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EDIT: host x86 target has the similar problem, Clang generates relocations as
Relocation section '.rela.text' at offset 0x340 contains 15 entries:
Offset Info Type Sym. Value Sym. Name + Addend
00000000002b 000400000004 R_X86_64_PLT32 0000000000000000 getarray - 4
00000000003a 000500000004 R_X86_64_PLT32 0000000000000000 putarray - 4
000000000041 000600000004 R_X86_64_PLT32 0000000000000000 getint - 4
00000000004c 000700000004 R_X86_64_PLT32 0000000000000000 putint - 4
000000000056 000800000004 R_X86_64_PLT32 0000000000000000 putch - 4
00000000005d 000900000004 R_X86_64_PLT32 0000000000000000 starttime - 4
0000000000e8 000a00000004 R_X86_64_PLT32 0000000000000000 stoptime - 4
0000000000f0 000700000004 R_X86_64_PLT32 0000000000000000 putint - 4
0000000000fa 000800000004 R_X86_64_PLT32 0000000000000000 putch - 4
000000000101 000600000004 R_X86_64_PLT32 0000000000000000 getint - 4
00000000010b 000b00000004 R_X86_64_PLT32 0000000000000000 getch - 4
000000000125 000b00000004 R_X86_64_PLT32 0000000000000000 getch - 4
00000000012c 000800000004 R_X86_64_PLT32 0000000000000000 putch - 4
000000000144 000800000004 R_X86_64_PLT32 0000000000000000 putch - 4
00000000016a 000c00000004 R_X86_64_PLT32 0000000000000000 __stack_chk_fail - 4
Relocation section '.rela.eh_frame' at offset 0x4a8 contains 1 entry:
Offset Info Type Sym. Value Sym. Name + Addend
000000000020 000200000002 R_X86_64_PC32 0000000000000000 .text + 0I am writing a baremetal RISC-V user mode application, and use Clang for cross compiling.
Clang is installed by pacman from arch linux offical repo.
clang version 17.0.6
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/binThe program declares some IO functions which will be implemented by linux syscall elsewhere.
#ifndef LIBSYSY_SYSY_H_
#define LIBSYSY_SYSY_H_
// SysY runtime library.
// Reference: https://bit.ly/3tzTFks
// Modified by MaxXing.
// Input & output functions
int getint(), getch(), getarray(int a[]);
void putint(int num), putch(int ch), putarray(int n, int a[]);
// Timing functions
void starttime();
void stoptime();
#endif // LIBSYSY_SYSY_H_
int main() {
// sum of array
int arr[20], n, sum = 0;
n = getarray(arr);
putarray(n, arr);
int count = getint();
putint(count);
putch(10);
starttime();
for (int j = 0; j < count; ++j) {
for (int k = 0; k < n; ++k) {
for (int i = 0; i < n; ++i) sum += arr[i] * arr[k];
}
}
stoptime();
putint(sum);
putch(10);
// read characters
n = getint();
getch();
for (int i = 0; i < n; ++i) putch(getch());
putch(10);
return 0;
}and the code is compiled with following commands.
clang -Wall -Werror -DNO_LIBC -nostdlib -nostdinc -static -target riscv64-unknown-linux-elf -march=rv64im -mabi=lp64 test.c -c -o test.oThe lld linker later will complain about undefined symbol '__stack_chk_guard' and '__stack_chk_fail' which is not expected to happen when '-nostdlib' is specified.
