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codegen: fix byte-aligned field offsets in unaligned nested packed structs

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This commit is contained in:
Xavier Bouchoux 2023-10-03 05:34:19 +00:00
parent 62d178e91a
commit 405705cb76
4 changed files with 38 additions and 8 deletions
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3
src/arch/wasm/CodeGen.zig
View File

@ -3828,7 +3828,8 @@ fn structFieldPtr(
if (result_ty.ptrInfo(mod).packed_offset.host_size != 0) {
break :offset @as(u32, 0);
}
break :offset struct_ty.packedStructFieldByteOffset(index, mod) + @divExact(struct_ptr_ty_info.packed_offset.bit_offset, 8);
const struct_type = mod.typeToStruct(struct_ty).?;
break :offset @divExact(mod.structPackedFieldBitOffset(struct_type, index) + struct_ptr_ty_info.packed_offset.bit_offset, 8);
},
.Union => 0,
else => unreachable,

3
src/codegen/llvm.zig
View File

@ -10140,6 +10140,7 @@ pub const FuncGen = struct {
const result_ty = self.typeOfIndex(inst);
const result_ty_info = result_ty.ptrInfo(mod);
const struct_ptr_ty_info = struct_ptr_ty.ptrInfo(mod);
const struct_type = mod.typeToStruct(struct_ty).?;
if (result_ty_info.packed_offset.host_size != 0) {
// From LLVM's perspective, a pointer to a packed struct and a pointer
@ -10151,7 +10152,7 @@ pub const FuncGen = struct {
// We have a pointer to a packed struct field that happens to be byte-aligned.
// Offset our operand pointer by the correct number of bytes.
const byte_offset = struct_ty.packedStructFieldByteOffset(field_index, mod) + @divExact(struct_ptr_ty_info.packed_offset.bit_offset, 8);
const byte_offset = @divExact(mod.structPackedFieldBitOffset(struct_type, field_index) + struct_ptr_ty_info.packed_offset.bit_offset, 8);
if (byte_offset == 0) return struct_ptr;
const usize_ty = try o.lowerType(Type.usize);
const llvm_index = try o.builder.intValue(usize_ty, byte_offset);

6
src/type.zig
View File

@ -3028,12 +3028,6 @@ pub const Type = struct {
};
}
pub fn packedStructFieldByteOffset(ty: Type, field_index: u32, mod: *Module) u32 {
const ip = &mod.intern_pool;
const struct_type = ip.indexToKey(ty.toIntern()).struct_type;
return @divExact(mod.structPackedFieldBitOffset(struct_type, field_index), 8);
}
pub const FieldOffset = struct {
field: usize,
offset: u64,

34
test/behavior/packed-struct.zig
View File

@ -622,6 +622,8 @@ test "@intFromPtr on a packed struct field unaligned and nested" {
}
test "packed struct fields modification" {
// Originally reported at https://github.com/ziglang/zig/issues/16615
const Small = packed struct {
val: u8 = 0,
lo: u4 = 0,
@ -989,6 +991,7 @@ test "bitcast back and forth" {
}
test "field access of packed struct smaller than its abi size inside struct initialized with rls" {
// Originally reported at https://github.com/ziglang/zig/issues/14200
if (builtin.zig_backend == .stage2_llvm and builtin.cpu.arch == .arm) return error.SkipZigTest;
const S = struct {
ps: packed struct { x: i2, y: i2 },
@ -1003,3 +1006,34 @@ test "field access of packed struct smaller than its abi size inside struct init
try expect(@as(i2, 0) == s.ps.x);
try expect(@as(i2, 1) == s.ps.y);
}
test "modify nested packed struct aligned field" {
// Originally reported at https://github.com/ziglang/zig/issues/14632
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
const Options = packed struct {
foo: bool = false,
bar: bool = false,
pretty_print: packed struct {
enabled: bool = false,
num_spaces: u4 = 4,
space_char: enum { space, tab } = .space,
indent: u8 = 0,
} = .{},
baz: bool = false,
};
var opts = Options{};
opts.pretty_print.indent += 1;
try std.testing.expectEqual(@as(u17, 0b00000000100100000), @bitCast(opts));
try std.testing.expect(!opts.foo);
try std.testing.expect(!opts.bar);
try std.testing.expect(!opts.pretty_print.enabled);
try std.testing.expectEqual(@as(u4, 4), opts.pretty_print.num_spaces);
try std.testing.expectEqual(@as(u8, 1), opts.pretty_print.indent);
try std.testing.expect(!opts.baz);
}