From 25ecdc4aa217e2c9bd8877bd3d795ca776fe7b0c Mon Sep 17 00:00:00 2001
From: Hannes Bredberg <hannesbredberg@gmail.com>
Date: Thu, 5 Oct 2023 01:57:14 +0200
Subject: [PATCH] All: Split loop into loop (no condition) and while (with
 condition)

---
 bootstrap/ast.zig                | 16 ++++++++++------
 bootstrap/ir.zig                 | 31 ++++++++++++++++++++++++-------
 bootstrap/parser.zig             | 21 ++++++++++++++-------
 bootstrap/sema.zig               | 32 +++++++++++++++++++++++++-------
 bootstrap/tokenizer.zig          |  1 +
 selfhost/parser.n                |  6 +++---
 selfhost/tokenizer.n             | 16 ++++++++--------
 std/mem.n                        |  8 ++++----
 std/os.n                         |  6 +++---
 std/os/syscalls.n                |  4 ++--
 std/print.n                      |  2 +-
 std/string.n                     |  2 +-
 tests/loop_with_condition/main.n |  2 +-
 13 files changed, 97 insertions(+), 50 deletions(-)

diff --git a/bootstrap/ast.zig b/bootstrap/ast.zig
index 59c41ae..eff4d39 100644
--- a/bootstrap/ast.zig
+++ b/bootstrap/ast.zig
@@ -230,7 +230,10 @@ pub const StatementNode = struct {
             first_not_taken: StmtIndex.OptIndex,
         },
         loop_statement: struct {
-            condition: ExprIndex.OptIndex,
+            first_child: StmtIndex.OptIndex,
+        },
+        while_statement: struct {
+            condition: ExprIndex.Index,
             first_child: StmtIndex.OptIndex,
         },
         switch_statement: struct {
@@ -533,13 +536,14 @@ fn dumpNode(node: anytype, indent_level: usize) anyerror!void {
                     try dumpStatementChain(stmt.first_not_taken, indent_level);
                 }
             },
+            .while_statement => |stmt| {
+                std.debug.print("while (", .{});
+                try dumpNode(expressions.get(stmt.condition), indent_level);
+                std.debug.print(") ", .{});
+                try dumpStatementChain(stmt.first_child, indent_level);
+            },
             .loop_statement => |stmt| {
                 std.debug.print("loop ", .{});
-                if(ExprIndex.unwrap(stmt.condition)) |cond_idx| {
-                    std.debug.print("(", .{});
-                    try dumpNode(expressions.get(cond_idx), indent_level);
-                    std.debug.print(") ", .{});
-                }
                 try dumpStatementChain(stmt.first_child, indent_level);
             },
             .break_statement => |stmt| {
diff --git a/bootstrap/ir.zig b/bootstrap/ir.zig
index 1f1ff70..2a730be 100644
--- a/bootstrap/ir.zig
+++ b/bootstrap/ir.zig
@@ -1964,6 +1964,26 @@ const IRWriter = struct {
                     self.basic_block = if_exit;
                 },
                 .loop_statement => |loop| {
+                    const loop_enter_branch = try self.emit(.{.goto = undefined});
+                    const loop_body_entry = blocks.insert(.{});
+                    decls.get(loop_enter_branch).instr.goto = try addEdge(self.basic_block, loop_body_entry);
+                    try blocks.get(self.basic_block).filled();
+
+                    const exit_block = blocks.insert(.{});
+                    stmt.ir_block = BlockIndex.toOpt(exit_block);
+                    const loop_body_end = try self.writeBlockStatementIntoBlock(loop.body.first_stmt, loop_body_entry);
+                    try blocks.get(exit_block).seal();
+
+                    if(loop.body.reaches_end) {
+                        const loop_instr = try self.emit(.{.goto = undefined});
+                        decls.get(loop_instr).instr.goto = try addEdge(loop_body_end, loop_body_entry);
+                    }
+
+                    try blocks.get(loop_body_end).filled();
+                    try blocks.get(loop_body_entry).seal();
+                    self.basic_block = exit_block;
+                },
+                .while_statement => |loop| {
                     const original_bb = self.basic_block;
                     const loop_enter_branch = try self.emit(.{.goto = undefined});
                     try blocks.get(original_bb).filled();
@@ -1971,13 +1991,10 @@ const IRWriter = struct {
                     const loop_body_block = blocks.insert(.{});
                     const loop_exit_block = blocks.insert(.{});
 
