This patch enables SimplifyUsingDistributiveLaws() to handle following pattens.

[oota-llvm.git] / lib / Transforms / InstCombine / InstCombineCompares.cpp

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 3a501132ebdba084e94fe951330ebb415aeb2e86..4cf836c03b213795355d623300e6a8a090dfe2b5 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1366,6 +1366,48 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
         return &ICI;
       }
 
+      // (icmp pred (and (or (lshr X, Y), X), 1), 0) -->
+      //    (icmp pred (and X, (or (shl 1, Y), 1), 0))
+      //
+      // iff pred isn't signed
+      {
+        Value *X, *Y, *LShr;
+        if (!ICI.isSigned() && RHSV == 0) {
+          if (match(LHSI->getOperand(1), m_One())) {
+            Constant *One = cast<Constant>(LHSI->getOperand(1));
+            Value *Or = LHSI->getOperand(0);
+            if (match(Or, m_Or(m_Value(LShr), m_Value(X))) &&
+                match(LShr, m_LShr(m_Specific(X), m_Value(Y)))) {
+              unsigned UsesRemoved = 0;
+              if (LHSI->hasOneUse())
+                ++UsesRemoved;
+              if (Or->hasOneUse())
+                ++UsesRemoved;
+              if (LShr->hasOneUse())
+                ++UsesRemoved;
+              Value *NewOr = nullptr;
+              // Compute X & ((1 << Y) | 1)
+              if (auto *C = dyn_cast<Constant>(Y)) {
+                if (UsesRemoved >= 1)
+                  NewOr =
+                      ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One);
+              } else {
+                if (UsesRemoved >= 3)
+                  NewOr = Builder->CreateOr(Builder->CreateShl(One, Y,
+                                                               LShr->getName(),
+                                                               /*HasNUW=*/true),
+                                            One, Or->getName());
+              }
+              if (NewOr) {
+                Value *NewAnd = Builder->CreateAnd(X, NewOr, LHSI->getName());
+                ICI.setOperand(0, NewAnd);
+                return &ICI;
+              }
+            }
+          }
+        }
+      }
+
       // Replace ((X & AndCst) > RHSV) with ((X & AndCst) != 0), if any
       // bit set in (X & AndCst) will produce a result greater than RHSV.
       if (ICI.getPredicate() == ICmpInst::ICMP_UGT) {