Hello Nick,
I found the e-mail address on an old binutils doc page, and
unfortunately I didn't realize how old it was. But true, the current
doc page address is present in the rpm info, next time I will register.
I wanted to know how exactly gcc translates such expressions like
n * 0x1001. People are talking about multiplication being not slower
than any other arithmetic operation on modern processors, but in fact I
got the code (n << 12) + n, no matter which form I used in the C
source. OK, it was with -O0, but it would be quite illogical to
translate multiplication to shift on -O0, and to multiplication on -O3.
Not frequently, but similar question occur from time to time.
The default assembly listing page width is too narrow, I don't like
reading folded source lines, truncated lines are even worse (or
better?). Even 132 characters are not enough, but rhs-width wouldn't
work with whatever sensible width.
I am attaching the asm source. I applied the same command line, except
-c replaced by -S.
br
PK
On Thu, 2024-09-26 at 16:33 +0100, Nick Clifton wrote:
> Hi Peter,
>
> > gcc -c -O1 -ggdb -masm=intel -Wa,-acdhlgn=gfp_library.lst -Wa,--
> > listing-lhs-width=4,--listing-rhs-width=132 -o gfp_library.o
> > gfp_library.c
>
> In the future if you have other bugs like this to report, please
> could you capture the compiler's assembler output and provide that
> as the test file, rather than the C source ? The reason being that
> this eliminates one step in the process and it means that I do not
> need to have exactly the same version of gcc installed on my machine.
>
> Also - it really helps if you can file a bug report with the binutils
> bugzilla system:
> https://sourceware.org/bugzilla/enter_bug.cgi?product=binutils
>
> This lets us track the bug and any discussion about it. Plus we can
> put comments in the code referring to the bug's PR number and even
> create
> new tests that refer back to the bug report as well.
>
> As it happens however I am able to reproduce the problem locally,
> and the first thing that occurs to be is to wonder why you are
> capturing an assembler listing ? And given that it is needed, why
> do you need a limit on the width of the source code in the listing ?
>
> The problem is obviously in the listing code, which is old and
> crufty.
> I am taking a look however and I may be able to find a solution.
>
> Cheers
> Nick
>
.file "gfp_library.c"
.intel_syntax noprefix
.text
.Ltext0:
.file 0 "/home/peter/tmp" "gfp_library.c"
.section .rodata.str1.1,"aMS",@progbits,1
.LC0:
.string "/usr/lib64/libc.so.6"
.LC1:
.string "realloc"
.text
.globl gfp_lib_init
.type gfp_lib_init, @function
gfp_lib_init:
.LFB1:
.file 1 "gfp_library.c"
.loc 1 20 1 view -0
.cfi_startproc
sub rsp, 8
.cfi_def_cfa_offset 16
.loc 1 21 3 view .LVU1
.loc 1 21 18 is_stmt 0 view .LVU2
mov esi, 1
mov edi, OFFSET FLAT:.LC0
call dlopen
.LVL0:
mov rdi, rax
.loc 1 21 16 discriminator 1 view .LVU3
mov QWORD PTR libc_so[rip], rax
.loc 1 23 12 view .LVU4
mov eax, 1
.loc 1 21 6 discriminator 1 view .LVU5
test rdi, rdi
je .L1
.LBB4:
.LBI4:
.loc 1 13 20 is_stmt 1 view .LVU6
.LBB5:
.loc 1 15 3 view .LVU7
.loc 1 15 24 is_stmt 0 view .LVU8
