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zig/src/link/Coff.zig
Andrew Kelley 9f8f446435 fixups to previous commit 
* std.fs.Dir.readFile: add doc comments to explain what it means when
   the returned slice has the same length as the supplied buffer.
 * introduce readSmallFile / writeSmallFile to abstract over the
   decision to use symlink or file contents to store data.
2020-10-09 16:45:39 -07:00

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const Coff = @This();
const std = @import("std");
const log = std.log.scoped(.link);
const Allocator = std.mem.Allocator;
const assert = std.debug.assert;
const fs = std.fs;
const allocPrint = std.fmt.allocPrint;
const mem = std.mem;
const trace = @import("../tracy.zig").trace;
const Module = @import("../Module.zig");
const Compilation = @import("../Compilation.zig");
const codegen = @import("../codegen.zig");
const link = @import("../link.zig");
const build_options = @import("build_options");
const Cache = @import("../Cache.zig");
const mingw = @import("../mingw.zig");
const allocation_padding = 4 / 3;
const minimum_text_block_size = 64 * allocation_padding;
const section_alignment = 4096;
const file_alignment = 512;
const default_image_base = 0x400_000;
const section_table_size = 2 * 40;
comptime {
assert(mem.isAligned(default_image_base, section_alignment));
}
pub const base_tag: link.File.Tag = .coff;
const msdos_stub = @embedFile("msdos-stub.bin");
base: link.File,
ptr_width: PtrWidth,
error_flags: link.File.ErrorFlags = .{},
text_block_free_list: std.ArrayListUnmanaged(*TextBlock) = .{},
last_text_block: ?*TextBlock = null,
/// Section table file pointer.
section_table_offset: u32 = 0,
/// Section data file pointer.
section_data_offset: u32 = 0,
/// Optiona header file pointer.
optional_header_offset: u32 = 0,
/// Absolute virtual address of the offset table when the executable is loaded in memory.
offset_table_virtual_address: u32 = 0,
/// Current size of the offset table on disk, must be a multiple of `file_alignment`
offset_table_size: u32 = 0,
/// Contains absolute virtual addresses
offset_table: std.ArrayListUnmanaged(u64) = .{},
/// Free list of offset table indices
offset_table_free_list: std.ArrayListUnmanaged(u32) = .{},
/// Virtual address of the entry point procedure relative to image base.
entry_addr: ?u32 = null,
/// Absolute virtual address of the text section when the executable is loaded in memory.
text_section_virtual_address: u32 = 0,
/// Current size of the `.text` section on disk, must be a multiple of `file_alignment`
text_section_size: u32 = 0,
offset_table_size_dirty: bool = false,
text_section_size_dirty: bool = false,
/// This flag is set when the virtual size of the whole image file when loaded in memory has changed
/// and needs to be updated in the optional header.
size_of_image_dirty: bool = false,
pub const PtrWidth = enum { p32, p64 };
pub const TextBlock = struct {
/// Offset of the code relative to the start of the text section
text_offset: u32,
/// Used size of the text block
size: u32,
/// This field is undefined for symbols with size = 0.
offset_table_index: u32,
/// Points to the previous and next neighbors, based on the `text_offset`.
/// This can be used to find, for example, the capacity of this `TextBlock`.
prev: ?*TextBlock,
next: ?*TextBlock,
pub const empty = TextBlock{
.text_offset = 0,
.size = 0,
.offset_table_index = undefined,
.prev = null,
.next = null,
};
/// Returns how much room there is to grow in virtual address space.
fn capacity(self: TextBlock) u64 {
if (self.next) |next| {
return next.text_offset - self.text_offset;
}
// This is the last block, the capacity is only limited by the address space.
return std.math.maxInt(u32) - self.text_offset;
}
fn freeListEligible(self: TextBlock) bool {
// No need to keep a free list node for the last block.
const next = self.next orelse return false;
const cap = next.text_offset - self.text_offset;
const ideal_cap = self.size * allocation_padding;
if (cap <= ideal_cap) return false;
const surplus = cap - ideal_cap;
return surplus >= minimum_text_block_size;
}
/// Absolute virtual address of the text block when the file is loaded in memory.
fn getVAddr(self: TextBlock, coff: Coff) u32 {
return coff.text_section_virtual_address + self.text_offset;
}
};
pub const SrcFn = void;
pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Options) !*Coff {
assert(options.object_format == .coff);
if (options.use_llvm) return error.LLVM_BackendIsTODO_ForCoff; // TODO
if (options.use_lld) return error.LLD_LinkingIsTODO_ForCoff; // TODO
const file = try options.emit.?.directory.handle.createFile(sub_path, .{
.truncate = false,
.read = true,
.mode = link.determineMode(options),
});
errdefer file.close();
const self = try createEmpty(allocator, options);
errdefer self.base.destroy();
self.base.file = file;
// TODO Write object specific relocations, COFF symbol table, then enable object file output.
