| Issue |
142513
|
| Summary |
[X86] 64-bit constant compiled to `movabs`+`add` after branch
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
dzaima
|
https://c.godbolt.org/z/GEb9G3bMq
This C code, compiled with `-O3`:
```c
#include <inttypes.h>
#include <stdlib.h>
uint64_t foo(uint64_t x) {
if (x >> 47 == 0xffe5) { // equivalent to (x & 0xffff800000000000) == 0x7ff2800000000000
abort();
}
return 0x7ff2800000000003;
}
```
produces:
```asm
foo:
shr rdi, 47
cmp edi, 65509
je .LBB0_2
movabs rax, 9219572124669181952 ; 0x7ff2800000000000
add rax, 3
ret
.LBB0_2:
push rax
call abort@PLT
```
where the `movabs` + `add` could trivially be just `movabs rax, 9219572124669181955`, as the `movabs` ends up being used only here.
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