improved zap discovery

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26148 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/Alpha/AlphaISelDAGToDAG.cpp b/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
index 1a442c07bce03e92e31a3056981b8d07640d7e7d..4c49fb9d0a28e094e1f9d4635ee02edf5850760e 100644 (file)
--- a/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
+++ b/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
@@ -363,6 +363,39 @@ void AlphaDAGToDAGISel::Select(SDOperand &Result, SDOperand Op) {
     }
     break;
 
+  case ISD::AND: {
+    ConstantSDNode* SC;
+    ConstantSDNode* MC;
+    if (N->getOperand(0).getOpcode() == ISD::SRL &&
+       (MC = dyn_cast<ConstantSDNode>(N->getOperand(1))) &&
+       (SC = dyn_cast<ConstantSDNode>(N->getOperand(0).getOperand(1))))
+      {
+       uint64_t sval = SC->getValue();
+       uint64_t mval = MC->getValue();
+       if (get_zapImm(mval)) //the result is a zap, let the autogened stuff deal
+         break;
+       // given mask X, and shift S, we want to see if there is any zap in the mask
+       // if we play around with the botton S bits
+       uint64_t dontcare = (~0ULL) >> (64 - sval);
+       uint64_t mask = mval << sval;
+
+       if (get_zapImm(mask | dontcare))
+         mask = mask | dontcare;
+
+       if (get_zapImm(mask)) {
+         SDOperand Src;
+         Select(Src, N->getOperand(0).getOperand(0));
+         SDOperand Z = 
+           SDOperand(CurDAG->getTargetNode(Alpha::ZAPNOTi, MVT::i64, Src, 
+                                           getI64Imm(get_zapImm(mask))), 0);
+         Result = SDOperand(CurDAG->getTargetNode(Alpha::SRL, MVT::i64, Z, 
+                                                  getI64Imm(sval)), 0);
+         return;
+       }
+      }
+    break;
+  }
+
   }
 
   SelectCode(Result, Op);