♻️ Refactor getStaticParameter to valueToDouble (#1443)

## Description

This PR reduces the current code duplication of `getStaticParameter`
which is used in both `QC` and `QCO`.
It additionally adds the conversion to a standard C++ double type since
there is no other use of the function in the code base so far.

An alternative to the currently returned `std::optional` would be a
`llvm::FailureOr<double>` which is simply a subclass of `std::optional`.
However, it is in my opinion slightly more annoying to use since it
requires `llvm::succeeded` and `llvm::failed` to check the result
instead of the implicit conversion to bool available in `std::optional`.
This is meant to make it slightly safer to use, but makes the code also
more verbose and less convenient which is why I decided against using
it. `std::optional` is an established standard C++ tool and people
usually know how to handle it correctly which cannot be said for
`llvm::FailureOr<double>`.

Required for #1426

## Checklist:

<!---
This checklist serves as a reminder of a couple of things that ensure
your pull request will be merged swiftly.
-->

- [ ] The pull request only contains commits that are focused and
relevant to this change.
- [ ] I have added appropriate tests that cover the new/changed
functionality.
- [ ] I have updated the documentation to reflect these changes.
- [ ] I have added entries to the changelog for any noteworthy
additions, changes, fixes, or removals.
- [ ] I have added migration instructions to the upgrade guide (if
needed).
- [ ] The changes follow the project's style guidelines and introduce no
new warnings.
- [ ] The changes are fully tested and pass the CI checks.
- [ ] I have reviewed my own code changes.

---------

Signed-off-by: Tamino Bauknecht <28907748+taminob@users.noreply.github.com>
Co-authored-by: Lukas Burgholzer <burgholzer@me.com>

Author: taminob

CHANGELOG.md

@@ -11,7 +11,7 @@ This project adheres to [Semantic Versioning], with the exception that minor rel
 
 ### Added
 
-- ✨ Add initial infrastructure for new QC and QCO MLIR dialects ([#1264], [#1402], [#1428], [#1430], [#1436]) ([**@burgholzer**], [**@denialhaag**], [**@taminob**], [**@DRovara**])
+- ✨ Add initial infrastructure for new QC and QCO MLIR dialects ([#1264], [#1402], [#1428], [#1430], [#1436], [#1443]) ([**@burgholzer**], [**@denialhaag**], [**@taminob**], [**@DRovara**])
 
 ### Changed
 
@@ -307,6 +307,7 @@ _📚 Refer to the [GitHub Release Notes](https://github.com/munich-quantum-tool
 
 <!-- PR links -->
 
+[#1443]: https://github.com/munich-quantum-toolkit/core/pull/1443
 [#1437]: https://github.com/munich-quantum-toolkit/core/pull/1437
 [#1436]: https://github.com/munich-quantum-toolkit/core/pull/1436
 [#1430]: https://github.com/munich-quantum-toolkit/core/pull/1430

mlir/include/mlir/Dialect/QC/IR/QCDialect.h

@@ -101,14 +101,6 @@ template <size_t T, size_t P> class TargetAndParameterArityTrait {
       }
       return this->getOperation()->getOperand(T + i);
     }
-
-    [[nodiscard]] static FloatAttr getStaticParameter(Value param) {
-      auto constantOp = param.getDefiningOp<arith::ConstantOp>();
-      if (!constantOp) {
-        return nullptr;
-      }
-      return dyn_cast<FloatAttr>(constantOp.getValue());
-    }
   };
 };
 

mlir/include/mlir/Dialect/QCO/IR/QCODialect.h

@@ -108,14 +108,6 @@ template <size_t T, size_t P> class TargetAndParameterArityTrait {
       return this->getOperation()->getOperand(T + i);
     }
 
