fix(experimental elaborator): Move code to declare trait impls earlier

.github/workflows/gates_report.yml

@@ -1,88 +1,94 @@
-# name: Report gates diff
-
-# on:
-#   push:
-#     branches:
-#       - master
-#   pull_request:
-
-# jobs:
-#   build-nargo:
-#     runs-on: ubuntu-latest
-#     strategy:
-#       matrix:
-#         target: [x86_64-unknown-linux-gnu]
-
-#     steps:
-#       - name: Checkout Noir repo
-#         uses: actions/checkout@v4
-
-#       - name: Setup toolchain
-#         uses: dtolnay/rust-toolchain@1.74.1
-
-#       - uses: Swatinem/rust-cache@v2
-#         with:
-#           key: ${{ matrix.target }}
-#           cache-on-failure: true
-#           save-if: ${{ github.event_name != 'merge_group' }}
-
-#       - name: Build Nargo
-#         run: cargo build --package nargo_cli --release
-
-#       - name: Package artifacts
-#         run: |
-#           mkdir dist
-#           cp ./target/release/nargo ./dist/nargo
-#           7z a -ttar -so -an ./dist/* | 7z a -si ./nargo-x86_64-unknown-linux-gnu.tar.gz
-
-#       - name: Upload artifact
-#         uses: actions/upload-artifact@v4
-#         with:
-#           name: nargo
-#           path: ./dist/*
-#           retention-days: 3
-
-
-#   compare_gas_reports:
-#     needs: [build-nargo]
-#     runs-on: ubuntu-latest
-#     permissions:
-#       pull-requests: write
-
-#     steps:
-#       - uses: actions/checkout@v4
-
-#       - name: Download nargo binary
-#         uses: actions/download-artifact@v4
-#         with:
-#           name: nargo
-#           path: ./nargo
-
-#       - name: Set nargo on PATH
-#         run: |
-#           nargo_binary="${{ github.workspace }}/nargo/nargo"
-#           chmod +x $nargo_binary
-#           echo "$(dirname $nargo_binary)" >> $GITHUB_PATH
-#           export PATH="$PATH:$(dirname $nargo_binary)"
-#           nargo -V
-
-#       - name: Generate gates report
-#         working-directory: ./test_programs
-#         run: |
-#           ./gates_report.sh
-#           mv gates_report.json ../gates_report.json
+name: Report gates diff
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build-nargo:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target: [x86_64-unknown-linux-gnu]
+
+    steps:
+      - name: Checkout Noir repo
+        uses: actions/checkout@v4
+
+      - name: Setup toolchain
+        uses: dtolnay/rust-toolchain@1.74.1
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: ${{ matrix.target }}
+          cache-on-failure: true
+          save-if: ${{ github.event_name != 'merge_group' }}
+
+      - name: Build Nargo
+        run: cargo build --package nargo_cli --release
+
+      - name: Package artifacts
+        run: |
+          mkdir dist
+          cp ./target/release/nargo ./dist/nargo
+          7z a -ttar -so -an ./dist/* | 7z a -si ./nargo-x86_64-unknown-linux-gnu.tar.gz
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: nargo
+          path: ./dist/*
+          retention-days: 3
+
+
+  compare_gates_reports:
+    needs: [build-nargo]
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install `bb`
+        run: |
+          ./scripts/install_bb.sh
+          echo "$HOME/.bb/" >> $GITHUB_PATH
+
+      - name: Download nargo binary
+        uses: actions/download-artifact@v4
+        with:
+          name: nargo
+          path: ./nargo
+
+      - name: Set nargo on PATH
+        run: |
+          nargo_binary="${{ github.workspace }}/nargo/nargo"
+          chmod +x $nargo_binary
+          echo "$(dirname $nargo_binary)" >> $GITHUB_PATH
+          export PATH="$PATH:$(dirname $nargo_binary)"
+          nargo -V
+
+      - name: Generate gates report
+        working-directory: ./test_programs
+        run: |
+          ./rebuild.sh
+          ./gates_report.sh
+          mv gates_report.json ../gates_report.json
 
