Teach codegen to handle:
(X != null) | (Y != null) --> (X|Y) != 0
(X == null) & (Y == null) --> (X|Y) == 0
so that instcombine can stop doing this for pointers. This is part of PR3351,
which is a case where instcombine doing this for pointers (inserting ptrtoint)
is pessimizing code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92406 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 74d624f..40eb9ee 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1195,6 +1195,18 @@
return false;
}
+ // Handle: (X != null) | (Y != null) --> (X|Y) != 0
+ // Handle: (X == null) & (Y == null) --> (X|Y) == 0
+ if (Cases[0].CmpRHS == Cases[1].CmpRHS &&
+ Cases[0].CC == Cases[1].CC &&
+ isa<Constant>(Cases[0].CmpRHS) &&
+ cast<Constant>(Cases[0].CmpRHS)->isNullValue()) {
+ if (Cases[0].CC == ISD::SETEQ && Cases[0].TrueBB == Cases[1].ThisBB)
+ return false;
+ if (Cases[0].CC == ISD::SETNE && Cases[0].FalseBB == Cases[1].ThisBB)
+ return false;
+ }
+
return true;
}