stage2: progress towards Block and CondBr codegen

src-self-hosted/Module.zig

@@ -2545,18 +2545,6 @@ fn analyzeInstBlock(self: *Module, scope: *Scope, inst: *zir.Inst.Block) InnerEr
     assert(child_block.instructions.items.len != 0);
     assert(child_block.instructions.items[child_block.instructions.items.len - 1].tag.isNoReturn());
 
-    if (label.results.items.len <= 1) {
-        // No need to add the Block instruction; we can add the instructions to the parent block directly.
-        // Blocks are terminated with a noreturn instruction which we do not want to include.
-        const instrs = child_block.instructions.items;
-        try parent_block.instructions.appendSlice(self.gpa, instrs[0 .. instrs.len - 1]);
-        if (label.results.items.len == 1) {
-            return label.results.items[0];
-        } else {
-            return self.constNoReturn(scope, inst.base.src);
-        }
-    }
-
     // Need to set the type and emit the Block instruction. This allows machine code generation
     // to emit a jump instruction to after the block when it encounters the break.
     try parent_block.instructions.append(self.gpa, &block_inst.base);
@@ -2579,7 +2567,10 @@ fn analyzeInstBreakVoid(self: *Module, scope: *Scope, inst: *zir.Inst.BreakVoid)
         if (block.label) |*label| {
             if (mem.eql(u8, label.name, label_name)) {
                 try label.results.append(self.gpa, void_inst);
-                return self.constNoReturn(scope, inst.base.src);
+                const b = try self.requireRuntimeBlock(scope, inst.base.src);
+                return self.addNewInstArgs(b, inst.base.src, Type.initTag(.noreturn), Inst.BreakVoid, .{
+                    .block = label.block_inst,
+                });
             }
         }
         opt_block = block.parent;
@@ -3366,6 +3357,8 @@ fn makeIntType(self: *Module, scope: *Scope, signed: bool, bits: u16) !Type {
 fn resolvePeerTypes(self: *Module, scope: *Scope, instructions: []*Inst) !Type {
     if (instructions.len == 0)
         return Type.initTag(.noreturn);
+    if (instructions.len == 1)
+        return instructions[0].ty;
     return self.fail(scope, instructions[0].src, "TODO peer type resolution", .{});
 }
 

src-self-hosted/codegen.zig

@@ -218,6 +218,11 @@ pub fn generateSymbol(
     }
 }
 
+const InnerError = error {
+    OutOfMemory,
+    CodegenFail,
+};
+
 const Function = struct {
     gpa: *Allocator,
     bin_file: *link.ElfFile,
@@ -379,8 +384,12 @@ const Function = struct {
     }
 
     fn genArch(self: *Function, comptime arch: std.Target.Cpu.Arch) !void {
+        return self.genBody(self.mod_fn.analysis.success, arch);
+    }
+
+    fn genBody(self: *Function, body: ir.Body, comptime arch: std.Target.Cpu.Arch) InnerError!void {
         const inst_table = &self.branch_stack.items[0].inst_table;
-        for (self.mod_fn.analysis.success.instructions) |inst| {
+        for (body.instructions) |inst| {
             const new_inst = try self.genFuncInst(inst, arch);
             try inst_table.putNoClobber(self.gpa, inst, new_inst);
         }
@@ -394,6 +403,7 @@ const Function = struct {
             .bitcast => return self.genBitCast(inst.cast(ir.Inst.BitCast).?),
             .block => return self.genBlock(inst.cast(ir.Inst.Block).?, arch),
             .breakpoint => return self.genBreakpoint(inst.src, arch),
+            .breakvoid => return self.genBreakVoid(inst.cast(ir.Inst.BreakVoid).?, arch),
             .call => return self.genCall(inst.cast(ir.Inst.Call).?, arch),
             .cmp => return self.genCmp(inst.cast(ir.Inst.Cmp).?, arch),
             .condbr => return self.genCondBr(inst.cast(ir.Inst.CondBr).?, arch),
@@ -686,9 +696,16 @@ const Function = struct {
     }
 
     fn genBlock(self: *Function, inst: *ir.Inst.Block, comptime arch: std.Target.Cpu.Arch) !MCValue {
+        // A block is nothing but a setup to be able to jump to the end.
+        try self.genBody(inst.args.body, arch);
+        return self.fail(inst.base.src, "TODO process jump relocs after block end", .{});
+    }
+
+    fn genBreakVoid(self: *Function, inst: *ir.Inst.BreakVoid, comptime arch: std.Target.Cpu.Arch) !MCValue {
         switch (arch) {
-            else => return self.fail(inst.base.src, "TODO implement codegen Block for {}", .{self.target.cpu.arch}),
+            else => return self.fail(inst.base.src, "TODO implement breakvoid for {}", .{self.target.cpu.arch}),
         }
+        return .none;
     }
 
     fn genAsm(self: *Function, inst: *ir.Inst.Assembly, comptime arch: Target.Cpu.Arch) !MCValue {

src-self-hosted/ir.zig

@@ -35,6 +35,10 @@ pub const Inst = struct {
         return @truncate(u1, self.deaths << index) != 0;
     }
 
+    pub fn specialOperandDeaths(self: Inst) bool {
+        return (self.deaths & 0b1000_0000) != 0;
+    }
+
     pub const Tag = enum {
         add,
         arg,
@@ -42,6 +46,7 @@ pub const Inst = struct {
         bitcast,
         block,
         breakpoint,
+        breakvoid,
         call,
         cmp,
         condbr,
@@ -74,6 +79,7 @@ pub const Inst = struct {
                 .sub,
                 => false,
 
+                .breakvoid,
                 .condbr,
                 .ret,
                 .retvoid,
@@ -159,6 +165,14 @@ pub const Inst = struct {
         args: void,
     };
 
+    pub const BreakVoid = struct {
+        pub const base_tag = Tag.breakvoid;
+        base: Inst,
+        args: struct {
+            block: *Block,
+        },
+    };
+
     pub const Call = struct {
         pub const base_tag = Tag.call;
         base: Inst,

src-self-hosted/zir.zig

@@ -1608,6 +1608,22 @@ const EmitZIR = struct {
                     break :blk &new_inst.base;
                 },
                 .breakpoint => try self.emitTrivial(inst.src, Inst.Breakpoint),
+                .breakvoid => blk: {
+                    const old_inst = inst.cast(ir.Inst.BreakVoid).?;
+                    const new_block = inst_table.get(&old_inst.args.block.base).?;
+                    const new_inst = try self.arena.allocator.create(Inst.BreakVoid);
+                    new_inst.* = .{
+                        .base = .{
+                            .src = inst.src,
+                            .tag = Inst.BreakVoid.base_tag,
+                        },
+                        .positionals = .{
+                            .label = new_block.cast(Inst.Block).?.positionals.label,
+                        },
+                        .kw_args = .{},
+                    };
+                    break :blk &new_inst.base;
+                },
                 .call => blk: {
                     const old_inst = inst.cast(ir.Inst.Call).?;
                     const new_inst = try self.arena.allocator.create(Inst.Call);