From 08154c0deb653e016d6eb285c85094048eeded89 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Mon, 13 Jul 2020 00:28:11 -0700
Subject: [PATCH] stage2: add retvoid support to CBE

---
 src-self-hosted/Module.zig                  |  5 +++--
 src-self-hosted/{cgen.zig => codegen/c.zig} | 15 ++++++++-------
 src-self-hosted/link.zig                    |  4 ++--
 test/stage2/cbe.zig                         |  1 +
 4 files changed, 14 insertions(+), 11 deletions(-)
 rename src-self-hosted/{cgen.zig => codegen/c.zig} (95%)

diff --git a/src-self-hosted/Module.zig b/src-self-hosted/Module.zig
index 03307ab96d..975158c477 100644
--- a/src-self-hosted/Module.zig
+++ b/src-self-hosted/Module.zig
@@ -1210,8 +1210,9 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
 
                 try self.astGenBlock(&gen_scope.base, body_block);
 
-                const last_inst = gen_scope.instructions.items[gen_scope.instructions.items.len - 1];
-                if (!last_inst.tag.isNoReturn()) {
+                if (!fn_type.fnReturnType().isNoReturn() and (gen_scope.instructions.items.len == 0 or
+                    !gen_scope.instructions.items[gen_scope.instructions.items.len - 1].tag.isNoReturn()))
+                {
                     const src = tree.token_locs[body_block.rbrace].start;
                     _ = try self.addZIRInst(&gen_scope.base, src, zir.Inst.ReturnVoid, .{}, .{});
                 }
diff --git a/src-self-hosted/cgen.zig b/src-self-hosted/codegen/c.zig
similarity index 95%
rename from src-self-hosted/cgen.zig
rename to src-self-hosted/codegen/c.zig
index 91dc4a81a4..ebc4ff7e1a 100644
--- a/src-self-hosted/cgen.zig
+++ b/src-self-hosted/codegen/c.zig
@@ -1,11 +1,11 @@
-const link = @import("link.zig");
-const Module = @import("Module.zig");
-
 const std = @import("std");
 
-const Inst = @import("ir.zig").Inst;
-const Value = @import("value.zig").Value;
-const Type = @import("type.zig").Type;
+const link = @import("../link.zig");
+const Module = @import("../Module.zig");
+
+const Inst = @import("../ir.zig").Inst;
+const Value = @import("../value.zig").Value;
+const Type = @import("../type.zig").Type;
 
 const C = link.File.C;
 const Decl = Module.Decl;
@@ -95,7 +95,8 @@ fn genFn(file: *C, decl: *Decl) !void {
                 .assembly => try genAsm(file, inst.cast(Inst.Assembly).?, decl),
                 .call => try genCall(file, inst.cast(Inst.Call).?, decl),
                 .ret => try genRet(file, inst.cast(Inst.Ret).?, decl, tv.ty.fnReturnType()),
-                else => |e| return file.fail(decl.src(), "TODO {}", .{e}),
+                .retvoid => try file.main.writer().print("return;", .{}),
+                else => |e| return file.fail(decl.src(), "TODO implement C codegen for {}", .{e}),
             }
         }
         try writer.writeAll("\n");
diff --git a/src-self-hosted/link.zig b/src-self-hosted/link.zig
index 64328d4df5..776f6de31c 100644
--- a/src-self-hosted/link.zig
+++ b/src-self-hosted/link.zig
@@ -7,7 +7,7 @@ const Module = @import("Module.zig");
 const fs = std.fs;
 const elf = std.elf;
 const codegen = @import("codegen.zig");
-const cgen = @import("cgen.zig");
+const c_codegen = @import("codegen/c.zig");
 
 const default_entry_addr = 0x8000000;
 
@@ -259,7 +259,7 @@ pub const File = struct {
         }
 
         pub fn updateDecl(self: *File.C, module: *Module, decl: *Module.Decl) !void {
-            cgen.generate(self, decl) catch |err| {
+            c_codegen.generate(self, decl) catch |err| {
                 if (err == error.CGenFailure) {
                     try module.failed_decls.put(module.gpa, decl, self.error_msg);
                 }
diff --git a/test/stage2/cbe.zig b/test/stage2/cbe.zig
index e642489b01..e817029b83 100644
--- a/test/stage2/cbe.zig
+++ b/test/stage2/cbe.zig
@@ -62,6 +62,7 @@ pub fn addCases(ctx: *TestContext) !void {
         \\	register size_t rax_constant __asm__("rax") = 231;
         \\	register size_t rdi_constant __asm__("rdi") = 0;
         \\	__asm volatile ("syscall" :: ""(rax_constant), ""(rdi_constant));
+        \\	return;
         \\}
         \\
     );