LLZKLoweringUtils.cpp

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//===-- LoweringUtils.cpp ---------------------------------------*- C++ -*-===//
//
// Part of the LLZK Project, under the Apache License v2.0.
// See LICENSE.txt for license information.
// Copyright 2026 Project LLZK
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
 
#include "llzk/Dialect/LLZK/IR/Ops.h"
#include "llzk/Transforms/LoweringUtils.h"
 
#include <mlir/IR/Block.h>
#include <mlir/IR/Builders.h>
#include <mlir/IR/BuiltinOps.h>
#include <mlir/IR/IRMapping.h>
#include <mlir/IR/Operation.h>
#include <mlir/IR/SymbolTable.h>
#include <mlir/Support/LogicalResult.h>
 
#include <llvm/ADT/STLExtras.h>
#include <llvm/ADT/SmallVector.h>
#include <llvm/Support/raw_ostream.h>
 
using namespace mlir;
using namespace llzk;
using namespace llzk::felt;
using namespace llzk::function;
using namespace llzk::component;
using namespace llzk::constrain;
 
namespace llzk {
 
namespace {
 
Value mapBlockArgumentInCompute(BlockArgument barg, FuncDefOp computeFunc) {
  // Constrain entry arguments map onto compute inputs: constrain(%self, args...)
  // corresponds to compute(args...), plus the compute-side `%self`.
  if (barg.getArgNumber() == 0) {
    return computeFunc.getSelfValueFromCompute();
  }
  return computeFunc.getArgument(barg.getArgNumber() - 1);
}
 
Value mapValueIntoCompute(
    Value val, FuncDefOp computeFunc, OpBuilder &builder, DenseMap<Value, Value> &memo
) {
  if (auto it = memo.find(val); it != memo.end()) {
    return it->second;
  }
  if (auto barg = llvm::dyn_cast<BlockArgument>(val)) {
    return memo[val] = mapBlockArgumentInCompute(barg, computeFunc);
  }
  return rebuildExprInCompute(val, computeFunc, builder, memo);
}
 
} // namespace
 
Value rebuildExprInCompute(
    Value val, FuncDefOp computeFunc, OpBuilder &builder, DenseMap<Value, Value> &memo
) {
  if (auto it = memo.find(val); it != memo.end()) {
    return it->second;
  }
 
  if (auto barg = llvm::dyn_cast<BlockArgument>(val)) {
    return memo[val] = mapBlockArgumentInCompute(barg, computeFunc);
  }
 
  if (auto readOp = val.getDefiningOp<MemberReadOp>()) {
    IRMapping mapper;
    for (Value operand : readOp->getOperands()) {
      Value rebuiltOperand = mapValueIntoCompute(operand, computeFunc, builder, memo);
      if (!rebuiltOperand) {
        return nullptr;
      }
      mapper.map(operand, rebuiltOperand);
    }
 
    Operation *rebuiltOp = builder.clone(*readOp.getOperation(), mapper);
    assert(rebuiltOp->getNumResults() == 1 && "member reads have exactly one result");
    return memo[val] = rebuiltOp->getResult(0);
  }
 
  if (auto callOp = val.getDefiningOp<CallOp>()) {
    if (!callOp.getMapOperands().empty()) {
      callOp
          .emitError(
              "cannot rebuild affine-instantiated function.call in compute-side auxiliary "
              "expression"
          )
          .report();
      return nullptr;
    }
 
    SymbolTableCollection tables;
    FailureOr<SymbolLookupResult<FuncDefOp>> target = callOp.getCalleeTarget(tables);
    if (failed(target)) {
      return nullptr;
    }
    FuncDefOp targetFunc = target->get();
    bool invalidTarget =
        (targetFunc.hasAllowConstraintAttr() && !computeFunc.hasAllowConstraintAttr()) ||
        (targetFunc.hasAllowWitnessAttr() && !computeFunc.hasAllowWitnessAttr()) ||
        (targetFunc.hasAllowNonNativeFieldOpsAttr() &&
         !computeFunc.hasAllowNonNativeFieldOpsAttr());
    if (invalidTarget) {
      callOp
          .emitError(
              "cannot rebuild function.call in compute-side auxiliary expression: callee "
              "requires attributes not present on the compute function"
          )
          .report();
      return nullptr;
    }
 