-                    var loop_start_block = loop_body_block;
-                    if(sema.ValueIndex.unwrap(loop.condition)) |sema_cond_idx| {
-                        loop_start_block = blocks.insert(.{});
-                        self.basic_block = loop_start_block;
-                        try self.evaluateShortCircuitingValue(sema_cond_idx, loop_body_block, loop_exit_block);
-                        try blocks.get(loop_start_block).filled();
-                    }
+                    const loop_start_block = blocks.insert(.{});
+                    self.basic_block = loop_start_block;
+                    try self.evaluateShortCircuitingValue(loop.condition, loop_body_block, loop_exit_block);
+                    try blocks.get(loop_start_block).filled();
 
                     decls.get(loop_enter_branch).instr.goto = try addEdge(original_bb, loop_start_block);
                     stmt.ir_block = BlockIndex.toOpt(loop_exit_block);
diff --git a/bootstrap/parser.zig b/bootstrap/parser.zig
index 89a2cc0..d66bd05 100644
--- a/bootstrap/parser.zig
+++ b/bootstrap/parser.zig
@@ -239,15 +239,21 @@ fn parseStatement(self: *@This()) anyerror!ast.StmtIndex.Index {
         },
         .loop_keyword => {
             _ = try self.tokenize();
-            const condition = if ((try self.peekToken()) == .@"(_ch") blk: {
-                _ = try self.tokenize();
-                const res = try self.parseExpression(null);
-                _ = try self.expect(.@")_ch");
-                break :blk ast.ExprIndex.toOpt(res);
-            } else .none;
             const body = try self.parseBlockStatement();
             return ast.statements.insert(.{.value = .{
                 .loop_statement = .{
+                    .first_child = body,
+                },
+            }});
+        },
+        .while_keyword => {
+            _ = try self.tokenize();
+            _ = try self.expect(.@"(_ch");
+            const condition = try self.parseExpression(null);
+            _ = try self.expect(.@")_ch");
+            const body = try self.parseBlockStatement();
+            return ast.statements.insert(.{.value = .{
+                .while_statement = .{
                     .condition = condition,
                     .first_child = body,
                 },
@@ -356,6 +362,7 @@ fn parseExpression(self: *@This(), precedence_in: ?usize) anyerror!ast.ExprIndex
         .continue_keyword => @panic("TODO: Continue expressions"),
         .endcase_keyword => @panic("TODO: Endcase expressions"),
         .if_keyword => @panic("TODO: If expressions"),
+        .while_keyword => @panic("TODO: While expressions"),
         .loop_keyword => @panic("TODO: Loop expressions"),
         .switch_keyword => @panic("TODO: Switch expressions"),
         .unreachable_keyword => return .@"unreachable",
@@ -679,7 +686,7 @@ fn parseExpression(self: *@This(), precedence_in: ?usize) anyerror!ast.ExprIndex
             .@":_ch", .@"~_ch", .@"!_ch",
             .break_keyword, .case_keyword, .const_keyword, .continue_keyword,
             .else_keyword, .endcase_keyword, .enum_keyword, .fn_keyword,
-            .if_keyword, .loop_keyword, .return_keyword, .struct_keyword,
+            .if_keyword, .loop_keyword, .while_keyword, .return_keyword, .struct_keyword,
             .switch_keyword, .var_keyword, .volatile_keyword, .__keyword, .bool_keyword,
             .type_keyword, .void_keyword, .anyopaque_keyword,
             .end_of_file, .true_keyword, .false_keyword, .undefined_keyword, .comptime_keyword,
diff --git a/bootstrap/sema.zig b/bootstrap/sema.zig
index 5660143..ec88a9c 100644
