From b4dbf18d4a1d0cf2e3d32c232c8c408a660bbb96 Mon Sep 17 00:00:00 2001
From: David Gonzalez Martin <davidgm94.work@protonmail.com>
Date: Thu, 18 Apr 2024 13:25:03 -0600
Subject: [PATCH] Improve handling of block termination in switches

---
 bootstrap/Compilation.zig | 50 ++++++++++++++++++++++++++++++++++-----
 src/main.nat              | 34 +++++++++++++-------------
 2 files changed, 61 insertions(+), 23 deletions(-)

diff --git a/bootstrap/Compilation.zig b/bootstrap/Compilation.zig
index b381599..89d2fa2 100644
--- a/bootstrap/Compilation.zig
+++ b/bootstrap/Compilation.zig
@@ -14427,6 +14427,7 @@ pub const Builder = struct {
                 };
 
                 const before_switch_bb = builder.current_basic_block;
+                const switch_exit_block = try builder.newBasicBlock(unit, context);
 
                 for (case_nodes) |case_node_index| {
                     builder.current_basic_block = before_switch_bb;
@@ -14500,6 +14501,17 @@ pub const Builder = struct {
                             try phi_instruction.addIncoming(context, v, case_block);
                             try builder.jump(unit, context, phi.block);
                         }
+                    } else if (builder.current_basic_block != .null) {
+                        const current_block = unit.basic_blocks.get(builder.current_basic_block);
+                        const v_ty = unit.types.get(v.type); 
+                        switch (v_ty.*) {
+                            .void => {
+                                assert(!current_block.terminated);
+                                try builder.jump(unit, context, switch_exit_block);
+                            },
+                            .noreturn => {},
+                            else => |t| @panic(@tagName(t)),
+                        }
                     }
 
                     if (conditions.length > 0) {
@@ -14538,12 +14550,38 @@ pub const Builder = struct {
                     }
                 }
 
-                return V{
-                    .value = .{
-                        .@"comptime" = .void,
-                    },
-                    .type = .void,
-                };
+                if (builder.current_basic_block != .null) {
+                    const current_block = unit.basic_blocks.get(builder.current_basic_block);
+                    assert(current_block.terminated);
+                    const sw_exit_block = unit.basic_blocks.get(switch_exit_block);
+                    assert(current_block.terminated);
+                    if (sw_exit_block.predecessors.length > 0) {
+                        builder.current_basic_block = switch_exit_block;
+
+                        switch (type_expect) {
+                            .type => |ti| switch (ti) {
+                                .void => return V{
+                                    .value = .{
+                                        .@"comptime" = .void,
+                                    },
+                                    .type = .void,
+                                },
+                                else => unreachable,
+                            },
+                            else => |t| @panic(@tagName(t)),
+                        }
+                    } else {
+                        return V{
+                            .value = .{
+                                .@"comptime" = .@"unreachable",
+                            },
+                            .type = .noreturn,
+                        };
+                    }
+                } else {
+                    unreachable;
+                }
+
             },
             else => |t| @panic(@tagName(t)),
         }
diff --git a/src/main.nat b/src/main.nat
index 03a4ad0..65ecc93 100644
--- a/src/main.nat
+++ b/src/main.nat
@@ -39,25 +39,25 @@ const lex = fn (arena: &Arena, bytes: []const u8) *!void {
 
     index = 0;
 
-    //while (index < length) {
-    //    const start_index = index;
-    //    const start_character = bytes[index];
+    while (index < length) {
+        const start_index = index;
+        const start_character = bytes[index];
 
-    //    switch (start_character) {
-    //        'a'...'z', 'A'...'Z', '_' => {
-    //            while (true) {
-    //                const ch = bytes[index];
-    //                if ((ch >= 'a' and ch <= 'z') or (ch >= 'A' and ch <= 'Z') or ch == '_' or (ch >= '0' and ch <= '9')) {
-    //                    index += 1;
-    //                    continue;
-    //                }
+        switch (start_character) {
+            'a'...'z', 'A'...'Z', '_' => {
+                while (true) {
+                    const ch = bytes[index];
+                    if ((ch >= 'a' and ch <= 'z') or (ch >= 'A' and ch <= 'Z') or ch == '_' or (ch >= '0' and ch <= '9')) {
+                        index += 1;
+                        continue;
+                    }
 
-    //                break;
-    //            }
-    //        },
-    //        else => unreachable,
-    //    }
-    //}
+                    break;
+                }
+            },
+            else => index += 1,
+        }
+    }
 }
 
 const get_argument = fn (real_argument: []const u8, wanted_argument: []const u8, command_arguments: []const [&:0]const u8, i_ptr: &usize) ?[]const u8 {