@@ -98,6 +98,49 @@ impl Ssa {
9898 function. constant_fold ( false , brillig_info) ;
9999 }
100100
101+ // It could happen that we inlined all calls to a given brillig function.
102+ // In that case it's unused so we can remove it. This is what we check next.
103+ self . remove_unused_brillig_functions ( brillig_functions)
104+ }
105+
106+ fn remove_unused_brillig_functions (
107+ mut self ,
108+ mut brillig_functions : BTreeMap < FunctionId , Function > ,
109+ ) -> Ssa {
110+ // Remove from the above map functions that are called
111+ for function in self . functions . values ( ) {
112+ for block_id in function. reachable_blocks ( ) {
113+ for instruction_id in function. dfg [ block_id] . instructions ( ) {
114+ let instruction = & function. dfg [ * instruction_id] ;
115+ let Instruction :: Call { func : func_id, arguments : _ } = instruction else {
116+ continue ;
117+ } ;
118+
119+ let func_value = & function. dfg [ * func_id] ;
120+ let Value :: Function ( func_id) = func_value else { continue } ;
121+
122+ if function. runtime ( ) . is_acir ( ) {
123+ brillig_functions. remove ( func_id) ;
124+ }
125+ }
126+ }
127+ }
128+
129+ // The ones that remain are never called: let's remove them.
130+ for ( func_id, func) in & brillig_functions {
131+ // We never want to remove the main function (it could be `unconstrained` or it
132+ // could have been turned into brillig if `--force-brillig` was given).
133+ // We also don't want to remove entry points.
134+ let runtime = func. runtime ( ) ;
135+ if self . main_id == * func_id
136+ || ( runtime. is_entry_point ( ) && matches ! ( runtime, RuntimeType :: Acir ( _) ) )
137+ {
138+ continue ;
139+ }
140+
141+ self . functions . remove ( func_id) ;
142+ }
143+
101144 self
102145 }
103146}
@@ -682,6 +725,11 @@ impl<'brillig> Context<'brillig> {
682725
683726 // Should we consider calls to slice_push_back and similar to be mutating operations as well?
684727 if let Store { value : array, .. } | ArraySet { array, .. } = instruction {
728+ if function. dfg . is_global ( * array) {
729+ // Early return as we expect globals to be immutable.
730+ return ;
731+ } ;
732+
685733 let instruction = match & function. dfg [ * array] {
686734 Value :: Instruction { instruction, .. } => & function. dfg [ * instruction] ,
687735 _ => return ,
@@ -1533,6 +1581,82 @@ mod test {
15331581 assert_normalized_ssa_equals ( ssa, expected) ;
15341582 }
15351583
1584+ #[ test]
1585+ fn inlines_brillig_call_with_entry_point_globals ( ) {
1586+ let src = "
1587+ g0 = Field 2
1588+
1589+ acir(inline) fn main f0 {
1590+ b0():
1591+ v1 = call f1() -> Field
1592+ return v1
1593+ }
1594+
1595+ brillig(inline) fn one f1 {
1596+ b0():
1597+ v1 = add g0, Field 3
1598+ return v1
1599+ }
1600+ " ;
1601+ let ssa = Ssa :: from_str ( src) . unwrap ( ) ;
1602+ let mut ssa = ssa. dead_instruction_elimination ( ) ;
1603+ let used_globals_map = std:: mem:: take ( & mut ssa. used_globals ) ;
1604+ let brillig = ssa. to_brillig_with_globals ( false , used_globals_map) ;
1605+
1606+ let expected = "
1607+ g0 = Field 2
1608+
1609+ acir(inline) fn main f0 {
1610+ b0():
1611+ return Field 5
1612+ }
1613+ " ;
1614+
1615+ let ssa = ssa. fold_constants_with_brillig ( & brillig) ;
1616+ assert_normalized_ssa_equals ( ssa, expected) ;
1617+ }
1618+
1619+ #[ test]
1620+ fn inlines_brillig_call_with_non_entry_point_globals ( ) {
1621+ let src = "
1622+ g0 = Field 2
1623+
1624+ acir(inline) fn main f0 {
1625+ b0():
1626+ v1 = call f1() -> Field
1627+ return v1
1628+ }
1629+
1630+ brillig(inline) fn entry_point f1 {
1631+ b0():
1632+ v1 = call f2() -> Field
1633+ return v1
1634+ }
1635+
1636+ brillig(inline) fn one f2 {
1637+ b0():
1638+ v1 = add g0, Field 3
1639+ return v1
1640+ }
1641+ " ;
1642+ let ssa = Ssa :: from_str ( src) . unwrap ( ) ;
1643+ let mut ssa = ssa. dead_instruction_elimination ( ) ;
1644+ let used_globals_map = std:: mem:: take ( & mut ssa. used_globals ) ;
1645+ let brillig = ssa. to_brillig_with_globals ( false , used_globals_map) ;
1646+
1647+ let expected = "
1648+ g0 = Field 2
1649+
1650+ acir(inline) fn main f0 {
1651+ b0():
1652+ return Field 5
1653+ }
1654+ " ;
1655+
1656+ let ssa = ssa. fold_constants_with_brillig ( & brillig) ;
1657+ assert_normalized_ssa_equals ( ssa, expected) ;
1658+ }
1659+
15361660 #[ test]
15371661 fn does_not_use_cached_constrain_in_block_that_is_not_dominated ( ) {
15381662 let src = "
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