diff options
Diffstat (limited to 'src/arch')
| -rw-r--r-- | src/arch/x86_64/CodeGen.zig | 100 |
1 files changed, 96 insertions, 4 deletions
diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig index 80b50f228b..14aebc3724 100644 --- a/src/arch/x86_64/CodeGen.zig +++ b/src/arch/x86_64/CodeGen.zig @@ -1685,6 +1685,7 @@ fn airLoad(self: *Self, inst: Air.Inst.Index) !void { fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type) InnerError!void { _ = ptr_ty; + const abi_size = value_ty.abiSize(self.target.*); switch (ptr) { .none => unreachable, .undef => unreachable, @@ -1705,6 +1706,9 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type return self.fail("TODO implement storing to MCValue.embedded_in_code", .{}); }, .register => |reg| { + self.register_manager.freezeRegs(&.{reg}); + defer self.register_manager.unfreezeRegs(&.{reg}); + switch (value) { .none => unreachable, .undef => unreachable, @@ -1713,7 +1717,6 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type .compare_flags_unsigned => unreachable, .compare_flags_signed => unreachable, .immediate => |imm| { - const abi_size = value_ty.abiSize(self.target.*); switch (abi_size) { 1, 2, 4 => { // TODO this is wasteful! @@ -1736,13 +1739,30 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type .data = .{ .payload = payload }, }); }, + 8 => { + // TODO: optimization: if the imm is only using the lower + // 4 bytes and can be sign extended we can use a normal mov + // with indirect addressing (mov [reg64], imm32). + + // movabs does not support indirect register addressing + // so we need an extra register and an extra mov. + const tmp_reg = try self.copyToTmpRegister(value_ty, value); + _ = try self.addInst(.{ + .tag = .mov, + .ops = (Mir.Ops{ + .reg1 = reg.to64(), + .reg2 = tmp_reg.to64(), + .flags = 0b10, + }).encode(), + .data = .{ .imm = 0 }, + }); + }, else => { return self.fail("TODO implement set pointee with immediate of ABI size {d}", .{abi_size}); }, } }, .register => |src_reg| { - const abi_size = value_ty.abiSize(self.target.*); _ = try self.addInst(.{ .tag = .mov, .ops = (Mir.Ops{ @@ -1758,8 +1778,80 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type }, } }, - .memory => { - return self.fail("TODO implement storing to MCValue.memory", .{}); + .memory => |addr| { + if (self.bin_file.options.pie) { + return self.fail("TODO implement storing to memory when targeting PIE", .{}); + } + + // TODO: in case the address fits in an imm32 we can use [ds:imm32] + // instead of wasting an instruction copying the address to a register + + if (value.isRegister()) self.register_manager.freezeRegs(&.{value.register}); + defer if (value.isRegister()) self.register_manager.unfreezeRegs(&.{value.register}); + + const addr_reg = try self.copyToTmpRegister(ptr_ty, .{ .immediate = addr }); + // to get the actual address of the value we want to modify we have to go through the GOT + // mov reg, [reg] + _ = try self.addInst(.{ + .tag = .mov, + .ops = (Mir.Ops{ + .reg1 = addr_reg.to64(), + .reg2 = addr_reg.to64(), + .flags = 0b01, + }).encode(), + .data = .{ .imm = 0 }, + }); + + switch (value) { + .immediate => |imm| { + if (abi_size > 8) { + return self.fail("TODO saving imm to memory for abi_size {}", .{abi_size}); + } + + const payload = try self.addExtra(Mir.ImmPair{ + .dest_off = 0, + .operand = @intCast(u32, imm), + }); + const flags: u2 = switch (abi_size) { + 1 => 0b00, + 2 => 0b01, + 4 => 0b10, + 8 => 0b11, + else => unreachable, + }; + if (flags == 0b11) { + const top_bits: u32 = @intCast(u32, imm >> 32); + const can_extend = if (value_ty.isUnsignedInt()) + (top_bits == 0) and (imm & 0x8000_0000) == 0 + else + top_bits == 0xffff_ffff; + + if (!can_extend) { + return self.fail("TODO imm64 would get incorrectly sign extended", .{}); + } + } + _ = try self.addInst(.{ + .tag = .mov_mem_imm, + .ops = (Mir.Ops{ + .reg1 = addr_reg.to64(), + .flags = flags, + }).encode(), + .data = .{ .payload = payload }, + }); + }, + .register => |reg| { + _ = try self.addInst(.{ + .tag = .mov, + .ops = (Mir.Ops{ + .reg1 = addr_reg.to64(), + .reg2 = reg, + .flags = 0b10, + }).encode(), + .data = .{ .imm = 0 }, + }); + }, + else => return self.fail("TODO implement storing {} to MCValue.memory", .{value}), + } }, .stack_offset => { return self.fail("TODO implement storing to MCValue.stack_offset", .{}); |