT 9 libc_csu_init 6: 0000000120000a80 124 FUNC GLOBAL DEFAULT 9 main 7: 0000000120011018 0 OBJECT LOCAL DEFAULT 21 TMC_END__ 8: 00000001200008a0 0 FUNC GLOBAL DEFAULT 8 _init 9: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMCloneTable 10: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _Jv_RegisterClasses 11: 0000000120000bb0 0 FUNC GLOBAL DEFAULT UND libc_start_main@GLIBC_2.0 (2) 12: 0000000000000000 0 FUNC WEAK DEFAULT UND __gmon_start__ 13: 0000000120000ba0 0 FUNC GLOBAL DEFAULT UND printf@GLIBC_2.0 (2) 14: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterTMCloneTab

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Version symbols section '.gnu.version' contains 15 entries: Addr: 000000012000085e Offset: 0x00085e Link: 4 (.dynsym) 000: 0 (local) 1 (global) 1 (global) 1 (global)
004: 1 (global) 1 (global) 1 (global) 1 (global)
008: 1 (global) 0 (local) 0 (local) 2 (GLIBC_2.0)
00c: 0 (local) 2 (GLIBC_2.0) 0 (local)

Version needs section '.gnu.version_r' contains 1 entries: Addr: 0x0000000120000880 Offset: 0x000880 Link: 5 (.dynstr) 000000: Version: 1 File: libc.so.6 Cnt: 1 0x0010: Name: GLIBC_2.0 Flags: none Version: 2

Displaying notes found at file offset 0x00000cac with length 0x00000020: Owner Data size Description GNU 0x00000010 NT_GNU_ABI_TAG (ABI version tag) OS: Linux, ABI: 2.6.32 Attribute Section: gnu File Attributes Tag_GNU_MIPS_ABI_FP: Hard float (double precision)

Primary GOT: Canonical gp value: 0000000120019010

Reserved entries: Address Access Initial Purpose 0000000120011020 -32752(gp) 0000000000000000 Lazy resolver 0000000120011028 -32744(gp) 8000000000000000 Module pointer (GNU extension)

Local entries: Address Access Initial 0000000120011030 -32736(gp) 0000000120000a80 0000000120011038 -32728(gp) 0000000120000b00 0000000120011040 -32720(gp) 0000000120000b98 0000000120011048 -32712(gp) 0000000120010000 0000000120011050 -32704(gp) 0000000120011018 0000000120011058 -32696(gp) 0000000120000000 0000000120011060 -32688(gp) 00000001200008a0 0000000120011068 -32680(gp) 0000000120010fe8 0000000120011070 -32672(gp) 0000000120010ff0 0000000120011078 -32664(gp) 0000000000000000 0000000120011080 -32656(gp) 0000000000000000 0000000120011088 -32648(gp) 0000000000000000

Global entries: Address Access Initial Sym.Val. Type Ndx Name 0000000120011090 -32640(gp) 0000000000000000 0000000000000000 NOTYPE UND _ITM_registerTMCloneTable 0000000120011098 -32632(gp) 0000000000000000 0000000000000000 NOTYPE UND _Jv_RegisterClasses 00000001200110a0 -32624(gp) 0000000120000bb0 0000000120000bb0 FUNC UND libc_start_main 00000001200110a8 -32616(gp) 0000000000000000 0000000000000000 FUNC UND gmon_start__ 00000001200110b0 -32608(gp) 0000000120000ba0 0000000120000ba0 FUNC UND printf 00000001200110b8 -32600(gp) 0000000000000000 0000000000000000 NOTYPE UND _ITM_deregisterTMCloneTable

Regards, Leslie Zhai

atanasyan commented 6 years ago

In short, it's a difficult task. If you really need to support O32 ABI on 64-bit CPUs, I would recommend to start from the backend. Take a look at test/MC/Mips test cases with the -target-abi option. For example cpload.s. Add -mcpu=mips64r2 -target-abi o32 case to them, then teach the backend to emit a correct code, etc ...

By the way, a) could you switch to mips32r2 option? b) could you use or build and use a toolchain with N64 ABI support?

xiangzhai commented 6 years ago

Hi Simon,

Thanks for your response! and congratulations for new code owner of MIPS backend. My motivation is Compiling Linux kernel with LLVM[1] but our GCC toolchain[2] is able to pass the O32 ABI checking. And I have learned MIPS Software Standards (ABIs) in the Chapter 11 of 'See MIPS Run'[3], MIPS Architecture in the Chapter 6 of 'Digital Design and Computer Architecture'[4]. Please teach me how to fix the issue correctly, not like my monkey patch, thanks a lot!

  1. Compiling Android userspace and Linux kernel with LLVM http://llvm.org/devmtg/2017-10/#talk21
  2. Loongson GCC https://github.com/loongson-community/gcc
  3. See MIPS Run, Second Edition https://www.amazon.com/Second-Morgan-Kaufmann-Computer-Architecture/dp/0120884216
  4. https://www.amazon.com/Digital-Design-Computer-Architecture-Second/dp/0123944244

Regards, Leslie Zhai https://reviews.llvm.org/p/xiangzhai/

atanasyan commented 6 years ago

Unfortunately the backend does not support O32 ABI on 64-bit CPU so this fix just suppresses the error and leads to other errors and/or incorrectly generated code.