[elf linker] add --sort-section

Tested by: created a "hello world" C file and compiled with:

    zig cc -v main.c -Wl,--sort-section=name -o main

... and verified the `--sort-section=name` is passed to ld.lld.

Refs https://github.com/zigchroot/zig-chroot/issues/1

src/Compilation.zig

@@ -989,6 +989,7 @@ pub const InitOptions = struct {
     linker_optimization: ?u8 = null,
     linker_compress_debug_sections: ?link.CompressDebugSections = null,
     linker_module_definition_file: ?[]const u8 = null,
+    linker_sort_section: ?link.SortSection = null,
     major_subsystem_version: ?u32 = null,
     minor_subsystem_version: ?u32 = null,
     clang_passthrough_mode: bool = false,
@@ -1853,6 +1854,7 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
             .bind_global_refs_locally = options.linker_bind_global_refs_locally orelse false,
             .compress_debug_sections = options.linker_compress_debug_sections orelse .none,
             .module_definition_file = options.linker_module_definition_file,
+            .sort_section = options.linker_sort_section,
             .import_memory = options.linker_import_memory orelse false,
             .import_symbols = options.linker_import_symbols,
             .import_table = options.linker_import_table,
@@ -2684,6 +2686,7 @@ fn addNonIncrementalStuffToCacheManifest(comp: *Compilation, man: *Cache.Manifes
     man.hash.add(comp.bin_file.options.hash_style);
     man.hash.add(comp.bin_file.options.compress_debug_sections);
     man.hash.add(comp.bin_file.options.include_compiler_rt);
+    man.hash.addOptional(comp.bin_file.options.sort_section);
     if (comp.bin_file.options.link_libc) {
         man.hash.add(comp.bin_file.options.libc_installation != null);
         if (comp.bin_file.options.libc_installation) |libc_installation| {

src/link.zig

@@ -25,6 +25,8 @@ pub const SystemLib = struct {
     weak: bool = false,
 };
 
+pub const SortSection = enum { name, alignment };
+
 pub const CacheMode = enum { incremental, whole };
 
 pub fn hashAddSystemLibs(
@@ -159,6 +161,7 @@ pub const Options = struct {
     disable_lld_caching: bool,
     is_test: bool,
     hash_style: HashStyle,
+    sort_section: ?SortSection,
     major_subsystem_version: ?u32,
     minor_subsystem_version: ?u32,
     gc_sections: ?bool = null,

src/link/Elf.zig

@@ -1324,6 +1324,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v
         man.hash.addOptionalBytes(self.base.options.entry);
         man.hash.addOptional(self.base.options.image_base_override);
         man.hash.add(gc_sections);
+        man.hash.addOptional(self.base.options.sort_section);
         man.hash.add(self.base.options.eh_frame_hdr);
         man.hash.add(self.base.options.emit_relocs);
         man.hash.add(self.base.options.rdynamic);
@@ -1488,6 +1489,11 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v
             try argv.append(linker_script);
         }
 
+        if (self.base.options.sort_section) |how| {
+            const arg = try std.fmt.allocPrint(arena, "--sort-section={s}", .{@tagName(how)});
+            try argv.append(arg);
+        }
+
         if (gc_sections) {
             try argv.append("--gc-sections");
         }

src/main.zig

@@ -509,6 +509,7 @@ const usage_build_generic =
     \\      zlib                       Compression with deflate/inflate
     \\  --gc-sections                  Force removal of functions and data that are unreachable by the entry point or exported symbols
     \\  --no-gc-sections               Don't force removal of unreachable functions and data
+    \\  --sort-section=[value]         Sort wildcard section patterns by 'name' or 'alignment'
     \\  --subsystem [subsystem]        (Windows) /SUBSYSTEM:<subsystem> to the linker
     \\  --stack [size]                 Override default stack size
     \\  --image-base [addr]            Set base address for executable image
@@ -731,6 +732,7 @@ fn buildOutputType(
     var linker_script: ?[]const u8 = null;
     var version_script: ?[]const u8 = null;
     var disable_c_depfile = false;
+    var linker_sort_section: ?link.SortSection = null;
     var linker_gc_sections: ?bool = null;
     var linker_compress_debug_sections: ?link.CompressDebugSections = null;
     var linker_allow_shlib_undefined: ?bool = null;
@@ -1894,6 +1896,15 @@ fn buildOutputType(
                     linker_print_icf_sections = true;
                 } else if (mem.eql(u8, arg, "--print-map")) {
                     linker_print_map = true;
+                } else if (mem.eql(u8, arg, "--sort-section")) {
+                    i += 1;
+                    if (i >= linker_args.items.len) {
+                        fatal("expected linker arg after '{s}'", .{arg});
+                    }
+                    const arg1 = linker_args.items[i];
+                    linker_sort_section = std.meta.stringToEnum(link.SortSection, arg1) orelse {
+                        fatal("expected [name|alignment] after --sort-section, found '{s}'", .{arg1});
+                    };
                 } else if (mem.eql(u8, arg, "--allow-shlib-undefined") or
                     mem.eql(u8, arg, "-allow-shlib-undefined"))
                 {
@@ -3070,6 +3081,7 @@ fn buildOutputType(
         .version_script = version_script,
         .disable_c_depfile = disable_c_depfile,
         .soname = resolved_soname,
+        .linker_sort_section = linker_sort_section,
         .linker_gc_sections = linker_gc_sections,
         .linker_allow_shlib_undefined = linker_allow_shlib_undefined,
         .linker_bind_global_refs_locally = linker_bind_global_refs_locally,