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const std = @import("std");
const link = @import("../link.zig");
const Module = @import("../Module.zig");
const Inst = @import("../ir.zig").Inst;
const Value = @import("../value.zig").Value;
const Type = @import("../type.zig").Type;
const C = link.File.C;
const Decl = Module.Decl;
const mem = std.mem;
/// Maps a name from Zig source to C. This will always give the same output for
/// any given input.
fn map(allocator: *std.mem.Allocator, name: []const u8) ![]const u8 {
return allocator.dupe(u8, name);
}
fn renderType(file: *C, writer: std.ArrayList(u8).Writer, T: Type, src: usize) !void {
if (T.tag() == .usize) {
file.need_stddef = true;
try writer.writeAll("size_t");
} else {
switch (T.zigTypeTag()) {
.NoReturn => {
file.need_noreturn = true;
try writer.writeAll("noreturn void");
},
.Void => try writer.writeAll("void"),
.Int => {
if (T.tag() == .u8) {
file.need_stdint = true;
try writer.writeAll("uint8_t");
} else {
return file.fail(src, "TODO implement int types", .{});
}
},
else => |e| return file.fail(src, "TODO implement type {}", .{e}),
}
}
}
fn renderFunctionSignature(file: *C, writer: std.ArrayList(u8).Writer, decl: *Decl) !void {
const tv = decl.typed_value.most_recent.typed_value;
try renderType(file, writer, tv.ty.fnReturnType(), decl.src());
const name = try map(file.allocator, mem.spanZ(decl.name));
defer file.allocator.free(name);
try writer.print(" {}(", .{name});
if (tv.ty.fnParamLen() == 0)
try writer.writeAll("void)")
else
return file.fail(decl.src(), "TODO implement parameters", .{});
}
pub fn generate(file: *C, decl: *Decl) !void {
switch (decl.typed_value.most_recent.typed_value.ty.zigTypeTag()) {
.Fn => try genFn(file, decl),
.Array => try genArray(file, decl),
else => |e| return file.fail(decl.src(), "TODO {}", .{e}),
}
}
fn genArray(file: *C, decl: *Decl) !void {
const tv = decl.typed_value.most_recent.typed_value;
// TODO: prevent inline asm constants from being emitted
const name = try map(file.allocator, mem.span(decl.name));
defer file.allocator.free(name);
if (tv.val.cast(Value.Payload.Bytes)) |payload|
if (tv.ty.arraySentinel()) |sentinel|
if (sentinel.toUnsignedInt() == 0)
try file.constants.writer().print("const char *const {} = \"{}\";\n", .{ name, payload.data })
else
return file.fail(decl.src(), "TODO byte arrays with non-zero sentinels", .{})
else
return file.fail(decl.src(), "TODO byte arrays without sentinels", .{})
else
return file.fail(decl.src(), "TODO non-byte arrays", .{});
}
fn genFn(file: *C, decl: *Decl) !void {
const writer = file.main.writer();
const tv = decl.typed_value.most_recent.typed_value;
try renderFunctionSignature(file, writer, decl);
try writer.writeAll(" {");
const func: *Module.Fn = tv.val.cast(Value.Payload.Function).?.func;
const instructions = func.analysis.success.instructions;
if (instructions.len > 0) {
for (instructions) |inst| {
try writer.writeAll("\n\t");
switch (inst.tag) {
.assembly => try genAsm(file, inst.cast(Inst.Assembly).?, decl),
.call => try genCall(file, inst.cast(Inst.Call).?, decl),
.ret => try genRet(file, inst.cast(Inst.Ret).?, decl, tv.ty.fnReturnType()),
.retvoid => try file.main.writer().print("return;", .{}),
else => |e| return file.fail(decl.src(), "TODO implement C codegen for {}", .{e}),
}
}
try writer.writeAll("\n");
}
try writer.writeAll("}\n\n");
}
