<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Reference external functions without PLT"
href="https://llvm.org/bugs/show_bug.cgi?id=28306">28306</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Reference external functions without PLT
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hjl.tools@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>david.l.kreitzer@intel.com, llvm-bugs@lists.llvm.org, zia.ansari@intel.com
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>There are extensions to x86-64 psABI:
<a href="https://groups.google.com/forum/#!topic/x86-64-abi/de5_KnLHxtI">https://groups.google.com/forum/#!topic/x86-64-abi/de5_KnLHxtI</a>
and i386 psABI:
<a href="https://groups.google.com/forum/#!topic/ia32-abi/awsRSvJOJfs">https://groups.google.com/forum/#!topic/ia32-abi/awsRSvJOJfs</a>
with alternate code sequences to reference external functions without
PLT:
[hjl@gnu-tools-1 pr67400]$ cat z.i
extern int bar (void);
int
foo (void)
{
return bar ();
}
[hjl@gnu-tools-1 pr67400]$ cat f.i
extern int name (void);
void *
ptr (void)
{
return name;
}
[hjl@gnu-tools-1 pr67400]$ cat t.i
static __thread int ld;
extern __thread int gd;
int *
get_ld (void)
{
return &ld;
}
int *
get_gd (void)
{
return &gd;
}
[hjl@gnu-tools-1 pr67400]$ make
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -fno-plt -S z.i
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -fno-plt -S f.i
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -fno-plt -fPIC -S t.i
[hjl@gnu-tools-1 pr67400]$ cat z.s
.file "z.i"
.text
.p2align 4,,15
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
jmp *bar@GOTPCREL(%rip)
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 7.0.0 20160625 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 pr67400]$ cat f.s
.file "f.i"
.text
.p2align 4,,15
.globl ptr
.type ptr, @function
ptr:
.LFB0:
.cfi_startproc
movq name@GOTPCREL(%rip), %rax
ret
.cfi_endproc
.LFE0:
.size ptr, .-ptr
.ident "GCC: (GNU) 7.0.0 20160625 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 pr67400]$ cat t.s
.file "t.i"
.text
.p2align 4,,15
.globl get_ld
.type get_ld, @function
get_ld:
.LFB0:
.cfi_startproc
subq $8, %rsp
.cfi_def_cfa_offset 16
leaq ld@tlsld(%rip), %rdi
call *__tls_get_addr@GOTPCREL(%rip)
addq $8, %rsp
.cfi_def_cfa_offset 8
addq $ld@dtpoff, %rax
ret
.cfi_endproc
.LFE0:
.size get_ld, .-get_ld
.p2align 4,,15
.globl get_gd
.type get_gd, @function
get_gd:
.LFB1:
.cfi_startproc
subq $8, %rsp
.cfi_def_cfa_offset 16
.byte 0x66
leaq gd@tlsgd(%rip), %rdi
.byte 0x66
rex64
call *__tls_get_addr@GOTPCREL(%rip)
addq $8, %rsp
.cfi_def_cfa_offset 8
ret
.cfi_endproc
.LFE1:
.size get_gd, .-get_gd
.section .tbss,"awT",@nobits
.align 4
.type ld, @object
.size ld, 4
ld:
.zero 4
.ident "GCC: (GNU) 7.0.0 20160625 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 pr67400]$ make
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -fno-plt -m32 -S z.i
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -fno-plt -m32 -S f.i
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -O2 -fno-plt -m32 -fPIC -S
t.i
[hjl@gnu-tools-1 pr67400]$ cat z.s
.file "z.i"
.text
.p2align 4,,15
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
jmp *bar@GOT
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 7.0.0 20160625 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 pr67400]$ cat f.s
.file "f.i"
.text
.p2align 4,,15
.globl ptr
.type ptr, @function
ptr:
.LFB0:
.cfi_startproc
movl name@GOT, %eax
ret
.cfi_endproc
.LFE0:
.size ptr, .-ptr
.ident "GCC: (GNU) 7.0.0 20160625 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 pr67400]$ cat t.s
.file "t.i"
.text
.p2align 4,,15
.globl get_ld
.type get_ld, @function
get_ld:
.LFB0:
.cfi_startproc
call __x86.get_pc_thunk.dx
addl $_GLOBAL_OFFSET_TABLE_, %edx
subl $12, %esp
.cfi_def_cfa_offset 16
leal ld@tlsgd(%edx), %eax
call *___tls_get_addr@GOT(%edx)
addl $12, %esp
.cfi_def_cfa_offset 4
ret
.cfi_endproc
.LFE0:
.size get_ld, .-get_ld
.p2align 4,,15
.globl get_gd
.type get_gd, @function
get_gd:
.LFB1:
.cfi_startproc
call __x86.get_pc_thunk.dx
addl $_GLOBAL_OFFSET_TABLE_, %edx
subl $12, %esp
.cfi_def_cfa_offset 16
leal gd@tlsgd(%edx), %eax
call *___tls_get_addr@GOT(%edx)
addl $12, %esp
.cfi_def_cfa_offset 4
ret
.cfi_endproc
.LFE1:
.size get_gd, .-get_gd
.section .tbss,"awT",@nobits
.align 4
.type ld, @object
.size ld, 4
ld:
.zero 4
.section
.text.__x86.get_pc_thunk.dx,"axG",@progbits,__x86.get_pc_thunk.dx,comdat
.globl __x86.get_pc_thunk.dx
.hidden __x86.get_pc_thunk.dx
.type __x86.get_pc_thunk.dx, @function
__x86.get_pc_thunk.dx:
.LFB2:
.cfi_startproc
movl (%esp), %edx
ret
.cfi_endproc
.LFE2:
.ident "GCC: (GNU) 7.0.0 20160625 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 pr67400]$
llvm should also implement -fno-plt.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>