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Sema: only ABI sized packed structs are extern compatible
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@Vexu
Vexu committed Sep 2, 2022
1 parent 6aee07c commit b83c037
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Showing 9 changed files with 116 additions and 125 deletions.
47 changes: 31 additions & 16 deletions src/Sema.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5056,7 +5056,7 @@ pub fn analyzeExport(
try mod.ensureDeclAnalyzed(exported_decl_index);
const exported_decl = mod.declPtr(exported_decl_index);

if (!sema.validateExternType(exported_decl.ty, .other)) {
if (!try sema.validateExternType(block, src, exported_decl.ty, .other)) {
const msg = msg: {
const msg = try sema.errMsg(block, src, "unable to export type '{}'", .{exported_decl.ty.fmt(sema.mod)});
errdefer msg.destroy(sema.gpa);
Expand Down Expand Up @@ -7896,7 +7896,7 @@ fn funcCommon(
};
return sema.failWithOwnedErrorMsg(msg);
}
if (!Type.fnCallingConventionAllowsZigTypes(cc_workaround) and !sema.validateExternType(return_type, .ret_ty)) {
if (!Type.fnCallingConventionAllowsZigTypes(cc_workaround) and !try sema.validateExternType(block, ret_ty_src, return_type, .ret_ty)) {
const msg = msg: {
const msg = try sema.errMsg(block, ret_ty_src, "return type '{}' not allowed in function with calling convention '{s}'", .{
return_type.fmt(sema.mod), @tagName(cc_workaround),
Expand Down Expand Up @@ -8115,7 +8115,7 @@ fn analyzeParameter(
};
return sema.failWithOwnedErrorMsg(msg);
}
if (!Type.fnCallingConventionAllowsZigTypes(cc) and !sema.validateExternType(param.ty, .param_ty)) {
if (!Type.fnCallingConventionAllowsZigTypes(cc) and !try sema.validateExternType(block, param_src, param.ty, .param_ty)) {
const msg = msg: {
const msg = try sema.errMsg(block, param_src, "parameter of type '{}' not allowed in function with calling convention '{s}'", .{
param.ty.fmt(sema.mod), @tagName(cc),
Expand Down Expand Up @@ -15583,7 +15583,7 @@ fn zirPtrType(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
} else if (inst_data.size == .Many and elem_ty.zigTypeTag() == .Opaque) {
return sema.fail(block, elem_ty_src, "unknown-length pointer to opaque not allowed", .{});
} else if (inst_data.size == .C) {
if (!sema.validateExternType(elem_ty, .other)) {
if (!try sema.validateExternType(block, elem_ty_src, elem_ty, .other)) {
const msg = msg: {
const msg = try sema.errMsg(block, elem_ty_src, "C pointers cannot point to non-C-ABI-compatible type '{}'", .{elem_ty.fmt(sema.mod)});
errdefer msg.destroy(sema.gpa);
Expand Down Expand Up @@ -16681,7 +16681,7 @@ fn zirReify(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstData, in
} else if (ptr_size == .Many and elem_ty.zigTypeTag() == .Opaque) {
return sema.fail(block, src, "unknown-length pointer to opaque not allowed", .{});
} else if (ptr_size == .C) {
if (!sema.validateExternType(elem_ty, .other)) {
if (!try sema.validateExternType(block, src, elem_ty, .other)) {
const msg = msg: {
const msg = try sema.errMsg(block, src, "C pointers cannot point to non-C-ABI-compatible type '{}'", .{elem_ty.fmt(sema.mod)});
errdefer msg.destroy(sema.gpa);
Expand Down Expand Up @@ -20549,7 +20549,14 @@ const ExternPosition = enum {