switch (options.output_mode) {
.Exe => {},
.Obj => return error.TODOImplementWritingObjFiles,
.Lib => return error.TODOImplementWritingLibFiles,
}
var coff_file_header_offset: u32 = 0;
if (options.output_mode == .Exe) {
// Write the MS-DOS stub and the PE signature
try self.base.file.?.pwriteAll(msdos_stub ++ "PE\x00\x00", 0);
coff_file_header_offset = msdos_stub.len + 4;
}
// COFF file header
const data_directory_count = 0;
var hdr_data: [112 + data_directory_count * 8 + section_table_size]u8 = undefined;
var index: usize = 0;
const machine = self.base.options.target.cpu.arch.toCoffMachine();
if (machine == .Unknown) {
return error.UnsupportedCOFFArchitecture;
}
mem.writeIntLittle(u16, hdr_data[0..2], @enumToInt(machine));
index += 2;
// Number of sections (we only use .got, .text)
mem.writeIntLittle(u16, hdr_data[index..][0..2], 2);
index += 2;
// TimeDateStamp (u32), PointerToSymbolTable (u32), NumberOfSymbols (u32)
mem.set(u8, hdr_data[index..][0..12], 0);
index += 12;
const optional_header_size = switch (options.output_mode) {
.Exe => data_directory_count * 8 + switch (self.ptr_width) {
.p32 => @as(u16, 96),
.p64 => 112,
},
else => 0,
};
const section_table_offset = coff_file_header_offset + 20 + optional_header_size;
const default_offset_table_size = file_alignment;
const default_size_of_code = 0;
self.section_data_offset = mem.alignForwardGeneric(u32, self.section_table_offset + section_table_size, file_alignment);
const section_data_relative_virtual_address = mem.alignForwardGeneric(u32, self.section_table_offset + section_table_size, section_alignment);
self.offset_table_virtual_address = default_image_base + section_data_relative_virtual_address;
self.offset_table_size = default_offset_table_size;
self.section_table_offset = section_table_offset;
self.text_section_virtual_address = default_image_base + section_data_relative_virtual_address + section_alignment;
self.text_section_size = default_size_of_code;
// Size of file when loaded in memory
const size_of_image = mem.alignForwardGeneric(u32, self.text_section_virtual_address - default_image_base + default_size_of_code, section_alignment);
mem.writeIntLittle(u16, hdr_data[index..][0..2], optional_header_size);
index += 2;
// Characteristics
var characteristics: u16 = std.coff.IMAGE_FILE_DEBUG_STRIPPED | std.coff.IMAGE_FILE_RELOCS_STRIPPED; // TODO Remove debug info stripped flag when necessary
if (options.output_mode == .Exe) {
characteristics |= std.coff.IMAGE_FILE_EXECUTABLE_IMAGE;
}
switch (self.ptr_width) {
.p32 => characteristics |= std.coff.IMAGE_FILE_32BIT_MACHINE,
.p64 => characteristics |= std.coff.IMAGE_FILE_LARGE_ADDRESS_AWARE,
}
mem.writeIntLittle(u16, hdr_data[index..][0..2], characteristics);
index += 2;
assert(index == 20);
try self.base.file.?.pwriteAll(hdr_data[0..index], coff_file_header_offset);
if (options.output_mode == .Exe) {
self.optional_header_offset = coff_file_header_offset + 20;
// Optional header
index = 0;
mem.writeIntLittle(u16, hdr_data[0..2], switch (self.ptr_width) {
.p32 => @as(u16, 0x10b),
.p64 => 0x20b,
});
index += 2;
// Linker version (u8 + u8)
mem.set(u8, hdr_data[index..][0..2], 0);
index += 2;
// SizeOfCode (UNUSED, u32), SizeOfInitializedData (u32), SizeOfUninitializedData (u32), AddressOfEntryPoint (u32), BaseOfCode (UNUSED, u32)
mem.set(u8, hdr_data[index..][0..20], 0);
index += 20;
if (self.ptr_width == .p32) {
// Base of data relative to the image base (UNUSED)
mem.set(u8, hdr_data[index..][0..4], 0);
index += 4;
// Image base address
mem.writeIntLittle(u32, hdr_data[index..][0..4], default_image_base);
index += 4;
} else {
// Image base address
mem.writeIntLittle(u64, hdr_data[index..][0..8], default_image_base);
index += 8;
}
// Section alignment
mem.writeIntLittle(u32, hdr_data[index..][0..4], section_alignment);
index += 4;
// File alignment
mem.writeIntLittle(u32, hdr_data[index..][0..4], file_alignment);
index += 4;
// Required OS version, 6.0 is vista
mem.writeIntLittle(u16, hdr_data[index..][0..2], 6);
index += 2;
mem.writeIntLittle(u16, hdr_data[index..][0..2], 0);
index += 2;
// Image version
mem.set(u8, hdr_data[index..][0..4], 0);
index += 4;
// Required subsystem version, same as OS version
mem.writeIntLittle(u16, hdr_data[index..][0..2], 6);
index += 2;
mem.writeIntLittle(u16, hdr_data[index..][0..2], 0);
index += 2;
// Reserved zeroes (u32)
mem.set(u8, hdr_data[index..][0..4], 0);
index += 4;
mem.writeIntLittle(u32, hdr_data[index..][0..4], size_of_image);
index += 4;
mem.writeIntLittle(u32, hdr_data[index..][0..4], self.section_data_offset);
index += 4;
// CheckSum (u32)
mem.set(u8, hdr_data[index..][0..4], 0);
index += 4;
// Subsystem, TODO: Let users specify the subsystem, always CUI for now
mem.writeIntLittle(u16, hdr_data[index..][0..2], 3);
index += 2;
// DLL characteristics
mem.writeIntLittle(u16, hdr_data[index..][0..2], 0x0);
index += 2;
switch (self.ptr_width) {
.p32 => {
// Size of stack reserve + commit
mem.writeIntLittle(u32, hdr_data[index..][0..4], 0x1_000_000);
index += 4;
mem.writeIntLittle(u32, hdr_data[index..][0..4], 0x1_000);
index += 4;
// Size of heap reserve + commit
mem.writeIntLittle(u32, hdr_data[index..][0..4], 0x100_000);
index += 4;
mem.writeIntLittle(u32, hdr_data[index..][0..4], 0x1_000);
index += 4;
},
.p64 => {
// Size of stack reserve + commit
mem.writeIntLittle(u64, hdr_data[index..][0..8], 0x1_000_000);
index += 8;
mem.writeIntLittle(u64, hdr_data[index..][0..8], 0x1_000);
index += 8;
// Size of heap reserve + commit
mem.writeIntLittle(u64, hdr_data[index..][0..8], 0x100_000);
index += 8;
mem.writeIntLittle(u64, hdr_data[index..][0..8], 0x1_000);
index += 8;
},
}
// Reserved zeroes
mem.set(u8, hdr_data[index..][0..4], 0);
index += 4;
// Number of data directories
mem.writeIntLittle(u32, hdr_data[index..][0..4], data_directory_count);
index += 4;
// Initialize data directories to zero
mem.set(u8, hdr_data[index..][0 .. data_directory_count * 8], 0);
index += data_directory_count * 8;
assert(index == optional_header_size);
}
// Write section table.
