fix: fixes lattigo in place transform by ensuring that storage values keep level state invariant

lib/Analysis/LevelAnalysis/LevelAnalysis.cpp

@@ -50,37 +50,23 @@ static void debugLog(StringRef opName, ArrayRef<const LevelLattice*> operands,
   });
 };
 
-LevelState transferForward(mgmt::ModReduceOp op,
-                           ArrayRef<const LevelLattice*> operands) {
-  LevelState result = std::visit(
-      Overloaded{
-          [](MaxLevel) -> LevelState { return LevelState(Invalid{}); },
-          [](Uninit) -> LevelState { return LevelState(Invalid{}); },
-          [](Invalid) -> LevelState { return LevelState(Invalid{}); },
-          [](int val) -> LevelState { return LevelState(val + 1); },
-      },
-      operands[0]->getValue().get());
-  LLVM_DEBUG(debugLog("mod_reduce", operands, result));
-  return result;
-}
-
-LevelState transferForward(mgmt::LevelReduceOp op,
+LevelState transferForward(ReducesLevelOpInterface op,
                            ArrayRef<const LevelLattice*> operands) {
   LevelState result = std::visit(
       Overloaded{
           [](MaxLevel) -> LevelState { return LevelState(Invalid{}); },
           [](Uninit) -> LevelState { return LevelState(Invalid{}); },
           [](Invalid) -> LevelState { return LevelState(Invalid{}); },
           [&](int val) -> LevelState {
-            return LevelState(val + (int)op.getLevelToDrop());
+            return LevelState(val + op.getLevelsToDrop());
           },
       },
       operands[0]->getValue().get());
-  LLVM_DEBUG(debugLog("level_reduce", operands, result));
+  LLVM_DEBUG(debugLog("ReduceLevelOpInterface", operands, result));
   return result;
 }
 
-LevelState transferForward(mgmt::LevelReduceMinOp op,
+LevelState transferForward(ReducesAllLevelsOpInterface op,
                            ArrayRef<const LevelLattice*> operands) {
   LevelState result = std::visit(
       Overloaded{
@@ -92,11 +78,11 @@ LevelState transferForward(mgmt::LevelReduceMinOp op,
           [](int val) -> LevelState { return LevelState(MaxLevel{}); },
       },
       operands[0]->getValue().get());
-  LLVM_DEBUG(debugLog("level_reduce_min", operands, result));
+  LLVM_DEBUG(debugLog("ReduceAllLevelsOpInterface", operands, result));
   return result;
 }
 
-LevelState transferForward(mgmt::BootstrapOp op,
+LevelState transferForward(ResetsLevelOpInterface op,
                            ArrayRef<const LevelLattice*> operands) {
   LevelState result = std::visit(
       Overloaded{
@@ -106,15 +92,18 @@ LevelState transferForward(mgmt::BootstrapOp op,
           [](int val) -> LevelState { return LevelState(0); },
       },
       operands[0]->getValue().get());
-  LLVM_DEBUG(debugLog("bootstrap", operands, result));
+  LLVM_DEBUG(debugLog("ResetsLevelOpInterface", operands, result));
   return result;
 }
 
 LevelState deriveResultLevel(Operation* op,
                              ArrayRef<const LevelLattice*> operands) {
   return llvm::TypeSwitch<Operation&, LevelState>(*op)
-      .Case<mgmt::ModReduceOp, mgmt::LevelReduceOp, mgmt::BootstrapOp,
-            mgmt::LevelReduceMinOp>(
+      .Case<ResetsLevelOpInterface>(
+          [&](auto op) -> LevelState { return transferForward(op, operands); })
+      .Case<ReducesAllLevelsOpInterface>(
+          [&](auto op) -> LevelState { return transferForward(op, operands); })
+      .Case<ReducesLevelOpInterface>(
           [&](auto op) -> LevelState { return transferForward(op, operands); })
       .Default([&](auto& op) -> LevelState {
         LevelState result;

lib/Dialect/HEIRInterfaces.td

@@ -34,6 +34,41 @@ def ResetsMulDepthOpInterface : OpInterface<"ResetsMulDepthOpInterface"> {
   }];
 }
 