    SmallVector<Value> rebuiltArgs;
    rebuiltArgs.reserve(callOp.getArgOperands().size());
    for (Value arg : callOp.getArgOperands()) {
      Value rebuiltArg = rebuildExprInCompute(arg, computeFunc, builder, memo);
      if (!rebuiltArg) {
        return nullptr;
      }
      rebuiltArgs.push_back(rebuiltArg);
    }
 
    ArrayRef<Attribute> templateParams;
    if (ArrayAttr params = callOp.getTemplateParamsAttr()) {
      templateParams = params.getValue();
    }
 
    CallOp rebuilt = CallOp::create(
        builder, callOp.getLoc(), callOp.getResultTypes(), callOp.getCalleeAttr(), rebuiltArgs,
        templateParams
    );
    for (auto [oldResult, newResult] : llvm::zip(callOp.getResults(), rebuilt.getResults())) {
      memo[oldResult] = newResult;
    }
    return memo[val];
  }
 
  if (val.getType().isIndex()) {
    // Preserve index producers used by member-read access operands so rebuilt reads
    // keep the original access semantics.
    Operation *defOp = val.getDefiningOp();
    assert(defOp && "index block arguments should already be mapped");
 
    IRMapping mapper;
    for (Value operand : defOp->getOperands()) {
      Value rebuiltOperand = mapValueIntoCompute(operand, computeFunc, builder, memo);
      if (!rebuiltOperand) {
        return nullptr;
      }
      mapper.map(operand, rebuiltOperand);
    }
 
    Operation *rebuiltOp = builder.clone(*defOp, mapper);
    assert(
        rebuiltOp->getNumResults() == defOp->getNumResults() &&
        "cloned index op should preserve result count"
    );
    unsigned resultNumber = llvm::cast<OpResult>(val).getResultNumber();
    return memo[val] = rebuiltOp->getResult(resultNumber);
  }
 
  if (auto add = val.getDefiningOp<AddFeltOp>()) {
    Value lhs = rebuildExprInCompute(add.getLhs(), computeFunc, builder, memo);
    Value rhs = rebuildExprInCompute(add.getRhs(), computeFunc, builder, memo);
    if (!lhs || !rhs) {
      return nullptr;
    }
    return memo[val] = AddFeltOp::create(builder, add.getLoc(), add.getType(), lhs, rhs);
  }
 
  if (auto sub = val.getDefiningOp<SubFeltOp>()) {
    Value lhs = rebuildExprInCompute(sub.getLhs(), computeFunc, builder, memo);
    Value rhs = rebuildExprInCompute(sub.getRhs(), computeFunc, builder, memo);
    if (!lhs || !rhs) {
      return nullptr;
    }
    return memo[val] = SubFeltOp::create(builder, sub.getLoc(), sub.getType(), lhs, rhs);
  }
 
  if (auto mul = val.getDefiningOp<MulFeltOp>()) {
    Value lhs = rebuildExprInCompute(mul.getLhs(), computeFunc, builder, memo);
    Value rhs = rebuildExprInCompute(mul.getRhs(), computeFunc, builder, memo);
    if (!lhs || !rhs) {
      return nullptr;
    }
    return memo[val] = MulFeltOp::create(builder, mul.getLoc(), mul.getType(), lhs, rhs);
  }
 
  if (auto neg = val.getDefiningOp<NegFeltOp>()) {
    Value operand = rebuildExprInCompute(neg.getOperand(), computeFunc, builder, memo);
    if (!operand) {
      return nullptr;
    }
    return memo[val] = NegFeltOp::create(builder, neg.getLoc(), neg.getType(), operand);
  }
 
  if (auto div = val.getDefiningOp<DivFeltOp>()) {
    Value lhs = rebuildExprInCompute(div.getLhs(), computeFunc, builder, memo);
    Value rhs = rebuildExprInCompute(div.getRhs(), computeFunc, builder, memo);
    if (!lhs || !rhs) {
      return nullptr;
    }
    return memo[val] = DivFeltOp::create(builder, div.getLoc(), div.getType(), lhs, rhs);
  }
 
  if (auto c = val.getDefiningOp<FeltConstantOp>()) {
    return memo[val] = FeltConstantOp::create(builder, c.getLoc(), c.getValueAttr());
  }
 
  if (Operation *op = val.getDefiningOp()) {
    op->emitError("cannot rebuild unsupported operation in compute-side auxiliary expression")
        .report();
  }
  return nullptr;
}
 