/// Returns true if `ty` is allowed in extern types.
/// Does *NOT* require `ty` to be resolved in any way.
fn validateExternType(sema: *Sema, ty: Type, position: ExternPosition) bool {
/// Calls `resolveTypeLayout` for packed containers.
fn validateExternType(
sema: *Sema,
block: *Block,
src: LazySrcLoc,
ty: Type,
position: ExternPosition,
) !bool {
switch (ty.zigTypeTag()) {
.Type,
.ComptimeFloat,
Expand Down Expand Up @@ -20577,17 +20584,25 @@ fn validateExternType(sema: *Sema, ty: Type, position: ExternPosition) bool {
.Fn => return !Type.fnCallingConventionAllowsZigTypes(ty.fnCallingConvention()),
.Enum => {
var buf: Type.Payload.Bits = undefined;
return sema.validateExternType(ty.intTagType(&buf), position);
return sema.validateExternType(block, src, ty.intTagType(&buf), position);
},
.Struct, .Union => switch (ty.containerLayout()) {
.Extern, .Packed => return true,
else => return false,
.Extern => return true,
.Packed => {
const target = sema.mod.getTarget();
const bit_size = try ty.bitSizeAdvanced(target, sema.kit(block, src));
switch (bit_size) {
8, 16, 32, 64, 128 => return true,
else => return false,
}
},
.Auto => return false,
},
.Array => {
if (position == .ret_ty or position == .param_ty) return false;
return sema.validateExternType(ty.elemType2(), .other);
return sema.validateExternType(block, src, ty.elemType2(), .other);
},
.Vector => return sema.validateExternType(ty.elemType2(), .other),
.Vector => return sema.validateExternType(block, src, ty.elemType2(), .other),
.Optional => return ty.isPtrLikeOptional(),
}
}
Expand Down Expand Up @@ -20639,8 +20654,8 @@ fn explainWhyTypeIsNotExtern(
try mod.errNoteNonLazy(src_loc, msg, "enum tag type '{}' is not extern compatible", .{tag_ty.fmt(sema.mod)});
try sema.explainWhyTypeIsNotExtern(msg, src_loc, tag_ty, position);
},
.Struct => try mod.errNoteNonLazy(src_loc, msg, "only structs with packed or extern layout are extern compatible", .{}),
.Union => try mod.errNoteNonLazy(src_loc, msg, "only unions with packed or extern layout are extern compatible", .{}),
.Struct => try mod.errNoteNonLazy(src_loc, msg, "only extern structs and ABI sized packed structs are extern compatible", .{}),
.Union => try mod.errNoteNonLazy(src_loc, msg, "only extern unions and ABI sized packed unions are extern compatible", .{}),
.Array => {
if (position == .ret_ty) {
return mod.errNoteNonLazy(src_loc, msg, "arrays are not allowed as a return type", .{});
Expand Down Expand Up @@ -24119,7 +24134,7 @@ fn coerceVarArgParam(
};