// First, the .got section
hdr_data[index..][0..8].* = ".got\x00\x00\x00\x00".*;
index += 8;
if (options.output_mode == .Exe) {
// Virtual size (u32)
mem.writeIntLittle(u32, hdr_data[index..][0..4], default_offset_table_size);
index += 4;
// Virtual address (u32)
mem.writeIntLittle(u32, hdr_data[index..][0..4], self.offset_table_virtual_address - default_image_base);
index += 4;
} else {
mem.set(u8, hdr_data[index..][0..8], 0);
index += 8;
}
// Size of raw data (u32)
mem.writeIntLittle(u32, hdr_data[index..][0..4], default_offset_table_size);
index += 4;
// File pointer to the start of the section
mem.writeIntLittle(u32, hdr_data[index..][0..4], self.section_data_offset);
index += 4;
// Pointer to relocations (u32), PointerToLinenumbers (u32), NumberOfRelocations (u16), NumberOfLinenumbers (u16)
mem.set(u8, hdr_data[index..][0..12], 0);
index += 12;
// Section flags
mem.writeIntLittle(u32, hdr_data[index..][0..4], std.coff.IMAGE_SCN_CNT_INITIALIZED_DATA | std.coff.IMAGE_SCN_MEM_READ);
index += 4;
// Then, the .text section
hdr_data[index..][0..8].* = ".text\x00\x00\x00".*;
index += 8;
if (options.output_mode == .Exe) {
// Virtual size (u32)
mem.writeIntLittle(u32, hdr_data[index..][0..4], default_size_of_code);
index += 4;
// Virtual address (u32)
mem.writeIntLittle(u32, hdr_data[index..][0..4], self.text_section_virtual_address - default_image_base);
index += 4;
} else {
mem.set(u8, hdr_data[index..][0..8], 0);
index += 8;
}
// Size of raw data (u32)
mem.writeIntLittle(u32, hdr_data[index..][0..4], default_size_of_code);
index += 4;
// File pointer to the start of the section
mem.writeIntLittle(u32, hdr_data[index..][0..4], self.section_data_offset + default_offset_table_size);
index += 4;
// Pointer to relocations (u32), PointerToLinenumbers (u32), NumberOfRelocations (u16), NumberOfLinenumbers (u16)
mem.set(u8, hdr_data[index..][0..12], 0);
index += 12;
// Section flags
mem.writeIntLittle(
u32,
hdr_data[index..][0..4],
std.coff.IMAGE_SCN_CNT_CODE | std.coff.IMAGE_SCN_MEM_EXECUTE | std.coff.IMAGE_SCN_MEM_READ | std.coff.IMAGE_SCN_MEM_WRITE,
);
index += 4;
assert(index == optional_header_size + section_table_size);
try self.base.file.?.pwriteAll(hdr_data[0..index], self.optional_header_offset);
try self.base.file.?.setEndPos(self.section_data_offset + default_offset_table_size + default_size_of_code);
return self;
}
pub fn createEmpty(gpa: *Allocator, options: link.Options) !*Coff {
const ptr_width: PtrWidth = switch (options.target.cpu.arch.ptrBitWidth()) {
0...32 => .p32,
33...64 => .p64,
else => return error.UnsupportedCOFFArchitecture,
};
const self = try gpa.create(Coff);
self.* = .{
.base = .{
.tag = .coff,
.options = options,
.allocator = gpa,
.file = null,
},
.ptr_width = ptr_width,
};
return self;
}
pub fn allocateDeclIndexes(self: *Coff, decl: *Module.Decl) !void {
try self.offset_table.ensureCapacity(self.base.allocator, self.offset_table.items.len + 1);
if (self.offset_table_free_list.popOrNull()) |i| {
decl.link.coff.offset_table_index = i;
} else {
decl.link.coff.offset_table_index = @intCast(u32, self.offset_table.items.len);
_ = self.offset_table.addOneAssumeCapacity();
const entry_size = self.base.options.target.cpu.arch.ptrBitWidth() / 8;
if (self.offset_table.items.len > self.offset_table_size / entry_size) {
self.offset_table_size_dirty = true;
}
}
self.offset_table.items[decl.link.coff.offset_table_index] = 0;
}
fn allocateTextBlock(self: *Coff, text_block: *TextBlock, new_block_size: u64, alignment: u64) !u64 {
const new_block_min_capacity = new_block_size * allocation_padding;
// We use these to indicate our intention to update metadata, placing the new block,
// and possibly removing a free list node.
// It would be simpler to do it inside the for loop below, but that would cause a
// problem if an error was returned later in the function. So this action
// is actually carried out at the end of the function, when errors are no longer possible.