-#       - name: Compare gates reports
-#         id: gates_diff
-#         uses: vezenovm/noir-gates-diff@acf12797860f237117e15c0d6e08d64253af52b6
-#         with:
-#           report: gates_report.json
-#           summaryQuantile: 0.9 # only display the 10% most significant circuit size diffs in the summary (defaults to 20%)
-
-#       - name: Add gates diff to sticky comment
-#         if: github.event_name == 'pull_request' || github.event_name == 'pull_request_target'
-#         uses: marocchino/sticky-pull-request-comment@v2
-#         with:
-#           # delete the comment in case changes no longer impact circuit sizes
-#           delete: ${{ !steps.gates_diff.outputs.markdown }}
-#           message: ${{ steps.gates_diff.outputs.markdown }}
+      - name: Compare gates reports
+        id: gates_diff
+        uses: vezenovm/noir-gates-diff@acf12797860f237117e15c0d6e08d64253af52b6
+        with:
+          report: gates_report.json
+          summaryQuantile: 0.9 # only display the 10% most significant circuit size diffs in the summary (defaults to 20%)
+
+      - name: Add gates diff to sticky comment
+        if: github.event_name == 'pull_request' || github.event_name == 'pull_request_target'
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          # delete the comment in case changes no longer impact circuit sizes
+          delete: ${{ !steps.gates_diff.outputs.markdown }}
+          message: ${{ steps.gates_diff.outputs.markdown }}

acvm-repo/acvm/src/compiler/transformers/csat.rs

@@ -87,7 +87,7 @@
     // This optimization will search for combinations of terms which can be represented in a single assert-zero opcode
     // Case 1 : qM * wL * wR + qL * wL + qR * wR + qO * wO + qC
     // This polynomial does not require any further optimizations, it can be safely represented in one opcode
     // ie a polynomial with 1 mul(bi-variate) term and 3 (univariate) terms where 2 of those terms match the bivariate term
     // wL and wR, we can represent it in one opcode
     // GENERALIZED for WIDTH: instead of the number 3, we use `WIDTH`
     //
@@ -210,16 +210,16 @@
                             }
                         } else {
                             // No more usable elements left in the old opcode
-                            opcode.linear_combinations = remaining_linear_terms;
                             break;
                         }
                     }
+                    opcode.linear_combinations.extend(remaining_linear_terms);
+
                     // Constraint this intermediate_opcode to be equal to the temp variable by adding it into the IndexMap
                     // We need a unique name for our intermediate variable
                     // XXX: Another optimization, which could be applied in another algorithm
                     // If two opcodes have a large fan-in/out and they share a few common terms, then we should create intermediate variables for them
                     // Do some sort of subset matching algorithm for this on the terms of the polynomial
-
                     let inter_var = Self::get_or_create_intermediate_vars(
                         intermediate_variables,
                         intermediate_opcode,

compiler/noirc_evaluator/src/ssa.rs

@@ -56,6 +56,7 @@ pub(crate) fn optimize_into_acir(
         .run_pass(Ssa::defunctionalize, "After Defunctionalization:")
         .run_pass(Ssa::remove_paired_rc, "After Removing Paired rc_inc & rc_decs:")
         .run_pass(Ssa::inline_functions, "After Inlining:")
+        .run_pass(Ssa::resolve_is_unconstrained, "After Resolving IsUnconstrained:")
         // Run mem2reg with the CFG separated into blocks
         .run_pass(Ssa::mem2reg, "After Mem2Reg:")
         .run_pass(Ssa::as_slice_optimization, "After `as_slice` optimization")

