Intrinsics: add LLVMHalfElementsVectorType constraint

This is like the LLVMMatchType, except the verifier checks that the
second argument is a vector with the same base type and half the
number of elements.

This will be used by the ARM64 backend.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205079 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DerivedTypes.h

@@ -400,6 +400,26 @@ public:
     return VectorType::get(EltTy, VTy->getNumElements());
   }
 
+  /// VectorType::getHalfElementsVectorType - This static method returns
+  /// a VectorType with half as many elements as the input type and the
+  /// same element type.
+  ///
+  static VectorType *getHalfElementsVectorType(VectorType *VTy) {
+    unsigned NumElts = VTy->getNumElements();
+    assert ((NumElts & 1) == 0 &&
+            "Cannot halve vector with odd number of elements.");
+    return VectorType::get(VTy->getElementType(), NumElts/2);
+  }
+
+  /// VectorType::getDoubleElementsVectorType - This static method returns
+  /// a VectorType with twice  as many elements as the input type and the
+  /// same element type.
+  ///
+  static VectorType *getDoubleElementsVectorType(VectorType *VTy) {
+    unsigned NumElts = VTy->getNumElements();
+    return VectorType::get(VTy->getElementType(), NumElts*2);
+  }
+
   /// isValidElementType - Return true if the specified type is valid as a
   /// element type.
   static bool isValidElementType(Type *ElemTy);

include/llvm/IR/Intrinsics.h

@@ -79,7 +79,7 @@ namespace Intrinsic {
     enum IITDescriptorKind {
       Void, VarArg, MMX, Metadata, Half, Float, Double,
       Integer, Vector, Pointer, Struct,
-      Argument, ExtendArgument, TruncArgument,
+      Argument, ExtendArgument, TruncArgument, HalfVecArgument
     } Kind;
     
     union {
@@ -99,12 +99,12 @@ namespace Intrinsic {
     };
     unsigned getArgumentNumber() const {
       assert(Kind == Argument || Kind == ExtendArgument ||
-             Kind == TruncArgument);
+             Kind == TruncArgument || Kind == HalfVecArgument);
       return Argument_Info >> 2;
     }
     ArgKind getArgumentKind() const {
       assert(Kind == Argument || Kind == ExtendArgument ||
-             Kind == TruncArgument);
+             Kind == TruncArgument || Kind == HalfVecArgument);
       return (ArgKind)(Argument_Info&3);
     }
     

include/llvm/IR/Intrinsics.td

@@ -113,6 +113,10 @@ class LLVMMatchType<int num>
 class LLVMExtendedType<int num> : LLVMMatchType<num>;
 class LLVMTruncatedType<int num> : LLVMMatchType<num>;
 
+// Match the type of another intrinsic parameter that is expected to be a
+// vector type, but change the element count to be half as many
+class LLVMHalfElementsVectorType<int num> : LLVMMatchType<num>;
+
 def llvm_void_ty       : LLVMType<isVoid>;
 def llvm_anyint_ty     : LLVMType<iAny>;
 def llvm_anyfloat_ty   : LLVMType<fAny>;