var block_placement: ?*TextBlock = null;
var free_list_removal: ?usize = null;
const vaddr = blk: {
var i: usize = 0;
while (i < self.text_block_free_list.items.len) {
const free_block = self.text_block_free_list.items[i];
const next_block_text_offset = free_block.text_offset + free_block.capacity();
const new_block_text_offset = mem.alignForwardGeneric(u64, free_block.getVAddr(self.*) + free_block.size, alignment) - self.text_section_virtual_address;
if (new_block_text_offset < next_block_text_offset and next_block_text_offset - new_block_text_offset >= new_block_min_capacity) {
block_placement = free_block;
const remaining_capacity = next_block_text_offset - new_block_text_offset - new_block_min_capacity;
if (remaining_capacity < minimum_text_block_size) {
free_list_removal = i;
}
break :blk new_block_text_offset + self.text_section_virtual_address;
} else {
if (!free_block.freeListEligible()) {
_ = self.text_block_free_list.swapRemove(i);
} else {
i += 1;
}
continue;
}
} else if (self.last_text_block) |last| {
const new_block_vaddr = mem.alignForwardGeneric(u64, last.getVAddr(self.*) + last.size, alignment);
block_placement = last;
break :blk new_block_vaddr;
} else {
break :blk self.text_section_virtual_address;
}
};
const expand_text_section = block_placement == null or block_placement.?.next == null;
if (expand_text_section) {
const needed_size = @intCast(u32, mem.alignForwardGeneric(u64, vaddr + new_block_size - self.text_section_virtual_address, file_alignment));
if (needed_size > self.text_section_size) {
const current_text_section_virtual_size = mem.alignForwardGeneric(u32, self.text_section_size, section_alignment);
const new_text_section_virtual_size = mem.alignForwardGeneric(u32, needed_size, section_alignment);
if (current_text_section_virtual_size != new_text_section_virtual_size) {
self.size_of_image_dirty = true;
// Write new virtual size
var buf: [4]u8 = undefined;
mem.writeIntLittle(u32, &buf, new_text_section_virtual_size);
try self.base.file.?.pwriteAll(&buf, self.section_table_offset + 40 + 8);
}
self.text_section_size = needed_size;
self.text_section_size_dirty = true;
}
self.last_text_block = text_block;
}
text_block.text_offset = @intCast(u32, vaddr - self.text_section_virtual_address);
text_block.size = @intCast(u32, new_block_size);
// This function can also reallocate a text block.
// In this case we need to "unplug" it from its previous location before
// plugging it in to its new location.
if (text_block.prev) |prev| {
prev.next = text_block.next;
}
if (text_block.next) |next| {
next.prev = text_block.prev;
}
if (block_placement) |big_block| {
text_block.prev = big_block;
text_block.next = big_block.next;
big_block.next = text_block;
} else {
text_block.prev = null;
text_block.next = null;
}
if (free_list_removal) |i| {
_ = self.text_block_free_list.swapRemove(i);
}
return vaddr;
}
fn growTextBlock(self: *Coff, text_block: *TextBlock, new_block_size: u64, alignment: u64) !u64 {
const block_vaddr = text_block.getVAddr(self.*);
const align_ok = mem.alignBackwardGeneric(u64, block_vaddr, alignment) == block_vaddr;
const need_realloc = !align_ok or new_block_size > text_block.capacity();
if (!need_realloc) return @as(u64, block_vaddr);
return self.allocateTextBlock(text_block, new_block_size, alignment);
}
fn shrinkTextBlock(self: *Coff, text_block: *TextBlock, new_block_size: u64) void {
text_block.size = @intCast(u32, new_block_size);
if (text_block.capacity() - text_block.size >= minimum_text_block_size) {
self.text_block_free_list.append(self.base.allocator, text_block) catch {};
}
}
fn freeTextBlock(self: *Coff, text_block: *TextBlock) void {
var already_have_free_list_node = false;
{
var i: usize = 0;
// TODO turn text_block_free_list into a hash map
while (i < self.text_block_free_list.items.len) {
if (self.text_block_free_list.items[i] == text_block) {
_ = self.text_block_free_list.swapRemove(i);
continue;
}
if (self.text_block_free_list.items[i] == text_block.prev) {
already_have_free_list_node = true;
}
i += 1;
}
}
if (self.last_text_block == text_block) {
self.last_text_block = text_block.prev;
}
if (text_block.prev) |prev| {
prev.next = text_block.next;
if (!already_have_free_list_node and prev.freeListEligible()) {
// The free list is heuristics, it doesn't have to be perfect, so we can
// ignore the OOM here.
self.text_block_free_list.append(self.base.allocator, prev) catch {};
}
}
if (text_block.next) |next| {
next.prev = text_block.prev;
}
}
fn writeOffsetTableEntry(self: *Coff, index: usize) !void {
const entry_size = self.base.options.target.cpu.arch.ptrBitWidth() / 8;
const endian = self.base.options.target.cpu.arch.endian();
const offset_table_start = self.section_data_offset;
if (self.offset_table_size_dirty) {
const current_raw_size = self.offset_table_size;
const new_raw_size = self.offset_table_size * 2;
log.debug("growing offset table from raw size {} to {}\n", .{ current_raw_size, new_raw_size });
// Move the text section to a new place in the executable
const current_text_section_start = self.section_data_offset + current_raw_size;
const new_text_section_start = self.section_data_offset + new_raw_size;
const amt = try self.base.file.?.copyRangeAll(current_text_section_start, self.base.file.?, new_text_section_start, self.text_section_size);
if (amt != self.text_section_size) return error.InputOutput;
// Write the new raw size in the .got header
var buf: [8]u8 = undefined;
mem.writeIntLittle(u32, buf[0..4], new_raw_size);
try self.base.file.?.pwriteAll(buf[0..4], self.section_table_offset + 16);
// Write the new .text section file offset in the .text section header
mem.writeIntLittle(u32, buf[0..4], new_text_section_start);
try self.base.file.?.pwriteAll(buf[0..4], self.section_table_offset + 40 + 20);
const current_virtual_size = mem.alignForwardGeneric(u32, self.offset_table_size, section_alignment);
const new_virtual_size = mem.alignForwardGeneric(u32, new_raw_size, section_alignment);
// If we had to move in the virtual address space, we need to fix the VAs in the offset table, as well as the virtual address of the `.text` section
// and the virutal size of the `.got` section
if (new_virtual_size != current_virtual_size) {
log.debug("growing offset table from virtual size {} to {}\n", .{ current_virtual_size, new_virtual_size });
self.size_of_image_dirty = true;
const va_offset = new_virtual_size - current_virtual_size;
// Write .got virtual size
mem.writeIntLittle(u32, buf[0..4], new_virtual_size);
try self.base.file.?.pwriteAll(buf[0..4], self.section_table_offset + 8);
// Write .text new virtual address
self.text_section_virtual_address = self.text_section_virtual_address + va_offset;
