[DirectX] Specify overload type of DXIL Op exp2 precisely

Add a test to verify error generation for exp2 with overload type double.

Use type property instead of record name string to identify precise type.

Author: bharadwajy

llvm/lib/Target/DirectX/DXIL.td

@@ -260,7 +260,8 @@ def Sin  : DXILOpMapping<13, unary, int_sin,
                          [llvm_halforfloat_ty, LLVMMatchType<0>]>;
 def Exp2 : DXILOpMapping<21, unary, int_exp2,
                          "Returns the base 2 exponential, or 2**x, of the specified value."
-                         "exp2(x) = 2**x.">;
+                         "exp2(x) = 2**x.",
+                         [llvm_halforfloat_ty, LLVMMatchType<0>]>;
 def Frac : DXILOpMapping<22, unary, int_dx_frac,
                          "Returns a fraction from 0 to 1 that represents the "
                          "decimal part of the input.",

llvm/test/CodeGen/DirectX/exp2_error.ll

@@ -0,0 +1,13 @@
+; RUN: not opt -S -dxil-op-lower %s 2>&1 | FileCheck %s
+
+; DXIL operation exp2 does not support double overload type
+; CHECK: LLVM ERROR: Invalid Overload
+
+define noundef double @exp2_double(double noundef %a) #0 {
+entry:
+  %a.addr = alloca double, align 8
+  store double %a, ptr %a.addr, align 8
+  %0 = load double, ptr %a.addr, align 8
+  %elt.exp2 = call double @llvm.exp2.f64(double %0)
+  ret double %elt.exp2
+}

llvm/utils/TableGen/DXILEmitter.cpp

@@ -95,12 +95,9 @@ static ParameterKind getParameterKind(const Record *R) {
   case MVT::Other:
     // Handle DXIL-specific overload types
     {
-      auto RetKind = StringSwitch<ParameterKind>(R->getNameInitAsString())
-                         .Cases("llvm_i16ori32_ty", "llvm_halforfloat_ty",
-                                ParameterKind::OVERLOAD)
-                         .Default(ParameterKind::INVALID);
-      if (RetKind != ParameterKind::INVALID) {
-        return RetKind;
+      if ((R->getValueAsInt("isHalfOrFloat")) ||
+          (R->getValueAsInt("isI16OrI32"))) {
+        return ParameterKind::OVERLOAD;
       }
     }
     LLVM_FALLTHROUGH;