https://sourceware.org/bugzilla/show_bug.cgi?id=27897
Bug ID: 27897
Summary: gold generates wrong TLS relocation for IE access
model
Product: binutils
Version: 2.36
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: gold
Assignee: ccoutant at gmail dot com
Reporter: luobodi at hotmail dot com
CC: ian at airs dot com
Target Milestone: ---
Test code (I'm using GCC 11.1 with binutils 2.36):
```cpp
static thread_local int value1
__attribute__((tls_model("global-dynamic"))) = 10;
int Get1() { return value1; }
static thread_local int value2
__attribute__((tls_model("initial-exec")));
int Get2() { return value2; }
```
When compiled with `g++ something.cc -std=c++2a -fPIC -shared -o something.so
-fuse-ld=gold -save-temps`, `readelf -a --wide something.so |grep value2` shows
a relocation of type `R_X86_64_DTPMOD64` for `value2`.
Since `value2` is annotated as `initial-exec`, I would expected an
`R_X86_64_TPOFF64` be emitted instead.
Further investigation suggests that gold is somehow confused by
`_ZL6value1@tlsgd(%rip)` generated by GCC (for accessing `value`).
If I either:
- Remove `value1` from the source (there won't be `value1@tlsgd` then), or
- Specify `initial-exec` on `value1` (hence avoid `value1@tlsgd`), or
- Manually replace `tlsgd` with `tlsld` in `something.so-something.s` (produced
by `-save-temps`)
gold can emit an `R_X86_64_TPOFF64` for `value2` correctly.
`something.so-something.s` is attached below if it helps:
```asm
.file "something.cc"
.text
.section .tdata,"awT",@progbits
.align 4
.type _ZL6value1, @object
.size _ZL6value1, 4
_ZL6value1:
.long 10
.text
.globl _Z4Get1v
.type _Z4Get1v, @function
_Z4Get1v:
.LFB0:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
data16 leaq _ZL6value1@tlsgd(%rip), %rdi
.value 0x6666
rex64
call __tls_get_addr@PLT
movl (%rax), %eax
popq %rbp
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE0:
.size _Z4Get1v, .-_Z4Get1v
.section .tbss,"awT",@nobits
.align 4
.type _ZL6value2, @object
.size _ZL6value2, 4
_ZL6value2:
.zero 4
.text
.globl _Z4Get2v
.type _Z4Get2v, @function
_Z4Get2v:
.LFB1:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
movq _ZL6value2@gottpoff(%rip), %rax
movl %fs:(%rax), %eax
popq %rbp
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE1:
.size _Z4Get2v, .-_Z4Get2v
.ident "GCC: (GNU) 11.1.0"
.section .note.GNU-stack,"",@progbits
```
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