From 526c84eb8bfa61d9a218c3c0bd623aff8a48f25f Mon Sep 17 00:00:00 2001
From: Tom French <15848336+TomAFrench@users.noreply.github.com>
Date: Thu, 9 Jan 2025 11:28:25 +0000
Subject: [PATCH] chore: mark casts as able to be deduplicated (#6996)

---
 compiler/noirc_evaluator/src/ssa.rs                | 2 +-
 compiler/noirc_evaluator/src/ssa/ir/instruction.rs | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/compiler/noirc_evaluator/src/ssa.rs b/compiler/noirc_evaluator/src/ssa.rs
index 2500b8685a1..4f0a5b72840 100644
--- a/compiler/noirc_evaluator/src/ssa.rs
+++ b/compiler/noirc_evaluator/src/ssa.rs
@@ -171,7 +171,7 @@ fn optimize_all(builder: SsaBuilder, options: &SsaEvaluatorOptions) -> Result<Ss
         )?
         .run_pass(Ssa::simplify_cfg, "Simplifying (2nd)")
         .run_pass(Ssa::flatten_cfg, "Flattening")
-        .run_pass(Ssa::remove_bit_shifts, "After Removing Bit Shifts")
+        .run_pass(Ssa::remove_bit_shifts, "Removing Bit Shifts")
         // Run mem2reg once more with the flattened CFG to catch any remaining loads/stores
         .run_pass(Ssa::mem2reg, "Mem2Reg (2nd)")
         // Run the inlining pass again to handle functions with `InlineType::NoPredicates`.
diff --git a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
index aadd35040cf..17cde96cddc 100644
--- a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
+++ b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
@@ -473,6 +473,9 @@ impl Instruction {
             // removed entirely.
             Noop => true,
 
+            // Cast instructions can always be deduplicated
+            Cast(_, _) => true,
+
             // Arrays can be mutated in unconstrained code so code that handles this case must
             // take care to track whether the array was possibly mutated or not before
             // deduplicating. Since we don't know if the containing pass checks for this, we
@@ -484,7 +487,6 @@ impl Instruction {
             // with one that was disabled. See
             // https://github.com/noir-lang/noir/pull/4716#issuecomment-2047846328.
             Binary(_)
-            | Cast(_, _)
             | Not(_)
             | Truncate { .. }
             | IfElse { .. }