const coerced_ty = sema.typeOf(coerced);
if (!sema.validateExternType(coerced_ty, .other)) {
if (!try sema.validateExternType(block, inst_src, coerced_ty, .other)) {
const msg = msg: {
const msg = try sema.errMsg(block, inst_src, "cannot pass '{}' to variadic function", .{coerced_ty.fmt(sema.mod)});
errdefer msg.destroy(sema.gpa);
Expand Down Expand Up @@ -28321,7 +28336,7 @@ fn semaStructFields(mod: *Module, struct_obj: *Module.Struct) CompileError!void
};
return sema.failWithOwnedErrorMsg(msg);
}
if (struct_obj.layout == .Extern and !sema.validateExternType(field.ty, .other)) {
if (struct_obj.layout == .Extern and !try sema.validateExternType(&block_scope, src, field.ty, .other)) {
const msg = msg: {
const tree = try sema.getAstTree(&block_scope);
const fields_src = enumFieldSrcLoc(decl, tree.*, 0, i);
Expand Down Expand Up @@ -28658,7 +28673,7 @@ fn semaUnionFields(mod: *Module, union_obj: *Module.Union) CompileError!void {
};
return sema.failWithOwnedErrorMsg(msg);
}
if (union_obj.layout == .Extern and !sema.validateExternType(field_ty, .union_field)) {
if (union_obj.layout == .Extern and !try sema.validateExternType(&block_scope, src, field_ty, .union_field)) {
const msg = msg: {
const tree = try sema.getAstTree(&block_scope);
const field_src = enumFieldSrcLoc(decl, tree.*, 0, field_i);
Expand Down
8 changes: 8 additions & 0 deletions src/arch/wasm/abi.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,10 @@ pub fn classifyType(ty: Type, target: Target) [2]Class {
if (!ty.hasRuntimeBitsIgnoreComptime()) return none;
switch (ty.zigTypeTag()) {
.Struct => {
if (ty.containerLayout() == .Packed) {
if (ty.bitSize(target) <= 64) return direct;
return .{ .direct, .direct };
}
// When the struct type is non-scalar
if (ty.structFieldCount() > 1) return memory;
// When the struct's alignment is non-natural
Expand Down Expand Up @@ -57,6 +61,10 @@ pub fn classifyType(ty: Type, target: Target) [2]Class {
return direct;
},
.Union => {
if (ty.containerLayout() == .Packed) {
if (ty.bitSize(target) <= 64) return direct;
return .{ .direct, .direct };
}
const layout = ty.unionGetLayout(target);
std.debug.assert(layout.tag_size == 0);
if (ty.unionFields().count() > 1) return memory;
Expand Down
12 changes: 12 additions & 0 deletions src/arch/x86_64/abi.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -174,6 +174,12 @@ pub fn classifySystemV(ty: Type, target: Target) [8]Class {
// "If the size of the aggregate exceeds a single eightbyte, each is classified
// separately.".
const ty_size = ty.abiSize(target);
if (ty.containerLayout() == .Packed) {
assert(ty_size <= 128);
result[0] = .integer;
if (ty_size > 64) result[1] = .integer;
return result;
}
if (ty_size > 64)
return memory_class;

Expand Down Expand Up @@ -284,6 +290,12 @@ pub fn classifySystemV(ty: Type, target: Target) [8]Class {
// "If the size of the aggregate exceeds a single eightbyte, each is classified
// separately.".
const ty_size = ty.abiSize(target);
if (ty.containerLayout() == .Packed) {
assert(ty_size <= 128);
result[0] = .integer;
if (ty_size > 64) result[1] = .integer;
return result;
}
if (ty_size > 64)
return memory_class;

Expand Down
57 changes: 23 additions & 34 deletions src/codegen/llvm.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9674,22 +9674,7 @@ fn lowerFnRetTy(dg: *DeclGen, fn_info: Type.Payload.Function.Data) !*const llvm.
}
},
.C => {
const is_scalar = switch (fn_info.return_type.zigTypeTag()) {
.Void,
.Bool,
.NoReturn,
.Int,
.Float,
.Pointer,
.Optional,
.ErrorSet,
.Enum,
.AnyFrame,
.Vector,
=> true,

else => false,
};
const is_scalar = isScalar(fn_info.return_type);
switch (target.cpu.arch) {
.mips, .mipsel => return dg.lowerType(fn_info.return_type),
.x86_64 => switch (target.os.tag) {
Expand Down Expand Up @@ -9837,24 +9822,7 @@ const ParamTypeIterator = struct {
@panic("TODO implement async function lowering in the LLVM backend");
},
.C => {
const is_scalar = switch (ty.zigTypeTag()) {
.Void,
.Bool,
.NoReturn,
.Int,
.Float,
.Pointer,
.Optional,
.ErrorSet,
.Enum,
.AnyFrame,
.Vector,
=> true,
.Struct => ty.containerLayout() == .Packed,
.Union => ty.containerLayout() == .Packed,

else => false,
};
const is_scalar = isScalar(ty);
switch (it.target.cpu.arch) {
.riscv32, .riscv64 => {
it.zig_index += 1;
Expand Down Expand Up @@ -10108,6 +10076,27 @@ fn isByRef(ty: Type) bool {
}
}

fn isScalar(ty: Type) bool {
return switch (ty.zigTypeTag()) {
.Void,
.Bool,
.NoReturn,
.Int,
.Float,
.Pointer,
.Optional,
.ErrorSet,
.Enum,
.AnyFrame,
.Vector,
=> true,