+def ResetsLevelOpInterface : OpInterface<"ResetsLevelOpInterface"> {
+  let cppNamespace = "::mlir::heir";
+  let description = [{
+    An interface that signals when an operation resets level
+    among its results, such as a `mgmt.bootstrap`.
+  }];
+}
+
+def ReducesLevelOpInterface : OpInterface<"ReducesLevelOpInterface"> {
+  let cppNamespace = "::mlir::heir";
+  let description = [{
+    An interface that signals when an operation reduces level
+    among its results, such as a `mgmt.mod_reduce` or `ckks.rescale`.
+  }];
+
+  let methods = [
+    InterfaceMethod<
+      /*desc=*/"Return the number of levels to reduce by.",
+      /*retTy=*/"int",
+      /*methodName=*/"getLevelsToDrop",
+      /*args=*/(ins ),
+      /*body=*/[{}],
+      /*defaultBody=*/[{ return 1; }]
+    >,
+  ];
+}
+
+def ReducesAllLevelsOpInterface : OpInterface<"ReducesAllLevelsOpInterface"> {
+  let cppNamespace = "::mlir::heir";
+  let description = [{
+    An interface that signals when an operation reduces all level
+    among its results, such as a `mgmt.level_reduce_min`.
+  }];
+}
+
 def LUTOpInterface : OpInterface<"LUTOpInterface"> {
   let cppNamespace = "::mlir::heir";
   let description = [{

lib/Dialect/Lattigo/IR/LattigoBGVOps.td

@@ -182,8 +182,8 @@ def Lattigo_BGVMulOp : Lattigo_BGVBinaryInPlaceOp<"mul", [IncreasesMulDepthOpInt
   }];
 }
 
-class Lattigo_BGVUnaryOp<string mnemonic> :
-        Lattigo_BGVOp<mnemonic> {
+class Lattigo_BGVUnaryOp<string mnemonic, list<Trait> traits = []> :
+        Lattigo_BGVOp<mnemonic, traits> {
   let arguments = (ins
     Lattigo_BGVEvaluator:$evaluator,
     Lattigo_RLWECiphertext:$input
@@ -198,7 +198,7 @@ def Lattigo_BGVRelinearizeNewOp : Lattigo_BGVUnaryOp<"relinearize_new"> {
   }];
 }
 
-def Lattigo_BGVRescaleNewOp : Lattigo_BGVUnaryOp<"rescale_new"> {
+def Lattigo_BGVRescaleNewOp : Lattigo_BGVUnaryOp<"rescale_new", [ReducesLevelOpInterface]> {
   let summary = "Rescale a ciphertext in the Lattigo BGV dialect";
   let description = [{
     This operation rescales a ciphertext value in the Lattigo BGV dialect.
@@ -258,7 +258,7 @@ def Lattigo_BGVRelinearizeOp : Lattigo_BGVUnaryInPlaceOp<"relinearize"> {
   }];
 }
 
-def Lattigo_BGVRescaleOp : Lattigo_BGVUnaryInPlaceOp<"rescale"> {
+def Lattigo_BGVRescaleOp : Lattigo_BGVUnaryInPlaceOp<"rescale", [ReducesLevelOpInterface]> {
   let summary = "Rescale a ciphertext in the Lattigo BGV dialect";
   let description = [{
     This operation rescales a ciphertext value in the Lattigo BGV dialect.

lib/Dialect/Lattigo/IR/LattigoCKKSOps.td

@@ -215,8 +215,8 @@ def Lattigo_CKKSMulOp : Lattigo_CKKSBinaryInPlaceOp<"mul", [IncreasesMulDepthOpI
   }];
 }
 
-class Lattigo_CKKSUnaryOp<string mnemonic> :
-        Lattigo_CKKSOp<mnemonic> {
+class Lattigo_CKKSUnaryOp<string mnemonic, list<Trait> traits = []> :
+        Lattigo_CKKSOp<mnemonic, traits> {
   let arguments = (ins
     Lattigo_CKKSEvaluator:$evaluator,
     Lattigo_RLWECiphertext:$input
@@ -231,7 +231,7 @@ def Lattigo_CKKSRelinearizeNewOp : Lattigo_CKKSUnaryOp<"relinearize_new"> {
   }];
 }
 
