forked from ziglang/zig
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C.zig
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C.zig
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const std = @import("std");
const mem = std.mem;
const assert = std.debug.assert;
const Allocator = std.mem.Allocator;
const Module = @import("../Module.zig");
const Compilation = @import("../Compilation.zig");
const fs = std.fs;
const codegen = @import("../codegen/c.zig");
const link = @import("../link.zig");
const trace = @import("../tracy.zig").trace;
const C = @This();
const Type = @import("../type.zig").Type;
pub const base_tag: link.File.Tag = .c;
pub const zig_h = @embedFile("C/zig.h");
base: link.File,
/// This linker backend does not try to incrementally link output C source code.
/// Instead, it tracks all declarations in this table, and iterates over it
/// in the flush function, stitching pre-rendered pieces of C code together.
decl_table: std.AutoArrayHashMapUnmanaged(*Module.Decl, void) = .{},
/// Per-declaration data. For functions this is the body, and
/// the forward declaration is stored in the FnBlock.
pub const DeclBlock = struct {
code: std.ArrayListUnmanaged(u8),
pub const empty: DeclBlock = .{
.code = .{},
};
};
/// Per-function data.
pub const FnBlock = struct {
fwd_decl: std.ArrayListUnmanaged(u8),
typedefs: codegen.TypedefMap.Unmanaged,
pub const empty: FnBlock = .{
.fwd_decl = .{},
.typedefs = .{},
};
};
pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Options) !*C {
assert(options.object_format == .c);
if (options.use_llvm) return error.LLVMHasNoCBackend;
if (options.use_lld) return error.LLDHasNoCBackend;
const file = try options.emit.?.directory.handle.createFile(sub_path, .{
// Truncation is done on `flush`.
.truncate = false,
.mode = link.determineMode(options),
});
errdefer file.close();
var c_file = try allocator.create(C);
errdefer allocator.destroy(c_file);
c_file.* = C{
.base = .{
.tag = .c,
.options = options,
.file = file,
.allocator = allocator,
},
};
return c_file;
}
pub fn deinit(self: *C) void {
for (self.decl_table.keys()) |key| {
deinitDecl(self.base.allocator, key);
}
self.decl_table.deinit(self.base.allocator);
}
pub fn allocateDeclIndexes(self: *C, decl: *Module.Decl) !void {
_ = self;
_ = decl;
}
pub fn freeDecl(self: *C, decl: *Module.Decl) void {
_ = self.decl_table.swapRemove(decl);
deinitDecl(self.base.allocator, decl);
}
fn deinitDecl(gpa: *Allocator, decl: *Module.Decl) void {
decl.link.c.code.deinit(gpa);
decl.fn_link.c.fwd_decl.deinit(gpa);
for (decl.fn_link.c.typedefs.values()) |value| {
gpa.free(value.rendered);
}
decl.fn_link.c.typedefs.deinit(gpa);
}
pub fn updateDecl(self: *C, module: *Module, decl: *Module.Decl) !void {
const tracy = trace(@src());
defer tracy.end();
// Keep track of all decls so we can iterate over them on flush().
_ = try self.decl_table.getOrPut(self.base.allocator, decl);
const fwd_decl = &decl.fn_link.c.fwd_decl;
const typedefs = &decl.fn_link.c.typedefs;
const code = &decl.link.c.code;
fwd_decl.shrinkRetainingCapacity(0);
{
for (typedefs.values()) |value| {
module.gpa.free(value.rendered);
}
}
typedefs.clearRetainingCapacity();
code.shrinkRetainingCapacity(0);
var object: codegen.Object = .{
.dg = .{
.module = module,
.error_msg = null,
.decl = decl,
.fwd_decl = fwd_decl.toManaged(module.gpa),
.typedefs = typedefs.promote(module.gpa),
},
.gpa = module.gpa,
.code = code.toManaged(module.gpa),
.value_map = codegen.CValueMap.init(module.gpa),
.indent_writer = undefined, // set later so we can get a pointer to object.code
};
object.indent_writer = .{ .underlying_writer = object.code.writer() };
defer {
object.value_map.deinit();
object.blocks.deinit(module.gpa);
object.code.deinit();
object.dg.fwd_decl.deinit();
for (object.dg.typedefs.values()) |value| {
module.gpa.free(value.rendered);
}
object.dg.typedefs.deinit();
}
codegen.genDecl(&object) catch |err| switch (err) {
error.AnalysisFail => {
try module.failed_decls.put(module.gpa, decl, object.dg.error_msg.?);
return;
},
else => |e| return e,
};
fwd_decl.* = object.dg.fwd_decl.moveToUnmanaged();
typedefs.* = object.dg.typedefs.unmanaged;
object.dg.typedefs.unmanaged = .{};
code.* = object.code.moveToUnmanaged();
// Free excess allocated memory for this Decl.
fwd_decl.shrinkAndFree(module.gpa, fwd_decl.items.len);
code.shrinkAndFree(module.gpa, code.items.len);
}
pub fn updateDeclLineNumber(self: *C, module: *Module, decl: *Module.Decl) !void {
// The C backend does not have the ability to fix line numbers without re-generating
// the entire Decl.
return self.updateDecl(module, decl);
}
pub fn flush(self: *C, comp: *Compilation) !void {
return self.flushModule(comp);
}
pub fn flushModule(self: *C, comp: *Compilation) !void {
const tracy = trace(@src());
defer tracy.end();
const module = self.base.options.module.?;
// This code path happens exclusively with -ofmt=c. The flush logic for
// emit-h is in `flushEmitH` below.
