sorry, i didn't copy test/objdump/gdb stuff from
https://github.com/ziyao233/tinycc/issues/1, that's pretty long, below are the
detail:
change:
diff --git a/tccasm.c b/tccasm.c
index 109eb17c..197d07a4 100644
--- a/tccasm.c
+++ b/tccasm.c
@@ -535,12 +535,19 @@ static void asm_parse_directive(TCCState *s1, int global)
v = asm_int_expr(s1);
}
zero_pad:
- if (sec->sh_type != SHT_NOBITS) {
+ if (sec->sh_type == SHT_PROGBITS && (sec->sh_flags & SHF_EXECINSTR)) {
+ int pad = ind % sec->sh_addralign;
+# if !defined TCC_TARGET_X86_64 && !defined TCC_TARGET_I386
+ // current non-x86 gen_fill_nops requires pad bytes to be multiple
of 4
+ pad = ((pad + 3) / 4) * 4;
+# endif
+ gen_fill_nops(pad);
+ } else if (sec->sh_type != SHT_NOBITS) {
sec->data_offset = ind;
ptr = section_ptr_add(sec, size);
memset(ptr, v, size);
- }
- ind += size;
+ ind += size;
+ }
break;
case TOK_ASMDIR_quad:
#ifdef TCC_TARGET_X86_64
minimal_test.s:
.global main
main:
xorl %eax, %eax
.p2align 4 # replacing .p2align with .align with specific sizes would
also lead to broken binary
ret
./tcc minimal_test.s -o minimal_test.s
./minimal_test
for-loop-test.s:
.data
.balign 1
.Lstring.2:
.ascii "i = %d\012\000"
/* end data */
.text
.balign 16
.globl main
main:
endbr64
pushq %rbp
movq %rsp, %rbp
subq $8, %rsp
pushq %rbx
movl $0, %ebx
.p2align 4
.Lbb2:
cmpl $5, %ebx
jge .Lbb4
movl %ebx, %esi
leaq .Lstring.2(%rip), %rdi
movl $0, %eax
callq printf
addl $1, %ebx
jmp .Lbb2
.Lbb4:
movl $0, %eax
popq %rbx
leave
ret
.type main, @function
.size main, .-main
/* end function main */
.section .note.GNU-stack,"",@progbits
./tcc for-loop-test.s -o for-loop-test
./for-loop-test
after applying the change, it'll work, otherwise, there will be segmentation
fault:
objdump before change:
$ objdump -d minimal_test
minimal_tesr: file format elf64-x86-64
Disassembly of section .text:
00000000006009c0 <main@@Base-0x35>:
6009c0: f3 0f 1e fa endbr64
6009c4: 31 ed xor %ebp,%ebp
6009c6: 49 89 d1 mov %rdx,%r9
6009c9: 5e pop %rsi
6009ca: 48 89 e2 mov %rsp,%rdx
6009cd: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
6009d1: 50 push %rax
6009d2: 54 push %rsp
6009d3: 45 31 c0 xor %r8d,%r8d
6009d6: 31 c9 xor %ecx,%ecx
6009d8: 48 8b 3d c9 02 40 00 mov 0x4002c9(%rip),%rdi #
a00ca8 <main@@Base+0x4002b3>
6009df: ff 15 cb 02 40 00 call *0x4002cb(%rip) # a00cb0
<main@@Base+0x4002bb>
6009e5: f4 hlt
6009e6: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
6009ed: 00 00 00
6009f0: f3 0f 1e fa endbr64
6009f4: c3 ret
00000000006009f5 <main@@Base>:
6009f5: 31 c0 xor %eax,%eax
6009f7: c3 ret
Disassembly of section .init:
00000000006009f8 <.init>:
6009f8: f3 0f 1e fa endbr64
6009fc: 48 83 ec 08 sub $0x8,%rsp
600a00: 48 8b 05 b1 02 40 00 mov 0x4002b1(%rip),%rax #
a00cb8 <__gmon_start__@Base>
600a07: 48 85 c0 test %rax,%rax
600a0a: 74 02 je 600a0e <main@@Base+0x19>
600a0c: ff d0 call *%rax
600a0e: 48 83 c4 08 add $0x8,%rsp
600a12: c3 ret
Disassembly of section .fini:
0000000000600a14 <.fini>:
600a14: f3 0f 1e fa endbr64
600a18: 48 83 ec 08 sub $0x8,%rsp
600a1c: 48 83 c4 08 add $0x8,%rsp
600a20: c3 ret
gdb with core dump for segmentation fault:
$ gdb minimal_test wsl-crash-1777429245-19155-_home_jin_tinycc_tcc-11.dmp
GNU gdb (Ubuntu 15.0.50.20240403-0ubuntu1) 15.0.50.20240403-git
Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...
(No debugging symbols found in a.out)
warning: core file may not match specified executable file.
