If an integer PHI has an illegal type (according to the data layout) and
it is only used by `trunc` or `trunc(lshr)` operations, we split the PHI
into various instructions in its predecessors:
6d1543a167/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp (L1536-L1543)
So this can produce code like the following:
Before:
```
pred:
...
bb:
%p = phi i8 [ %somevalue, %pred ], ...
...
%tobool = trunc i8 %p to i1
use %tobool
...
```
In this code, `%p` has an illegal integer type, `i8`, and its only used
in a `trunc` instruction later. In this case this pass puts extraction
code in its predecessors:
After:
```
pred:
...
%t = and i8 %somevalue, 1
%extract = icmp ne i8 %t, 0
bb:
%p.new = phi i1 [ %extract, %pred ], ...
use %p.new instead of %tobool
```
But this doesn't work if `pred` is a `catchswitch` BB because it cannot
have any non-PHI instructions. This CL ensures we bail out in that case.
Fixes https://github.com/llvm/llvm-project/issues/55803.
Reviewed By: dschuff
Differential Revision: https://reviews.llvm.org/D127699
This tries to bail out if the PHI is in a `catchswitch` BB in
InstCombine. A PHI cannot be combined into a non-PHI instruction if it
is in a `catchswitch` BB, because `catchswitch` BB cannot have any
non-PHI instruction other than `catchswitch` itself.
The given test case started crashing after D98058.
Reviewed By: lebedev.ri, rnk
Differential Revision: https://reviews.llvm.org/D105309