--- a/bootstrap/sema.zig
+++ b/bootstrap/sema.zig
@@ -523,19 +523,33 @@ fn analyzeStatementChain(
                 const body_scope = scopes.insert(.{
                     .outer_scope = ScopeIndex.toOpt(block_scope_idx),
                 });
-                const condition = if(ast.ExprIndex.unwrap(loop.condition)) |loop_cond_idx| blk: {
-                    break :blk ValueIndex.toOpt(try semaASTExpr(block_scope_idx, loop_cond_idx, false, .bool, null));
-                } else .none;
-                const loop_stmt_idx = stmt_builder.insert(.{.value = .{.loop_statement = .{.condition = condition, .body = undefined, .breaks = false}}});
+                const loop_stmt_idx = stmt_builder.insert(.{.value = .{.loop_statement = .{.body = undefined, .breaks = false}}});
                 const body = try analyzeStatementChain(body_scope, loop.first_child, return_type, StatementIndex.toOpt(loop_stmt_idx));
                 const loop_stmt = statements.get(loop_stmt_idx);
                 loop_stmt.value.loop_statement.body = body;
-                reaches_end = loop_stmt.value.loop_statement.breaks or condition != .none;
+                reaches_end = loop_stmt.value.loop_statement.breaks;
+            },
+            .while_statement => |loop| {
+                const body_scope = scopes.insert(.{
+                    .outer_scope = ScopeIndex.toOpt(block_scope_idx),
+                });
+                const condition = try semaASTExpr(block_scope_idx, loop.condition, false, .bool, null);
+                const while_stmt_idx = stmt_builder.insert(.{.value = .{.while_statement = .{.condition = condition, .body = undefined, .breaks = false}}});
+                const body = try analyzeStatementChain(body_scope, loop.first_child, return_type, StatementIndex.toOpt(while_stmt_idx));
+                statements.get(while_stmt_idx).value.while_statement.body = body;
+                reaches_end = true;
             },
             .break_statement => {
                 if(StatementIndex.unwrap(current_break_block)) |break_block| {
                     reaches_end = false;
-                    statements.get(break_block).value.loop_statement.breaks = true;
+                    switch(statements.get(break_block).value) {
+                        inline
+                        .loop_statement, .while_statement
+                        => |*stmt| {
+                            stmt.breaks = true;
+                        },
+                        else => unreachable,
+                    }
                     _ = stmt_builder.insert(.{.value = .{.break_statement = break_block}});
                 } else {
                     return error.BreakOutsideLoop;
@@ -2446,8 +2460,12 @@ pub const Statement = struct {
             taken: Block,
             not_taken: Block,
         },
+        while_statement: struct {
+            condition: ValueIndex.Index,
+            body: Block,
+            breaks: bool,
+        },
         loop_statement: struct {
-            condition: ValueIndex.OptIndex,
             body: Block,
             breaks: bool,
         },
diff --git a/bootstrap/tokenizer.zig b/bootstrap/tokenizer.zig
index aae854e..1c55ad4 100644
--- a/bootstrap/tokenizer.zig
+++ b/bootstrap/tokenizer.zig
@@ -120,6 +120,7 @@ pub const Token = union(enum) {
     unreachable_keyword,
     var_keyword,
     volatile_keyword,
+    while_keyword,
     __keyword,
 
 
diff --git a/selfhost/parser.n b/selfhost/parser.n
index ea54c8d..e103c39 100644
--- a/selfhost/parser.n
+++ b/selfhost/parser.n
@@ -183,7 +183,7 @@ fn parse_statement(context: *ParserContext) u32 {
 
