Cache the isTrivial property.

The check for isTrivial takes ~20% of the optimizer compile time (in debug
mode) and using a cache accelerates the compile time.



Swift SVN r14346

include/swift/SIL/SILModule.h

@@ -127,6 +127,9 @@ private:
   /// This is a cache of builtin Function declarations to numeric ID mappings.
   llvm::DenseMap<Identifier, BuiltinInfo> BuiltinIDCache;
 
+  /// This is a cache of the isTrivial property for SILTypes.
+  llvm::DenseMap<SILType, bool> TrivialTypeCache;
+
   /// This is the set of undef values we've created, for uniquing purposes.
   llvm::DenseMap<SILType, SILUndef*> UndefValues;
 
@@ -163,6 +166,19 @@ public:
     FunctionTable.erase(F->getName());
   }
 
+  bool isTrivialType(SILType Ty) {
+    auto It = TrivialTypeCache.find(Ty);
+
+    // Check if this type is already in the cache.
+    if (It != TrivialTypeCache.end())
+      return It->second;
+
+    // Check if the type is trivial and store the result in the cache.
+    bool IsTriv = getTypeLowering(Ty).isTrivial();
+    TrivialTypeCache[Ty] = IsTriv;
+    return IsTriv;
+  }
+
   /// Construct a SIL module from an AST module.
   ///
   /// The module will be constructed in the Raw stage. The provided AST module