'readelf -r' tells:
Relocation section '.rela.text' at offset 0x608 contains 58 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000010 001900000014 R_RISCV_GOT_HI20 0000000000000000 __stack_chk_guard + 0
000000000014 000300000018 R_RISCV_PCREL_LO1 0000000000000010 .Lpcrel_hi0 + 0
000000000014 000000000033 R_RISCV_RELAX 0
000000000038 001a00000013 R_RISCV_CALL_PLT 0000000000000000 getarray + 0
000000000038 000000000033 R_RISCV_RELAX 0
00000000004c 001b00000013 R_RISCV_CALL_PLT 0000000000000000 putarray + 0
00000000004c 000000000033 R_RISCV_RELAX 0
000000000054 001c00000013 R_RISCV_CALL_PLT 0000000000000000 getint + 0
000000000054 000000000033 R_RISCV_RELAX 0
000000000064 001d00000013 R_RISCV_CALL_PLT 0000000000000000 putint + 0
000000000064 000000000033 R_RISCV_RELAX 0
000000000070 001e00000013 R_RISCV_CALL_PLT 0000000000000000 putch + 0
000000000070 000000000033 R_RISCV_RELAX 0
000000000078 001f00000013 R_RISCV_CALL_PLT 0000000000000000 starttime + 0
000000000078 000000000033 R_RISCV_RELAX 0
000000000088 000400000011 R_RISCV_JAL 000000000000008c .LBB0_1 + 0
000000000098 000500000011 R_RISCV_JAL 0000000000000150 .LBB0_12 + 0
00000000009c 000600000011 R_RISCV_JAL 00000000000000a0 .LBB0_2 + 0
0000000000a8 000700000011 R_RISCV_JAL 00000000000000ac .LBB0_3 + 0
0000000000b8 000800000011 R_RISCV_JAL 000000000000013c .LBB0_10 + 0
0000000000bc 000900000011 R_RISCV_JAL 00000000000000c0 .LBB0_4 + 0
0000000000c8 000a00000011 R_RISCV_JAL 00000000000000cc .LBB0_5 + 0
0000000000d8 000b00000011 R_RISCV_JAL 0000000000000128 .LBB0_8 + 0
0000000000dc 000c00000011 R_RISCV_JAL 00000000000000e0 .LBB0_6 + 0
000000000114 000d00000011 R_RISCV_JAL 0000000000000118 .LBB0_7 + 0
000000000124 000a00000011 R_RISCV_JAL 00000000000000cc .LBB0_5 + 0
000000000128 000e00000011 R_RISCV_JAL 000000000000012c .LBB0_9 + 0
000000000138 000700000011 R_RISCV_JAL 00000000000000ac .LBB0_3 + 0
00000000013c 000f00000011 R_RISCV_JAL 0000000000000140 .LBB0_11 + 0
00000000014c 000400000011 R_RISCV_JAL 000000000000008c .LBB0_1 + 0
000000000150 002000000013 R_RISCV_CALL_PLT 0000000000000000 stoptime + 0
000000000150 000000000033 R_RISCV_RELAX 0
00000000015c 001d00000013 R_RISCV_CALL_PLT 0000000000000000 putint + 0
00000000015c 000000000033 R_RISCV_RELAX 0
000000000168 001e00000013 R_RISCV_CALL_PLT 0000000000000000 putch + 0
000000000168 000000000033 R_RISCV_RELAX 0
000000000170 001c00000013 R_RISCV_CALL_PLT 0000000000000000 getint + 0
000000000170 000000000033 R_RISCV_RELAX 0
00000000017c 002100000013 R_RISCV_CALL_PLT 0000000000000000 getch + 0
00000000017c 000000000033 R_RISCV_RELAX 0
00000000018c 001000000011 R_RISCV_JAL 0000000000000190 .LBB0_13 + 0
00000000019c 001100000011 R_RISCV_JAL 00000000000001c8 .LBB0_16 + 0
0000000001a0 001200000011 R_RISCV_JAL 00000000000001a4 .LBB0_14 + 0
0000000001a4 002100000013 R_RISCV_CALL_PLT 0000000000000000 getch + 0
0000000001a4 000000000033 R_RISCV_RELAX 0
0000000001ac 001e00000013 R_RISCV_CALL_PLT 0000000000000000 putch + 0
0000000001ac 000000000033 R_RISCV_RELAX 0
0000000001b4 001300000011 R_RISCV_JAL 00000000000001b8 .LBB0_15 + 0
0000000001c4 001000000011 R_RISCV_JAL 0000000000000190 .LBB0_13 + 0
0000000001cc 001e00000013 R_RISCV_CALL_PLT 0000000000000000 putch + 0
0000000001cc 000000000033 R_RISCV_RELAX 0
0000000001d4 001900000014 R_RISCV_GOT_HI20 0000000000000000 __stack_chk_guard + 0
0000000001d8 001400000018 R_RISCV_PCREL_LO1 00000000000001d4 .Lpcrel_hi1 + 0
0000000001d8 000000000033 R_RISCV_RELAX 0
0000000001e8 001500000011 R_RISCV_JAL 0000000000000204 .LBB0_18 + 0
0000000001ec 001600000011 R_RISCV_JAL 00000000000001f0 .LBB0_17 + 0
000000000204 002200000013 R_RISCV_CALL_PLT 0000000000000000 __stack_chk_fail + 0
000000000204 000000000033 R_RISCV_RELAX 0
Relocation section '.rela.eh_frame' at offset 0xb78 contains 3 entries:
Offset Info Type Sym. Value Sym. Name + Addend
00000000001c 000200000039 R_RISCV_32_PCREL 0000000000000000 <null> + 0
000000000020 001700000023 R_RISCV_ADD32 000000000000020c <null> + 0
000000000020 000200000027 R_RISCV_SUB32 0000000000000000 <null> + 0It shows that Clang generate the relocation of '__stack_chk_guard' and '__stack_chk_fail'.
