| Issue |
55411
|
| Summary |
[s390] integrated assembler miscompiles mvc+clc instructions
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
hcahca
|
Compiling this simple test program:
```
test:
mvc 32(8,%r0),.Lsomething
clc 0(1,%r1),.Lsomething
.Lsomething:
.quad 0
```
with `clang --target=s390x-linux-gnu -fintegrated-as -m64 test.S` results in an object file with incorrect relocations for the second displacement of the mvc and clc instructions:
```
> objdump -hdr test.o
Disassembly of section .text:
0000000000000000 <test>:
0: d2 07 00 20 00 00 mvc 32(8,%r0),0
2: R_390_12 .text+0xc
6: d5 00 10 00 00 00 clc 0(1,%r1),0
8: R_390_12 .text+0xc
```
Compare this with the result when using gcc/gas `gcc -c test.S`:
```
> objdump -hdr test.o
Disassembly of section .text:
0000000000000000 <test>:
0: d2 07 00 20 00 00 mvc 32(8,%r0),0
4: R_390_12 .text+0xc
6: d5 00 10 00 00 00 clc 0(1,%r1),0
a: R_390_12 .text+0xc
```
FWIW, as reference: this causes a miscompile for the Linux Kernel on s390: https://lore.kernel.org/linux-s390/Ynwh%[email protected]/T/#m57bd178adca225e8822d65d796dbec33c7ac0de6
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