.Struct => ty.containerLayout() == .Packed,
.Union => ty.containerLayout() == .Packed,
else => false,
};
}

/// This function returns true if we expect LLVM to lower x86_fp80 correctly
/// and false if we expect LLVM to crash if it counters an x86_fp80 type.
fn backendSupportsF80(target: std.Target) bool {
Expand Down
78 changes: 29 additions & 49 deletions test/c_abi/cfuncs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -86,24 +86,8 @@ struct MedStructMixed {
void zig_med_struct_mixed(struct MedStructMixed);
struct MedStructMixed zig_ret_med_struct_mixed();

struct SmallPackedStruct {
uint8_t a: 2;
uint8_t b: 2;
uint8_t c: 2;
uint8_t d: 2;
uint8_t e: 1;
};

struct BigPackedStruct {
uint64_t a: 64;
uint64_t b: 64;
uint64_t c: 64;
uint64_t d: 64;
uint8_t e: 8;
};

//void zig_small_packed_struct(struct SmallPackedStruct); // #1481
void zig_big_packed_struct(struct BigPackedStruct);
void zig_small_packed_struct(uint8_t);
void zig_big_packed_struct(__int128);

struct SplitStructInts {
uint64_t a;
Expand Down Expand Up @@ -176,13 +160,19 @@ void run_c_tests(void) {
}

{
struct BigPackedStruct s = {1, 2, 3, 4, 5};
__int128 s = 0;
s |= 1 << 0;
s |= (__int128)2 << 64;
zig_big_packed_struct(s);
}

{
struct SmallPackedStruct s = {0, 1, 2, 3, 1};
//zig_small_packed_struct(s);
uint8_t s = 0;
s |= 0 << 0;
s |= 1 << 2;
s |= 2 << 4;
s |= 3 << 6;
zig_small_packed_struct(s);
}

{
Expand Down Expand Up @@ -378,42 +368,32 @@ void c_split_struct_mixed(struct SplitStructMixed x) {
assert_or_panic(y.c == 1337.0f);
}

struct SmallPackedStruct c_ret_small_packed_struct() {
struct SmallPackedStruct s = {
.a = 0,
.b = 1,
.c = 2,
.d = 3,
.e = 1,
};
uint8_t c_ret_small_packed_struct() {
uint8_t s = 0;
s |= 0 << 0;
s |= 1 << 2;
s |= 2 << 4;
s |= 3 << 6;
return s;
}

void c_small_packed_struct(struct SmallPackedStruct x) {
assert_or_panic(x.a == 0);
assert_or_panic(x.a == 1);
assert_or_panic(x.a == 2);
assert_or_panic(x.a == 3);
assert_or_panic(x.e == 1);
void c_small_packed_struct(uint8_t x) {
assert_or_panic(((x >> 0) & 0x3) == 0);
assert_or_panic(((x >> 2) & 0x3) == 1);
assert_or_panic(((x >> 4) & 0x3) == 2);
assert_or_panic(((x >> 6) & 0x3) == 3);
}

struct BigPackedStruct c_ret_big_packed_struct() {
struct BigPackedStruct s = {
.a = 1,
.b = 2,
.c = 3,
.d = 4,
.e = 5,
};
__int128 c_ret_big_packed_struct() {
__int128 s = 0;
s |= 1 << 0;
s |= (__int128)2 << 64;
return s;
}

void c_big_packed_struct(struct BigPackedStruct x) {
assert_or_panic(x.a == 1);
assert_or_panic(x.b == 2);
assert_or_panic(x.c == 3);
assert_or_panic(x.d == 4);
assert_or_panic(x.e == 5);
void c_big_packed_struct(__int128 x) {
assert_or_panic(((x >> 0) & 0xFFFFFFFFFFFFFFFF) == 1);
assert_or_panic(((x >> 64) & 0xFFFFFFFFFFFFFFFF) == 2);
}

struct SplitStructMixed c_ret_split_struct_mixed() {
Expand Down

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