compiler/noirc_evaluator/src/ssa/acir_gen/acir_ir/acir_variable.rs

@@ -614,13 +614,44 @@ impl AcirContext {
                 expr.push_multiplication_term(FieldElement::one(), lhs_witness, rhs_witness);
                 self.add_data(AcirVarData::Expr(expr))
             }
-            (
-                AcirVarData::Expr(_) | AcirVarData::Witness(_),
-                AcirVarData::Expr(_) | AcirVarData::Witness(_),
-            ) => {
+            (AcirVarData::Expr(expression), AcirVarData::Witness(witness))
+            | (AcirVarData::Witness(witness), AcirVarData::Expr(expression))
+                if expression.is_linear() =>
+            {
+                let mut expr = Expression::default();
+                for term in expression.linear_combinations.iter() {
+                    expr.push_multiplication_term(term.0, term.1, witness);
+                }
+                expr.push_addition_term(expression.q_c, witness);
+                self.add_data(AcirVarData::Expr(expr))
+            }
+            (AcirVarData::Expr(lhs_expr), AcirVarData::Expr(rhs_expr)) => {
+                let degree_one = if lhs_expr.is_linear() && rhs_expr.is_degree_one_univariate() {
+                    Some((lhs_expr, rhs_expr))
+                } else if rhs_expr.is_linear() && lhs_expr.is_degree_one_univariate() {
+                    Some((rhs_expr, lhs_expr))
+                } else {
+                    None
+                };
+                if let Some((lin, univariate)) = degree_one {
+                    let mut expr = Expression::default();
+                    let rhs_term = univariate.linear_combinations[0];
+                    for term in lin.linear_combinations.iter() {
+                        expr.push_multiplication_term(term.0 * rhs_term.0, term.1, rhs_term.1);
+                    }
+                    expr.push_addition_term(lin.q_c * rhs_term.0, rhs_term.1);
+                    expr.sort();
+                    expr = expr.add_mul(univariate.q_c, &lin);
+                    self.add_data(AcirVarData::Expr(expr))
+                } else {
+                    let lhs = self.get_or_create_witness_var(lhs)?;
+                    let rhs = self.get_or_create_witness_var(rhs)?;
+                    self.mul_var(lhs, rhs)?
+                }
+            }
+            _ => {
                 let lhs = self.get_or_create_witness_var(lhs)?;
                 let rhs = self.get_or_create_witness_var(rhs)?;
-
                 self.mul_var(lhs, rhs)?
             }
         };

compiler/noirc_evaluator/src/ssa/ir/instruction.rs

@@ -65,6 +65,7 @@ pub(crate) enum Intrinsic {
     FromField,
     AsField,
     AsWitness,
+    IsUnconstrained,
 }
 
 impl std::fmt::Display for Intrinsic {
@@ -89,6 +90,7 @@ impl std::fmt::Display for Intrinsic {
             Intrinsic::FromField => write!(f, "from_field"),
             Intrinsic::AsField => write!(f, "as_field"),
             Intrinsic::AsWitness => write!(f, "as_witness"),
+            Intrinsic::IsUnconstrained => write!(f, "is_unconstrained"),
         }
     }
 }
@@ -116,7 +118,8 @@ impl Intrinsic {
             | Intrinsic::SliceRemove
             | Intrinsic::StrAsBytes
             | Intrinsic::FromField
-            | Intrinsic::AsField => false,
+            | Intrinsic::AsField
+            | Intrinsic::IsUnconstrained => false,
 
             // Some black box functions have side-effects
             Intrinsic::BlackBox(func) => matches!(func, BlackBoxFunc::RecursiveAggregation),
@@ -145,6 +148,7 @@ impl Intrinsic {
             "from_field" => Some(Intrinsic::FromField),
             "as_field" => Some(Intrinsic::AsField),
             "as_witness" => Some(Intrinsic::AsWitness),
+            "is_unconstrained" => Some(Intrinsic::IsUnconstrained),
             other => BlackBoxFunc::lookup(other).map(Intrinsic::BlackBox),
         }
     }

