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DaGenix opened this issue Aug 9, 2014 · 17 comments
Closed

Named labels in asm!() blocks cause crashes on Mac OSX #16378

DaGenix opened this issue Aug 9, 2014 · 17 comments
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A-inline-assembly Area: Inline assembly (`asm!(…)`) C-bug Category: This is a bug. I-crash Issue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics. O-macos Operating system: macOS requires-nightly This issue requires a nightly compiler in some way.

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@DaGenix
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DaGenix commented Aug 9, 2014

The following code crashes on Mac OSX:

#![feature(asm)]

fn main() {
    unsafe {
        asm!(" test:") 
    }
}
@DaGenix DaGenix mentioned this issue Aug 9, 2014
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@sinistersnare
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On http://play.rust-lang.org this does not crash. link

@DaGenix
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DaGenix commented Aug 9, 2014

I think the crash only happens on Max OSX. I believe that play.rust-lang.org runs on Linux. I've used asm!() with named labels on Linux without any issues.

@sinistersnare
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I figure, I just wanted to point it out :)

@huonw
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huonw commented Aug 9, 2014

Does the code crash at runtime or is it crashing the compiler? (What's the crash behaviour? A segfault?)

@huonw huonw added the A-mac-osx label Aug 9, 2014
@DaGenix
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DaGenix commented Aug 9, 2014

It compiles fine, but crashes when its run with:

Segmentation fault: 11

@huonw
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huonw commented Aug 9, 2014

What's the output of rustc --emit=asm look like? (creates a .s file)

@DaGenix
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DaGenix commented Aug 9, 2014

Here is test2.s:

    .section    __TEXT,__text,regular,pure_instructions
    .section    __DWARF,__debug_info,regular,debug
Lsection_info:
    .section    __DWARF,__debug_abbrev,regular,debug
Lsection_abbrev:
    .section    __DWARF,__debug_line,regular,debug
Lsection_line:
    .section    __DWARF,__debug_str,regular,debug
Linfo_string:
    .section    __DWARF,__debug_loc,regular,debug
Lsection_debug_loc:
    .section    __DWARF,__debug_ranges,regular,debug
Ldebug_range:
    .section    __TEXT,__text,regular,pure_instructions
    .align  4, 0x90
__ZN4main20h8b95006aaacf56a1eaaE:
Lfunc_begin0:
    .file   1 "test2.rs"
    .loc    1 3 0
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB0_0
    movabsq $8, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB0_0:
    pushq   %rbp
Ltmp0:
    .cfi_def_cfa_offset 16
Ltmp1:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp2:
    .cfi_def_cfa_register %rbp
    .loc    1 5 0 prologue_end
Ltmp3:
    ## InlineAsm Start
test:
    ## InlineAsm End
    popq    %rbp
    retq
Ltmp4:
Lfunc_end0:
    .cfi_endproc

    .globl  _main
    .align  4, 0x90
_main:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB1_0
    movabsq $24, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB1_0:
    pushq   %rbp
Ltmp5:
    .cfi_def_cfa_offset 16
Ltmp6:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp7:
    .cfi_def_cfa_register %rbp
    subq    $16, %rsp
    leaq    __ZN4main20h8b95006aaacf56a1eaaE(%rip), %rax
    movq    %rdi, -8(%rbp)
    movq    %rax, %rdi
    movq    -8(%rbp), %rax
    movq    %rsi, -16(%rbp)
    movq    %rax, %rsi
    movq    -16(%rbp), %rdx
    callq   __ZN10lang_start20h3eb2912460ad7fe8BueE
    addq    $16, %rsp
    popq    %rbp
    retq
    .cfi_endproc