mem.writeIntLittle(u32, buf[0..4], self.text_section_virtual_address - default_image_base);
try self.base.file.?.pwriteAll(buf[0..4], self.section_table_offset + 40 + 12);
// Fix the VAs in the offset table
for (self.offset_table.items) |*va, idx| {
if (va.* != 0) {
va.* += va_offset;
switch (entry_size) {
4 => {
mem.writeInt(u32, buf[0..4], @intCast(u32, va.*), endian);
try self.base.file.?.pwriteAll(buf[0..4], offset_table_start + idx * entry_size);
},
8 => {
mem.writeInt(u64, &buf, va.*, endian);
try self.base.file.?.pwriteAll(&buf, offset_table_start + idx * entry_size);
},
else => unreachable,
}
}
}
}
self.offset_table_size = new_raw_size;
self.offset_table_size_dirty = false;
}
// Write the new entry
switch (entry_size) {
4 => {
var buf: [4]u8 = undefined;
mem.writeInt(u32, &buf, @intCast(u32, self.offset_table.items[index]), endian);
try self.base.file.?.pwriteAll(&buf, offset_table_start + index * entry_size);
},
8 => {
var buf: [8]u8 = undefined;
mem.writeInt(u64, &buf, self.offset_table.items[index], endian);
try self.base.file.?.pwriteAll(&buf, offset_table_start + index * entry_size);
},
else => unreachable,
}
}
pub fn updateDecl(self: *Coff, module: *Module, decl: *Module.Decl) !void {
// TODO COFF/PE debug information
// TODO Implement exports
const tracy = trace(@src());
defer tracy.end();
var code_buffer = std.ArrayList(u8).init(self.base.allocator);
defer code_buffer.deinit();
const typed_value = decl.typed_value.most_recent.typed_value;
const res = try codegen.generateSymbol(&self.base, decl.src(), typed_value, &code_buffer, .none);
const code = switch (res) {
.externally_managed => |x| x,
.appended => code_buffer.items,
.fail => |em| {
decl.analysis = .codegen_failure;
try module.failed_decls.put(module.gpa, decl, em);
return;
},
};
const required_alignment = typed_value.ty.abiAlignment(self.base.options.target);
const curr_size = decl.link.coff.size;
if (curr_size != 0) {
const capacity = decl.link.coff.capacity();
const need_realloc = code.len > capacity or
!mem.isAlignedGeneric(u32, decl.link.coff.text_offset, required_alignment);
if (need_realloc) {
const curr_vaddr = self.getDeclVAddr(decl);
const vaddr = try self.growTextBlock(&decl.link.coff, code.len, required_alignment);
log.debug("growing {} from 0x{x} to 0x{x}\n", .{ decl.name, curr_vaddr, vaddr });
if (vaddr != curr_vaddr) {
log.debug(" (writing new offset table entry)\n", .{});
self.offset_table.items[decl.link.coff.offset_table_index] = vaddr;
try self.writeOffsetTableEntry(decl.link.coff.offset_table_index);
}
} else if (code.len < curr_size) {
self.shrinkTextBlock(&decl.link.coff, code.len);
}
} else {
const vaddr = try self.allocateTextBlock(&decl.link.coff, code.len, required_alignment);
log.debug("allocated text block for {} at 0x{x} (size: {Bi})\n", .{ mem.spanZ(decl.name), vaddr, code.len });
errdefer self.freeTextBlock(&decl.link.coff);
self.offset_table.items[decl.link.coff.offset_table_index] = vaddr;
try self.writeOffsetTableEntry(decl.link.coff.offset_table_index);
}
// Write the code into the file
try self.base.file.?.pwriteAll(code, self.section_data_offset + self.offset_table_size + decl.link.coff.text_offset);
// Since we updated the vaddr and the size, each corresponding export symbol also needs to be updated.
const decl_exports = module.decl_exports.get(decl) orelse &[0]*Module.Export{};
return self.updateDeclExports(module, decl, decl_exports);
}
pub fn freeDecl(self: *Coff, decl: *Module.Decl) void {
// Appending to free lists is allowed to fail because the free lists are heuristics based anyway.
self.freeTextBlock(&decl.link.coff);
self.offset_table_free_list.append(self.base.allocator, decl.link.coff.offset_table_index) catch {};
}
pub fn updateDeclExports(self: *Coff, module: *Module, decl: *const Module.Decl, exports: []const *Module.Export) !void {
for (exports) |exp| {
if (exp.options.section) |section_name| {
if (!mem.eql(u8, section_name, ".text")) {
try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
module.failed_exports.putAssumeCapacityNoClobber(
exp,
try Compilation.ErrorMsg.create(self.base.allocator, 0, "Unimplemented: ExportOptions.section", .{}),
);
continue;
}
}
if (mem.eql(u8, exp.options.name, "_start")) {
self.entry_addr = decl.link.coff.getVAddr(self.*) - default_image_base;
} else {
try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
module.failed_exports.putAssumeCapacityNoClobber(
exp,
try Compilation.ErrorMsg.create(self.base.allocator, 0, "Unimplemented: Exports other than '_start'", .{}),
);
continue;
}
}
}
pub fn flush(self: *Coff, comp: *Compilation) !void {
if (build_options.have_llvm and self.base.options.use_lld) {
return self.linkWithLLD(comp);
} else {
switch (self.base.options.effectiveOutputMode()) {
.Exe, .Obj => {},
.Lib => return error.TODOImplementWritingLibFiles,
}
return self.flushModule(comp);
}
}
pub fn flushModule(self: *Coff, comp: *Compilation) !void {
const tracy = trace(@src());
defer tracy.end();
if (self.text_section_size_dirty) {
// Write the new raw size in the .text header
var buf: [4]u8 = undefined;
mem.writeIntLittle(u32, &buf, self.text_section_size);
try self.base.file.?.pwriteAll(&buf, self.section_table_offset + 40 + 16);
try self.base.file.?.setEndPos(self.section_data_offset + self.offset_table_size + self.text_section_size);
self.text_section_size_dirty = false;
}
if (self.base.options.output_mode == .Exe and self.size_of_image_dirty) {
const new_size_of_image = mem.alignForwardGeneric(u32, self.text_section_virtual_address - default_image_base + self.text_section_size, section_alignment);
var buf: [4]u8 = undefined;
mem.writeIntLittle(u32, &buf, new_size_of_image);
try self.base.file.?.pwriteAll(&buf, self.optional_header_offset + 56);
self.size_of_image_dirty = false;
}
if (self.entry_addr == null and self.base.options.output_mode == .Exe) {
log.debug("flushing. no_entry_point_found = true\n", .{});
self.error_flags.no_entry_point_found = true;
} else {
log.debug("flushing. no_entry_point_found = false\n", .{});
self.error_flags.no_entry_point_found = false;
if (self.base.options.output_mode == .Exe) {
// Write AddressOfEntryPoint
var buf: [4]u8 = undefined;
mem.writeIntLittle(u32, &buf, self.entry_addr.?);
try self.base.file.?.pwriteAll(&buf, self.optional_header_offset + 16);
}
}
}
fn linkWithLLD(self: *Coff, comp: *Compilation) !void {
const tracy = trace(@src());
defer tracy.end();
var arena_allocator = std.heap.ArenaAllocator.init(self.base.allocator);
defer arena_allocator.deinit();
const arena = &arena_allocator.allocator;
const directory = self.base.options.emit.?.directory; // Just an alias to make it shorter to type.
