From 8d2a2ddcd90053483cc62c2cdf0797bee3490b10 Mon Sep 17 00:00:00 2001
From: guipublic <47281315+guipublic@users.noreply.github.com>
Date: Wed, 15 Jan 2025 15:26:53 +0100
Subject: [PATCH] fix: do not remove memory blocks used as brillig input
 (#7073)

---
 acvm-repo/acvm/src/compiler/optimizers/unused_memory.rs  | 9 ++++++++-
 .../compile_success_no_bug/regression_7062/Nargo.toml    | 7 +++++++
 .../compile_success_no_bug/regression_7062/src/main.nr   | 8 ++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 test_programs/compile_success_no_bug/regression_7062/Nargo.toml
 create mode 100644 test_programs/compile_success_no_bug/regression_7062/src/main.nr

diff --git a/acvm-repo/acvm/src/compiler/optimizers/unused_memory.rs b/acvm-repo/acvm/src/compiler/optimizers/unused_memory.rs
index 1963430210f..1325a3b03cd 100644
--- a/acvm-repo/acvm/src/compiler/optimizers/unused_memory.rs
+++ b/acvm-repo/acvm/src/compiler/optimizers/unused_memory.rs
@@ -1,4 +1,4 @@
-use acir::circuit::{opcodes::BlockId, Circuit, Opcode};
+use acir::circuit::{brillig::BrilligInputs, opcodes::BlockId, Circuit, Opcode};
 use std::collections::HashSet;
 
 /// `UnusedMemoryOptimizer` will remove initializations of memory blocks which are unused.
@@ -29,6 +29,13 @@ impl<F> UnusedMemoryOptimizer<F> {
                 Opcode::MemoryOp { block_id, .. } => {
                     unused_memory_initialization.remove(block_id);
                 }
+                Opcode::BrilligCall { inputs, .. } => {
+                    for input in inputs {
+                        if let BrilligInputs::MemoryArray(block) = input {
+                            unused_memory_initialization.remove(block);
+                        }
+                    }
+                }
                 _ => (),
             }
         }
diff --git a/test_programs/compile_success_no_bug/regression_7062/Nargo.toml b/test_programs/compile_success_no_bug/regression_7062/Nargo.toml
new file mode 100644
index 00000000000..0e11219ad98
--- /dev/null
+++ b/test_programs/compile_success_no_bug/regression_7062/Nargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "regression_7062"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.31.0"
+
+[dependencies]
diff --git a/test_programs/compile_success_no_bug/regression_7062/src/main.nr b/test_programs/compile_success_no_bug/regression_7062/src/main.nr
new file mode 100644
index 00000000000..c640062b45b
--- /dev/null
+++ b/test_programs/compile_success_no_bug/regression_7062/src/main.nr
@@ -0,0 +1,8 @@
+fn main(args: [Field; 2]) {
+    /// Safety: n/a
+    unsafe { store(args) };
+    // Dummy test to remove the 'underconstraint bug'
+    assert(args[0] + args[1] != 0);
+}
+
+pub unconstrained fn store(_: [Field]) {}
\ No newline at end of file