fix: do not simply divisions

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

@@ -232,7 +232,11 @@ impl Instruction {
         use Instruction::*;
 
         match self {
-            Binary(_) | Cast(_, _) | Not(_) | ArrayGet { .. } | ArraySet { .. } => true,
+            Binary(bin) => {
+                // In ACIR, a division with a false predicate outputs (0,0), so it cannot replace another instruction unless they have the same predicate
+                bin.operator != BinaryOp::Div
+            }
+            Cast(_, _) | Not(_) | ArrayGet { .. } | ArraySet { .. } => true,
 
             // Unclear why this instruction causes problems.
             Truncate { .. } => false,

test_programs/execution_success/regression_3607/Nargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "regression_3607"
+type = "bin"
+authors = [""]
+
+[dependencies]

test_programs/execution_success/regression_3607/Prover.toml

@@ -0,0 +1 @@
+x = "1"

test_programs/execution_success/regression_3607/src/main.nr

@@ -0,0 +1,8 @@
+fn main(mut x: u32) {
+    if x == 0 {
+        x = (x+1) / x;
+    } else {
+        x = (x+1) / x;
+    }
+    assert(x != 0);
+}