[InstCombine] consolidate commutation variants of matchSelectFromAndOr() in one place; NFCI

By putting all the possible commutations together, we simplify the code.
Note that this is NFCI, but I'm adding tests that actually exercise each
commutation pattern because we don't have this anywhere else.

llvm-svn: 273702

1 files changed, 18 insertions, 27 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index e518db13a7f..c76cfba4f14 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1628,26 +1628,18 @@ Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
   return LastInst;
 }
 
-/// We have an expression of the form (A&C)|(B&D).  Check if A is (cond?-1:0)
-/// and either B or D is ~(cond?-1,0) or (cond?0,-1), then we can simplify this
-/// expression to "cond ? C : D or B".
-static Instruction *matchSelectFromAndOr(Value *A, Value *B, Value *C, Value *D,
+/// We have an expression of the form (A & C) | (B & D). If A is (Cond?-1:0)
+/// and B is ~(Cond?-1,0), then simplify this expression to "Cond ? C : D".
+static Instruction *matchSelectFromAndOr(Value *A, Value *C, Value *B, Value *D,
                                          InstCombiner::BuilderTy &Builder) {
   // If A is not a select of -1/0, this cannot match.
   Value *Cond = nullptr;
   if (match(A, m_SExt(m_Value(Cond))) &&
       Cond->getType()->getScalarType()->isIntegerTy(1)) {
 
-    // ((cond ? -1:0) & C) | (B & (cond ? 0:-1)) -> cond ? C : B.
-    if (match(D, m_Not(m_SExt(m_Specific(Cond)))))
-      return SelectInst::Create(Cond, C, B);
-    if (match(D, m_SExt(m_Not(m_Specific(Cond)))))
-      return SelectInst::Create(Cond, C, B);
-
     // ((cond ? -1:0) & C) | ((cond ? 0:-1) & D) -> cond ? C : D.
-    if (match(B, m_Not(m_SExt(m_Specific(Cond)))))
-      return SelectInst::Create(Cond, C, D);
-    if (match(B, m_SExt(m_Not(m_Specific(Cond)))))
+    if (match(B, m_CombineOr(m_Not(m_SExt(m_Specific(Cond))),
+                             m_SExt(m_Not(m_Specific(Cond))))))
       return SelectInst::Create(Cond, C, D);
   }
 
@@ -1662,15 +1654,6 @@ static Instruction *matchSelectFromAndOr(Value *A, Value *B, Value *C, Value *D,
 
     Type *SrcType = cast<BitCastInst>(A)->getSrcTy();
 
-    // ((bc Cond) & C) | (B & (bc ~Cond)) --> bc (select Cond, (bc C), (bc B))
-    if (match(D, m_CombineOr(m_BitCast(m_Not(m_SExt(m_Specific(Cond)))),
-                             m_BitCast(m_SExt(m_Not(m_Specific(Cond))))))) {
-      Value *BitcastC = Builder.CreateBitCast(C, SrcType);
-      Value *BitcastB = Builder.CreateBitCast(B, SrcType);
-      Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastB);
-      return CastInst::Create(Instruction::BitCast, Select, A->getType());
-    }
-
     // ((bc Cond) & C) | ((bc ~Cond) & D) --> bc (select Cond, (bc C), (bc D))
     if (match(B, m_CombineOr(m_BitCast(m_Not(m_SExt(m_Specific(Cond)))),
                              m_BitCast(m_SExt(m_Not(m_Specific(Cond))))))) {
@@ -2276,14 +2259,22 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
       }
     }
 
-    // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) ->  C0 ? A : B, and commuted variants.
-    if (Instruction *Match = matchSelectFromAndOr(A, B, C, D, *Builder))
+    // (Cond & C) | (~Cond & D) -> Cond ? C : D, and commuted variants.
+    if (Instruction *Match = matchSelectFromAndOr(A, C, B, D, *Builder))
+      return Match;
+    if (Instruction *Match = matchSelectFromAndOr(A, C, D, B, *Builder))
+      return Match;
+    if (Instruction *Match = matchSelectFromAndOr(C, A, B, D, *Builder))
+      return Match;
+    if (Instruction *Match = matchSelectFromAndOr(C, A, D, B, *Builder))
+      return Match;
+    if (Instruction *Match = matchSelectFromAndOr(B, D, A, C, *Builder))
       return Match;
-    if (Instruction *Match = matchSelectFromAndOr(B, A, D, C, *Builder))
+    if (Instruction *Match = matchSelectFromAndOr(B, D, C, A, *Builder))
       return Match;
-    if (Instruction *Match = matchSelectFromAndOr(C, B, A, D, *Builder))
+    if (Instruction *Match = matchSelectFromAndOr(D, B, A, C, *Builder))
       return Match;
-    if (Instruction *Match = matchSelectFromAndOr(D, A, B, C, *Builder))
+    if (Instruction *Match = matchSelectFromAndOr(D, B, C, A, *Builder))
       return Match;
 
     // ((A&~B)|(~A&B)) -> A^B