Emit a redundant check for immediates at root context, e.g. (imm 0).
This allows formation of OpcodeSwitch for top level patterns, in
particular on X86.  This saves about 1K of data space in the x86
table and makes the dispatch much more efficient.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97440 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/DAGISelMatcher.h b/utils/TableGen/DAGISelMatcher.h
index 8b6b322..1634cd2 100644
--- a/utils/TableGen/DAGISelMatcher.h
+++ b/utils/TableGen/DAGISelMatcher.h
@@ -55,7 +55,6 @@
     CheckPredicate,       // Fail if node predicate fails.
     CheckOpcode,          // Fail if not opcode.
     SwitchOpcode,         // Dispatch based on opcode.
-    CheckMultiOpcode,     // Fail if not in opcode list.
     CheckType,            // Fail if not correct type.
     CheckChildType,       // Fail if child has wrong type.
     CheckInteger,         // Fail if wrong val.
diff --git a/utils/TableGen/DAGISelMatcherGen.cpp b/utils/TableGen/DAGISelMatcherGen.cpp
index 95cfa5b..62442d0 100644
--- a/utils/TableGen/DAGISelMatcherGen.cpp
+++ b/utils/TableGen/DAGISelMatcherGen.cpp
@@ -205,8 +205,17 @@
     AddMatcher(new CheckPredicateMatcher(N->getPredicateFns()[i]));
   
   // Direct match against an integer constant.
-  if (IntInit *II = dynamic_cast<IntInit*>(N->getLeafValue()))
+  if (IntInit *II = dynamic_cast<IntInit*>(N->getLeafValue())) {
+    // If this is the root of the dag we're matching, we emit a redundant opcode
+    // check to ensure that this gets folded into the normal top-level
+    // OpcodeSwitch.
+    if (N == Pattern.getSrcPattern()) {
+      const SDNodeInfo &NI = CGP.getSDNodeInfo(CGP.getSDNodeNamed("imm"));
+      AddMatcher(new CheckOpcodeMatcher(NI));
+    }
+
     return AddMatcher(new CheckIntegerMatcher(II->getValue()));
+  }
   
   DefInit *DI = dynamic_cast<DefInit*>(N->getLeafValue());
   if (DI == 0) {