It seems to me a bug of Clang packaging because if '-fno-stack-protector' and '-S -emit-llvm' are specified, the diff shows `sspstrong` attributes in LLVM IR:
6c6
< ; Function Attrs: noinline nounwind optnone sspstrong uwtable
---
> ; Function Attrs: noinline nounwind optnone uwtable
148c148
< attributes #0 = { noinline nounwind optnone sspstrong uwtable "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic-rv64" "target-features"="+64bit,+m,+relax,-a,-c,-d,-e,-experimental-smaia,-experimental-ssaia,-experimental-zacas,-experimental-zfa,-experimental-zfbfmin,-experimental-zicond,-experimental-zihintntl,-experimental-ztso,-experimental-zvbb,-experimental-zvbc,-experimental-zvfbfmin,-experimental-zvfbfwma,-experimental-zvkg,-experimental-zvkn,-experimental-zvknc,-experimental-zvkned,-experimental-zvkng,-experimental-zvknha,-experimental-zvknhb,-experimental-zvks,-experimental-zvksc,-experimental-zvksed,-experimental-zvksg,-experimental-zvksh,-experimental-zvkt,-f,-h,-save-restore,-svinval,-svnapot,-svpbmt,-v,-xcvbitmanip,-xcvmac,-xsfcie,-xsfvcp,-xtheadba,-xtheadbb,-xtheadbs,-xtheadcmo,-xtheadcondmov,-xtheadfmemidx,-xtheadmac,-xtheadmemidx,-xtheadmempair,-xtheadsync,-xtheadvdot,-xventanacondops,-zawrs,-zba,-zbb,-zbc,-zbkb,-zbkc,-zbkx,-zbs,-zca,-zcb,-zcd,-zce,-zcf,-zcmp,-zcmt,-zdinx,-zfh,-zfhmin,-zfinx,-zhinx,-zhinxmin,-zicbom,-zicbop,-zicboz,-zicntr,-zicsr,-zifencei,-zihintpause,-zihpm,-zk,-zkn,-zknd,-zkne,-zknh,-zkr,-zks,-zksed,-zksh,-zkt,-zmmul,-zve32f,-zve32x,-zve64d,-zve64f,-zve64x,-zvfh,-zvl1024b,-zvl128b,-zvl16384b,-zvl2048b,-zvl256b,-zvl32768b,-zvl32b,-zvl4096b,-zvl512b,-zvl64b,-zvl65536b,-zvl8192b" }
---
> attributes #0 = { noinline nounwind optnone uwtable "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic-rv64" "target-features"="+64bit,+m,+relax,-a,-c,-d,-e,-experimental-smaia,-experimental-ssaia,-experimental-zacas,-experimental-zfa,-experimental-zfbfmin,-experimental-zicond,-experimental-zihintntl,-experimental-ztso,-experimental-zvbb,-experimental-zvbc,-experimental-zvfbfmin,-experimental-zvfbfwma,-experimental-zvkg,-experimental-zvkn,-experimental-zvknc,-experimental-zvkned,-experimental-zvkng,-experimental-zvknha,-experimental-zvknhb,-experimental-zvks,-experimental-zvksc,-experimental-zvksed,-experimental-zvksg,-experimental-zvksh,-experimental-zvkt,-f,-h,-save-restore,-svinval,-svnapot,-svpbmt,-v,-xcvbitmanip,-xcvmac,-xsfcie,-xsfvcp,-xtheadba,-xtheadbb,-xtheadbs,-xtheadcmo,-xtheadcondmov,-xtheadfmemidx,-xtheadmac,-xtheadmemidx,-xtheadmempair,-xtheadsync,-xtheadvdot,-xventanacondops,-zawrs,-zba,-zbb,-zbc,-zbkb,-zbkc,-zbkx,-zbs,-zca,-zcb,-zcd,-zce,-zcf,-zcmp,-zcmt,-zdinx,-zfh,-zfhmin,-zfinx,-zhinx,-zhinxmin,-zicbom,-zicbop,-zicboz,-zicntr,-zicsr,-zifencei,-zihintpause,-zihpm,-zk,-zkn,-zknd,-zkne,-zknh,-zkr,-zks,-zksed,-zksh,-zkt,-zmmul,-zve32f,-zve32x,-zve64d,-zve64f,-zve64x,-zvfh,-zvl1024b,-zvl128b,-zvl16384b,-zvl2048b,-zvl256b,-zvl32768b,-zvl32b,-zvl4096b,-zvl512b,-zvl64b,-zvl65536b,-zvl8192b" }I also compiled Clang from llvm-project release 17.0.6/18.1.0/18.1.6 with default compile configurations, and I failed to reproduce the problem above with these Clang in my machine.
Last edited by TimeOrange (2024-06-05 05:49:01)
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