fix: Move remove_if_else pass after second inlining (#4976)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->

## Summary\*

For the test added in this PR I bumped the `max_iter` in
`try_merge_only_changed_indices`. We then get the following panic:
```
The application panicked (crashed).
Message:  internal error: entered unreachable code: All Value::Instructions should already be known during inlining after creating the original inlined instruction. Unknown value v41 = Instruction { instruction: Id(76), position: 0, typ: Array([Numeric(Unsigned { bit_size: 32 })], 30) }
Location: compiler/noirc_evaluator/src/ssa/opt/inlining.rs:253
``` 
We have to inline immediately following mem2reg before extra
instructions are added by the remove_if_else pass.

## Additional Context



## Documentation\*

Check one:
- [ ] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [ ] I have tested the changes locally.
- [ ] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

compiler/noirc_evaluator/src/ssa.rs

@@ -59,10 +59,12 @@ pub(crate) fn optimize_into_acir(
         .run_pass(Ssa::remove_bit_shifts, "After Removing Bit Shifts:")
         // Run mem2reg once more with the flattened CFG to catch any remaining loads/stores
         .run_pass(Ssa::mem2reg, "After Mem2Reg:")
-        .run_pass(Ssa::remove_if_else, "After Remove IfElse:")
         // Run the inlining pass again to handle functions with `InlineType::NoPredicates`.
         // Before flattening is run, we treat functions marked with the `InlineType::NoPredicates` as an entry point.
+        // This pass must come immediately following `mem2reg` as the succeeding passes
+        // may create an SSA which inlining fails to handle.
         .run_pass(Ssa::inline_functions_with_no_predicates, "After Inlining:")
+        .run_pass(Ssa::remove_if_else, "After Remove IfElse:")
         .run_pass(Ssa::fold_constants, "After Constant Folding:")
         .run_pass(Ssa::remove_enable_side_effects, "After EnableSideEffects removal:")
         .run_pass(Ssa::fold_constants_using_constraints, "After Constraint Folding:")

compiler/noirc_evaluator/src/ssa/opt/flatten_cfg/value_merger.rs

@@ -306,7 +306,7 @@ impl<'a> ValueMerger<'a> {
 
         // Arbitrarily limit this to looking at at most 10 past ArraySet operations.
         // If there are more than that, we assume 2 completely separate arrays are being merged.
-        let max_iters = 1;
+        let max_iters = 2;
         let mut seen_then = Vec::with_capacity(max_iters);
         let mut seen_else = Vec::with_capacity(max_iters);
 

test_programs/execution_success/array_if_cond_simple/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "array_if_cond_simple"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.28.0"
+
+[dependencies]

test_programs/execution_success/array_if_cond_simple/Prover.toml

@@ -0,0 +1,2 @@
+x = true
+y = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

test_programs/execution_success/array_if_cond_simple/src/main.nr

@@ -0,0 +1,8 @@
+fn main(x: bool, mut y: [u32; 30]) {
+    if x {
+        y[0] = 1;
+    }
+
+    let z = y[0] + y[1];
+    assert(z == 1);
+}