 fn parse_block_body(context: *ParserContext) u32 {
     var stmts = builder.Builder{};
-    loop(context.peek() != .@"}") {
+    while(context.peek() != .@"}") {
         stmts.add(parse_statement(context), node_next.ptr());
     }
     return stmts.head;
@@ -199,7 +199,7 @@ fn parse_block(context: *ParserContext) u32 {
 fn parse_function_expression(context: *ParserContext) u32 {
     context.expect("Expected '(' before parameter list".&, .@"(");
     var stmt_builder = builder.Builder{};
-    loop(context.peek() != .@")") {
+    while(context.peek() != .@")") {
         if(context.peek() == .comptime_keyword) {
             context.advance();
         }
@@ -374,7 +374,7 @@ fn parse_primary_with_postfix(context: *ParserContext, require: bool, precedence
         else if(p == .@"(") {
             result = context.add_advance(.function_call);
             var argument_builder = builder.Builder{};
-            loop(context.peek() != .@")") {
+            while(context.peek() != .@")") {
                 argument_builder.add(parse_expression(context), node_next.ptr());
                 if(context.peek() == .@",") {
                     context.advance();
diff --git a/selfhost/tokenizer.n b/selfhost/tokenizer.n
index 209a8da..452c43e 100644
--- a/selfhost/tokenizer.n
+++ b/selfhost/tokenizer.n
@@ -190,17 +190,17 @@ fn init() void {
 
     {
         var ch: u32 = 0;
-        loop(ch <= 0xFF) {
+        while(ch <= 0xFF) {
             is_ident_char[ch] = false;
             ch += 1;
         }
         ch = 'a';
-        loop(ch <= 'z') {
+        while(ch <= 'z') {
             is_ident_char[ch] = true;
             ch += 1;
         }
         ch = 'A';
-        loop(ch <= 'Z') {
+        while(ch <= 'Z') {
             is_ident_char[ch] = true;
             ch += 1;
         }
@@ -324,22 +324,22 @@ fn init() void {
 
     {
         var ch: u32 = 0;
-        loop(ch <= 0xFF) {
+        while(ch <= 0xFF) {
             digit_value[ch] = 0xFF;
             ch += 1;
         }
         ch = '0';
-        loop(ch <= '9') {
+        while(ch <= '9') {
             digit_value[ch] = @truncate(u8, ch) - '0';
             ch += 1;
         }
         ch = 'a';
-        loop(ch <= 'f') {
+        while(ch <= 'f') {
             digit_value[ch] = @truncate(u8, ch) - 'a';
             ch += 1;
         }
         ch = 'A';
-        loop(ch <= 'F') {
+        while(ch <= 'F') {
             digit_value[ch] = @truncate(u8, ch) - 'A';
             ch += 1;
         }
@@ -359,7 +359,7 @@ fn init() void {
                 base = 2;
             }
         }
-        loop(digit_value[context.peek(0)] < base) {
+        while(digit_value[context.peek(0)] < base) {
             context.advance(1);
         }
     }.&);
diff --git a/std/mem.n b/std/mem.n
index 9686825..86da0ce 100644
--- a/std/mem.n
+++ b/std/mem.n
@@ -13,7 +13,7 @@ fn swap(comptime T: type, a: *T, b: *T) inline void {
 }
 
 fn reverse_range(comptime T: type, beg: *T, end: *T) void {
-    loop(beg < end) {
+    while(beg < end) {
         swap_no_check_equal(T, beg, end);
         beg += 1;
         end -= 1;
@@ -26,7 +26,7 @@ fn reverse(comptime T: type, ptr: *T, len: u64) inline void {
 
 fn copy(dest: *u8, src: *const u8, len: u64) void {
     var offset: u64 = 0;
-    loop(offset < len) {
+    while(offset < len) {
         dest[offset] = src[offset];
         offset += 1;
     }
@@ -34,7 +34,7 @@ fn copy(dest: *u8, src: *const u8, len: u64) void {
 
