| Issue |
147813
|
| Summary |
`musttail` generates redundant moves on 32-bit platforms
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
brandtbucher
|
For example, this code:
```cpp
int bar(int);
int
foo_tail(int x)
{
// Correct, compiles to a single jmp:
return bar(x);
}
int
foo_musttail(int x)
{
// Buggy, loads and re-spills all parameters:
__attribute__((musttail)) return bar(x);
}
```
Compiles to:
```s
_foo_tail:
jmp _bar
_foo_musttail:
movl 4(%esp), %eax
movl %eax, 4(%esp)
jmp _bar
```
[Compiler Explorer](https://godbolt.org/z/sYoMMjoxY)
Adding more parameters to the function (and tail call) increases the number of redundant loads/spills, too.
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