RNS: allow mod arith types as basis types

lib/Dialect/RNS/IR/BUILD

@@ -25,6 +25,7 @@ cc_library(
         ":ops_inc_gen",
         ":type_interfaces_inc_gen",
         ":types_inc_gen",
+        "@heir//lib/Dialect/ModArith/IR:Dialect",
         "@heir//lib/Dialect/Polynomial/IR:Dialect",
         "@llvm-project//llvm:Support",
         "@llvm-project//mlir:IR",
@@ -45,6 +46,7 @@ cc_library(
         ":dialect_inc_gen",
         ":type_interfaces_inc_gen",
         ":types_inc_gen",
+        "@heir//lib/Dialect/ModArith/IR:Dialect",
         "@heir//lib/Dialect/Polynomial/IR:Dialect",
         "@llvm-project//llvm:Support",
         "@llvm-project//mlir:IR",

lib/Dialect/RNS/IR/RNSTypeInterfaces.td

@@ -20,11 +20,13 @@ def RNSBasisTypeInterface : TypeInterface<"RNSBasisTypeInterface"> {
       are both polynomial types, even if they have different coefficient
       moduli.
 
-      `isCompatibleWith` must be both commutative and associative, in the sense
+      Another example is using mod arith types as the basis types, where
+      by the nature of chinese reminder theorem, it is required that
+      the modulus of them must be mutually coprime.
+
+      `isCompatibleWith` must be commutative, in the sense
       that `type1.isCompatibleWith(type2)` if and only if
-      `type2.isCompatibleWith(type1)`, and further
-      `type2.isCompatibleWith(type3)` if and only if
-      `type1.isCompatibleWith(type3)`.
+      `type2.isCompatibleWith(type1)`.
     }],
     "bool", "isCompatibleWith", (ins "::mlir::Type":$otherRnsBasisType)>
   ];

lib/Dialect/RNS/IR/RNSTypes.cpp

@@ -1,5 +1,7 @@
 #include "lib/Dialect/RNS/IR/RNSTypes.h"
 
+#include "lib/Dialect/ModArith/IR/ModArithDialect.h"
+#include "lib/Dialect/ModArith/IR/ModArithTypes.h"
 #include "lib/Dialect/Polynomial/IR/PolynomialDialect.h"
 #include "lib/Dialect/Polynomial/IR/PolynomialTypes.h"
 #include "lib/Dialect/RNS/IR/RNSTypeInterfaces.h"
@@ -17,18 +19,38 @@ using polynomial::PolynomialDialect;
 using polynomial::PolynomialType;
 
 namespace heir {
+
+using mod_arith::ModArithDialect;
+using mod_arith::ModArithType;
+
 namespace rns {
 
 LogicalResult RNSType::verify(
     llvm::function_ref<mlir::InFlightDiagnostic()> emitError,
     llvm::ArrayRef<mlir::Type> basisTypes) {
   bool compatible = true;
-  RNSBasisTypeInterface first =
-      llvm::dyn_cast<RNSBasisTypeInterface>(basisTypes[0]);
-  if (!first) return failure();
 
-  for (auto other : basisTypes) {
-    compatible &= first.isCompatibleWith(other);
+  auto getInterface = [&](Type type) -> FailureOr<RNSBasisTypeInterface> {
+    auto res = mlir::dyn_cast<RNSBasisTypeInterface>(type);
+    if (!res) {
+      return emitError() << type << " does not have RNSBasisTypeInterface";
+    }
+    return res;
+  };
+
+  size_t numTypes = basisTypes.size();
+  for (auto i = 0; i != numTypes; ++i) {
+    for (auto j = i + 1; j != numTypes; ++j) {
+      auto resI = getInterface(basisTypes[i]);
+      if (failed(resI)) {
+        return resI;
+      }
+      auto resJ = getInterface(basisTypes[j]);
+      if (failed(resJ)) {
+        return resJ;
+      }
+      compatible &= (*resI).isCompatibleWith(*resJ);
+    }
   }
 
   if (!compatible) {
@@ -60,11 +82,42 @@ struct PolynomialRNSBasisTypeInterface
   }
 };
 
+struct ModArithRNSBasisTypeInterface
+    : public RNSBasisTypeInterface::ExternalModel<ModArithRNSBasisTypeInterface,
+                                                  ModArithType> {
+  bool isCompatibleWith(Type type, Type otherRnsBasisType) const {
+    auto thisType = mlir::dyn_cast<ModArithType>(type);
+    if (!thisType) {
+      return false;
+    }
+
+    auto other = mlir::dyn_cast<ModArithType>(otherRnsBasisType);
+    if (!other) {
+      return false;
+    }
+
+    APInt thisModulus = thisType.getModulus().getValue();
+    APInt otherModulus = other.getModulus().getValue();
+
+    // require same bitwidth
+    if (thisModulus.getBitWidth() != otherModulus.getBitWidth()) {
+      return false;
+    }
+
+    // coprime test
+    return llvm::APIntOps::GreatestCommonDivisor(thisModulus, otherModulus) ==
+           1;
+  }
+};
+
 void registerExternalRNSTypeInterfaces(DialectRegistry &registry) {
   registry.addExtension(
       +[](MLIRContext *ctx, ::mlir::polynomial::PolynomialDialect *dialect) {
         PolynomialType::attachInterface<PolynomialRNSBasisTypeInterface>(*ctx);
       });
+  registry.addExtension(+[](MLIRContext *ctx, ModArithDialect *dialect) {
+    ModArithType::attachInterface<ModArithRNSBasisTypeInterface>(*ctx);
+  });
 }
 
 }  // namespace rns

tests/Dialect/RNS/IR/syntax.mlir

@@ -1,4 +1,4 @@
-// RUN: heir-opt --verify-diagnostics %s
+// RUN: heir-opt --verify-diagnostics --split-input-file %s
 
 #ideal = #polynomial.int_polynomial<1 + x**1024>
 #ideal_2 = #polynomial.int_polynomial<1 + x**2048>
@@ -22,3 +22,32 @@ func.func @test_syntax(%arg0: !ty) -> !ty {
 !poly_ty_bad = !polynomial.polynomial<ring=#ring_bad>
 // expected-error@+1 {{RNS type has incompatible basis types}}
 !ty_bad = !rns.rns<!poly_ty_1, !poly_ty_2, !poly_ty_bad>
+
+// -----
+// mod arith
+
+!Zp1 = !mod_arith.int<3721063133 : i64>
+!Zp2 = !mod_arith.int<2737228591 : i64>
+!Zp3 = !mod_arith.int<3180146689 : i64>
+
+!ty_modarith = !rns.rns<!Zp1, !Zp2, !Zp3>
+
+func.func @test_syntax_modarith(%arg0: !ty_modarith) -> !ty_modarith {
+  return %arg0 : !ty_modarith
+}
+
+// expected-error@+1 {{RNS type has incompatible basis types}}
+!ty_modarith_bad = !rns.rns<!Zp1, !Zp2, !Zp1>
+
+// -----
+
+!Zp1 = !mod_arith.int<3721063133 : i64>
+!Zp2 = !mod_arith.int<65537 : i32>
+
+// expected-error@+1 {{RNS type has incompatible basis types}}
+!ty_modarith_bad = !rns.rns<!Zp1, !Zp2>
+
+// -----
+
+// expected-error@+1 {{does not have RNSBasisTypeInterface}}
+!ty_int_bad = !rns.rns<i32, i64>