-def Lattigo_CKKSRescaleNewOp : Lattigo_CKKSUnaryOp<"rescale_new"> {
+def Lattigo_CKKSRescaleNewOp : Lattigo_CKKSUnaryOp<"rescale_new", [ReducesLevelOpInterface]> {
   let summary = "Rescale a ciphertext in the Lattigo CKKS dialect";
   let description = [{
     This operation rescales a ciphertext value in the Lattigo CKKS dialect.
@@ -284,7 +284,7 @@ def Lattigo_CKKSRelinearizeOp : Lattigo_CKKSUnaryInPlaceOp<"relinearize"> {
   }];
 }
 
-def Lattigo_CKKSRescaleOp : Lattigo_CKKSUnaryInPlaceOp<"rescale"> {
+def Lattigo_CKKSRescaleOp : Lattigo_CKKSUnaryInPlaceOp<"rescale", [ReducesLevelOpInterface]> {
   let summary = "Rescale a ciphertext in the Lattigo CKKS dialect";
   let description = [{
     This operation rescales a ciphertext value in the Lattigo CKKS dialect.
@@ -322,7 +322,7 @@ def Lattigo_CKKSRotateOp : Lattigo_CKKSUnaryInPlaceOp<"rotate", [
   let hasVerifier = 1;
 }
 
-def Lattigo_CKKSBootstrapOp : Lattigo_CKKSUnaryOp<"bootstrap"> {
+def Lattigo_CKKSBootstrapOp : Lattigo_CKKSUnaryOp<"bootstrap", [ResetsLevelOpInterface]> {
   let summary = "Bootstrap a ciphertext in the Lattigo CKKS dialect";
   let description = [{
     Bootstraps a ciphertext value in the Lattigo CKKS dialect.

lib/Dialect/Lattigo/IR/LattigoOps.cpp

@@ -47,6 +47,10 @@ LogicalResult RLWENewEncryptorOp::verify() {
   return success();
 }
 
+int RLWEDropLevelNewOp::getLevelsToDrop() { return getLevelToDrop(); }
+
+int RLWEDropLevelOp::getLevelsToDrop() { return getLevelToDrop(); }
+
 LogicalResult BGVRotateColumnsNewOp::verify() {
   return containsExactlyOneOrEmitError(getOperation(), getDynamicShift(),
                                        getStaticShift());

lib/Dialect/Lattigo/IR/LattigoRLWEOps.td

@@ -122,7 +122,8 @@ def Lattigo_RLWEDecryptOp : Lattigo_RLWEOp<"decrypt"> {
   let results = (outs Lattigo_RLWEPlaintext:$plaintext);
 }
 
-def Lattigo_RLWEDropLevelNewOp : Lattigo_RLWEOp<"drop_level_new"> {
+def Lattigo_RLWEDropLevelNewOp : Lattigo_RLWEOp<"drop_level_new", 
+  [DeclareOpInterfaceMethods<ReducesLevelOpInterface, ["getLevelsToDrop"]>]> {
   let summary = "Drop level of a ciphertext";
   let arguments = (ins
     Lattigo_RLWEEvaluator:$evaluator,
@@ -132,7 +133,8 @@ def Lattigo_RLWEDropLevelNewOp : Lattigo_RLWEOp<"drop_level_new"> {
   let results = (outs Lattigo_RLWECiphertext:$output);
 }
 
-def Lattigo_RLWEDropLevelOp : Lattigo_RLWEOp<"drop_level", [InPlaceOpInterface]> {
+def Lattigo_RLWEDropLevelOp : Lattigo_RLWEOp<"drop_level", 
+  [InPlaceOpInterface, DeclareOpInterfaceMethods<ReducesLevelOpInterface, ["getLevelsToDrop"]>]> {
   let summary = "Drop level of a ciphertext";
   let description = [{
     This operation drops the level of a ciphertext