 fn set(dest: *u8, value: u8, len: u64) void {
     var offset: u64 = 0;
-    loop(offset < len) {
+    while(offset < len) {
         dest[offset] = value;
         offset += 1;
     }
@@ -54,7 +54,7 @@ fn zeroes(comptime T: type, comptime len: u64) inline |out_buf| [len]T {
 
 fn equals(comptime T: type, lhs: *const T, rhs: *const T, len: u64) bool {
     var i: u64 = 0;
-    loop(i < len) {
+    while(i < len) {
         if(lhs[i] != rhs[i]) {
             return false;
         }
diff --git a/std/os.n b/std/os.n
index 1ac9763..59ed3dc 100644
--- a/std/os.n
+++ b/std/os.n
@@ -21,21 +21,21 @@ fn dir_name(path: *const u8) |out_buf| [MAX_PATH]u8 {
         return;
     }
     var i = string.len(path) - 1;
-    loop(path[i] == '/') {
+    while(path[i] == '/') {
         i -= 1;
     }
     if(i == 0) {
         std.mem.copy(@int_to_ptr(*u8, @ptr_to_int(out_buf)), "/".&, 2);
         return;
     }
-    loop(path[i] != '/') {
+    while(path[i] != '/') {
         i -= 1;
     }
     if(i == 0) {
         std.mem.copy(@int_to_ptr(*u8, @ptr_to_int(out_buf)), ".".&, 2);
         return;
     }
-    loop(path[i] == '/') {
+    while(path[i] == '/') {
         i -= 1;
     }
     std.mem.copy(@int_to_ptr(*u8, @ptr_to_int(out_buf)), path, i + 1);
diff --git a/std/os/syscalls.n b/std/os/syscalls.n
index 2c7e177..ee76903 100644
--- a/std/os/syscalls.n
+++ b/std/os/syscalls.n
@@ -21,7 +21,7 @@ fn read(fd: u32, buf: *u8, size: u64) inline u64 {
 }
 
 fn read_all(fd: u32, buf: *u8, size: u64) u64 {
-    loop(size > 0) {
+    while(size > 0) {
         const bytes_read = read(fd, buf, size);
         size -= bytes_read;
         buf += bytes_read;
@@ -33,7 +33,7 @@ fn write(fd: u32, buf: *const u8, size: u64) inline u64 {
 }
 
 fn write_all(fd: u32, buf: *const u8, size: u64) void {
-    loop(size > 0) {
+    while(size > 0) {
         const written = write(fd, buf, size);
         size -= written;
         buf += written;
diff --git a/std/print.n b/std/print.n
index db889b2..5c82cde 100644
--- a/std/print.n
+++ b/std/print.n
@@ -45,7 +45,7 @@ fn log_hex_upper(s: *const u8, value: u64) void {
 }
 
 fn str(s: *const u8) void {
-    loop(s.* != 0) {
+    while(s.* != 0) {
         char(s.*);
         s += 1;
     }
diff --git a/std/string.n b/std/string.n
index 31ac884..e4c571b 100644
--- a/std/string.n
+++ b/std/string.n
@@ -20,7 +20,7 @@ fn write_u32_decimal(value: u32) inline |out_buf| [11]u8 {
 
 fn len(string: *const u8) u64 {
     var result: u64 = 0;
-    loop(string[result] != 0) {
+    while(string[result] != 0) {
         result += 1;
     }
     return result;
diff --git a/tests/loop_with_condition/main.n b/tests/loop_with_condition/main.n
index 3e42acd..ec68671 100644
--- a/tests/loop_with_condition/main.n
+++ b/tests/loop_with_condition/main.n
@@ -3,7 +3,7 @@ const test_lib = @import("../test_lib.n");
 
 fn main() noreturn {
     var i: u32 = 0;
-    loop(i < 10) {
+    while(i < 10) {
         std.print.unsigned_decimal(i);
         i += 1;
     }