Ldebug_end0:
    .section    __DWARF,__debug_str,regular,debug
Linfo_string0:
    .asciz  "rustc version 0.12.0-pre-nightly (a1429bca5 2014-08-08 21:36:11 +0000)"
Linfo_string1:
    .asciz  "./test2.rs"
Linfo_string2:
    .asciz  "/Users/enix/code/rusttest"
Linfo_string3:
    .asciz  "test2"
Linfo_string4:
    .asciz  "main"
Linfo_string5:
    .asciz  "_ZN5test24mainE"
    .section    __DWARF,__debug_info,regular,debug
L__DWARF__debug_info_begin0:
    .long   75
    .short  2
Lset0 = Lsection_abbrev-Lsection_abbrev
    .long   Lset0
    .byte   8
    .byte   1
Lset1 = Linfo_string0-Linfo_string
    .long   Lset1
    .short  36864
Lset2 = Linfo_string1-Linfo_string
    .long   Lset2
Lset3 = Lline_table_start0-Lsection_line
    .long   Lset3
Lset4 = Linfo_string2-Linfo_string
    .long   Lset4
    .quad   Lfunc_begin0
Lset5 = Lfunc_end0-Lfunc_begin0
    .long   Lset5
    .byte   2
Lset6 = Linfo_string3-Linfo_string
    .long   Lset6
    .byte   3
    .quad   Lfunc_begin0
    .quad   Lfunc_end0
    .byte   1
    .byte   86
Lset7 = Linfo_string5-Linfo_string
    .long   Lset7
Lset8 = Linfo_string4-Linfo_string
    .long   Lset8
    .byte   1
    .byte   3
    .byte   1
    .byte   0
    .byte   0
L__DWARF__debug_info_end0:
    .section    __DWARF,__debug_abbrev,regular,debug
    .byte   1
    .byte   17
    .byte   1
    .byte   37
    .byte   14
    .byte   19
    .byte   5
    .byte   3
    .byte   14
    .byte   16
    .byte   6
    .byte   27
    .byte   14
    .byte   17
    .byte   1
    .byte   18
    .byte   6
    .byte   0
    .byte   0
    .byte   2
    .byte   57
    .byte   1
    .byte   3
    .byte   14
    .byte   0
    .byte   0
    .byte   3
    .byte   46
    .byte   0
    .byte   17
    .byte   1
    .byte   18
    .byte   1
    .byte   64
    .byte   10
    .ascii  "\207@"
    .byte   14
    .byte   3
    .byte   14
    .byte   58
    .byte   11
    .byte   59
    .byte   11
    .byte   50
    .byte   11
    .byte   0
    .byte   0
    .byte   0
    .section    __DWARF,__debug_ranges,regular,debug
    .section    __DWARF,__debug_loc,regular,debug
    .section    __DWARF,__apple_names,regular,debug
Lnames_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   2
    .long   2
    .long   12
    .long   0
    .long   1
    .short  1
    .short  6
    .long   0
    .long   1
    .long   2090499946
    .long   1217565201
    .long   LNames0-Lnames_begin
    .long   LNames1-Lnames_begin
LNames0:
Lset9 = Linfo_string4-Linfo_string
    .long   Lset9
    .long   1
    .long   47
    .long   0
LNames1:
Lset10 = Linfo_string5-Linfo_string
    .long   Lset10
    .long   1
    .long   47
    .long   0
    .section    __DWARF,__apple_objc,regular,debug
Lobjc_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   1
    .long   0
    .long   12
    .long   0
    .long   1
    .short  1
    .short  6
    .long   -1
    .section    __DWARF,__apple_namespac,regular,debug
Lnamespac_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   1
    .long   1
    .long   12
    .long   0
    .long   1
    .short  1
    .short  6
    .long   0
    .long   275477815
    .long   Lnamespac0-Lnamespac_begin
Lnamespac0:
Lset11 = Linfo_string3-Linfo_string
    .long   Lset11
    .long   1
    .long   42
    .long   0
    .section    __DWARF,__apple_types,regular,debug
Ltypes_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   1
    .long   0
    .long   20
    .long   0
    .long   3
    .short  1
    .short  6
    .short  3
    .short  5
    .short  4
    .short  11
    .long   -1

.subsections_via_symbols
    .section    __DWARF,__debug_line,regular,debug
Lline_table_start0:

@DaGenix
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DaGenix commented Aug 9, 2014

At a quick glance, I don't see anything obviously wrong, so, I don't really know whats happening.