fn genRet(file: *C, inst: *Inst.Ret, decl: *Decl, expected_return_type: Type) !void {
const writer = file.main.writer();
const ret_value = inst.args.operand;
const value = ret_value.value().?;
if (expected_return_type.eql(ret_value.ty))
return file.fail(decl.src(), "TODO return {}", .{expected_return_type})
else if (expected_return_type.isInt() and ret_value.ty.tag() == .comptime_int)
if (value.intFitsInType(expected_return_type, file.options.target))
if (expected_return_type.intInfo(file.options.target).bits <= 64)
try writer.print("return {};", .{value.toUnsignedInt()})
else
return file.fail(decl.src(), "TODO return ints > 64 bits", .{})
else
return file.fail(decl.src(), "comptime int {} does not fit in {}", .{ value.toUnsignedInt(), expected_return_type })
else
return file.fail(decl.src(), "return type mismatch: expected {}, found {}", .{ expected_return_type, ret_value.ty });
}
fn genCall(file: *C, inst: *Inst.Call, decl: *Decl) !void {
const writer = file.main.writer();
const header = file.header.writer();
if (inst.args.func.cast(Inst.Constant)) |func_inst| {
if (func_inst.val.cast(Value.Payload.Function)) |func_val| {
const target = func_val.func.owner_decl;
const target_ty = target.typed_value.most_recent.typed_value.ty;
const ret_ty = target_ty.fnReturnType().tag();
if (target_ty.fnReturnType().hasCodeGenBits() and inst.base.isUnused()) {
try writer.print("(void)", .{});
}
const tname = mem.spanZ(target.name);
if (file.called.get(tname) == null) {
try file.called.put(tname, void{});
try renderFunctionSignature(file, header, target);
try header.writeAll(";\n");
}
try writer.print("{}();", .{tname});
} else {
return file.fail(decl.src(), "TODO non-function call target?", .{});
}
if (inst.args.args.len != 0) {
return file.fail(decl.src(), "TODO function arguments", .{});
}
} else {
return file.fail(decl.src(), "TODO non-constant call inst?", .{});
}
}
fn genAsm(file: *C, inst: *Inst.Assembly, decl: *Decl) !void {
const as = inst.args;
const writer = file.main.writer();
for (as.inputs) |i, index| {
if (i[0] == '{' and i[i.len - 1] == '}') {
const reg = i[1 .. i.len - 1];
const arg = as.args[index];
if (arg.cast(Inst.Constant)) |c| {
if (c.val.tag() == .int_u64) {
try writer.writeAll("register ");
try renderType(file, writer, arg.ty, decl.src());
try writer.print(" {}_constant __asm__(\"{}\") = {};\n\t", .{ reg, reg, c.val.toUnsignedInt() });
} else {
return file.fail(decl.src(), "TODO inline asm {} args", .{c.val.tag()});
}
} else {
return file.fail(decl.src(), "TODO non-constant inline asm args", .{});
}
} else {
return file.fail(decl.src(), "TODO non-explicit inline asm regs", .{});
}
}
try writer.print("__asm {} (\"{}\"", .{ if (as.is_volatile) @as([]const u8, "volatile") else "", as.asm_source });
if (as.output) |o| {
return file.fail(decl.src(), "TODO inline asm output", .{});
}
if (as.inputs.len > 0) {
if (as.output == null) {
try writer.writeAll(" :");
}
try writer.writeAll(": ");
for (as.inputs) |i, index| {
if (i[0] == '{' and i[i.len - 1] == '}') {
const reg = i[1 .. i.len - 1];
const arg = as.args[index];
if (index > 0) {
try writer.writeAll(", ");
}
if (arg.cast(Inst.Constant)) |c| {
try writer.print("\"\"({}_constant)", .{reg});
} else {
// This is blocked by the earlier test
unreachable;
}
} else {
// This is blocked by the earlier test
unreachable;
}
}
}
try writer.writeAll(");");
}
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