mov esi, OFFSET FLAT:.LC1
call dlsym
.LVL1:
.LBE5:
.LBE4:
.loc 1 21 48 discriminator 1 view .LVU9
test rax, rax
sete al
movzx eax, al
.L1:
.loc 1 26 1 view .LVU10
add rsp, 8
.cfi_def_cfa_offset 8
ret
.cfi_endproc
.LFE1:
.size gfp_lib_init, .-gfp_lib_init
.local libc_so
.comm libc_so,8,8
.Letext0:
.file 2 "/usr/lib/gcc/x86_64-redhat-linux/14/include/stddef.h"
.file 3 "/usr/include/dlfcn.h"
.section .debug_info,"",@progbits
.Ldebug_info0:
.long 0x16c
.value 0x5
.byte 0x1
.byte 0x8
.long .Ldebug_abbrev0
.uleb128 0x9
.long .LASF8
.byte 0x1d
.long .LASF0
.long .LASF1
.quad .Ltext0
.quad .Letext0-.Ltext0
.long .Ldebug_line0
.uleb128 0x3
.long .LASF2
.byte 0x2
.byte 0xd6
.byte 0x17
.long 0x3a
.uleb128 0x4
.byte 0x8
.byte 0x7
.long .LASF4
.uleb128 0x3
.long .LASF3
.byte 0x1
.byte 0x7
.byte 0xf
.long 0x4d
.uleb128 0xa
.long 0x61
.long 0x61
.uleb128 0x1
.long 0x61
.uleb128 0x1
.long 0x2e
.byte 0
.uleb128 0xb
.byte 0x8
.uleb128 0x5
.long 0x61
.uleb128 0xc
.long .LASF9
.byte 0x1
.byte 0x9
.byte 0x14
.long 0x61
.uleb128 0x9
.byte 0x3
.quad libc_so
.uleb128 0xd
.long .LASF10
.byte 0x1
.byte 0xa
.byte 0x14
.long 0x8a
.uleb128 0x6
.long 0x41
.uleb128 0x7
.long .LASF6
.byte 0x40
.long 0x61
.long 0xa8
.uleb128 0x1
.long 0x63
.uleb128 0x1
.long 0xad
.byte 0
.uleb128 0x6
.long 0xb9
.uleb128 0x5
.long 0xa8
.uleb128 0x4
.byte 0x1
.byte 0x6
.long .LASF5
.uleb128 0xe
.long 0xb2
.uleb128 0x7
.long .LASF7
.byte 0x38
.long 0x61
.long 0xd7
.uleb128 0x1
.long 0xa8
.uleb128 0x1
.long 0xd7
.byte 0
.uleb128 0xf
.byte 0x4
.byte 0x5
.string "int"
.uleb128 0x10
.long .LASF11
.byte 0x1
.byte 0x13
.byte 0x5
.long 0xd7
.quad .LFB1
.quad .LFE1-.LFB1
.uleb128 0x1
.byte 0x9c
.long 0x162
.uleb128 0x11
.long 0x162
.quad .LBI4
.byte .LVU6
.quad .LBB4
.quad .LBE4-.LBB4
.byte 0x1
.byte 0x16
.byte 0x17
.long 0x141
.uleb128 0x8
.quad .LVL1
.long 0x8f
.uleb128 0x2
.uleb128 0x1
.byte 0x54
.uleb128 0x9
.byte 0x3
.quad .LC1
.byte 0
.byte 0
.uleb128 0x8
.quad .LVL0
.long 0xbe
.uleb128 0x2
.uleb128 0x1
.byte 0x55
.uleb128 0x9
.byte 0x3
.quad .LC0
.uleb128 0x2
.uleb128 0x1
.byte 0x54
.uleb128 0x1
.byte 0x31
.byte 0
.byte 0
.uleb128 0x12
.long .LASF12
.byte 0x1
.byte 0xd
.byte 0x14
.long 0x8a
.byte 0x1
.byte 0
.section .debug_abbrev,"",@progbits
.Ldebug_abbrev0:
.uleb128 0x1
.uleb128 0x5
.byte 0
.uleb128 0x49
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x2
.uleb128 0x49
.byte 0
.uleb128 0x2
.uleb128 0x18
.uleb128 0x7e
.uleb128 0x18
.byte 0
.byte 0
.uleb128 0x3
.uleb128 0x16
.byte 0
.uleb128 0x3
.uleb128 0xe
.uleb128 0x3a
.uleb128 0xb
.uleb128 0x3b
.uleb128 0xb
.uleb128 0x39
.uleb128 0xb
.uleb128 0x49
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x4
.uleb128 0x24
.byte 0
.uleb128 0xb
.uleb128 0xb
.uleb128 0x3e
.uleb128 0xb
.uleb128 0x3
.uleb128 0xe
.byte 0
.byte 0
.uleb128 0x5
.uleb128 0x37
.byte 0
.uleb128 0x49
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x6
.uleb128 0xf
.byte 0
.uleb128 0xb
.uleb128 0x21
.sleb128 8
.uleb128 0x49
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x7
.uleb128 0x2e
.byte 0x1
.uleb128 0x3f
.uleb128 0x19
.uleb128 0x3
.uleb128 0xe
.uleb128 0x3a
.uleb128 0x21
.sleb128 3
.uleb128 0x3b
.uleb128 0xb
.uleb128 0x39
.uleb128 0x21
