| commit | 00c527abab3dfea5f3122f8151d69e77655eb033 | [log] [tgz] |
|---|---|---|
| author | Hans Wennborg <hans@hanshq.net> | Thu Mar 27 10:23:30 2025 +0100 |
| committer | GitHub <noreply@github.com> | Thu Mar 27 10:23:30 2025 +0100 |
| tree | 1e046480f687998afbb9bef60faaa493b5bf7849 | |
| parent | db98e2922f0121f2c6fb3d6f42b40f9774f9a563 [diff] |
[Coro] Allow spilling @llvm.coro.suspend() to the coro frame (#133088)
It was excluded from spilling in a263a60, possibly by accident.
In the linked bug, we hit a situation like this:
```
%s = call @llvm.coro.suspend(...)
|
switch (%s)
case v1: / \ case v2:
... ...
| suspend point
| ...
\ /
%x = phi [v1] [v2]
|
...
|
use(%x)
```
Instcombine will notice that %x correlates exactly with %s, and so
use(%x) becomes use(%s).
However, corosplit would substitute different values for %s when
splitting the function, so even though %s had a particular value when
control actually passed through the switch, it could have a *different*
value when reaching use(%s).
This illustrates that while IR from the frontend typically does not use
these suspend return values across suspend points, mid-level
optimizations on the presplit coroutine may introduce new uses of
suspend values, so they must be considered eligible to spill to the
coroutine frame.
Fixes: #130326
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