Select

src/bootstrap.zig

@@ -721,7 +721,7 @@ pub const Value = struct {
         int_from_enum: *Value,
         int_from_pointer: *Value,
         pointer_cast: *Value,
-        select,
+        select: Select,
         trap,
         truncate: *Value,
         va_start,
@@ -746,6 +746,13 @@ pub const Value = struct {
             va_copy,
             va_arg,
         };
+
+        const Select = struct {
+            condition: *Value,
+            true_value: *Value,
+            false_value: *Value,
+        };
+
         const VaArg = struct {
             list: *Value,
             type: *Type,
@@ -2556,6 +2563,31 @@ pub const Module = struct {
                     },
                 };
             },
+            .select => blk: {
+                module.skip_space();
+                module.expect_character(left_parenthesis);
+                module.skip_space();
+                const condition = module.parse_value(function, .{});
+                module.expect_character(',');
+                module.skip_space();
+                const true_value = module.parse_value(function, .{});
+                module.expect_character(',');
+                module.skip_space();
+                const false_value = module.parse_value(function, .{});
+                module.skip_space();
+                module.expect_character(right_parenthesis);
+                break :blk .{
+                    .bb = .{
+                    .intrinsic = .{
+                        .select = .{
+                            .condition = condition,
+                            .true_value = true_value,
+                            .false_value = false_value,
+                        },
+                    },
+                }
+                };
+            },
             .trap => blk: {
                 module.skip_space();
                 module.expect_character(left_parenthesis);
@@ -4848,6 +4880,11 @@ pub const Module = struct {
                         module.report_error();
                     }
                 },
+                .select => |select| {
+                    module.analyze_value_type(function, select.condition, .{});
+                    module.analyze_value_type(function, select.true_value, .{ .type = expected_type });
+                    module.analyze_value_type(function, select.false_value, .{ .type = expected_type });
+                },
                 .truncate => |value_to_truncate| {
                     module.analyze_value_type(function, value_to_truncate, .{});
                     if (expected_type.get_bit_size() >= value_to_truncate.type.?.get_bit_size()) {
@@ -5415,6 +5452,20 @@ pub const Module = struct {
                     module.emit_value(function, pointer_value);
                     break :blk pointer_value.llvm.?;
                 },
+                .select => |select| blk: {
+                    module.emit_value(function, select.condition);
+                    const condition = switch (select.condition.type.?.bb) {
+                        .integer => |integer| switch (integer.bit_count) {
+                            1 => select.condition.llvm.?,
+                            else => @trap(),
+                        },
+                        else => @trap(),
+                    };
+                    module.emit_value(function, select.true_value);
+                    module.emit_value(function, select.false_value);
+                    const result = module.llvm.builder.create_select(condition, select.true_value.llvm.?, select.false_value.llvm.?);
+                    break :blk result;
+                },
                 .trap => blk: {
                     // TODO: lookup in advance
                     const intrinsic_id = module.llvm.intrinsic_table.trap;

src/main.zig

@@ -227,4 +227,5 @@ const names = &[_][]const u8{
     "ret_c_bool",
     "return_type_builtin",
     "return_u64_u64",
+    "select",
 };