The transform is:
(or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D))
By the time the OR is visited, both the SELECTs have been visited and not
optimized and the OR itself hasn't been transformed so we do this transform in
the hopes that the new ORs will be optimized.
The transform is explicitly disabled for vector-selects until "codegen matures
to handle them better".
Patch by Muhammad Tauqir!
llvm-svn: 175380
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index bf065fe..4332467 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2071,6 +2071,20 @@
return BinaryOperator::CreateOr(Inner, C1);
}
+ // Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D))
+ // Since this OR statement hasn't been optimized further yet, we hope
+ // that this transformation will allow the new ORs to be optimized.
+ {
+ Value *X = 0, *Y = 0;
+ if (Op0->hasOneUse() && Op1->hasOneUse() &&
+ match(Op0, m_Select(m_Value(X), m_Value(A), m_Value(B))) &&
+ match(Op1, m_Select(m_Value(Y), m_Value(C), m_Value(D))) && X == Y) {
+ Value *orTrue = Builder->CreateOr(A, C);
+ Value *orFalse = Builder->CreateOr(B, D);
+ return SelectInst::Create(X, orTrue, orFalse);
+ }
+ }
+
return Changed ? &I : 0;
}