// If there is no Zig code to compile, then we should skip flushing the output file because it
// will not be part of the linker line anyway.
const module_obj_path: ?[]const u8 = if (self.base.options.module) |module| blk: {
const use_stage1 = build_options.is_stage1 and self.base.options.use_llvm;
if (use_stage1) {
const obj_basename = try std.zig.binNameAlloc(arena, .{
.root_name = self.base.options.root_name,
.target = self.base.options.target,
.output_mode = .Obj,
});
const o_directory = self.base.options.module.?.zig_cache_artifact_directory;
const full_obj_path = try o_directory.join(arena, &[_][]const u8{obj_basename});
break :blk full_obj_path;
}
try self.flushModule(comp);
const obj_basename = self.base.intermediary_basename.?;
const full_obj_path = try directory.join(arena, &[_][]const u8{obj_basename});
break :blk full_obj_path;
} else null;
const is_lib = self.base.options.output_mode == .Lib;
const is_dyn_lib = self.base.options.link_mode == .Dynamic and is_lib;
const is_exe_or_dyn_lib = is_dyn_lib or self.base.options.output_mode == .Exe;
const link_in_crt = self.base.options.link_libc and self.base.options.output_mode == .Exe;
const target = self.base.options.target;
// See link/Elf.zig for comments on how this mechanism works.
const id_symlink_basename = "lld.id";
var man: Cache.Manifest = undefined;
defer if (!self.base.options.disable_lld_caching) man.deinit();
var digest: [Cache.hex_digest_len]u8 = undefined;
if (!self.base.options.disable_lld_caching) {
man = comp.cache_parent.obtain();
self.base.releaseLock();
try man.addListOfFiles(self.base.options.objects);
for (comp.c_object_table.items()) |entry| {
_ = try man.addFile(entry.key.status.success.object_path, null);
}
try man.addOptionalFile(module_obj_path);
man.hash.addOptional(self.base.options.stack_size_override);
man.hash.addOptional(self.base.options.image_base_override);
man.hash.addListOfBytes(self.base.options.extra_lld_args);
man.hash.addListOfBytes(self.base.options.lib_dirs);
man.hash.add(self.base.options.is_compiler_rt_or_libc);
if (self.base.options.link_libc) {
man.hash.add(self.base.options.libc_installation != null);
if (self.base.options.libc_installation) |libc_installation| {
man.hash.addBytes(libc_installation.crt_dir.?);
if (target.abi == .msvc) {
man.hash.addBytes(libc_installation.msvc_lib_dir.?);
man.hash.addBytes(libc_installation.kernel32_lib_dir.?);
}
}
}
man.hash.addStringSet(self.base.options.system_libs);
man.hash.addOptional(self.base.options.subsystem);
man.hash.add(self.base.options.is_test);
// We don't actually care whether it's a cache hit or miss; we just need the digest and the lock.
_ = try man.hit();
digest = man.final();
var prev_digest_buf: [digest.len]u8 = undefined;
const prev_digest: []u8 = Cache.readSmallFile(
directory.handle,
id_symlink_basename,
&prev_digest_buf,
) catch |err| blk: {
log.debug("COFF LLD new_digest={} error: {}", .{ digest, @errorName(err) });
// Handle this as a cache miss.
break :blk prev_digest_buf[0..0];
};
if (mem.eql(u8, prev_digest, &digest)) {
log.debug("COFF LLD digest={} match - skipping invocation", .{digest});
// Hot diggity dog! The output binary is already there.
self.base.lock = man.toOwnedLock();
return;
}
log.debug("COFF LLD prev_digest={} new_digest={}", .{ prev_digest, digest });
// We are about to change the output file to be different, so we invalidate the build hash now.
directory.handle.deleteFile(id_symlink_basename) catch |err| switch (err) {
error.FileNotFound => {},
else => |e| return e,
};
}
const full_out_path = try directory.join(arena, &[_][]const u8{self.base.options.emit.?.sub_path});
if (self.base.options.output_mode == .Obj) {
// LLD's COFF driver does not support the equvialent of `-r` so we do a simple file copy
// here. TODO: think carefully about how we can avoid this redundant operation when doing
// build-obj. See also the corresponding TODO in linkAsArchive.
