authorgravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2022-02-03 14:31:16+01:00
committergravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2022-02-03 14:31:16+01:00
logf4e0641450032004b9200a4d5fa754e189a123f3
tree9aaeba50b3fe5b62c9ac75708519e1d41420ceea
parente52af268569e0005fb0c40c30154c50591e2fc6c

x64: use freeze/unfreeze api; TODO for PIE

2 files changed, 34 insertions(+), 26 deletions(-)

src/arch/x86_64/CodeGen.zig+34-23
...@@ -1685,6 +1685,7 @@ fn airLoad(self: *Self, inst: Air.Inst.Index) !void {...@@ -1685,6 +1685,7 @@ fn airLoad(self: *Self, inst: Air.Inst.Index) !void {
16851685
1686fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type) InnerError!void {1686fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type) InnerError!void {
1687 _ = ptr_ty;1687 _ = ptr_ty;
1688 const abi_size = value_ty.abiSize(self.target.*);
1688 switch (ptr) {1689 switch (ptr) {
1689 .none => unreachable,1690 .none => unreachable,
1690 .undef => unreachable,1691 .undef => unreachable,
...@@ -1705,6 +1706,9 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type...@@ -1705,6 +1706,9 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
1705 return self.fail("TODO implement storing to MCValue.embedded_in_code", .{});1706 return self.fail("TODO implement storing to MCValue.embedded_in_code", .{});
1706 },1707 },
1707 .register => |reg| {1708 .register => |reg| {
1709 self.register_manager.freezeRegs(&.{reg});
1710 defer self.register_manager.unfreezeRegs(&.{reg});
1711
1708 switch (value) {1712 switch (value) {
1709 .none => unreachable,1713 .none => unreachable,
1710 .undef => unreachable,1714 .undef => unreachable,
...@@ -1713,7 +1717,6 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type...@@ -1713,7 +1717,6 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
1713 .compare_flags_unsigned => unreachable,1717 .compare_flags_unsigned => unreachable,
1714 .compare_flags_signed => unreachable,1718 .compare_flags_signed => unreachable,
1715 .immediate => |imm| {1719 .immediate => |imm| {
1716 const abi_size = value_ty.abiSize(self.target.*);
1717 switch (abi_size) {1720 switch (abi_size) {
1718 1, 2, 4 => {1721 1, 2, 4 => {
1719 // TODO this is wasteful!1722 // TODO this is wasteful!
...@@ -1760,7 +1763,6 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type...@@ -1760,7 +1763,6 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
1760 }1763 }
1761 },1764 },
1762 .register => |src_reg| {1765 .register => |src_reg| {
1763 const abi_size = value_ty.abiSize(self.target.*);
1764 _ = try self.addInst(.{1766 _ = try self.addInst(.{
1765 .tag = .mov,1767 .tag = .mov,
1766 .ops = (Mir.Ops{1768 .ops = (Mir.Ops{
...@@ -1777,9 +1779,16 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type...@@ -1777,9 +1779,16 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
1777 }1779 }
1778 },1780 },
1779 .memory => |addr| {1781 .memory => |addr| {
1782 if (self.bin_file.options.pie) {
1783 return self.fail("TODO implement storing to memory when targeting PIE", .{});
1784 }
1785
1780 // TODO: in case the address fits in an imm32 we can use [ds:imm32]1786 // TODO: in case the address fits in an imm32 we can use [ds:imm32]
1781 // instead of wasting an instruction copying the address to a register1787 // instead of wasting an instruction copying the address to a register
17821788
1789 if (value.isRegister()) self.register_manager.freezeRegs(&.{value.register});
1790 defer if (value.isRegister()) self.register_manager.unfreezeRegs(&.{value.register});
1791
1783 const addr_reg = try self.copyToTmpRegister(ptr_ty, .{ .immediate = addr });1792 const addr_reg = try self.copyToTmpRegister(ptr_ty, .{ .immediate = addr });
1784 // to get the actual address of the value we want to modify we have to go through the GOT1793 // to get the actual address of the value we want to modify we have to go through the GOT
1785 // mov reg, [reg]1794 // mov reg, [reg]
...@@ -1793,37 +1802,39 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type...@@ -1793,37 +1802,39 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
1793 .data = .{ .imm = 0 },1802 .data = .{ .imm = 0 },
1794 });1803 });
17951804
1796 const abi_size = value_ty.abiSize(self.target.*);
1797 switch (value) {1805 switch (value) {
1798 .immediate => |imm| {1806 .immediate => |imm| {
1807 if (abi_size > 8) {
1808 return self.fail("TODO saving imm to memory for abi_size {}", .{abi_size});
1809 }
1810
1799 const payload = try self.addExtra(Mir.ImmPair{1811 const payload = try self.addExtra(Mir.ImmPair{
1800 .dest_off = 0,1812 .dest_off = 0,
1801 .operand = @intCast(u32, imm),1813 .operand = @intCast(u32, imm),
1802 });1814 });
1815 const flags: u2 = switch (abi_size) {
1816 1 => 0b00,
1817 2 => 0b01,
1818 4 => 0b10,
1819 8 => 0b11,
1820 else => unreachable,
1821 };
1822 if (flags == 0b11) {
1823 const top_bits: u32 = @intCast(u32, imm >> 32);
1824 const can_extend = if (value_ty.isUnsignedInt())
1825 (top_bits == 0) and (imm & 0x8000_0000) == 0
1826 else
1827 top_bits == 0xffff_ffff;
1828
1829 if (!can_extend) {
1830 return self.fail("TODO imm64 would get incorrectly sign extended", .{});
1831 }
1832 }
1803 _ = try self.addInst(.{1833 _ = try self.addInst(.{
1804 .tag = .mov_mem_imm,1834 .tag = .mov_mem_imm,
1805 .ops = (Mir.Ops{1835 .ops = (Mir.Ops{
1806 .reg1 = addr_reg.to64(),1836 .reg1 = addr_reg.to64(),
1807 .flags = switch (abi_size) {1837 .flags = flags,
1808 1 => 0b00,
1809 2 => 0b01,
1810 4 => 0b10,
1811 8 => flag: {
1812 const top_bits: u32 = @intCast(u32, imm >> 32);
1813 const can_extend = if (value_ty.isUnsignedInt())
1814 (top_bits == 0) and (imm & 0x8000_0000) == 0
1815 else
1816 top_bits == 0xffff_ffff;
1817
1818 if (!can_extend) {
1819 return self.fail("TODO imm64 would get incorrectly sign extended", .{});
1820 }
1821 break :flag 0b11;
1822 },
1823 else => {
1824 return self.fail("TODO saving imm to memory for abi_size {}", .{abi_size});
1825 },
1826 },
1827 }).encode(),1838 }).encode(),
1828 .data = .{ .payload = payload },1839 .data = .{ .payload = payload },
1829 });1840 });
test/behavior/bugs/1486.zig-3
...@@ -1,13 +1,10 @@...@@ -1,13 +1,10 @@
1const std = @import("std");1const std = @import("std");
2const builtin = @import("builtin");
3const expect = std.testing.expect;2const expect = std.testing.expect;
43
5const ptr = &global;4const ptr = &global;
6var global: usize = 123;5var global: usize = 123;
76
8test "constant pointer to global variable causes runtime load" {7test "constant pointer to global variable causes runtime load" {
9 if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
10
11 global = 1234;8 global = 1234;
12 try expect(&global == ptr);9 try expect(&global == ptr);
13 try expect(ptr.* == 1234);10 try expect(ptr.* == 1234);