.sleb128 14
.uleb128 0x27
.uleb128 0x19
.uleb128 0x49
.uleb128 0x13
.uleb128 0x3c
.uleb128 0x19
.uleb128 0x1
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x8
.uleb128 0x48
.byte 0x1
.uleb128 0x7d
.uleb128 0x1
.uleb128 0x7f
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x9
.uleb128 0x11
.byte 0x1
.uleb128 0x25
.uleb128 0xe
.uleb128 0x13
.uleb128 0xb
.uleb128 0x3
.uleb128 0x1f
.uleb128 0x1b
.uleb128 0x1f
.uleb128 0x11
.uleb128 0x1
.uleb128 0x12
.uleb128 0x7
.uleb128 0x10
.uleb128 0x17
.byte 0
.byte 0
.uleb128 0xa
.uleb128 0x15
.byte 0x1
.uleb128 0x27
.uleb128 0x19
.uleb128 0x49
.uleb128 0x13
.uleb128 0x1
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0xb
.uleb128 0xf
.byte 0
.uleb128 0xb
.uleb128 0xb
.byte 0
.byte 0
.uleb128 0xc
.uleb128 0x34
.byte 0
.uleb128 0x3
.uleb128 0xe
.uleb128 0x3a
.uleb128 0xb
.uleb128 0x3b
.uleb128 0xb
.uleb128 0x39
.uleb128 0xb
.uleb128 0x49
.uleb128 0x13
.uleb128 0x2
.uleb128 0x18
.byte 0
.byte 0
.uleb128 0xd
.uleb128 0x34
.byte 0
.uleb128 0x3
.uleb128 0xe
.uleb128 0x3a
.uleb128 0xb
.uleb128 0x3b
.uleb128 0xb
.uleb128 0x39
.uleb128 0xb
.uleb128 0x49
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0xe
.uleb128 0x26
.byte 0
.uleb128 0x49
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0xf
.uleb128 0x24
.byte 0
.uleb128 0xb
.uleb128 0xb
.uleb128 0x3e
.uleb128 0xb
.uleb128 0x3
.uleb128 0x8
.byte 0
.byte 0
.uleb128 0x10
.uleb128 0x2e
.byte 0x1
.uleb128 0x3f
.uleb128 0x19
.uleb128 0x3
.uleb128 0xe
.uleb128 0x3a
.uleb128 0xb
.uleb128 0x3b
.uleb128 0xb
.uleb128 0x39
.uleb128 0xb
.uleb128 0x27
.uleb128 0x19
.uleb128 0x49
.uleb128 0x13
.uleb128 0x11
.uleb128 0x1
.uleb128 0x12
.uleb128 0x7
.uleb128 0x40
.uleb128 0x18
.uleb128 0x7a
.uleb128 0x19
.uleb128 0x1
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x11
.uleb128 0x1d
.byte 0x1
.uleb128 0x31
.uleb128 0x13
.uleb128 0x52
.uleb128 0x1
.uleb128 0x2138
.uleb128 0xb
.uleb128 0x11
.uleb128 0x1
.uleb128 0x12
.uleb128 0x7
.uleb128 0x58
.uleb128 0xb
.uleb128 0x59
.uleb128 0xb
.uleb128 0x57
.uleb128 0xb
.uleb128 0x1
.uleb128 0x13
.byte 0
.byte 0
.uleb128 0x12
.uleb128 0x2e
.byte 0
.uleb128 0x3
.uleb128 0xe
.uleb128 0x3a
.uleb128 0xb
.uleb128 0x3b
.uleb128 0xb
.uleb128 0x39
.uleb128 0xb
.uleb128 0x27
.uleb128 0x19
.uleb128 0x49
.uleb128 0x13
.uleb128 0x20
.uleb128 0xb
.byte 0
.byte 0
.byte 0
.section .debug_aranges,"",@progbits
.long 0x2c
.value 0x2
.long .Ldebug_info0
.byte 0x8
.byte 0
.value 0
.value 0
.quad .Ltext0
.quad .Letext0-.Ltext0
.quad 0
.quad 0
.section .debug_line,"",@progbits
.Ldebug_line0:
.section .debug_str,"MS",@progbits,1
.LASF4:
.string "long unsigned int"
.LASF2:
.string "size_t"
.LASF3:
.string "realloc_ft"
.LASF12:
.string "get_realloc"
.LASF9:
.string "libc_so"
.LASF7:
.string "dlopen"
.LASF10:
.string "libc_realloc"
.LASF6:
.string "dlsym"
.LASF8:
.string "GNU C17 14.2.1 20240912 (Red Hat 14.2.1-3) -masm=intel
-mtune=generic -march=x86-64 -ggdb -O1"
.LASF5:
.string "char"
.LASF11:
.string "gfp_lib_init"
.section .debug_line_str,"MS",@progbits,1
.LASF1:
.string "/home/peter/tmp"
.LASF0:
.string "gfp_library.c"
.ident "GCC: (GNU) 14.2.1 20240912 (Red Hat 14.2.1-3)"
.section .note.GNU-stack,"",@progbits