As a note, the crashes occur with and without debugging information (-g) and without and without optimization (-O).

@DaGenix
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DaGenix commented Aug 9, 2014

As another note, the following compiles and runs file:

#![feature(asm)]

fn main() {
    unsafe {
        asm!("") 
    }
}

It compiles down to:

    .section    __TEXT,__text,regular,pure_instructions
    .section    __DWARF,__debug_info,regular,debug
Lsection_info:
    .section    __DWARF,__debug_abbrev,regular,debug
Lsection_abbrev:
    .section    __DWARF,__debug_line,regular,debug
Lsection_line:
    .section    __DWARF,__debug_str,regular,debug
Linfo_string:
    .section    __DWARF,__debug_loc,regular,debug
Lsection_debug_loc:
    .section    __DWARF,__debug_ranges,regular,debug
Ldebug_range:
    .section    __TEXT,__text,regular,pure_instructions
    .align  4, 0x90
__ZN4main20h503ced65c10fa3edeaaE:
Lfunc_begin0:
    .file   1 "test3.rs"
    .loc    1 3 0
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB0_0
    movabsq $8, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB0_0:
    pushq   %rbp
Ltmp0:
    .cfi_def_cfa_offset 16
Ltmp1:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp2:
    .cfi_def_cfa_register %rbp
    .loc    1 5 0 prologue_end
Ltmp3:
    ## InlineAsm Start
    ## InlineAsm End
    popq    %rbp
    retq
Ltmp4:
Lfunc_end0:
    .cfi_endproc

    .globl  _main
    .align  4, 0x90
_main:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB1_0
    movabsq $24, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB1_0:
    pushq   %rbp
Ltmp5:
    .cfi_def_cfa_offset 16
Ltmp6:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp7:
    .cfi_def_cfa_register %rbp
    subq    $16, %rsp
    leaq    __ZN4main20h503ced65c10fa3edeaaE(%rip), %rax
    movq    %rdi, -8(%rbp)
    movq    %rax, %rdi
    movq    -8(%rbp), %rax
    movq    %rsi, -16(%rbp)
    movq    %rax, %rsi
    movq    -16(%rbp), %rdx
    callq   __ZN10lang_start20h3eb2912460ad7fe8BueE
    addq    $16, %rsp
    popq    %rbp
    retq
    .cfi_endproc

