[llvm] r333363 - [Tablegen] Avoid generating empty switch statements. NFC

[Andrea Di Biagio via llvm-commits]

Author: adibiagio
Date: Sun May 27 12:08:12 2018
New Revision: 333363

URL: http://llvm.org/viewvc/llvm-project?rev=333363&view=rev
Log:
[Tablegen] Avoid generating empty switch statements. NFC

This fixes an MSVC warning (warning C4065: switch statement contains 'default'
but no 'case' labels) introduced with revision 333293.

Modified:
    llvm/trunk/utils/TableGen/SubtargetEmitter.cpp

Modified: llvm/trunk/utils/TableGen/SubtargetEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/SubtargetEmitter.cpp?rev=333363&r1=333362&r2=333363&view=diff
==============================================================================
--- llvm/trunk/utils/TableGen/SubtargetEmitter.cpp (original)
+++ llvm/trunk/utils/TableGen/SubtargetEmitter.cpp Sun May 27 12:08:12 2018
@@ -1506,7 +1506,7 @@ void SubtargetEmitter::emitSchedModelHel
   }
 
   if (!VariantClasses.empty()) {
-    OS << "  switch (SchedClass) {\n";
+    bool FoundPredicates = false;
     for (unsigned VC : VariantClasses) {
       // Emit code for each variant scheduling class.
       const CodeGenSchedClass &SC = SchedModels.getSchedClass(VC);
@@ -1527,6 +1527,12 @@ void SubtargetEmitter::emitSchedModelHel
       if (ProcIndices.empty())
         continue;
 
+      // Emit a switch statement only if there are predicates to expand.
+      if (!FoundPredicates) {
+        OS << "  switch (SchedClass) {\n";
+        FoundPredicates = true;
+      }
+
       OS << "  case " << VC << ": // " << SC.Name << '\n';
       PredicateExpander PE;
       PE.setByRef(false);
@@ -1556,9 +1562,9 @@ void SubtargetEmitter::emitSchedModelHel
         OS << "    return " << SC.Index << ";\n";
       OS << "    break;\n";
     }
-    // Add a default case to avoid generating a potentially empty switch.
-    OS << "  default : break;\n"
-       << "  };\n";
+
+    if (FoundPredicates)
+     OS << "  };\n";
   }
 
   if (OnlyExpandMCInstPredicates) {