| Issue |
171752
|
| Summary |
[aarch64] Unnecessary masking of lower bits after ubfiz
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
purplesyringa
|
[Godbolt](https://godbolt.org/z/oo6ocGK55)
```cpp
#include <stdint.h>
uint8_t f(uint8_t x, uint64_t n) {
return (uint16_t)((x << 1) | (x << 8)) >> n;
}
```
```asm
f(unsigned char, unsigned long):
ubfiz w8, w0, #1, #8
orr w8, w8, w0, lsl #8
and w8, w8, #0xfffe ; why is this `and` here?
lsr w0, w8, w1
ret
```
Happens during isel, not sure why.
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