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macho: require _main as global export in self-hosted

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Clean up type and description flags generation for exports
in self-hosted MachO backend.
This commit is contained in:
Jakub Konka 2021-05-14 11:46:50 +02:00
parent 8eea5eddf7
commit 00ebbe6df2
2 changed files with 32 additions and 15 deletions
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33
src/link/MachO.zig
View File

@ -1369,15 +1369,32 @@ pub fn updateDeclExports(
continue;
}
}
const n_desc = switch (exp.options.linkage) {
.Internal => macho.REFERENCE_FLAG_PRIVATE_DEFINED,
.Strong => blk: {
if (mem.eql(u8, exp.options.name, "_start")) {
var n_type: u8 = macho.N_SECT | macho.N_EXT;
var n_desc: u16 = 0;
switch (exp.options.linkage) {
.Internal => {
// Symbol should be hidden, or in MachO lingo, private extern.
// We should also mark the symbol as Weak: n_desc == N_WEAK_DEF.
// TODO work out when to add N_WEAK_REF.
n_type |= macho.N_PEXT;
n_desc |= macho.N_WEAK_DEF;
},
.Strong => {
// Check if the export is _main, and note if os.
// Otherwise, don't do anything since we already have all the flags
// set that we need for global (strong) linkage.
// n_type == N_SECT | N_EXT
if (mem.eql(u8, exp.options.name, "_main")) {
self.entry_addr = decl_sym.n_value;
}
break :blk macho.REFERENCE_FLAG_DEFINED;
},
.Weak => macho.N_WEAK_REF,
.Weak => {
// Weak linkage is specified as part of n_desc field.
// Symbol's n_type is like for a symbol with strong linkage.
n_desc |= macho.N_WEAK_DEF;
},
.LinkOnce => {
try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
module.failed_exports.putAssumeCapacityNoClobber(
@ -1386,8 +1403,8 @@ pub fn updateDeclExports(
);
continue;
},
};
const n_type = decl_sym.n_type | macho.N_EXT;
}
if (exp.link.macho.sym_index) |i| {
const sym = &self.globals.items[i];
sym.* = .{

14
test/stage2/darwin.zig
View File

@ -17,7 +17,7 @@ pub fn addCases(ctx: *TestContext) !void {
// Incorrect return type
case.addError(
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\}
, &[_][]const u8{":2:1: error: expected noreturn, found void"});
@ -26,7 +26,7 @@ pub fn addCases(ctx: *TestContext) !void {
\\extern "c" fn write(usize, usize, usize) usize;
\\extern "c" fn exit(usize) noreturn;
\\
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\ print();
\\
\\ exit(0);
@ -46,7 +46,7 @@ pub fn addCases(ctx: *TestContext) !void {
\\extern "c" fn write(usize, usize, usize) usize;
\\extern "c" fn exit(usize) noreturn;
\\
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\ print();
\\ print();
\\ print();
@ -73,7 +73,7 @@ pub fn addCases(ctx: *TestContext) !void {
\\extern "c" fn write(usize, usize, usize) usize;
\\extern "c" fn exit(usize) noreturn;
\\
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\ print();
\\
\\ exit(0);
@ -93,7 +93,7 @@ pub fn addCases(ctx: *TestContext) !void {
\\extern "c" fn write(usize, usize, usize) usize;
\\extern "c" fn exit(usize) noreturn;
\\
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\ print();
\\ print();
\\
@ -119,7 +119,7 @@ pub fn addCases(ctx: *TestContext) !void {
case.addCompareOutput(
\\extern "c" fn exit(usize) noreturn;
\\
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\ exit(0);
\\}
,
@ -130,7 +130,7 @@ pub fn addCases(ctx: *TestContext) !void {
\\extern "c" fn exit(usize) noreturn;
\\extern "c" fn write(usize, usize, usize) usize;
\\
\\export fn _start() noreturn {
\\export fn _main() noreturn {
\\ _ = write(1, @ptrToInt("Hey!\n"), 5);
\\ exit(0);
\\}