From cb580f16d2d5b189869fff9a1df4747eda67cda7 Mon Sep 17 00:00:00 2001
From: Andi Drebes <andi.drebes@zama.ai>
Date: Fri, 30 Jul 2021 14:47:50 +0200
Subject: [PATCH] feat(compiler): Add operation HLFHE.zero generating an
 encrypted zero

---
 compiler/include/zamalang/Dialect/HLFHE/IR/HLFHEOps.td | 6 ++++++
 compiler/tests/Dialect/HLFHE/ops.mlir                  | 9 +++++++++
 2 files changed, 15 insertions(+)

diff --git a/compiler/include/zamalang/Dialect/HLFHE/IR/HLFHEOps.td b/compiler/include/zamalang/Dialect/HLFHE/IR/HLFHEOps.td
index ccd8de077..4d6882772 100644
--- a/compiler/include/zamalang/Dialect/HLFHE/IR/HLFHEOps.td
+++ b/compiler/include/zamalang/Dialect/HLFHE/IR/HLFHEOps.td
@@ -18,6 +18,12 @@ include "zamalang/Dialect/HLFHE/IR/HLFHETypes.td"
 class HLFHE_Op<string mnemonic, list<OpTrait> traits = []> :
     Op<HLFHE_Dialect, mnemonic, traits>;
 
+// Generates an encrypted zero constant
+def ZeroOp : HLFHE_Op<"zero"> {
+    let arguments = (ins);
+    let results = (outs EncryptedIntegerType:$out);
+}
+
 def AddEintIntOp : HLFHE_Op<"add_eint_int"> {
     let arguments = (ins EncryptedIntegerType:$a, AnyInteger:$b);
     let results = (outs EncryptedIntegerType);
diff --git a/compiler/tests/Dialect/HLFHE/ops.mlir b/compiler/tests/Dialect/HLFHE/ops.mlir
index c40ba3c8b..2afd85ba9 100644
--- a/compiler/tests/Dialect/HLFHE/ops.mlir
+++ b/compiler/tests/Dialect/HLFHE/ops.mlir
@@ -1,5 +1,14 @@
 // RUN: zamacompiler --round-trip %s  2>&1| FileCheck %s
 
+// CHECK-LABEL: func @zero() -> !HLFHE.eint<2>
+func @zero() -> !HLFHE.eint<2> {
+  // CHECK-NEXT: %[[RET:.*]] = "HLFHE.zero"() : () -> !HLFHE.eint<2>
+  // CHECK-NEXT: return %[[RET]] : !HLFHE.eint<2>
+
+  %1 = "HLFHE.zero"() : () -> !HLFHE.eint<2>
+  return %1: !HLFHE.eint<2>
+}
+
 // CHECK-LABEL: func @add_eint_int(%arg0: !HLFHE.eint<2>) -> !HLFHE.eint<2>
 func @add_eint_int(%arg0: !HLFHE.eint<2>) -> !HLFHE.eint<2> {
   // CHECK-NEXT: %[[V1:.*]] = constant 1 : i3