[New LWP 19155]
This GDB supports auto-downloading debuginfo from the following URLs:
<https://debuginfod.ubuntu.com>
Enable debuginfod for this session? (y or [n])
Debuginfod has been disabled.
To make this setting permanent, add 'set debuginfod enabled off' to .gdbinit.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `./tcc -B. -run ssa/asm/p2align-test.s'.
Program terminated with signal SIGSEGV, Segmentation fault.
--Type <RET> for more, q to quit, c to continue without paging--
#0 0x00006540507db002 in ?? ()
(gdb) backtrace
#0 0x00006540507db002 in ?? ()
#1 0x00006540507db2a6 in ?? ()
#2 0x00007b1c1a444fb0 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3 0x00007ffda1f0f8c0 in ?? ()
#4 0x00007ffda1f0f8b0 in ?? ()
#5 0x0000000000000001 in ?? ()
#6 0x00007ffda1f0f6f0 in ?? ()
#7 0x0000654038414a4e in ?? ()
#8 0x00007ffda1f0f600 in ?? ()
#9 0x00007ffda1f0f8b0 in ?? ()
#10 0x0000000100000000 in ?? ()
#11 0x00006540507d52a0 in ?? ()
#12 0x00000000a1f0f630 in ?? ()
#13 0x00006540507db257 in ?? ()
#14 0x0000654038453c95 in ?? ()
#15 0x00007ffda1f0f8c0 in ?? ()
#16 0x00007ffda1f0f898 in ?? ()
#17 0x63f9c39cb7e728be in ?? ()
#18 0x0000000000000004 in ?? ()
#19 0x0000000000000000 in ?? ()
(gdb) info registers
rax 0x0 0
rbx 0x7ffda1f0f898 140727320377496
rcx 0x6540507db000 111326902726656
rdx 0x7ffda1f0f8c0 140727320377536
rsi 0x7ffda1f0f8b0 140727320377520
rdi 0x1 1
rbp 0x7ffda1f0f5d0 0x7ffda1f0f5d0
rsp 0x7ffda1f0f5a8 0x7ffda1f0f5a8
r8 0x6540507db257 111326902727255
r9 0x7 7
r10 0x7ffda1f0f8c0 140727320377536
r11 0x73e66e7403628b81 8351484003557215105
r12 0x4 4
r13 0x0 0
r14 0x654038465118 111326496444696
r15 0x7b1c1a771000 135360633311232
rip 0x6540507db002 0x6540507db002
eflags 0x10246 [ PF ZF IF RF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
fs_base 0x7b1c1a640740 135360632063808
gs_base 0x0 0
(gdb) x/100i $rip
=> 0x6540507db002: add %al,(%rax)
0x6540507db004: add %al,(%rax)
0x6540507db006: add %al,(%rax)
0x6540507db008: add %al,(%rax)
0x6540507db00a: add %al,(%rax)
0x6540507db00c: add %al,(%rax)
0x6540507db00e: add %al,(%rax)
0x6540507db010: ret
0x6540507db011: add %al,(%rax)
0x6540507db013: add %al,(%rax)
0x6540507db015: add %al,(%rax)
0x6540507db017: add %dl,0x48(%rbp)
0x6540507db01a: mov %esp,%ebp
0x6540507db01c: sub $0x30,%rsp
0x6540507db023: mov %rdi,-0x8(%rbp)
0x6540507db027: mov %rsi,-0x10(%rbp)
0x6540507db02b: mov %rdx,-0x18(%rbp)
0x6540507db02f: mov $0x0,%eax
0x6540507db034: mov %eax,-0x1c(%rbp)
0x6540507db037: mov -0x1c(%rbp),%eax
0x6540507db03a: movslq %eax,%rax
0x6540507db03d: shl $0x3,%rax
0x6540507db041: mov 0x678(%rip),%rcx # 0x6540507db6c0
0x6540507db048: add %rax,%rcx
0x6540507db04b: mov 0x676(%rip),%rax # 0x6540507db6c8
0x6540507db052: cmp %rax,%rcx
0x6540507db055: je 0x6540507db09e
--Type <RET> for more, q to quit, c to continue without paging--
0x6540507db05b: mov -0x1c(%rbp),%eax
0x6540507db05e: mov %eax,%ecx
0x6540507db060: add $0x1,%eax
0x6540507db063: mov %eax,-0x1c(%rbp)
0x6540507db066: movslq %ecx,%rcx
0x6540507db069: shl $0x3,%rcx
0x6540507db06d: mov 0x64c(%rip),%rax # 0x6540507db6c0
0x6540507db074: add %rcx,%rax
0x6540507db077: mov (%rax),%rax
0x6540507db07a: mov %rax,-0x28(%rbp)
0x6540507db07e: mov -0x18(%rbp),%rax
0x6540507db082: mov %rax,%r10
0x6540507db085: mov -0x10(%rbp),%rax
0x6540507db089: mov %rax,%rsi
0x6540507db08c: mov -0x8(%rbp),%eax