Ldebug_end0:
    .section    __DWARF,__debug_str,regular,debug
Linfo_string0:
    .asciz  "rustc version 0.12.0-pre-nightly (a1429bca5 2014-08-08 21:36:11 +0000)"
Linfo_string1:
    .asciz  "./test3.rs"
Linfo_string2:
    .asciz  "/Users/enix/code/rusttest"
Linfo_string3:
    .asciz  "test3"
Linfo_string4:
    .asciz  "main"
Linfo_string5:
    .asciz  "_ZN5test34mainE"
    .section    __DWARF,__debug_info,regular,debug
L__DWARF__debug_info_begin0:
    .long   75
    .short  2
Lset0 = Lsection_abbrev-Lsection_abbrev
    .long   Lset0
    .byte   8
    .byte   1
Lset1 = Linfo_string0-Linfo_string
    .long   Lset1
    .short  36864
Lset2 = Linfo_string1-Linfo_string
    .long   Lset2
Lset3 = Lline_table_start0-Lsection_line
    .long   Lset3
Lset4 = Linfo_string2-Linfo_string
    .long   Lset4
    .quad   Lfunc_begin0
Lset5 = Lfunc_end0-Lfunc_begin0
    .long   Lset5
    .byte   2
Lset6 = Linfo_string3-Linfo_string
    .long   Lset6
    .byte   3
    .quad   Lfunc_begin0
    .quad   Lfunc_end0
    .byte   1
    .byte   86
Lset7 = Linfo_string5-Linfo_string
    .long   Lset7
Lset8 = Linfo_string4-Linfo_string
    .long   Lset8
    .byte   1
    .byte   3
    .byte   1
    .byte   0
    .byte   0
L__DWARF__debug_info_end0:
    .section    __DWARF,__debug_abbrev,regular,debug
    .byte   1
    .byte   17
    .byte   1
    .byte   37
    .byte   14
    .byte   19
    .byte   5
    .byte   3
    .byte   14
    .byte   16
    .byte   6
    .byte   27
    .byte   14
    .byte   17
    .byte   1
    .byte   18
    .byte   6
    .byte   0
    .byte   0
    .byte   2
    .byte   57
    .byte   1
    .byte   3
    .byte   14
    .byte   0
    .byte   0
    .byte   3
    .byte   46
    .byte   0
    .byte   17
    .byte   1
    .byte   18
    .byte   1
    .byte   64
    .byte   10
    .ascii  "\207@"
    .byte   14
    .byte   3
    .byte   14
    .byte   58
    .byte   11
    .byte   59
    .byte   11
    .byte   50
    .byte   11
    .byte   0
    .byte   0
    .byte   0
    .section    __DWARF,__debug_ranges,regular,debug
    .section    __DWARF,__debug_loc,regular,debug
    .section    __DWARF,__apple_names,regular,debug
Lnames_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   2
    .long   2
    .long   12
    .long   0
    .long   1
    .short  1
    .short  6
    .long   0
    .long   -1
    .long   2090499946
    .long   -1785934126
    .long   LNames0-Lnames_begin
    .long   LNames1-Lnames_begin
LNames0:
Lset9 = Linfo_string4-Linfo_string
    .long   Lset9
    .long   1
    .long   47
    .long   0
LNames1:
Lset10 = Linfo_string5-Linfo_string
    .long   Lset10
    .long   1
    .long   47
    .long   0
    .section    __DWARF,__apple_objc,regular,debug
Lobjc_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   1
    .long   0
    .long   12
    .long   0
    .long   1
    .short  1
    .short  6
    .long   -1
    .section    __DWARF,__apple_namespac,regular,debug
Lnamespac_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   1
    .long   1
    .long   12
    .long   0
    .long   1
    .short  1
    .short  6
    .long   0
    .long   275477816
    .long   Lnamespac0-Lnamespac_begin
Lnamespac0:
Lset11 = Linfo_string3-Linfo_string
    .long   Lset11
    .long   1
    .long   42
    .long   0
    .section    __DWARF,__apple_types,regular,debug
Ltypes_begin:
    .long   1212240712
    .short  1
    .short  0
    .long   1
    .long   0
    .long   20
    .long   0
    .long   3
    .short  1
    .short  6
    .short  3
    .short  5
    .short  4
    .short  11
    .long   -1

.subsections_via_symbols
    .section    __DWARF,__debug_line,regular,debug
Lline_table_start0:

Diffing the two, I get:

(test2.s is the program that crashes, test3.s is the one that doesn't)

--- test2.s 2014-08-09 02:17:59.000000000 -0400
+++ test3.s 2014-08-09 02:23:10.000000000 -0400
@@ -13,9 +13,9 @@
 Ldebug_range:
    .section    __TEXT,__text,regular,pure_instructions
    .align  4, 0x90
-__ZN4main20h8b95006aaacf56a1eaaE:
+__ZN4main20h503ced65c10fa3edeaaE:
 Lfunc_begin0:
-   .file   1 "test2.rs"
+   .file   1 "test3.rs"
    .loc    1 3 0
    .cfi_startproc
    cmpq    %gs:816, %rsp
@@ -36,7 +36,6 @@
    .loc    1 5 0 prologue_end
 Ltmp3:
    ## InlineAsm Start
-test:
    ## InlineAsm End
    popq    %rbp
    retq
@@ -64,7 +63,7 @@
 Ltmp7:
    .cfi_def_cfa_register %rbp
    subq    $16, %rsp
-   leaq    __ZN4main20h8b95006aaacf56a1eaaE(%rip), %rax
+   leaq    __ZN4main20h503ced65c10fa3edeaaE(%rip), %rax
    movq    %rdi, -8(%rbp)
    movq    %rax, %rdi
    movq    -8(%rbp), %rax
@@ -82,15 +81,15 @@
 Linfo_string0:
    .asciz  "rustc version 0.12.0-pre-nightly (a1429bca5 2014-08-08 21:36:11 +0000)"
 Linfo_string1:
-   .asciz  "./test2.rs"
+   .asciz  "./test3.rs"
 Linfo_string2:
    .asciz  "/Users/enix/code/rusttest"
 Linfo_string3:
-   .asciz  "test2"
+   .asciz  "test3"
 Linfo_string4:
    .asciz  "main"
 Linfo_string5:
-   .asciz  "_ZN5test24mainE"
+   .asciz  "_ZN5test34mainE"
    .section    __DWARF,__debug_info,regular,debug
 L__DWARF__debug_info_begin0:
    .long   75
@@ -193,9 +192,9 @@
    .short  1
    .short  6
    .long   0
-   .long   1
+   .long   -1
    .long   2090499946
-   .long   1217565201
+   .long   -1785934126
    .long   LNames0-Lnames_begin
    .long   LNames1-Lnames_begin
 LNames0:
@@ -236,7 +235,7 @@
    .short  1
    .short  6
    .long   0
-   .long   275477815
+   .long   275477816
    .long   Lnamespac0-Lnamespac_begin
 Lnamespac0:
 Lset11 = Linfo_string3-Linfo_string