compiler/noirc_evaluator/src/ssa/ir/instruction/call.rs

@@ -294,6 +294,7 @@ pub(super) fn simplify_call(
             SimplifyResult::SimplifiedToInstruction(instruction)
         }
         Intrinsic::AsWitness => SimplifyResult::None,
+        Intrinsic::IsUnconstrained => SimplifyResult::None,
     }
 }
 

compiler/noirc_evaluator/src/ssa/opt/mod.rs

@@ -17,5 +17,6 @@ mod rc;
 mod remove_bit_shifts;
 mod remove_enable_side_effects;
 mod remove_if_else;
+mod resolve_is_unconstrained;
 mod simplify_cfg;
 mod unrolling;

compiler/noirc_evaluator/src/ssa/opt/remove_enable_side_effects.rs

@@ -158,7 +158,8 @@ impl Context {
                     | Intrinsic::FromField
                     | Intrinsic::AsField
                     | Intrinsic::AsSlice
-                    | Intrinsic::AsWitness => false,
+                    | Intrinsic::AsWitness
+                    | Intrinsic::IsUnconstrained => false,
                 },
 
                 // We must assume that functions contain a side effect as we cannot inspect more deeply.

compiler/noirc_evaluator/src/ssa/opt/remove_if_else.rs

@@ -232,6 +232,7 @@ fn slice_capacity_change(
         | Intrinsic::BlackBox(_)
         | Intrinsic::FromField
         | Intrinsic::AsField
-        | Intrinsic::AsWitness => SizeChange::None,
+        | Intrinsic::AsWitness
+        | Intrinsic::IsUnconstrained => SizeChange::None,
     }
 }

compiler/noirc_evaluator/src/ssa/opt/resolve_is_unconstrained.rs

@@ -0,0 +1,56 @@
+use crate::ssa::{
+    ir::{
+        function::{Function, RuntimeType},
+        instruction::{Instruction, Intrinsic},
+        types::Type,
+        value::Value,
+    },
+    ssa_gen::Ssa,
+};
+use acvm::FieldElement;
+use fxhash::FxHashSet as HashSet;
+
+impl Ssa {
+    /// An SSA pass to find any calls to `Intrinsic::IsUnconstrained` and replacing any uses of the result of the intrinsic
+    /// with the resolved boolean value.
+    /// Note that this pass must run after the pass that does runtime separation, since in SSA generation an ACIR function can end up targeting brillig.
+    #[tracing::instrument(level = "trace", skip(self))]
+    pub(crate) fn resolve_is_unconstrained(mut self) -> Self {
+        for func in self.functions.values_mut() {
+            replace_is_unconstrained_result(func);
+        }
+        self
+    }
+}
+
+fn replace_is_unconstrained_result(func: &mut Function) {
+    let mut is_unconstrained_calls = HashSet::default();
+    // Collect all calls to is_unconstrained
+    for block_id in func.reachable_blocks() {
+        for &instruction_id in func.dfg[block_id].instructions() {
+            let target_func = match &func.dfg[instruction_id] {
+                Instruction::Call { func, .. } => *func,
+                _ => continue,
+            };
+
+            if let Value::Intrinsic(Intrinsic::IsUnconstrained) = &func.dfg[target_func] {
+                is_unconstrained_calls.insert(instruction_id);
+            }
+        }
+    }
+
+    for instruction_id in is_unconstrained_calls {
+        let call_returns = func.dfg.instruction_results(instruction_id);
+        let original_return_id = call_returns[0];
+
+        // We replace the result with a fresh id. This will be unused, so the DIE pass will remove the leftover intrinsic call.
+        func.dfg.replace_result(instruction_id, original_return_id);
+
+        let is_within_unconstrained = func.dfg.make_constant(
+            FieldElement::from(matches!(func.runtime(), RuntimeType::Brillig)),
+            Type::bool(),
+        );
+        // Replace all uses of the original return value with the constant
+        func.dfg.set_value_from_id(original_return_id, is_within_unconstrained);
+    }
+}