[clang] [llvm] [DXIL] implement dot intrinsic lowering for integers (PR #85662)

[Farzon Lotfi via cfe-commits]

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@@ -39,11 +39,44 @@ static bool isIntrinsicExpansion(Function &F) {
   case Intrinsic::dx_uclamp:
   case Intrinsic::dx_lerp:
   case Intrinsic::dx_rcp:
+  case Intrinsic::dx_sdot:
+  case Intrinsic::dx_udot:
     return true;
   }
   return false;
 }
 
+static bool expandIntegerDot(CallInst *Orig, Intrinsic::ID DotIntrinsic) {
+  assert(DotIntrinsic == Intrinsic::dx_sdot ||
+         DotIntrinsic == Intrinsic::dx_udot);
+  Intrinsic::ID MadIntrinsic = DotIntrinsic == Intrinsic::dx_sdot
+                                   ? Intrinsic::dx_imad
+                                   : Intrinsic::dx_umad;
+  Value *A = Orig->getOperand(0);
+  Value *B = Orig->getOperand(1);
+  Type *ATy = A->getType();
+  Type *BTy = B->getType();
+  assert(ATy->isVectorTy() && BTy->isVectorTy());
+
+  IRBuilder<> Builder(Orig->getParent());
+  Builder.SetInsertPoint(Orig);
+
+  auto *AVec = dyn_cast<FixedVectorType>(A->getType());
+  Value *Elt0 = Builder.CreateExtractElement(A, (uint64_t)0);
+  Value *Elt1 = Builder.CreateExtractElement(B, (uint64_t)0);
+  Value *Result = Builder.CreateMul(Elt0, Elt1);
+  for (unsigned I = 1; I < AVec->getNumElements(); I++) {
+    Elt0 = Builder.CreateExtractElement(A, I);
+    Elt1 = Builder.CreateExtractElement(B, I);
+    Result = Builder.CreateIntrinsic(Result->getType(), MadIntrinsic,
+                                     ArrayRef<Value *>{Elt0, Elt1, Result},
+                                     nullptr, "dx.mad");
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farzonl wrote:

i thought about that, but then i would need to add a conditional to change the string and it didn't seem worth it.

https://github.com/llvm/llvm-project/pull/85662