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stage2: include enough inline asm support for more plan9 syscalls

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Also make the exit more correct by exiting 0 rather than random
stuff on the stack.
This commit is contained in:
Jacob G-W 2021-06-21 13:10:31 -04:00 committed by Andrew Kelley
parent f1aadfa77b
commit 1c2facaf6b
2 changed files with 44 additions and 6 deletions
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8
lib/std/start.zig
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@ -123,11 +123,15 @@ fn exit2(code: usize) noreturn {
},
else => @compileError("TODO"),
},
// exits(0)
.plan9 => switch (builtin.stage2_arch) {
.x86_64 => {
asm volatile ("syscall"
asm volatile (
\\push $0
\\push $0
\\syscall
:
: [number] "{rbp}" (8)
: [syscall_number] "{rbp}" (8)
: "rcx", "r11", "memory"
);
},

38
src/codegen.zig
View File

@ -3330,11 +3330,45 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
try self.genSetReg(inst.base.src, arg.ty, reg, arg_mcv);
}
if (mem.eql(u8, inst.asm_source, "syscall")) {
{
var iter = std.mem.tokenize(inst.asm_source, "\n\r");
while (iter.next()) |ins| {
if (mem.eql(u8, ins, "syscall")) {
try self.code.appendSlice(&[_]u8{ 0x0f, 0x05 });
} else if (inst.asm_source.len != 0) {
} else if (mem.indexOf(u8, ins, "push")) |_| {
const arg = ins[4..];
if (mem.indexOf(u8, arg, "$")) |l| {
const n = std.fmt.parseInt(u8, ins[4 + l + 1 ..], 10) catch return self.fail(inst.base.src, "TODO implement more inline asm int parsing", .{});
try self.code.appendSlice(&.{ 0x6a, n });
} else if (mem.indexOf(u8, arg, "%%")) |l| {
const reg_name = ins[4 + l + 2 ..];
const reg = parseRegName(reg_name) orelse
return self.fail(inst.base.src, "unrecognized register: '{s}'", .{reg_name});
const low_id: u8 = reg.low_id();
if (reg.isExtended()) {
try self.code.appendSlice(&.{ 0x41, 0b1010000 | low_id });
} else {
try self.code.append(0b1010000 | low_id);
}
} else return self.fail(inst.base.src, "TODO more push operands", .{});
} else if (mem.indexOf(u8, ins, "pop")) |_| {
const arg = ins[3..];
if (mem.indexOf(u8, arg, "%%")) |l| {
const reg_name = ins[3 + l + 2 ..];
const reg = parseRegName(reg_name) orelse
return self.fail(inst.base.src, "unrecognized register: '{s}'", .{reg_name});
const low_id: u8 = reg.low_id();
if (reg.isExtended()) {
try self.code.appendSlice(&.{ 0x41, 0b1011000 | low_id });
} else {
try self.code.append(0b1011000 | low_id);
}
} else return self.fail(inst.base.src, "TODO more pop operands", .{});
} else {
return self.fail(inst.base.src, "TODO implement support for more x86 assembly instructions", .{});
}
}
}
if (inst.output_constraint) |output| {
if (output.len < 4 or output[0] != '=' or output[1] != '{' or output[output.len - 1] != '}') {