link: accept the update arena in flush

This branch introduced an arena allocator for temporary allocations in
Compilation.update. Almost every implementation of flush() inside the
linker code was already creating a local arena that had the lifetime of
the function call. This commit passes the update arena so that all those
local ones can be deleted, resulting in slightly more efficient memory
usage with every compilation update.

While at it, this commit also removes the Compilation parameter from the
linker flush function API since a reference to the Compilation is now
already stored in `link.File`.

1 files changed, 11 insertions, 14 deletions

diff --git a/src/link/MachO/zld.zig b/src/link/MachO/zld.zig
index 81b10c59d9..b266bfeb47 100644
--- a/src/link/MachO/zld.zig
+++ b/src/link/MachO/zld.zig
@@ -1,27 +1,24 @@
 pub fn linkWithZld(
     macho_file: *MachO,
-    comp: *Compilation,
+    arena: Allocator,
     prog_node: *std.Progress.Node,
 ) link.File.FlushError!void {
     const tracy = trace(@src());
     defer tracy.end();
 
-    const gpa = macho_file.base.comp.gpa;
-    const target = macho_file.base.comp.root_mod.resolved_target.result;
+    const comp = macho_file.base.comp;
+    const gpa = comp.gpa;
+    const target = comp.root_mod.resolved_target.result;
     const emit = macho_file.base.emit;
 
-    var arena_allocator = std.heap.ArenaAllocator.init(gpa);
-    defer arena_allocator.deinit();
-    const arena = arena_allocator.allocator();
-
     const directory = emit.directory; // Just an alias to make it shorter to type.
     const full_out_path = try directory.join(arena, &[_][]const u8{emit.sub_path});
-    const opt_zcu = macho_file.base.comp.module;
+    const opt_zcu = comp.module;
 
     // If there is no Zig code to compile, then we should skip flushing the output file because it
     // will not be part of the linker line anyway.
     const module_obj_path: ?[]const u8 = if (opt_zcu != null) blk: {
-        try macho_file.flushModule(comp, prog_node);
+        try macho_file.flushModule(arena, prog_node);
 
         if (fs.path.dirname(full_out_path)) |dirname| {
             break :blk try fs.path.join(arena, &.{ dirname, macho_file.base.zcu_object_sub_path.? });
@@ -35,8 +32,8 @@ pub fn linkWithZld(
     sub_prog_node.context.refresh();
     defer sub_prog_node.end();
 
-    const output_mode = macho_file.base.comp.config.output_mode;
-    const link_mode = macho_file.base.comp.config.link_mode;
+    const output_mode = comp.config.output_mode;
+    const link_mode = comp.config.link_mode;
     const cpu_arch = target.cpu.arch;
     const is_lib = output_mode == .Lib;
     const is_dyn_lib = link_mode == .Dynamic and is_lib;
@@ -50,7 +47,7 @@ pub fn linkWithZld(
 
     var digest: [Cache.hex_digest_len]u8 = undefined;
 
-    const objects = macho_file.base.comp.objects;
+    const objects = comp.objects;
 
     if (!macho_file.base.disable_lld_caching) {
         man = comp.cache_parent.obtain();
@@ -76,7 +73,7 @@ pub fn linkWithZld(
         man.hash.add(macho_file.headerpad_max_install_names);
         man.hash.add(macho_file.base.gc_sections);
         man.hash.add(macho_file.dead_strip_dylibs);
-        man.hash.add(macho_file.base.comp.root_mod.strip);
+        man.hash.add(comp.root_mod.strip);
         try MachO.hashAddFrameworks(&man, macho_file.frameworks);
         man.hash.addListOfBytes(macho_file.base.rpath_list);
         if (is_dyn_lib) {
@@ -406,7 +403,7 @@ pub fn linkWithZld(
         try macho_file.createDyldPrivateAtom();
         try macho_file.createTentativeDefAtoms();
 
-        if (macho_file.base.comp.config.output_mode == .Exe) {
+        if (comp.config.output_mode == .Exe) {
             const global = macho_file.getEntryPoint().?;
             if (macho_file.getSymbol(global).undf()) {
                 // We do one additional check here in case the entry point was found in one of the dylibs.