@DaGenix
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DaGenix commented Aug 9, 2014

Oh, as another note, both of those assembly files were the result of compiling with -g and without any optimization.

@huonw
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huonw commented Aug 9, 2014

The output would likely be shorter and far easier to digest without -g.

@DaGenix
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DaGenix commented Aug 9, 2014

the program that crashes (with -O and no -g):

    .section    __TEXT,__text,regular,pure_instructions
    .align  4, 0x90
__ZN4main20h8b95006aaacf56a1eaaE:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB0_2
    movabsq $8, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB0_2:
    pushq   %rbp
Ltmp0:
    .cfi_def_cfa_offset 16
Ltmp1:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp2:
    .cfi_def_cfa_register %rbp
    ## InlineAsm Start
test:
    ## InlineAsm End
    popq    %rbp
    retq
    .cfi_endproc

    .globl  _main
    .align  4, 0x90
_main:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB1_2
    movabsq $8, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB1_2:
    pushq   %rbp
Ltmp3:
    .cfi_def_cfa_offset 16
Ltmp4:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp5:
    .cfi_def_cfa_register %rbp
    movq    %rsi, %rax
    movq    %rdi, %rcx
    leaq    __ZN4main20h8b95006aaacf56a1eaaE(%rip), %rdi
    movq    %rcx, %rsi
    movq    %rax, %rdx
    popq    %rbp
    jmp __ZN10lang_start20h3eb2912460ad7fe8BueE
    .cfi_endproc


.subsections_via_symbols

And the 2nd program that doesn't:

    .section    __TEXT,__text,regular,pure_instructions
    .align  4, 0x90
__ZN4main20h503ced65c10fa3edeaaE:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB0_2
    movabsq $8, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB0_2:
    pushq   %rbp
Ltmp0:
    .cfi_def_cfa_offset 16
Ltmp1:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp2:
    .cfi_def_cfa_register %rbp
    ## InlineAsm Start
    ## InlineAsm End
    popq    %rbp
    retq
    .cfi_endproc

    .globl  _main
    .align  4, 0x90
_main:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB1_2
    movabsq $8, %r10
    movabsq $0, %r11
    callq   ___morestack
    retq
LBB1_2:
    pushq   %rbp
Ltmp3:
    .cfi_def_cfa_offset 16
Ltmp4:
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
Ltmp5:
    .cfi_def_cfa_register %rbp
    movq    %rsi, %rax
    movq    %rdi, %rcx
    leaq    __ZN4main20h503ced65c10fa3edeaaE(%rip), %rdi
    movq    %rcx, %rsi
    movq    %rax, %rdx
    popq    %rbp
    jmp __ZN10lang_start20h3eb2912460ad7fe8BueE
    .cfi_endproc


.subsections_via_symbols

and the diff:

--- test2.s 2014-08-09 02:30:46.000000000 -0400
+++ test3.s 2014-08-09 02:30:20.000000000 -0400
@@ -1,6 +1,6 @@
    .section    __TEXT,__text,regular,pure_instructions
    .align  4, 0x90
-__ZN4main20h8b95006aaacf56a1eaaE:
+__ZN4main20h503ced65c10fa3edeaaE:
    .cfi_startproc
    cmpq    %gs:816, %rsp
    ja  LBB0_2
@@ -18,7 +18,6 @@
 Ltmp2:
    .cfi_def_cfa_register %rbp
    ## InlineAsm Start
-test:
    ## InlineAsm End
    popq    %rbp
    retq
@@ -45,7 +44,7 @@
    .cfi_def_cfa_register %rbp
    movq    %rsi, %rax
    movq    %rdi, %rcx
-   leaq    __ZN4main20h8b95006aaacf56a1eaaE(%rip), %rdi
+   leaq    __ZN4main20h503ced65c10fa3edeaaE(%rip), %rdi
    movq    %rcx, %rsi
    movq    %rax, %rdx
    popq    %rbp

@zzmp zzmp mentioned this issue Aug 9, 2014
Merged
@ghost ghost mentioned this issue Mar 23, 2015
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@steveklabnik steveklabnik added the A-inline-assembly Area: Inline assembly (`asm!(…)`) label Apr 28, 2015
@steveklabnik
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Triage: this ticket is quite old, but I don't have a mac to test to see if it reproduces today.

@mark-buer
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Just tested it (using latest nightly installed via rustup).
Running the compiled program (from original post) crashes with:

Segmentation fault: 11

@Mark-Simulacrum Mark-Simulacrum added C-bug Category: This is a bug. I-crash Issue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics. labels Jul 21, 2017
@etaoins
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etaoins commented Jan 11, 2018

This still occurs with nightly. Interestingly, if the LLVM IR is compiled with an external llc/opt 5.0.1 it works fine:

> cat broken.rs
#![feature(asm)]

fn main() {
    unsafe {
        asm!(" test:")
    }
    println!("HERE")
}

> rustc broken.rs; and ./broken
fish: 'and ./broken' terminated by signal SIGSEGV (Address boundary error)

> opt -O2 broken.ll | llc -O2 -o broken.s; and clang build/x86_64-apple-darwin/stage2/lib/libstd-774948d0982f7640.dylib  broken.s  -o broken
> ./broken
HERE

@Centril Centril added the requires-nightly This issue requires a nightly compiler in some way. label Oct 25, 2019
@stevecheckoway
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I gave an explanation of what's happening #63977 (comment)

@Amanieu
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Amanieu commented May 23, 2020

You should only use local labels in inline assembly. This is stated in the documentation for the new asm! macro.

@Amanieu Amanieu closed this as completed May 23, 2020
bors added a commit to rust-lang-ci/rust that referenced this issue Jan 21, 2024
@bors
Auto merge of rust-lang#16378 - roife:fix/issue-15470, r=Veykril
f4fec4f 
fix: better handling of SelfParam in assist 'inline_call'

fix rust-lang#15470.

The current `inline_call` directly translates `&self` into `let ref this = ...;` and `&mut self` into `let ref mut this = ...;`. However, it does not handle some complex scenarios.

This PR addresses the following transformations (assuming the receiving object is `obj`):

- `self`: `let this = obj`
- `mut self`: `let mut this = obj`
- `&self`: `let this = &obj`
- `&mut self`
  + If `obj` is `let mut obj = ...`, use a mutable reference: `let this = &mut obj`
  + If `obj` is `let obj = &mut ...;`, perform a reborrow: `let this = &mut *obj`
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A-inline-assembly Area: Inline assembly (`asm!(…)`) C-bug Category: This is a bug. I-crash Issue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics. O-macos Operating system: macOS requires-nightly This issue requires a nightly compiler in some way.
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@steveklabnik @Amanieu @etaoins @Centril @huonw @stevecheckoway @DaGenix @sinistersnare @mark-buer @Mark-Simulacrum