-    [[nodiscard]] static FloatAttr getStaticParameter(Value param) {
-      auto constantOp = param.getDefiningOp<arith::ConstantOp>();
-      if (!constantOp) {
-        return nullptr;
-      }
-      return dyn_cast<FloatAttr>(constantOp.getValue());
-    }
-
     Value getInputForOutput(Value output) {
       const auto& op = this->getOperation();
       for (size_t i = 0; i < T; ++i) {

mlir/include/mlir/Dialect/QCO/QCOUtils.h

@@ -10,8 +10,9 @@
 
 #pragma once
 
+#include "mlir/Dialect/Utils/Utils.h"
+
 #include <mlir/Dialect/Arith/IR/Arith.h>
-#include <mlir/Dialect/Utils/Utils.h>
 #include <mlir/IR/PatternMatch.h>
 
 namespace mlir::qco {
@@ -188,13 +189,8 @@ mergeTwoTargetOneParameter(OpType op, mlir::PatternRewriter& rewriter) {
 template <typename OpType>
 inline mlir::LogicalResult
 removeTrivialOneTargetOneParameter(OpType op, mlir::PatternRewriter& rewriter) {
-  const auto paramAttr = OpType::getStaticParameter(op.getOperand(1));
-  if (!paramAttr) {
-    return failure();
-  }
-
-  const auto paramValue = paramAttr.getValueAsDouble();
-  if (std::abs(paramValue) > utils::TOLERANCE) {
+  const auto param = utils::valueToDouble(op.getOperand(1));
+  if (!param || std::abs(*param) > utils::TOLERANCE) {
     return failure();
   }
 
@@ -215,13 +211,8 @@ removeTrivialOneTargetOneParameter(OpType op, mlir::PatternRewriter& rewriter) {
 template <typename OpType>
 inline mlir::LogicalResult
 removeTrivialTwoTargetOneParameter(OpType op, mlir::PatternRewriter& rewriter) {
-  const auto paramAttr = OpType::getStaticParameter(op.getOperand(2));
-  if (!paramAttr) {
-    return failure();
-  }
-
-  const auto paramValue = paramAttr.getValueAsDouble();
-  if (std::abs(paramValue) > utils::TOLERANCE) {
+  const auto param = utils::valueToDouble(op.getOperand(2));
+  if (!param || std::abs(*param) > utils::TOLERANCE) {
     return failure();
   }
 

mlir/include/mlir/Dialect/Utils/Utils.h

@@ -28,8 +28,9 @@ constexpr auto TOLERANCE = 1e-15;
  * @param parameter The parameter as a variant (double or Value).
  * @return Value The parameter as a Value.
  */
-inline Value variantToValue(OpBuilder& builder, const OperationState& state,
-                            const std::variant<double, Value>& parameter) {
+[[nodiscard]] inline Value
+variantToValue(OpBuilder& builder, const OperationState& state,
+               const std::variant<double, Value>& parameter) {
   Value operand;
   if (std::holds_alternative<double>(parameter)) {
     operand = builder.create<arith::ConstantOp>(
@@ -40,4 +41,32 @@ inline Value variantToValue(OpBuilder& builder, const OperationState& state,
   return operand;
 }
 
+/**
+ * @brief Try to convert a mlir::Value to a standard C++ double
+ *
+ * @details
+ * Resolving the mlir::Value will only work if it is a static value, so a value
+ * defined via a "arith.constant" operation. It must also be of type
+ * float or integer.
+ */
+[[nodiscard]] inline std::optional<double> valueToDouble(Value value) {
+  auto constantOp = value.getDefiningOp<arith::ConstantOp>();
+  if (!constantOp) {
+    return std::nullopt;
+  }
+  auto floatAttr = dyn_cast<FloatAttr>(constantOp.getValue());
+  if (floatAttr) {
+    return floatAttr.getValueAsDouble();
+  }
+  auto intAttr = dyn_cast<IntegerAttr>(constantOp.getValue());
+  if (intAttr) {
+    if (intAttr.getType().isUnsignedInteger()) {
+      return static_cast<double>(intAttr.getValue().getZExtValue());
+    }
+    // interpret both signed+signless as signed integers
+    return static_cast<double>(intAttr.getValue().getSExtValue());
+  }
+  return std::nullopt;
+}
+
 } // namespace mlir::utils

mlir/lib/Dialect/QCO/IR/Operations/StandardGates/GPhaseOp.cpp

@@ -13,7 +13,6 @@
 
 #include <cmath>
 #include <mlir/IR/Builders.h>
-#include <mlir/IR/BuiltinAttributes.h>
 #include <mlir/IR/MLIRContext.h>
 #include <mlir/IR/OperationSupport.h>
 #include <mlir/IR/PatternMatch.h>
@@ -34,13 +33,8 @@ struct RemoveTrivialGPhase final : OpRewritePattern<GPhaseOp> {
 
