From 1795b8eb4e8db95cb639349c6c1bc4b0b82741bb Mon Sep 17 00:00:00 2001
From: Jakub Konka <kubkon@jakubkonka.com>
Date: Tue, 4 Apr 2023 08:48:48 +0200
Subject: [PATCH] macho: emit TLS sections

---
 src/link/MachO.zig | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/link/MachO.zig b/src/link/MachO.zig
index 5ec9c9c356..ad0dd8ac1d 100644
--- a/src/link/MachO.zig
+++ b/src/link/MachO.zig
@@ -138,6 +138,8 @@ got_section_index: ?u8 = null,
 data_const_section_index: ?u8 = null,
 la_symbol_ptr_section_index: ?u8 = null,
 data_section_index: ?u8 = null,
+tls_vars_section_index: ?u8 = null,
+tls_data_section_index: ?u8 = null,
 
 locals: std.ArrayListUnmanaged(macho.nlist_64) = .{},
 globals: std.ArrayListUnmanaged(SymbolWithLoc) = .{},
@@ -2366,6 +2368,7 @@ fn getDeclOutputSection(self: *MachO, decl_index: Module.Decl.Index) u8 {
     const val = decl.val;
     const zig_ty = ty.zigTypeTag();
     const mode = self.base.options.optimize_mode;
+    const single_threaded = self.base.options.single_threaded;
     const sect_id: u8 = blk: {
         // TODO finish and audit this function
         if (val.isUndefDeep()) {
@@ -2376,7 +2379,10 @@ fn getDeclOutputSection(self: *MachO, decl_index: Module.Decl.Index) u8 {
             }
         }
 
-        if (val.castTag(.variable)) |_| {
+        if (val.castTag(.variable)) |variable| {
+            if (variable.data.is_threadlocal and !single_threaded) {
+                break :blk self.tls_data_section_index.?;
+            }
             break :blk self.data_section_index.?;
         }
 
@@ -2800,6 +2806,28 @@ fn populateMissingMetadata(self: *MachO) !void {
         self.segment_table_dirty = true;
     }
 
+    if (!self.base.options.single_threaded) {
+        if (self.tls_vars_section_index == null) {
+            self.tls_vars_section_index = try self.allocateSection("__DATA2", "__thread_vars", .{
+                .size = @sizeOf(u64) * 3,
+                .alignment = @alignOf(u64),
+                .flags = macho.S_THREAD_LOCAL_VARIABLES,
+                .prot = macho.PROT.READ | macho.PROT.WRITE,
+            });
+            self.segment_table_dirty = true;
+        }
+
+        if (self.tls_data_section_index == null) {
+            self.tls_data_section_index = try self.allocateSection("__DATA3", "__thread_data", .{
+                .size = @sizeOf(u64),
+                .alignment = @alignOf(u64),
+                .flags = macho.S_THREAD_LOCAL_REGULAR,
+                .prot = macho.PROT.READ | macho.PROT.WRITE,
+            });
+            self.segment_table_dirty = true;
+        }
+    }
+
     if (self.linkedit_segment_cmd_index == null) {
         self.linkedit_segment_cmd_index = @intCast(u8, self.segments.items.len);