Implement data unpacking intrinsics

* Add support for data unpacking intrinsics
  * spir-v reader
  * type determiner
  * intrinsic table
  * spir-v, hlsl and msl writers

Bug: tint:341
Change-Id: I8f40d19d59a4699af75cd579fe8398c735a77a59
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41320
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Alan Baker <alanbaker@google.com>

src/semantic/intrinsic.h

@@ -101,7 +101,12 @@ enum class IntrinsicType {
   kTextureSampleGrad,
   kTextureSampleLevel,
   kTextureStore,
-  kTrunc
+  kTrunc,
+  kUnpack4x8Snorm,
+  kUnpack4x8Unorm,
+  kUnpack2x16Snorm,
+  kUnpack2x16Unorm,
+  kUnpack2x16Float,
 };
 
 /// @returns the name of the intrinsic function type. The spelling, including
@@ -143,6 +148,11 @@ bool IsImageQueryIntrinsic(IntrinsicType i);
 /// @returns true if the given `i` is a data packing intrinsic
 bool IsDataPackingIntrinsic(IntrinsicType i);
 
+/// Determines if the given `i` is a data unpacking intrinsic
+/// @param i the intrinsic
+/// @returns true if the given `i` is a data unpacking intrinsic
+bool IsDataUnpackingIntrinsic(IntrinsicType i);
+
 /// Intrinsic holds the semantic information for an intrinsic function.
 class Intrinsic : public Castable<Intrinsic, CallTarget> {
  public:
@@ -185,6 +195,9 @@ class Intrinsic : public Castable<Intrinsic, CallTarget> {
   /// @returns true if intrinsic is a data packing intrinsic
   bool IsDataPacking() const;
 
+  /// @returns true if intrinsic is a data unpacking intrinsic
+  bool IsDataUnpacking() const;
+
  private:
   IntrinsicType const type_;
 };

src/semantic/sem_intrinsic.cc

@@ -188,6 +188,16 @@ const char* str(IntrinsicType i) {
       return "textureStore";
     case IntrinsicType::kTrunc:
       return "trunc";
+    case IntrinsicType::kUnpack4x8Snorm:
+      return "unpack4x8snorm";
+    case IntrinsicType::kUnpack4x8Unorm:
+      return "unpack4x8unorm";
+    case IntrinsicType::kUnpack2x16Snorm:
+      return "unpack2x16snorm";
+    case IntrinsicType::kUnpack2x16Unorm:
+      return "unpack2x16unorm";
+    case IntrinsicType::kUnpack2x16Float:
+      return "unpack2x16float";
   }
   return "<unknown>";
 }
@@ -238,6 +248,14 @@ bool IsDataPackingIntrinsic(IntrinsicType i) {
          i == IntrinsicType::kPack2x16Float;
 }
 
+bool IsDataUnpackingIntrinsic(IntrinsicType i) {
+  return i == IntrinsicType::kUnpack4x8Snorm ||
+         i == IntrinsicType::kUnpack4x8Unorm ||
+         i == IntrinsicType::kUnpack2x16Snorm ||
+         i == IntrinsicType::kUnpack2x16Unorm ||
+         i == IntrinsicType::kUnpack2x16Float;
+}
+
 Intrinsic::Intrinsic(IntrinsicType type,
                      type::Type* return_type,
                      const ParameterList& parameters)
@@ -273,5 +291,9 @@ bool Intrinsic::IsDataPacking() const {
   return IsDataPackingIntrinsic(type_);
 }
 
+bool Intrinsic::IsDataUnpacking() const {
+  return IsDataUnpackingIntrinsic(type_);
+}
+
 }  // namespace semantic
 }  // namespace tint