add alloca as an expression

crates/compiler/mono/src/debug/checker.rs

@@ -30,6 +30,7 @@ pub enum UseKind {
     ErasedMake(ErasedField),
     Erased,
     FunctionPointer,
+    Alloca,
 }
 
 pub enum ProblemKind<'a> {
@@ -524,6 +525,17 @@ impl<'a, 'r> Ctx<'a, 'r> {
                 self.check_sym_exists(symbol);
                 None
             }
+            Expr::Alloca {
+                initializer,
+                element_layout,
+            } => {
+                if let Some(initializer) = initializer {
+                    self.check_sym_exists(*initializer);
+                    self.check_sym_layout(*initializer, *element_layout, UseKind::Alloca);
+                }
+
+                None
+            }
             Expr::RuntimeErrorFunction(_) => None,
         }
     }

crates/compiler/mono/src/debug/report.rs

@@ -513,6 +513,7 @@ fn format_use_kind(use_kind: UseKind) -> &'static str {
         },
         UseKind::Erased => "erasure",
         UseKind::FunctionPointer => "function pointer",
+        UseKind::Alloca => "alloca initializer",
     }
 }
 

crates/compiler/mono/src/drop_specialization.rs

@@ -247,6 +247,7 @@ fn specialize_drops_stmt<'a, 'i>(
                     RuntimeErrorFunction(_)
                     | FunctionPointer { .. }
                     | GetTagId { .. }
+                    | Alloca { .. }
                     | EmptyArray
                     | NullPointer => { /* do nothing */ }
                 }
@@ -1620,6 +1621,8 @@ fn low_level_no_rc(lowlevel: &LowLevel) -> RC {
         | RefCountDecDataPtr | RefCountIsUnique => {
             unreachable!("Only inserted *after* borrow checking: {:?}", lowlevel);
         }
+
+        SetJmp | LongJmp | SetLongJmpBuffer => unreachable!("only inserted in dev backend codegen"),
     }
 }
 

crates/compiler/mono/src/inc_dec.rs

@@ -1138,6 +1138,9 @@ fn insert_refcount_operations_binding<'a>(
         Expr::Reset { .. } | Expr::ResetRef { .. } => {
             unreachable!("Reset(ref) should not exist at this point")
         }
+        Expr::Alloca { .. } => {
+            unreachable!("Alloca should not exist at this point")
+        }
     }
 }
 
@@ -1366,6 +1369,10 @@ fn lowlevel_borrow_signature(arena: &Bump, op: LowLevel) -> &[Ownership] {
         PtrCast => arena.alloc_slice_copy(&[owned]),
         Alloca => arena.alloc_slice_copy(&[owned]),
 
+        SetJmp | LongJmp | SetLongJmpBuffer => {
+            unreachable!("only inserted in dev backend codegen")
+        }
+
         PtrClearTagId | RefCountIncRcPtr | RefCountDecRcPtr | RefCountIncDataPtr
         | RefCountDecDataPtr | RefCountIsUnique => {
             unreachable!("Only inserted *after* borrow checking: {:?}", op);

crates/compiler/mono/src/ir.rs

@@ -329,7 +329,7 @@ pub enum HostExposedLayouts<'a> {
     },
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum SelfRecursive {
     NotSelfRecursive,
     SelfRecursive(JoinPointId),
@@ -1924,6 +1924,11 @@ pub enum Expr<'a> {
         lambda_name: LambdaName<'a>,
     },
 
+    Alloca {
+        element_layout: InLayout<'a>,
+        initializer: Option<Symbol>,
+    },
+
     Reset {
         symbol: Symbol,
         update_mode: UpdateModeId,
@@ -2142,7 +2147,7 @@ impl<'a> Expr<'a> {
                 structure,
                 index,
                 ..
-            } => text!(alloc, "UnionAtIndex (Id {}) (Index {}) ", tag_id, index)
+            } => text!(alloc, "UnionAtIndex (Id {tag_id}) (Index {index}) ")
                 .append(symbol_to_doc(alloc, *structure, pretty)),
 
             UnionFieldPtrAtIndex {
@@ -2150,13 +2155,15 @@ impl<'a> Expr<'a> {
                 structure,
                 index,
                 ..
-            } => text!(
-                alloc,
-                "UnionFieldPtrAtIndex (Id {}) (Index {}) ",
-                tag_id,
-                index
-            )
-            .append(symbol_to_doc(alloc, *structure, pretty)),
+            } => text!(alloc, "UnionFieldPtrAtIndex (Id {tag_id}) (Index {index}) ",)
+                .append(symbol_to_doc(alloc, *structure, pretty)),
+
+            Alloca { initializer, .. } => match initializer {
+                Some(initializer) => {
+                    text!(alloc, "Alloca ").append(symbol_to_doc(alloc, *initializer, pretty))
+                }
+                None => text!(alloc, "Alloca <uninitialized>"),
+            },
         }
     }
 
@@ -7935,6 +7942,17 @@ fn substitute_in_expr<'a>(
             }),
             None => None,
         },
+
+        Alloca {
+            element_layout,
+            initializer,
+        } => match substitute(subs, (*initializer)?) {
+            Some(initializer) => Some(Alloca {
+                element_layout: *element_layout,
+                initializer: Some(initializer),
+            }),
+            None => None,
+        },
     }
 }
 

crates/compiler/mono/src/tail_recursion.rs

@@ -1109,6 +1109,7 @@ fn expr_contains_symbol(expr: &Expr, needle: Symbol) -> bool {
             value.map(|v| v == needle).unwrap_or(false) || needle == *callee
         }
         Expr::ErasedLoad { symbol, field: _ } => needle == *symbol,
+        Expr::Alloca { initializer, .. } => &Some(needle) == initializer,
     }
 }