barf.txt

gdb ./a.out
GNU gdb 6.3.50-20050815 (Apple version gdb-1820) (Sat Jun 16 02:40:11 UTC 2012)
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This GDB was configured as "x86_64-apple-darwin"...Reading symbols for shared libraries .. done

(gdb) run
Starting program: /private/tmp/y/a.out
Reading symbols for shared libraries +.............................. done

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x0000000100000f00
0x0000000100000f20 in f ()
(gdb) disassemble
Dump of assembler code for function f:
0x0000000100000f20 <f+0>:  add    DWORD PTR [rax],eax
0x0000000100000f22 <f+2>:	add    BYTE PTR [rax],al
0x0000000100000f24 <f+4>:	ret
0x0000000100000f25 <f+5>:	nop    WORD PTR cs:[rax+rax+0x0]
End of assembler dump.
(gdb)

foo.ll

; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s

@i = linkonce_odr global i32 1

; CHECK: f:
; CHECK-NEXT: .long  1
define void @f() prefix i32 1 {
  ret void
}

; CHECK: g:
; CHECK-NEXT: .quad  i
define void @g() prefix i32* @i {
  ret void
}

foo.s

  .section	__TEXT,__text,regular,pure_instructions
	.globl	_f
	.align	4, 0x90
_f:                                     ## @f
	.long	1                       ## 0x1
## BB#0:
	ret

	.globl	_g
	.align	4, 0x90
_g:                                     ## @g
	.quad	_i
## BB#0:
	ret

	.section	__DATA,__datacoal_nt,coalesced
	.globl	_i                      ## @i
	.weak_definition	_i
	.align	2
_i:
	.long	1                       ## 0x1


.subsections_via_symbols

x.c

void f();
void g();

int main()
{
  f();
  g();
  return 0;
}