// We collect a list of buffers to write, and write them all at once with pwritev 😎
var all_buffers = std.ArrayList(std.os.iovec_const).init(comp.gpa);
defer all_buffers.deinit();
// This is at least enough until we get to the function bodies without error handling.
try all_buffers.ensureCapacity(self.decl_table.count() + 2);
var file_size: u64 = zig_h.len;
all_buffers.appendAssumeCapacity(.{
.iov_base = zig_h,
.iov_len = zig_h.len,
});
var err_typedef_buf = std.ArrayList(u8).init(comp.gpa);
defer err_typedef_buf.deinit();
const err_typedef_writer = err_typedef_buf.writer();
const err_typedef_item = all_buffers.addOneAssumeCapacity();
render_errors: {
if (module.global_error_set.size == 0) break :render_errors;
var it = module.global_error_set.iterator();
while (it.next()) |entry| {
try err_typedef_writer.print("#define zig_error_{s} {d}\n", .{ entry.key_ptr.*, entry.value_ptr.* });
}
try err_typedef_writer.writeByte('\n');
}
var fn_count: usize = 0;
var typedefs = std.HashMap(Type, void, Type.HashContext64, std.hash_map.default_max_load_percentage).init(comp.gpa);
defer typedefs.deinit();
// Typedefs, forward decls and non-functions first.
// TODO: performance investigation: would keeping a list of Decls that we should
// generate, rather than querying here, be faster?
for (self.decl_table.keys()) |decl| {
if (!decl.has_tv) continue;
const buf = buf: {
if (decl.val.castTag(.function)) |_| {
try typedefs.ensureUnusedCapacity(@intCast(u32, decl.fn_link.c.typedefs.count()));
var it = decl.fn_link.c.typedefs.iterator();
while (it.next()) |new| {
const gop = typedefs.getOrPutAssumeCapacity(new.key_ptr.*);
if (!gop.found_existing) {
try err_typedef_writer.writeAll(new.value_ptr.rendered);
}
}
fn_count += 1;
break :buf decl.fn_link.c.fwd_decl.items;
} else {
break :buf decl.link.c.code.items;
}
};
all_buffers.appendAssumeCapacity(.{
.iov_base = buf.ptr,
.iov_len = buf.len,
});
file_size += buf.len;
}
err_typedef_item.* = .{
.iov_base = err_typedef_buf.items.ptr,
.iov_len = err_typedef_buf.items.len,
};
file_size += err_typedef_buf.items.len;
// Now the function bodies.
try all_buffers.ensureCapacity(all_buffers.items.len + fn_count);
for (self.decl_table.keys()) |decl| {
if (!decl.has_tv) continue;
if (decl.val.castTag(.function)) |_| {
const buf = decl.link.c.code.items;
all_buffers.appendAssumeCapacity(.{
.iov_base = buf.ptr,
.iov_len = buf.len,
});
file_size += buf.len;
}
}
const file = self.base.file.?;
try file.setEndPos(file_size);
try file.pwritevAll(all_buffers.items, 0);
}
pub fn flushEmitH(module: *Module) !void {
const tracy = trace(@src());
defer tracy.end();
const emit_h = module.emit_h orelse return;
// We collect a list of buffers to write, and write them all at once with pwritev 😎
var all_buffers = std.ArrayList(std.os.iovec_const).init(module.gpa);
defer all_buffers.deinit();
try all_buffers.ensureCapacity(emit_h.decl_table.count() + 1);
var file_size: u64 = zig_h.len;
all_buffers.appendAssumeCapacity(.{
.iov_base = zig_h,
.iov_len = zig_h.len,
});
for (emit_h.decl_table.keys()) |decl| {
const decl_emit_h = decl.getEmitH(module);
const buf = decl_emit_h.fwd_decl.items;
all_buffers.appendAssumeCapacity(.{
.iov_base = buf.ptr,
.iov_len = buf.len,
});
file_size += buf.len;
}
const directory = emit_h.loc.directory orelse module.comp.local_cache_directory;
const file = try directory.handle.createFile(emit_h.loc.basename, .{
// We set the end position explicitly below; by not truncating the file, we possibly
// make it easier on the file system by doing 1 reallocation instead of two.
.truncate = false,
});
defer file.close();
try file.setEndPos(file_size);
try file.pwritevAll(all_buffers.items, 0);
}
pub fn updateDeclExports(
self: *C,
module: *Module,
decl: *Module.Decl,
exports: []const *Module.Export,
) !void {
_ = exports;
_ = decl;
_ = module;
_ = self;
}