codegen: emit load instruction for (now-stack) params

- comp_ctx: make ParameterMap use ptrs to Parameter

src/codegen.zig

@@ -236,11 +236,16 @@ pub const Codegen = struct {
                 return switch (metadata.using) {
                     .Function => blk: {
                         var param = metadata.from_function.?.parameters.get(vari.lexeme).?.value;
-                        // var llvm_func = self.llvm_table.get(self.current_function_name.?).?.value;
-                        // break :blk llvm.LLVMGetParam(llvm_func, @intCast(c_uint, param.idx));
 
-                        std.debug.warn("fn param alloca {} {}\n", param.name, param.llvm_alloca);
+                        var buf = try self.allocator.alloc(u8, 512);
-                        break :blk param.llvm_alloca.?;
+                        errdefer self.allocator.free(buf);
+
+                        var load_str = try std.fmt.bufPrint(buf, "{}_loaded", param.name);
+
+                        var load_cstr = try std.cstr.addNullByte(self.allocator, load_str);
+                        errdefer self.allocator.free(load_cstr);
+
+                        break :blk llvm.LLVMBuildLoad(builder, param.llvm_alloca.?, load_cstr.ptr);
                     },
 
                     .Scope => @panic("TODO local variables"),

src/comp_ctx.zig

@@ -85,7 +85,7 @@ pub const Parameter = struct {
     llvm_alloca: llvm.LLVMValueRef = null,
 };
 
-pub const ParameterMap = std.StringHashMap(Parameter);
+pub const ParameterMap = std.StringHashMap(*Parameter);
 
 // functions, for our purposes, other than symbols, have:
 //  - a return type
@@ -274,11 +274,14 @@ pub const CompilationContext = struct {
         var param_map = ParameterMap.init(self.allocator);
 
         for (decl.params.toSlice()) |param, idx| {
-            _ = try param_map.put(param.name.lexeme, Parameter{
+            var param_sym = try self.allocator.create(Parameter);
+
+            param_sym.* = Parameter{
                 .name = param.name.lexeme,
                 .idx = idx,
                 .typ = param_types.at(idx),
-            });
+            };
+            _ = try param_map.put(param.name.lexeme, param_sym);
         }
 
         const lex = decl.func_name.lexeme;