Commit 91c3206b45074821749f52043937bf6ed6d9a105 | zig

author	Jakub Konka <kubkon@jakubkonka.com> 2021-11-09 16:56:36+01:00
committer	Andrew Kelley <andrew@ziglang.org> 2021-11-10 11:33:24-05:00
log	91c3206b45074821749f52043937bf6ed6d9a105
tree	5d6d674d146e4189bc22865bed42dea0f9ada320
parent	b521510cd4e68407226dd95c9e87cc97ca5a0796

macho: use start.zig for macOS entrypoint

This effectively allows us to compile

```zig
pub fn main() void {}
```

which then calls into `std.start`.

Changes required to make this happen:
* handle signed int to immediate in x86_64 and aarch64 codegen
* ensure that on arm64 macOS, `.x19` is a caller-preserved register -
  I'm not sure about that one at all and would like to brainstorm it
  with anyone interested and especially Joachim.
* finally, fix a bug in the linker - mark new got entry as dirty upon
  atom growth.

5 files changed, 40 insertions(+), 15 deletions(-)

src
- arch
  - aarch64
    CodeGen.zig
    bits.zig
  - x86_64
    CodeGen.zig
- link
  - MachO.zig
test
- stage2
  - darwin.zig

src/arch/aarch64/CodeGen.zig+3

...	...	@@ -2393,6 +2393,9 @@ fn genTypedValue(self: *Self, typed_value: TypedValue) InnerError!MCValue {
2393	2393	},
2394	2394	.Int => {
2395	2395	const info = typed_value.ty.intInfo(self.target.*);
	2396	if (info.bits <= ptr_bits and info.signedness == .signed) {
	2397	return MCValue{ .immediate = @bitCast(u64, typed_value.val.toSignedInt()) };
	2398	}
2396	2399	if (info.bits > ptr_bits or info.signedness == .signed) {
2397	2400	return self.fail("TODO const int bigger than ptr and signed int", .{});
2398	2401	}

src/arch/aarch64/bits.zig+13-3

...	...	@@ -1,4 +1,5 @@
1	1	const std = @import("std");
	2	const builtin = @import("builtin");
2	3	const DW = std.dwarf;
3	4	const assert = std.debug.assert;
4	5	const testing = std.testing;
...	...	@@ -58,10 +59,19 @@ pub const Register = enum(u6) {
58	59
59	60	// zig fmt: on
60	61
61		pub const callee_preserved_regs = [_]Register{
62		.x19, .x20, .x21, .x22, .x23,
63		.x24, .x25, .x26, .x27, .x28,
	62	const callee_preserved_regs_impl = if (builtin.os.tag.isDarwin()) struct {
	63	pub const callee_preserved_regs = [_]Register{
	64	.x20, .x21, .x22, .x23,
	65	.x24, .x25, .x26, .x27,
	66	.x28,
	67	};
	68	} else struct {
	69	pub const callee_preserved_regs = [_]Register{
	70	.x19, .x20, .x21, .x22, .x23,
	71	.x24, .x25, .x26, .x27, .x28,
	72	};
64	73	};
	74	pub const callee_preserved_regs = callee_preserved_regs_impl.callee_preserved_regs;
65	75
66	76	pub const c_abi_int_param_regs = [_]Register{ .x0, .x1, .x2, .x3, .x4, .x5, .x6, .x7 };
67	77	pub const c_abi_int_return_regs = [_]Register{ .x0, .x1, .x2, .x3, .x4, .x5, .x6, .x7 };

src/arch/x86_64/CodeGen.zig+3

...	...	@@ -3178,6 +3178,9 @@ fn genTypedValue(self: *Self, typed_value: TypedValue) InnerError!MCValue {
3178	3178	},
3179	3179	.Int => {
3180	3180	const info = typed_value.ty.intInfo(self.target.*);
	3181	if (info.bits <= ptr_bits and info.signedness == .signed) {
	3182	return MCValue{ .immediate = @bitCast(u64, typed_value.val.toSignedInt()) };
	3183	}
3181	3184	if (info.bits > ptr_bits or info.signedness == .signed) {
3182	3185	return self.fail("TODO const int bigger than ptr and signed int", .{});
3183	3186	}

src/link/MachO.zig+1

...	...	@@ -3285,6 +3285,7 @@ fn placeDecl(self: MachO, decl: Module.Decl, code_len: usize) !*macho.nlist_64
3285	3285	.seg = self.data_const_segment_cmd_index.?,
3286	3286	.sect = self.got_section_index.?,
3287	3287	}).? + 1);
	3288	got_atom.dirty = true;
3288	3289	}
3289	3290
3290	3291	symbol.n_value = vaddr;

test/stage2/darwin.zig+20-12

...	...	@@ -45,18 +45,32 @@ pub fn addCases(ctx: *TestContext) !void {
45	45	"Hello, World!\n",
46	46	);
47	47
	48	// Now using start.zig without an explicit extern exit fn
	49	case.addCompareOutput(
	50	\\extern fn write(usize, usize, usize) usize;
	51	\\
	52	\\pub fn main() void {
	53	\\ print();
	54	\\}
	55	\\
	56	\\fn print() void {
	57	\\ const msg = @ptrToInt("Hello, World!\n");
	58	\\ const len = 14;
	59	\\ _ = write(1, msg, len);
	60	\\}
	61	,
	62	"Hello, World!\n",
	63	);
	64
48	65	// Print it 4 times and force growth and realloc.
49	66	case.addCompareOutput(
50	67	\\extern fn write(usize, usize, usize) usize;
51		\\extern fn exit(usize) noreturn;
52	68	\\
53		\\pub export fn main() noreturn {
	69	\\pub fn main() void {
54	70	\\ print();
55	71	\\ print();
56	72	\\ print();
57	73	\\ print();
58		\\
59		\\ exit(0);
60	74	\\}
61	75	\\
62	76	\\fn print() void {
...	...	@@ -75,12 +89,9 @@ pub fn addCases(ctx: *TestContext) !void {
75	89	// Print it once, and change the message.
76	90	case.addCompareOutput(
77	91	\\extern fn write(usize, usize, usize) usize;
78		\\extern fn exit(usize) noreturn;
79	92	\\
80		\\pub export fn main() noreturn {
	93	\\pub fn main() void {
81	94	\\ print();
82		\\
83		\\ exit(0);
84	95	\\}
85	96	\\
86	97	\\fn print() void {
...	...	@@ -95,13 +106,10 @@ pub fn addCases(ctx: *TestContext) !void {
95	106	// Now we print it twice.
96	107	case.addCompareOutput(
97	108	\\extern fn write(usize, usize, usize) usize;
98		\\extern fn exit(usize) noreturn;
99	109	\\
100		\\pub export fn main() noreturn {
	110	\\pub fn main() void {
101	111	\\ print();
102	112	\\ print();
103		\\
104		\\ exit(0);
105	113	\\}
106	114	\\
107	115	\\fn print() void {