LogicalResult checkForAuxMemberConflicts(StructDefOp structDef, StringRef prefix) {
  auto res = structDef.walk([&prefix](MemberDefOp memberDefOp) -> WalkResult {
    if (memberDefOp.getName().starts_with(prefix)) {
      return memberDefOp.emitOpError().append(
          "name conflicts with reserved prefix '", prefix, '\''
      );
    }
    return WalkResult::advance();
  });
  return failure(res.wasInterrupted());
}
 
LogicalResult checkFuncBodyIsStraightLine(FuncDefOp func, StringRef passName) {
  auto emitStraightLineError = [&func, &passName](Operation *op) -> LogicalResult {
    StringRef funcName;
    if (func.isStructCompute()) {
      funcName = "compute";
    } else if (func.isStructConstrain()) {
      funcName = "constrain";
    } else {
      funcName = "function";
    }
    return op->emitError()
           << passName << " expects a straight-line " << funcName
           << " body; run `llzk-flatten` or another control-flow lowering pass first";
  };
 
  Region &body = func.getBody();
  if (!body.hasOneBlock()) {
    return emitStraightLineError(func.getOperation());
  }
 
  auto res = body.walk([&emitStraightLineError](Operation *op) -> WalkResult {
    if (op->getNumRegions() != 0 || op->getNumSuccessors() != 0) {
      return emitStraightLineError(op);
    }
    return WalkResult::advance();
  });
  return failure(res.wasInterrupted());
}
 
void replaceSubsequentUsesWith(Value oldVal, Value newVal, Operation *afterOp) {
  assert(afterOp && "afterOp must be a valid Operation*");
 
  for (auto &use : llvm::make_early_inc_range(oldVal.getUses())) {
    Operation *user = use.getOwner();
 
    // Skip uses that are:
    // - Before afterOp in the same block.
    // - Inside afterOp itself.
    if ((user->getBlock() == afterOp->getBlock()) &&
        (user == afterOp || user->isBeforeInBlock(afterOp))) {
      continue;
    }
 
    // Replace this use of oldVal with newVal.
    use.set(newVal);
  }
}
 
MemberDefOp addAuxMember(StructDefOp structDef, StringRef name, Type type) {
  assert(type && "auxiliary member type must be non-null");
 
  OpBuilder builder(structDef);
  builder.setInsertionPointToEnd(structDef.getBody());
  return MemberDefOp::create(builder, structDef.getLoc(), builder.getStringAttr(name), type);
}
 
unsigned getFeltDegree(Value val, DenseMap<Value, unsigned> &memo) {
  if (auto it = memo.find(val); it != memo.end()) {
    return it->second;
  }
 
  if (isa<FeltConstantOp>(val.getDefiningOp())) {
    return memo[val] = 0;
  }
  if (isa<NonDetOp, MemberReadOp>(val.getDefiningOp()) || isa<BlockArgument>(val)) {
    return memo[val] = 1;
  }
  if (auto add = val.getDefiningOp<AddFeltOp>()) {
    return memo[val] =
               std::max(getFeltDegree(add.getLhs(), memo), getFeltDegree(add.getRhs(), memo));
  }
  if (auto sub = val.getDefiningOp<SubFeltOp>()) {
    return memo[val] =
               std::max(getFeltDegree(sub.getLhs(), memo), getFeltDegree(sub.getRhs(), memo));
  }
  if (auto mul = val.getDefiningOp<MulFeltOp>()) {
    return memo[val] = getFeltDegree(mul.getLhs(), memo) + getFeltDegree(mul.getRhs(), memo);
  }
  if (auto div = val.getDefiningOp<DivFeltOp>()) {
    return memo[val] = getFeltDegree(div.getLhs(), memo) + getFeltDegree(div.getRhs(), memo);
  }
  if (auto neg = val.getDefiningOp<NegFeltOp>()) {
    return memo[val] = getFeltDegree(neg.getOperand(), memo);
  }
 
  llvm::errs() << "Unhandled felt op in degree computation: " << val << '\n';
  llvm_unreachable("Unhandled op in getFeltDegree");
}
 
} // namespace llzk