   LogicalResult matchAndRewrite(GPhaseOp op,
                                 PatternRewriter& rewriter) const override {
-    const auto thetaAttr = GPhaseOp::getStaticParameter(op.getTheta());
-    if (!thetaAttr) {
-      return failure();
-    }
-
-    const auto thetaValue = thetaAttr.getValueAsDouble();
-    if (std::abs(thetaValue) > TOLERANCE) {
+    const auto theta = valueToDouble(op.getTheta());
+    if (!theta || std::abs(*theta) > TOLERANCE) {
       return failure();
     }
 

mlir/lib/Dialect/QCO/IR/Operations/StandardGates/ROp.cpp

@@ -13,7 +13,6 @@
 
 #include <cmath>
 #include <mlir/IR/Builders.h>
-#include <mlir/IR/BuiltinAttributes.h>
 #include <mlir/IR/MLIRContext.h>
 #include <mlir/IR/OperationSupport.h>
 #include <mlir/IR/PatternMatch.h>
@@ -35,13 +34,8 @@ struct ReplaceRWithRX final : OpRewritePattern<ROp> {
 
   LogicalResult matchAndRewrite(ROp op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = ROp::getStaticParameter(op.getPhi());
-    if (!phi) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    if (std::abs(phiValue) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    if (!phi || std::abs(*phi) > TOLERANCE) {
       return failure();
     }
 
@@ -61,13 +55,8 @@ struct ReplaceRWithRY final : OpRewritePattern<ROp> {
 
   LogicalResult matchAndRewrite(ROp op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = ROp::getStaticParameter(op.getPhi());
-    if (!phi) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    if (std::abs(phiValue - (std::numbers::pi / 2.0)) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    if (!phi || std::abs(*phi - (std::numbers::pi / 2.0)) > TOLERANCE) {
       return failure();
     }
 

mlir/lib/Dialect/QCO/IR/Operations/StandardGates/U2Op.cpp

@@ -34,16 +34,10 @@ struct ReplaceU2WithH final : OpRewritePattern<U2Op> {
 
   LogicalResult matchAndRewrite(U2Op op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = U2Op::getStaticParameter(op.getPhi());
-    const auto lambda = U2Op::getStaticParameter(op.getLambda());
-    if (!phi || !lambda) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    const auto lambdaValue = lambda.getValueAsDouble();
-    if (std::abs(phiValue) > TOLERANCE ||
-        std::abs(lambdaValue - std::numbers::pi) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    const auto lambda = valueToDouble(op.getLambda());
+    if (!phi || std::abs(*phi) > TOLERANCE || !lambda ||
+        std::abs(*lambda - std::numbers::pi) > TOLERANCE) {
       return failure();
     }
 
@@ -62,16 +56,10 @@ struct ReplaceU2WithRX final : OpRewritePattern<U2Op> {
 
   LogicalResult matchAndRewrite(U2Op op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = U2Op::getStaticParameter(op.getPhi());
-    const auto lambda = U2Op::getStaticParameter(op.getLambda());
-    if (!phi || !lambda) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    const auto lambdaValue = lambda.getValueAsDouble();
-    if (std::abs(phiValue + (std::numbers::pi / 2.0)) > TOLERANCE ||
-        std::abs(lambdaValue - (std::numbers::pi / 2.0)) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    const auto lambda = valueToDouble(op.getLambda());
+    if (!phi || std::abs(*phi + (std::numbers::pi / 2.0)) > TOLERANCE ||
+        !lambda || std::abs(*lambda - (std::numbers::pi / 2.0)) > TOLERANCE) {
       return failure();
     }
 
