stage2: add initial impl of LLVM backend in self-hosted compiler

1 files changed, 43 insertions, 2 deletions

diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index 6232a64e4a..479dc415e5 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -24,6 +24,7 @@ const build_options = @import("build_options");
 const target_util = @import("../target.zig");
 const glibc = @import("../glibc.zig");
 const Cache = @import("../Cache.zig");
+const llvm_backend = @import("../llvm_backend.zig");
 
 const default_entry_addr = 0x8000000;
 
@@ -33,6 +34,9 @@ base: File,
 
 ptr_width: PtrWidth,
 
+/// If this is not null, an object file is created by LLVM and linked with LLD afterwards.
+llvm_ir_module: ?*llvm_backend.LLVMIRModule = null,
+
 /// Stored in native-endian format, depending on target endianness needs to be bswapped on read/write.
 /// Same order as in the file.
 sections: std.ArrayListUnmanaged(elf.Elf64_Shdr) = std.ArrayListUnmanaged(elf.Elf64_Shdr){},
@@ -224,7 +228,13 @@ pub const SrcFn = struct {
 pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Options) !*Elf {
     assert(options.object_format == .elf);
 
-    if (options.use_llvm) return error.LLVMBackendUnimplementedForELF; // TODO
+    if (options.use_llvm) {
+        const self = try createEmpty(allocator, options);
+        errdefer self.base.destroy();
+
+        self.llvm_ir_module = try llvm_backend.LLVMIRModule.create(allocator, sub_path, options);
+        return self;
+    }
 
     const file = try options.emit.?.directory.handle.createFile(sub_path, .{
         .truncate = false,
@@ -288,6 +298,7 @@ pub fn createEmpty(gpa: *Allocator, options: link.Options) !*Elf {
 }
 
 pub fn deinit(self: *Elf) void {
+    if (self.llvm_ir_module) |ir_module| ir_module.deinit(self.base.allocator);
     self.sections.deinit(self.base.allocator);
     self.program_headers.deinit(self.base.allocator);
     self.shstrtab.deinit(self.base.allocator);
@@ -423,6 +434,8 @@ fn updateString(self: *Elf, old_str_off: u32, new_name: []const u8) !u32 {
 }
 
 pub fn populateMissingMetadata(self: *Elf) !void {
+    if (self.llvm_ir_module) |_| return;
+
     const small_ptr = switch (self.ptr_width) {
         .p32 => true,
         .p64 => false,
@@ -727,6 +740,11 @@ pub fn flushModule(self: *Elf, comp: *Compilation) !void {
     const tracy = trace(@src());
     defer tracy.end();
 
+    if (self.llvm_ir_module) |llvm_ir_module| {
+        try llvm_ir_module.flushModule(comp);
+        return;
+    }
+
     // TODO This linker code currently assumes there is only 1 compilation unit and it corresponds to the
     // Zig source code.
     const module = self.base.options.module orelse return error.LinkingWithoutZigSourceUnimplemented;
@@ -1261,6 +1279,9 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
     const stack_size = self.base.options.stack_size_override orelse 16777216;
     const allow_shlib_undefined = self.base.options.allow_shlib_undefined orelse !self.base.options.is_native_os;
     const compiler_rt_path: ?[]const u8 = if (self.base.options.include_compiler_rt) blk: {
+        // TODO: remove when stage2 can build compiler_rt.zig
+        if (!build_options.is_stage1) break :blk null;
+
         if (is_exe_or_dyn_lib) {
             break :blk comp.compiler_rt_static_lib.?.full_object_path;
         } else {
@@ -1552,7 +1573,12 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
     }
 
     // libc
-    if (is_exe_or_dyn_lib and !self.base.options.skip_linker_dependencies and !self.base.options.link_libc) {
+    // TODO: enable when stage2 can build c.zig
+    if (is_exe_or_dyn_lib and
+        !self.base.options.skip_linker_dependencies and
+        !self.base.options.link_libc and
+        build_options.is_stage1)
+    {
         try argv.append(comp.libc_static_lib.?.full_object_path);
     }
 
@@ -2046,6 +2072,8 @@ fn allocateTextBlock(self: *Elf, text_block: *TextBlock, new_block_size: u64, al
 }
 
 pub fn allocateDeclIndexes(self: *Elf, decl: *Module.Decl) !void {
+    if (self.llvm_ir_module) |_| return;
+
     if (decl.link.elf.local_sym_index != 0) return;
 
     try self.local_symbols.ensureCapacity(self.base.allocator, self.local_symbols.items.len + 1);
@@ -2082,6 +2110,8 @@ pub fn allocateDeclIndexes(self: *Elf, decl: *Module.Decl) !void {
 }
 
 pub fn freeDecl(self: *Elf, decl: *Module.Decl) void {
+    if (self.llvm_ir_module) |_| return;
+
     // Appending to free lists is allowed to fail because the free lists are heuristics based anyway.
     self.freeTextBlock(&decl.link.elf);
     if (decl.link.elf.local_sym_index != 0) {
@@ -2119,6 +2149,11 @@ pub fn updateDecl(self: *Elf, module: *Module, decl: *Module.Decl) !void {
     const tracy = trace(@src());
     defer tracy.end();
 
+    if (self.llvm_ir_module) |llvm_ir_module| {
+        try llvm_ir_module.updateDecl(module, decl);
+        return;
+    }
+
     var code_buffer = std.ArrayList(u8).init(self.base.allocator);
     defer code_buffer.deinit();
 
@@ -2594,6 +2629,8 @@ pub fn updateDeclExports(
     decl: *const Module.Decl,
     exports: []const *Module.Export,
 ) !void {
+    if (self.llvm_ir_module) |_| return;
+
     const tracy = trace(@src());
     defer tracy.end();
 
@@ -2667,6 +2704,8 @@ pub fn updateDeclLineNumber(self: *Elf, module: *Module, decl: *const Module.Dec
     const tracy = trace(@src());
     defer tracy.end();
 
+    if (self.llvm_ir_module) |_| return;
+
     const container_scope = decl.scope.cast(Module.Scope.Container).?;
     const tree = container_scope.file_scope.contents.tree;
     const file_ast_decls = tree.root_node.decls();
@@ -2685,6 +2724,8 @@ pub fn updateDeclLineNumber(self: *Elf, module: *Module, decl: *const Module.Dec
 }
 
 pub fn deleteExport(self: *Elf, exp: Export) void {
+    if (self.llvm_ir_module) |_| return;
+
     const sym_index = exp.sym_index orelse return;
     self.global_symbol_free_list.append(self.base.allocator, sym_index) catch {};
     self.global_symbols.items[sym_index].st_info = 0;