| Issue |
169645
|
| Summary |
[DAG] SDPatternMatch - m_Reassociatable mismatches
|
| Labels |
good first issue,
llvm:SelectionDAG
|
| Assignees |
|
| Reporter |
RKSimon
|
Noticed while working on #169644
If we attempt to match a m_ReassociatableAdd pattern containing both the m_Value and m_Deferred for a given SDValue, the matcher gets corrupted and fails to match the correct SDValue pairs
foldAddToAvg:
```
if ((!LegalOperations || hasOperation(ISD::AVGFLOORU, VT)) &&
(sd_match(N,
m_Add(m_And(m_Value(A), m_Value(B)),
m_Srl(m_Xor(m_Deferred(A), m_Deferred(B)), m_One()))) ||
sd_match(N, m_ReassociatableAdd(
m_Srl(m_Value(A), m_One()), m_Srl(m_Value(B), m_One()),
m_ReassociatableAnd(m_Deferred(A), m_Deferred(B),
m_One()))))) {
return DAG.getNode(ISD::AVGFLOORU, DL, VT, A, B);
}
```
in this case we end up with the same SDValue being matched for A and B.
Hopefully this is just an evaluation ordering issue, but there might be something else going on.
Good first issue for someone who likes template programming!
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