From 182d8314086961a2e02f9f1dd673e95f83687367 Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Sat, 28 Sep 2019 20:52:45 -0300
Subject: [PATCH] comp_ctx: use more pointers to variable metadata

---
 src/codegen.zig  |  1 +
 src/comp_ctx.zig | 44 +++++++++++++++++++++++++++++---------------
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/src/codegen.zig b/src/codegen.zig
index 592a79b..ce6e787 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -381,6 +381,7 @@ pub const Codegen = struct {
                 );
 
                 stmt.*.VarDecl.llvm_alloca = variable;
+                var_metadata.*.llvm_alloca = variable;
 
                 var llvm_expr = try self.emitExpr(builder, vardecl.value);
                 _ = llvm.LLVMBuildStore(builder, llvm_expr, variable);
diff --git a/src/comp_ctx.zig b/src/comp_ctx.zig
index 56d829c..f691c7d 100644
--- a/src/comp_ctx.zig
+++ b/src/comp_ctx.zig
@@ -146,12 +146,24 @@ pub const VariableMetadata = struct {
     from_scope: ?*Scope = null,
     from_function: ?*FunctionSymbol = null,
 
-    pub fn withScope(scope: *Scope, typ: SymbolUnderlyingType) VariableMetadata {
-        return VariableMetadata{ .typ = typ, .from_scope = scope, .using = .Scope };
+    pub fn withScope(
+        allocator: *std.mem.Allocator,
+        scope: *Scope,
+        typ: SymbolUnderlyingType,
+    ) !*VariableMetadata {
+        var meta = try allocator.create(VariableMetadata);
+        meta.* = VariableMetadata{ .typ = typ, .from_scope = scope, .using = .Scope };
+        return meta;
     }
 
-    pub fn withParam(func: *FunctionSymbol, typ: SymbolUnderlyingType) VariableMetadata {
-        return VariableMetadata{ .typ = typ, .from_function = func, .using = .Function };
+    pub fn withParam(
+        allocator: *std.mem.Allocator,
+        func: *FunctionSymbol,
+        typ: SymbolUnderlyingType,
+    ) !*VariableMetadata {
+        var meta = try allocator.create(VariableMetadata);
+        meta.* = VariableMetadata{ .typ = typ, .from_function = func, .using = .Function };
+        return meta;
     }
 };
 
@@ -350,41 +362,43 @@ pub const CompilationContext = struct {
         self: *@This(),
         scope_opt: ?*Scope,
         name: []const u8,
-    ) ?VariableMetadata {
+    ) error{OutOfMemory}!?*VariableMetadata {
         if (scope_opt == null) return null;
         var scope = scope_opt.?;
 
         var kv_opt = scope.env.get(name);
         if (kv_opt) |kv| {
-            return VariableMetadata.withScope(scope, kv.value);
+            return try VariableMetadata.withScope(self.allocator, scope, kv.value);
         } else {
             return self.resolveVarTypeInScope(scope.parent, name);
         }
     }
 
     /// Resolve a given name's type, assuming it is a variable.
-    pub fn resolveVarType(self: *@This(), name: []const u8) !VariableMetadata {
-        var var_type: ?VariableMetadata = null;
+    pub fn resolveVarType(self: *@This(), name: []const u8) !*VariableMetadata {
+        var var_type: ?*VariableMetadata = null;
 
         if (self.current_scope) |scope| {
-            var_type = self.resolveVarTypeInScope(scope, name);
+            var_type = try self.resolveVarTypeInScope(scope, name);
             if (var_type) |typ| return typ;
         }
 
         if (self.cur_function) |cur_function| {
             var kv_opt = cur_function.parameters.get(name);
-            if (kv_opt) |kv| return VariableMetadata.withParam(cur_function, kv.value.typ);
+            if (kv_opt) |kv|
+                return try VariableMetadata.withParam(
+                    self.allocator,
+                    cur_function,
+                    kv.value.typ,
+                );
         }
 
         std.debug.warn("Unknown name {}\n", name);
         return CompilationError.UnknownName;
     }
 
-    pub fn insertMetadata(self: *@This(), ptr: *const ast.Expr, metadata: VariableMetadata) !void {
-        var meta = try self.allocator.create(VariableMetadata);
-        meta.* = metadata;
-
+    pub fn insertMetadata(self: *@This(), ptr: *const ast.Expr, metadata: *VariableMetadata) !void {
         std.debug.assert(ast.ExprType(ptr.*) == .Variable);
-        _ = try self.metadata_map.put(ptr, meta);
+        _ = try self.metadata_map.put(ptr, metadata);
     }
 };