[AMDGPU]: Allow combining into v_dot4

Differential Revision: https://reviews.llvm.org/D155995

Change-Id: Id15d232629a32a3549b13d47bf84d7a61b28b928

Author: jrbyrnes

llvm/include/llvm/CodeGen/ByteProvider.h

@@ -32,6 +32,11 @@ template <typename ISelOp> class ByteProvider {
   ByteProvider(std::optional<ISelOp> Src, int64_t DestOffset, int64_t SrcOffset)
       : Src(Src), DestOffset(DestOffset), SrcOffset(SrcOffset) {}
 
+  ByteProvider(std::optional<ISelOp> Src, int64_t DestOffset, int64_t SrcOffset,
+               std::optional<bool> IsSigned)
+      : Src(Src), DestOffset(DestOffset), SrcOffset(SrcOffset),
+        IsSigned(IsSigned) {}
+
   // TODO -- use constraint in c++20
   // Does this type correspond with an operation in selection DAG
   template <typename T> class is_op {
@@ -61,6 +66,9 @@ template <typename ISelOp> class ByteProvider {
   // DestOffset
   int64_t SrcOffset = 0;
 
+  // Whether or not the path to this Src involved signed extensions
+  std::optional<bool> IsSigned;
+
   ByteProvider() = default;
 
   static ByteProvider getSrc(std::optional<ISelOp> Val, int64_t ByteOffset,
@@ -70,6 +78,14 @@ template <typename ISelOp> class ByteProvider {
     return ByteProvider(Val, ByteOffset, VectorOffset);
   }
 
+  static ByteProvider getSrc(std::optional<ISelOp> Val, int64_t ByteOffset,
+                             int64_t VectorOffset,
+                             std::optional<bool> IsSigned) {
+    static_assert(is_op<ISelOp>().value,
+                  "ByteProviders must contain an operation in selection DAG.");
+    return ByteProvider(Val, ByteOffset, VectorOffset, IsSigned);
+  }
+
   static ByteProvider getConstantZero() {
     return ByteProvider<ISelOp>(std::nullopt, 0, 0);
   }