[PATCH] D49919: [InstCombine] Fold Select with OR condition
Dávid Bolvanský via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 27 10:46:36 PDT 2018
xbolva00 added inline comments.
================
Comment at: lib/Transforms/InstCombine/InstCombineSelect.cpp:65-87
+static Value *foldSelectInstBinaryOp(SelectInst &Sel) {
+ Value *A, *B;
+ Value *TrueVal = Sel.getTrueValue();
+ Value *FalseVal = Sel.getFalseValue();
+ if (match(Sel.getCondition(), m_c_Or(m_Value(A), m_Value(B)))) {
+ CmpInst::Predicate Pred1, Pred2;
+ Value *T1, *T2;
----------------
lebedev.ri wrote:
> lebedev.ri wrote:
> > One more thing - this is slightly too verbose. I suspect it may miss some commutative cases, too.
> > Please make better use of pattern matchers.
> >
> > How about:
> > ```
> > Value *foldSelectInstBinaryOp(SelectInst &Sel) {
> > Value *X, *V1, *V2;
> > CmpInst::Predicate Pred1, Pred2;
> > if (!match(&Sel, m_Select(m_c_Or(m_ICmp(Pred1, m_Value(X), m_Value(V1)),
> > m_c_ICmp(Pred2, m_Deferred(X), m_Value(V2))),
> > m_Deferred(X), m_Deferred(V1))) ||
> > !(Pred1 == Pred2 && Pred1 == ICmpInst::ICMP_NE))
> > return nullptr;
> > return X;
> > }
> >
> > ```
> Actually, you won't even need `V2` **right now**, i think, so,
> ```
> static Value *foldSelectInstBinaryOp(SelectInst &Sel) {
> Value *X, *V1;
> CmpInst::Predicate Pred1, Pred2;
> if (!match(&Sel, m_Select(m_c_Or(m_ICmp(Pred1, m_Value(X), m_Value(V1)),
> m_c_ICmp(Pred2, m_Deferred(X), m_Value())),
> m_Deferred(X), m_Deferred(V1))) ||
> !(Pred1 == Pred2 && Pred1 == ICmpInst::ICMP_NE))
> return nullptr;
> return X;
> }
> ```
Wow, nice simplification :) Thanks
Repository:
rL LLVM
https://reviews.llvm.org/D49919
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