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x86_64: rewrite .got.zig movs to standard loads when emitting objects

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This commit is contained in:
Jakub Konka 2023-11-02 13:21:25 +01:00
parent ccb2afacc0
commit d2c4597eb5
2 changed files with 26 additions and 7 deletions
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7
src/arch/x86_64/Emit.zig
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@ -85,14 +85,15 @@ pub fn emitMir(emit: *Emit) Error!void {
@tagName(emit.lower.bin_file.tag), @tagName(emit.lower.bin_file.tag),
}), }),
.linker_reloc => |data| if (emit.lower.bin_file.cast(link.File.Elf)) |elf_file| { .linker_reloc => |data| if (emit.lower.bin_file.cast(link.File.Elf)) |elf_file| {
const is_obj = emit.lower.bin_file.options.effectiveOutputMode() == .Obj;
const atom = elf_file.symbol(data.atom_index).atom(elf_file).?; const atom = elf_file.symbol(data.atom_index).atom(elf_file).?;
const sym_index = elf_file.zigObjectPtr().?.symbol(data.sym_index); const sym_index = elf_file.zigObjectPtr().?.symbol(data.sym_index);
const sym = elf_file.symbol(sym_index); const sym = elf_file.symbol(sym_index);
if (sym.flags.needs_zig_got and emit.lower.bin_file.options.effectiveOutputMode() != .Obj) { if (sym.flags.needs_zig_got and !is_obj) {
_ = try sym.getOrCreateZigGotEntry(sym_index, elf_file); _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
} }
if (emit.lower.bin_file.options.pic) { if (emit.lower.bin_file.options.pic) {
const r_type: u32 = if (sym.flags.needs_zig_got) const r_type: u32 = if (sym.flags.needs_zig_got and !is_obj)
link.File.Elf.R_X86_64_ZIG_GOTPCREL link.File.Elf.R_X86_64_ZIG_GOTPCREL
else if (sym.flags.needs_got) else if (sym.flags.needs_got)
std.elf.R_X86_64_GOTPCREL std.elf.R_X86_64_GOTPCREL
@ -104,7 +105,7 @@ pub fn emitMir(emit: *Emit) Error!void {
.r_addend = -4, .r_addend = -4,
}); });
} else { } else {
const r_type: u32 = if (sym.flags.needs_zig_got) const r_type: u32 = if (sym.flags.needs_zig_got and !is_obj)
link.File.Elf.R_X86_64_ZIG_GOT32 link.File.Elf.R_X86_64_ZIG_GOT32
else if (sym.flags.needs_got) else if (sym.flags.needs_got)
std.elf.R_X86_64_GOT32 std.elf.R_X86_64_GOT32

26
src/arch/x86_64/Lower.zig
View File

@ -319,6 +319,15 @@ fn reloc(lower: *Lower, target: Reloc.Target) Immediate {
} }
fn emit(lower: *Lower, prefix: Prefix, mnemonic: Mnemonic, ops: []const Operand) Error!void { fn emit(lower: *Lower, prefix: Prefix, mnemonic: Mnemonic, ops: []const Operand) Error!void {
const needsZigGot = struct {
fn needsZigGot(sym: bits.Symbol, ctx: *link.File) bool {
const elf_file = ctx.cast(link.File.Elf).?;
const sym_index = elf_file.zigObjectPtr().?.symbol(sym.sym_index);
return elf_file.symbol(sym_index).flags.needs_zig_got;
}
}.needsZigGot;
const is_obj = lower.bin_file.options.effectiveOutputMode() == .Obj;
var emit_prefix = prefix; var emit_prefix = prefix;
var emit_mnemonic = mnemonic; var emit_mnemonic = mnemonic;
var emit_ops_storage: [4]Operand = undefined; var emit_ops_storage: [4]Operand = undefined;
@ -334,7 +343,13 @@ fn emit(lower: *Lower, prefix: Prefix, mnemonic: Mnemonic, ops: []const Operand)
assert(mem_op.sib.scale_index.scale == 0); assert(mem_op.sib.scale_index.scale == 0);
_ = lower.reloc(.{ .linker_reloc = sym }); _ = lower.reloc(.{ .linker_reloc = sym });
break :op if (lower.bin_file.options.pic) switch (mnemonic) { break :op if (lower.bin_file.options.pic) switch (mnemonic) {
.mov, .lea => .{ .mem = Memory.rip(mem_op.sib.ptr_size, 0) }, .lea => {
break :op .{ .mem = Memory.rip(mem_op.sib.ptr_size, 0) };
},
.mov => {
if (is_obj and needsZigGot(sym, lower.bin_file)) emit_mnemonic = .lea;
break :op .{ .mem = Memory.rip(mem_op.sib.ptr_size, 0) };
},
else => unreachable, else => unreachable,
} else switch (mnemonic) { } else switch (mnemonic) {
.call => .{ .mem = Memory.sib(mem_op.sib.ptr_size, .{ .call => .{ .mem = Memory.sib(mem_op.sib.ptr_size, .{
@ -344,9 +359,12 @@ fn emit(lower: *Lower, prefix: Prefix, mnemonic: Mnemonic, ops: []const Operand)
emit_mnemonic = .mov; emit_mnemonic = .mov;
break :op .{ .imm = Immediate.s(0) }; break :op .{ .imm = Immediate.s(0) };
}, },
.mov => .{ .mem = Memory.sib(mem_op.sib.ptr_size, .{ .mov => {
.base = .{ .reg = .ds }, if (is_obj and needsZigGot(sym, lower.bin_file)) emit_mnemonic = .lea;
}) }, break :op .{ .mem = Memory.sib(mem_op.sib.ptr_size, .{
.base = .{ .reg = .ds },
}) };
},
else => unreachable, else => unreachable,
}; };
}, },