do not deduplicate division by a zero const

noir-lang · Feb 14, 2025 · 653a9a4 · 653a9a4
1 parent 3878037
commit 653a9a4
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diff --git a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
@@ -605,7 +605,7 @@ impl Instruction {
                     BinaryOp::Div | BinaryOp::Mod => {
                         // Div and Mod require a predicate if the RHS may be zero.
                         dfg.get_numeric_constant(binary.rhs)
-                            .map(|rhs| !rhs.is_zero())
+                            .map(|rhs| rhs.is_zero())
                             .unwrap_or(true)
                     }
                     BinaryOp::Add { unchecked: true }

diff --git a/compiler/noirc_evaluator/src/ssa/opt/constant_folding.rs b/compiler/noirc_evaluator/src/ssa/opt/constant_folding.rs
@@ -1785,4 +1785,55 @@ mod test {
         let ssa = ssa.fold_constants();
         assert_normalized_ssa_equals(ssa, src);
     }
+
+    #[test]
+    fn does_not_deduplicate_unsigned_division_by_zero_constant() {
+        // Regression test for https://github.com/noir-lang/noir/issues/7283
+        let src = "
+        acir(inline) fn main f0 {
+          b0(v0: u32, v1: u32, v2: u1):
+            enable_side_effects v2
+            v4 = div v1, u32 0
+            v5 = not v2
+            enable_side_effects v5
+            v6 = div v1, u32 0
+            return
+        }
+        ";
+
+        let ssa = Ssa::from_str(src).unwrap();
+        let ssa = ssa.fold_constants();
+        assert_normalized_ssa_equals(ssa, src);
+    }
+
+    #[test]
+    fn does_duplicate_unsigned_division_by_non_zero_constant() {
+        // Regression test for https://github.com/noir-lang/noir/issues/7283
+        let src = "
+        acir(inline) fn main f0 {
+          b0(v0: u32, v1: u32, v2: u1):
+            enable_side_effects v2
+            v4 = div v1, u32 2
+            v5 = not v2
+            enable_side_effects v5
+            v6 = div v1, u32 2
+            return
+        }
+        ";
+
+        let ssa = Ssa::from_str(src).unwrap();
+        let ssa = ssa.fold_constants();
+
+        let expected = "
+        acir(inline) fn main f0 {
+          b0(v0: u32, v1: u32, v2: u1):
+            enable_side_effects v2
+            v4 = div v1, u32 2
+            v5 = not v2
+            enable_side_effects v5
+            return
+        }
+        ";
+        assert_normalized_ssa_equals(ssa, expected);
+    }
 }