const the_object_path = blk: {
if (self.base.options.objects.len != 0)
break :blk self.base.options.objects[0];
if (comp.c_object_table.count() != 0)
break :blk comp.c_object_table.items()[0].key.status.success.object_path;
if (module_obj_path) |p|
break :blk p;
// TODO I think this is unreachable. Audit this situation when solving the above TODO
// regarding eliding redundant object -> object transformations.
return error.NoObjectsToLink;
};
// This can happen when using --enable-cache and using the stage1 backend. In this case
// we can skip the file copy.
if (!mem.eql(u8, the_object_path, full_out_path)) {
try fs.cwd().copyFile(the_object_path, fs.cwd(), full_out_path, .{});
}
} else {
// Create an LLD command line and invoke it.
var argv = std.ArrayList([]const u8).init(self.base.allocator);
defer argv.deinit();
// Even though we're calling LLD as a library it thinks the first argument is its own exe name.
try argv.append("lld");
try argv.append("-ERRORLIMIT:0");
try argv.append("-NOLOGO");
if (!self.base.options.strip) {
try argv.append("-DEBUG");
}
if (self.base.options.output_mode == .Exe) {
const stack_size = self.base.options.stack_size_override orelse 16777216;
try argv.append(try allocPrint(arena, "-STACK:{d}", .{stack_size}));
}
if (self.base.options.image_base_override) |image_base| {
try argv.append(try std.fmt.allocPrint(arena, "-BASE:{d}", .{image_base}));
}
if (target.cpu.arch == .i386) {
try argv.append("-MACHINE:X86");
} else if (target.cpu.arch == .x86_64) {
try argv.append("-MACHINE:X64");
} else if (target.cpu.arch.isARM()) {
if (target.cpu.arch.ptrBitWidth() == 32) {
try argv.append("-MACHINE:ARM");
} else {
try argv.append("-MACHINE:ARM64");
}
}
if (is_dyn_lib) {
try argv.append("-DLL");
}
try argv.append(try allocPrint(arena, "-OUT:{s}", .{full_out_path}));
if (self.base.options.link_libc) {
if (self.base.options.libc_installation) |libc_installation| {
try argv.append(try allocPrint(arena, "-LIBPATH:{s}", .{libc_installation.crt_dir.?}));
if (target.abi == .msvc) {
try argv.append(try allocPrint(arena, "-LIBPATH:{s}", .{libc_installation.msvc_lib_dir.?}));
try argv.append(try allocPrint(arena, "-LIBPATH:{s}", .{libc_installation.kernel32_lib_dir.?}));
}
}
}
for (self.base.options.lib_dirs) |lib_dir| {
try argv.append(try allocPrint(arena, "-LIBPATH:{s}", .{lib_dir}));
}
try argv.appendSlice(self.base.options.objects);
for (comp.c_object_table.items()) |entry| {
try argv.append(entry.key.status.success.object_path);
}
if (module_obj_path) |p| {
try argv.append(p);
}
const resolved_subsystem: ?std.Target.SubSystem = blk: {
if (self.base.options.subsystem) |explicit| break :blk explicit;
switch (target.os.tag) {
.windows => {
if (self.base.options.module) |module| {
if (module.stage1_flags.have_dllmain_crt_startup or is_dyn_lib)
break :blk null;
if (module.stage1_flags.have_c_main or self.base.options.is_test or
module.stage1_flags.have_winmain_crt_startup or
module.stage1_flags.have_wwinmain_crt_startup)
{
break :blk .Console;
}
if (module.stage1_flags.have_winmain or module.stage1_flags.have_wwinmain)
break :blk .Windows;
}
},
.uefi => break :blk .EfiApplication,
else => {},
}
break :blk null;
};
const Mode = enum { uefi, win32 };
const mode: Mode = mode: {
if (resolved_subsystem) |subsystem| switch (subsystem) {
.Console => {
try argv.append("-SUBSYSTEM:console");
break :mode .win32;
},
.EfiApplication => {
try argv.append("-SUBSYSTEM:efi_application");
break :mode .uefi;
},
.EfiBootServiceDriver => {
try argv.append("-SUBSYSTEM:efi_boot_service_driver");
break :mode .uefi;
},
.EfiRom => {
try argv.append("-SUBSYSTEM:efi_rom");
break :mode .uefi;
},
.EfiRuntimeDriver => {
try argv.append("-SUBSYSTEM:efi_runtime_driver");
break :mode .uefi;
},
.Native => {
try argv.append("-SUBSYSTEM:native");
break :mode .win32;
},
.Posix => {
try argv.append("-SUBSYSTEM:posix");
break :mode .win32;
},
.Windows => {
try argv.append("-SUBSYSTEM:windows");
break :mode .win32;
},
} else if (target.os.tag == .uefi) {
break :mode .uefi;
} else {
break :mode .win32;
}
};
switch (mode) {
.uefi => try argv.appendSlice(&[_][]const u8{
"-BASE:0",
"-ENTRY:EfiMain",
"-OPT:REF",
"-SAFESEH:NO",
"-MERGE:.rdata=.data",
"-ALIGN:32",
"-NODEFAULTLIB",
"-SECTION:.xdata,D",
}),
.win32 => {
if (link_in_crt) {
if (target.abi.isGnu()) {
try argv.append("-lldmingw");
if (target.cpu.arch == .i386) {
try argv.append("-ALTERNATENAME:__image_base__=___ImageBase");
} else {
try argv.append("-ALTERNATENAME:__image_base__=__ImageBase");
}
if (is_dyn_lib) {
try argv.append(try comp.get_libc_crt_file(arena, "dllcrt2.o"));
} else {
try argv.append(try comp.get_libc_crt_file(arena, "crt2.o"));
}
try argv.append(try comp.get_libc_crt_file(arena, "mingw32.lib"));
try argv.append(try comp.get_libc_crt_file(arena, "mingwex.lib"));
try argv.append(try comp.get_libc_crt_file(arena, "msvcrt-os.lib"));
for (mingw.always_link_libs) |name| {
if (!self.base.options.system_libs.contains(name)) {
const lib_basename = try allocPrint(arena, "{s}.lib", .{name});