0x6540507db08f: mov %rax,%rdi
0x6540507db092: mov %r10,%rdx
0x6540507db095: mov -0x28(%rbp),%r11
0x6540507db099: call *%r11
0x6540507db09c: jmp 0x6540507db037
0x6540507db09e: leave
0x6540507db09f: ret
0x6540507db0a0: push %rbp
0x6540507db0a1: mov %rsp,%rbp
0x6540507db0a4: sub $0x10,%rsp
0x6540507db0ab: mov $0x0,%eax
0x6540507db0b0: mov %eax,-0x4(%rbp)
--Type <RET> for more, q to quit, c to continue without paging--
0x6540507db0b3: mov -0x4(%rbp),%eax
0x6540507db0b6: movslq %eax,%rax
0x6540507db0b9: shl $0x3,%rax
0x6540507db0bd: mov 0x60c(%rip),%rcx # 0x6540507db6d0
0x6540507db0c4: add %rax,%rcx
0x6540507db0c7: mov 0x60a(%rip),%rax # 0x6540507db6d8
0x6540507db0ce: cmp %rax,%rcx
0x6540507db0d1: je 0x6540507db101
0x6540507db0d7: mov -0x4(%rbp),%eax
0x6540507db0da: add $0xffffffff,%eax
0x6540507db0dd: mov %eax,-0x4(%rbp)
0x6540507db0e0: movslq %eax,%rax
0x6540507db0e3: shl $0x3,%rax
0x6540507db0e7: mov 0x5e2(%rip),%rcx # 0x6540507db6d0
0x6540507db0ee: add %rax,%rcx
0x6540507db0f1: mov (%rcx),%rcx
0x6540507db0f4: mov %rcx,-0x10(%rbp)
0x6540507db0f8: mov -0x10(%rbp),%r11
0x6540507db0fc: call *%r11
0x6540507db0ff: jmp 0x6540507db0b3
0x6540507db101: leave
0x6540507db102: ret
0x6540507db103: push %rbp
0x6540507db104: mov %rsp,%rbp
0x6540507db107: sub $0x20,%rsp
0x6540507db10e: mov %rdi,-0x8(%rbp)
0x6540507db112: mov 0x568(%rip),%eax # 0x6540507db680
--Type <RET> for more, q to quit, c to continue without paging--
0x6540507db118: mov %eax,-0xc(%rbp)
0x6540507db11b: mov -0xc(%rbp),%eax
0x6540507db11e: cmp $0x0,%eax
0x6540507db121: je 0x6540507db174
0x6540507db127: mov -0xc(%rbp),%eax
0x6540507db12a: add $0xffffffff,%eax
0x6540507db12d: mov %eax,-0xc(%rbp)
0x6540507db130: mov -0xc(%rbp),%eax
0x6540507db133: movslq %eax,%rax
0x6540507db136: shl $0x3,%rax
0x6540507db13a: lea 0x33f(%rip),%rcx # 0x6540507db480
0x6540507db141: add %rax,%rcx
0x6540507db144: mov -0xc(%rbp),%eax
0x6540507db147: movslq %eax,%rax
0x6540507db14a: shl $0x3,%rax
0x6540507db14e: lea 0x42b(%rip),%rdx # 0x6540507db580
0x6540507db155: add %rax,%rdx
0x6540507db158: mov %rcx,-0x18(%rbp)
0x6540507db15c: mov (%rdx),%rdx
(gdb)
Regards
Jerry
________________________________
发件人: [email protected]
<[email protected]> 代表 grischka via
Tinycc-devel <[email protected]>
发送时间: Tuesday, May 5, 2026 4:56:22 PM
收件人: [email protected] <[email protected]>
抄送: grischka <[email protected]>
主题: Re: [Tinycc-devel] [patch]fix asm parse directive zero pad logic
On 04.05.2026 11:08, Jerry Jin wrote:
> Problem:
> ....
>
> Fix:
> ....
>
> Open issue:
> ....
There is missing
Test:
<how you will want to test your fix after you wrote it>
> Please review attached patch file, thanks!
I'm afraid there is no people here who want to extract patches
from email and run tests for other people ;)
There are some useful switches though for objdump that might
help:
$ objdump --help
$ objdump -d -z --insn-width=1 test.o
$ objdump -j .text -s test.o
Also you might want to write a short test file, for example:
test.S:
mov $0x12345678, %ebx
.p2align 4
ret
$ tcc -c test.S && objdump ... test.o
So this is how you could test your fix.
Of course you also need to know what .p2align is supposed to do
at all, exactly. If you do not know that then you cannot do
anything because you will not know whether your fix is correct
even when you test it.
>
> Regards
> Jerry
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