@@ -91,15 +79,10 @@ struct ReplaceU2WithRY final : OpRewritePattern<U2Op> {
 
   LogicalResult matchAndRewrite(U2Op op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = U2Op::getStaticParameter(op.getPhi());
-    const auto lambda = U2Op::getStaticParameter(op.getLambda());
-    if (!phi || !lambda) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    const auto lambdaValue = lambda.getValueAsDouble();
-    if (std::abs(phiValue) > TOLERANCE || std::abs(lambdaValue) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    const auto lambda = valueToDouble(op.getLambda());
+    if (!phi || std::abs(*phi) > TOLERANCE || !lambda ||
+        std::abs(*lambda) > TOLERANCE) {
       return failure();
     }
 

mlir/lib/Dialect/QCO/IR/Operations/StandardGates/UOp.cpp

@@ -13,7 +13,6 @@
 
 #include <cmath>
 #include <mlir/IR/Builders.h>
-#include <mlir/IR/BuiltinAttributes.h>
 #include <mlir/IR/MLIRContext.h>
 #include <mlir/IR/OperationSupport.h>
 #include <mlir/IR/PatternMatch.h>
@@ -35,15 +34,10 @@ struct ReplaceUWithP final : OpRewritePattern<UOp> {
 
   LogicalResult matchAndRewrite(UOp op,
                                 PatternRewriter& rewriter) const override {
-    const auto theta = UOp::getStaticParameter(op.getTheta());
-    const auto phi = UOp::getStaticParameter(op.getPhi());
-    if (!theta || !phi) {
-      return failure();
-    }
-
-    const auto thetaValue = theta.getValueAsDouble();
-    const auto phiValue = phi.getValueAsDouble();
-    if (std::abs(thetaValue) > TOLERANCE || std::abs(phiValue) > TOLERANCE) {
+    const auto theta = valueToDouble(op.getTheta());
+    const auto phi = valueToDouble(op.getPhi());
+    if (!theta || std::abs(*theta) > TOLERANCE || !phi ||
+        std::abs(*phi) > TOLERANCE) {
       return failure();
     }
 
@@ -63,16 +57,10 @@ struct ReplaceUWithRX final : OpRewritePattern<UOp> {
 
   LogicalResult matchAndRewrite(UOp op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = UOp::getStaticParameter(op.getPhi());
-    const auto lambda = UOp::getStaticParameter(op.getLambda());
-    if (!phi || !lambda) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    const auto lambdaValue = lambda.getValueAsDouble();
-    if (std::abs(phiValue + (std::numbers::pi / 2.0)) > TOLERANCE ||
-        std::abs(lambdaValue - (std::numbers::pi / 2.0)) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    const auto lambda = valueToDouble(op.getLambda());
+    if (!phi || std::abs(*phi + (std::numbers::pi / 2.0)) > TOLERANCE ||
+        !lambda || std::abs(*lambda - (std::numbers::pi / 2.0)) > TOLERANCE) {
       return failure();
     }
 
@@ -92,15 +80,10 @@ struct ReplaceUWithRY final : OpRewritePattern<UOp> {
 
   LogicalResult matchAndRewrite(UOp op,
                                 PatternRewriter& rewriter) const override {
-    const auto phi = UOp::getStaticParameter(op.getPhi());
-    const auto lambda = UOp::getStaticParameter(op.getLambda());
-    if (!phi || !lambda) {
-      return failure();
-    }
-
-    const auto phiValue = phi.getValueAsDouble();
-    const auto lambdaValue = lambda.getValueAsDouble();
-    if (std::abs(phiValue) > TOLERANCE || std::abs(lambdaValue) > TOLERANCE) {
+    const auto phi = valueToDouble(op.getPhi());
+    const auto lambda = valueToDouble(op.getLambda());
+    if (!phi || std::abs(*phi) > TOLERANCE || !lambda ||
+        std::abs(*lambda) > TOLERANCE) {
       return failure();
     }
 

mlir/lib/Dialect/QCO/IR/Operations/StandardGates/XXMinusYYOp.cpp

@@ -47,11 +47,10 @@ struct MergeSubsequentXXMinusYY final : OpRewritePattern<XXMinusYYOp> {
     }
 
     // Confirm betas are equal
-    auto beta = XXMinusYYOp::getStaticParameter(op.getBeta());
-    auto prevBeta = XXMinusYYOp::getStaticParameter(prevOp.getBeta());
+    auto beta = valueToDouble(op.getBeta());
+    auto prevBeta = valueToDouble(prevOp.getBeta());
     if (beta && prevBeta) {
-      if (std::abs(beta.getValueAsDouble() - prevBeta.getValueAsDouble()) >
-          TOLERANCE) {
+      if (std::abs(*beta - *prevBeta) > TOLERANCE) {
         return failure();
       }
     } else if (op.getBeta() != prevOp.getBeta()) {