try argv.append(try comp.get_libc_crt_file(arena, lib_basename));
}
}
} else {
const lib_str = switch (self.base.options.link_mode) {
.Dynamic => "",
.Static => "lib",
};
const d_str = switch (self.base.options.optimize_mode) {
.Debug => "d",
else => "",
};
switch (self.base.options.link_mode) {
.Static => try argv.append(try allocPrint(arena, "libcmt{s}.lib", .{d_str})),
.Dynamic => try argv.append(try allocPrint(arena, "msvcrt{s}.lib", .{d_str})),
}
try argv.append(try allocPrint(arena, "{s}vcruntime{s}.lib", .{ lib_str, d_str }));
try argv.append(try allocPrint(arena, "{s}ucrt{s}.lib", .{ lib_str, d_str }));
//Visual C++ 2015 Conformance Changes
//https://msdn.microsoft.com/en-us/library/bb531344.aspx
try argv.append("legacy_stdio_definitions.lib");
// msvcrt depends on kernel32 and ntdll
try argv.append("kernel32.lib");
try argv.append("ntdll.lib");
}
} else {
try argv.append("-NODEFAULTLIB");
if (!is_lib) {
if (self.base.options.module) |module| {
if (module.stage1_flags.have_winmain) {
try argv.append("-ENTRY:WinMain");
} else if (module.stage1_flags.have_wwinmain) {
try argv.append("-ENTRY:wWinMain");
} else if (module.stage1_flags.have_wwinmain_crt_startup) {
try argv.append("-ENTRY:wWinMainCRTStartup");
} else {
try argv.append("-ENTRY:WinMainCRTStartup");
}
} else {
try argv.append("-ENTRY:WinMainCRTStartup");
}
}
}
},
}
// libc++ dep
if (self.base.options.link_libcpp) {
try argv.append(comp.libcxxabi_static_lib.?.full_object_path);
try argv.append(comp.libcxx_static_lib.?.full_object_path);
try argv.append(comp.libunwind_static_lib.?.full_object_path);
}
// compiler-rt and libc
if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc) {
if (!self.base.options.link_libc) {
try argv.append(comp.libc_static_lib.?.full_object_path);
}
// MSVC compiler_rt is missing some stuff, so we build it unconditionally but
// and rely on weak linkage to allow MSVC compiler_rt functions to override ours.
try argv.append(comp.compiler_rt_static_lib.?.full_object_path);
}
for (self.base.options.system_libs.items()) |entry| {
const lib_basename = try allocPrint(arena, "{s}.lib", .{entry.key});
if (comp.crt_files.get(lib_basename)) |crt_file| {
try argv.append(crt_file.full_object_path);
} else {
try argv.append(lib_basename);
}
}
if (self.base.options.verbose_link) {
Compilation.dump_argv(argv.items);
}
const new_argv = try arena.allocSentinel(?[*:0]const u8, argv.items.len, null);
for (argv.items) |arg, i| {
new_argv[i] = try arena.dupeZ(u8, arg);
}
var stderr_context: LLDContext = .{
.coff = self,
.data = std.ArrayList(u8).init(self.base.allocator),
};
defer stderr_context.data.deinit();
var stdout_context: LLDContext = .{
.coff = self,
.data = std.ArrayList(u8).init(self.base.allocator),
};
defer stdout_context.data.deinit();
const llvm = @import("../llvm.zig");
const ok = llvm.Link(
.COFF,
new_argv.ptr,
new_argv.len,
append_diagnostic,
@ptrToInt(&stdout_context),
@ptrToInt(&stderr_context),
);
if (stderr_context.oom or stdout_context.oom) return error.OutOfMemory;
if (stdout_context.data.items.len != 0) {
std.log.warn("unexpected LLD stdout: {}", .{stdout_context.data.items});
}
if (!ok) {
// TODO parse this output and surface with the Compilation API rather than
// directly outputting to stderr here.
std.debug.print("{}", .{stderr_context.data.items});
return error.LLDReportedFailure;
}
if (stderr_context.data.items.len != 0) {
std.log.warn("unexpected LLD stderr: {}", .{stderr_context.data.items});
}
}
if (!self.base.options.disable_lld_caching) {
// Update the file with the digest. If it fails we can continue; it only
// means that the next invocation will have an unnecessary cache miss.
Cache.writeSmallFile(directory.handle, id_symlink_basename, &digest) catch |err| {
std.log.warn("failed to save linking hash digest file: {}", .{@errorName(err)});
};
// Again failure here only means an unnecessary cache miss.
man.writeManifest() catch |err| {
std.log.warn("failed to write cache manifest when linking: {}", .{@errorName(err)});
};
// We hang on to this lock so that the output file path can be used without
// other processes clobbering it.
self.base.lock = man.toOwnedLock();
}
}
const LLDContext = struct {
data: std.ArrayList(u8),
coff: *Coff,
oom: bool = false,
};
fn append_diagnostic(context: usize, ptr: [*]const u8, len: usize) callconv(.C) void {
const lld_context = @intToPtr(*LLDContext, context);
const msg = ptr[0..len];
lld_context.data.appendSlice(msg) catch |err| switch (err) {
error.OutOfMemory => lld_context.oom = true,
};
}
pub fn getDeclVAddr(self: *Coff, decl: *const Module.Decl) u64 {
return self.text_section_virtual_address + decl.link.coff.text_offset;
}
pub fn updateDeclLineNumber(self: *Coff, module: *Module, decl: *Module.Decl) !void {
// TODO Implement this
}
pub fn deinit(self: *Coff) void {
self.text_block_free_list.deinit(self.base.allocator);
self.offset_table.deinit(self.base.allocator);
self.offset_table_free_list.deinit(self.base.allocator);
}
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