[clang] [llvm] [HLSL] Implementation of dot intrinsic (PR #81190)

[Chris B via cfe-commits]

================
@@ -17959,6 +17964,52 @@ llvm::Value *CodeGenFunction::EmitScalarOrConstFoldImmArg(unsigned ICEArguments,
   return Arg;
 }
 
+Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
+                                            const CallExpr *E) {
+  if (!getLangOpts().HLSL)
+    return nullptr;
+
+  switch (BuiltinID) {
+  case Builtin::BI__builtin_hlsl_dot: {
+    Value *Op0 = EmitScalarExpr(E->getArg(0));
+    Value *Op1 = EmitScalarExpr(E->getArg(1));
+    llvm::Type *T0 = Op0->getType();
+    llvm::Type *T1 = Op1->getType();
+    if (!T0->isVectorTy() && !T1->isVectorTy()) {
+      if (T0->isFloatingPointTy()) {
+        return Builder.CreateFMul(Op0, Op1, "dx.dot");
+      }
+
+      if (T0->isIntegerTy()) {
+        return Builder.CreateMul(Op0, Op1, "dx.dot");
+      }
+      // Bools should have been promoted
+      assert(
+          false &&
+          "Dot product on a scalar is only supported on integers and floats.");
+    }
+    // A VectorSplat should have happened
+    assert(T0->isVectorTy() && T1->isVectorTy() &&
+           "Dot product of vector and scalar is not supported.");
+
+    // A vector sext or sitofp should have happened
+    assert(T0->getScalarType() == T1->getScalarType() &&
+           "Dot product of vectors need the same element types.");
+
+    auto *VecTy0 = E->getArg(0)->getType()->getAs<VectorType>();
+    auto *VecTy1 = E->getArg(1)->getType()->getAs<VectorType>();
----------------
llvm-beanz wrote:

These declarations need `[[maybe_unused]]` to avoid producing warnings in non-assert builds.

https://github.com/llvm/llvm-project/pull/81190