authorgravatar for git@vexu.euVeikka Tuominen <git@vexu.eu> 2022-10-05 15:35:11+03:00
committergravatar for noreply@github.comGitHub <noreply@github.com> 2022-10-05 15:35:11+03:00
loge563af13296cdb3e64f0f396fdc58112d4484968
tree46d5066948ebcce3825932839d25577014cb8ab6
parentf374ea2cd16cf5d0f6f8df6b50f55a9e315ae565
parenta560af96568a668bf0c01b3c58ad4dda647ea1b4
signaturebadge-question-mark Signed by PGP key 4AEE18F83AFDEB23

Merge pull request #12745 from Techcable/translate-c/packed-struct-implies-align1

translate-c: Translate clang packed struct C into Zig extern struct with align(1)

6 files changed, 174 insertions(+), 50 deletions(-)

src/clang.zig+6
...@@ -470,6 +470,9 @@ pub const FieldDecl = opaque {...@@ -470,6 +470,9 @@ pub const FieldDecl = opaque {
470 pub const getAlignedAttribute = ZigClangFieldDecl_getAlignedAttribute;470 pub const getAlignedAttribute = ZigClangFieldDecl_getAlignedAttribute;
471 extern fn ZigClangFieldDecl_getAlignedAttribute(*const FieldDecl, *const ASTContext) c_uint;471 extern fn ZigClangFieldDecl_getAlignedAttribute(*const FieldDecl, *const ASTContext) c_uint;
472472
473 pub const getPackedAttribute = ZigClangFieldDecl_getPackedAttribute;
474 extern fn ZigClangFieldDecl_getPackedAttribute(*const FieldDecl) bool;
475
473 pub const isAnonymousStructOrUnion = ZigClangFieldDecl_isAnonymousStructOrUnion;476 pub const isAnonymousStructOrUnion = ZigClangFieldDecl_isAnonymousStructOrUnion;
474 extern fn ZigClangFieldDecl_isAnonymousStructOrUnion(*const FieldDecl) bool;477 extern fn ZigClangFieldDecl_isAnonymousStructOrUnion(*const FieldDecl) bool;
475478
...@@ -1015,6 +1018,9 @@ pub const VarDecl = opaque {...@@ -1015,6 +1018,9 @@ pub const VarDecl = opaque {
1015 pub const getAlignedAttribute = ZigClangVarDecl_getAlignedAttribute;1018 pub const getAlignedAttribute = ZigClangVarDecl_getAlignedAttribute;
1016 extern fn ZigClangVarDecl_getAlignedAttribute(*const VarDecl, *const ASTContext) c_uint;1019 extern fn ZigClangVarDecl_getAlignedAttribute(*const VarDecl, *const ASTContext) c_uint;
10171020
1021 pub const getPackedAttribute = ZigClangVarDecl_getPackedAttribute;
1022 extern fn ZigClangVarDecl_getPackedAttribute(*const VarDecl) bool;
1023
1018 pub const getCleanupAttribute = ZigClangVarDecl_getCleanupAttribute;1024 pub const getCleanupAttribute = ZigClangVarDecl_getCleanupAttribute;
1019 extern fn ZigClangVarDecl_getCleanupAttribute(*const VarDecl) ?*const FunctionDecl;1025 extern fn ZigClangVarDecl_getCleanupAttribute(*const VarDecl) ?*const FunctionDecl;
10201026
src/translate_c.zig+61-16
...@@ -878,7 +878,7 @@ fn visitVarDecl(c: *Context, var_decl: *const clang.VarDecl, mangled_name: ?[]co...@@ -878,7 +878,7 @@ fn visitVarDecl(c: *Context, var_decl: *const clang.VarDecl, mangled_name: ?[]co
878 .is_export = is_export,878 .is_export = is_export,
879 .is_threadlocal = is_threadlocal,879 .is_threadlocal = is_threadlocal,
880 .linksection_string = linksection_string,880 .linksection_string = linksection_string,
881 .alignment = zigAlignment(var_decl.getAlignedAttribute(c.clang_context)),881 .alignment = ClangAlignment.forVar(c, var_decl).zigAlignment(),
882 .name = var_name,882 .name = var_name,
883 .type = type_node,883 .type = type_node,
884 .init = init_node,884 .init = init_node,
...@@ -1096,7 +1096,6 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD...@@ -1096,7 +1096,6 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
1096 break :blk Tag.opaque_literal.init();1096 break :blk Tag.opaque_literal.init();
1097 };1097 };
10981098
1099 const is_packed = record_decl.getPackedAttribute();
1100 var fields = std.ArrayList(ast.Payload.Record.Field).init(c.gpa);1099 var fields = std.ArrayList(ast.Payload.Record.Field).init(c.gpa);
1101 defer fields.deinit();1100 defer fields.deinit();
11021101
...@@ -1153,7 +1152,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD...@@ -1153,7 +1152,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
1153 const alignment = if (has_flexible_array and field_decl.getFieldIndex() == 0)1152 const alignment = if (has_flexible_array and field_decl.getFieldIndex() == 0)
1154 @intCast(c_uint, record_alignment)1153 @intCast(c_uint, record_alignment)
1155 else1154 else
1156 zigAlignment(field_decl.getAlignedAttribute(c.clang_context));1155 ClangAlignment.forField(c, field_decl, record_def).zigAlignment();
11571156
1158 if (is_anon) {1157 if (is_anon) {
1159 try c.decl_table.putNoClobber(c.gpa, @ptrToInt(field_decl.getCanonicalDecl()), field_name);1158 try c.decl_table.putNoClobber(c.gpa, @ptrToInt(field_decl.getCanonicalDecl()), field_name);
...@@ -1166,15 +1165,11 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD...@@ -1166,15 +1165,11 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
1166 });1165 });
1167 }1166 }
11681167
1169 if (!c.zig_is_stage1 and is_packed) {
1170 return failDecl(c, record_loc, name, "cannot translate packed record union", .{});
1171 }
1172
1173 const record_payload = try c.arena.create(ast.Payload.Record);1168 const record_payload = try c.arena.create(ast.Payload.Record);
1174 record_payload.* = .{1169 record_payload.* = .{
1175 .base = .{ .tag = ([2]Tag{ .@"struct", .@"union" })[@boolToInt(is_union)] },1170 .base = .{ .tag = ([2]Tag{ .@"struct", .@"union" })[@boolToInt(is_union)] },
1176 .data = .{1171 .data = .{
1177 .layout = if (is_packed) .@"packed" else .@"extern",1172 .layout = .@"extern",
1178 .fields = try c.arena.dupe(ast.Payload.Record.Field, fields.items),1173 .fields = try c.arena.dupe(ast.Payload.Record.Field, fields.items),
1179 .functions = try c.arena.dupe(Node, functions.items),1174 .functions = try c.arena.dupe(Node, functions.items),
1180 .variables = &.{},1175 .variables = &.{},
...@@ -1851,12 +1846,62 @@ fn transCStyleCastExprClass(...@@ -1851,12 +1846,62 @@ fn transCStyleCastExprClass(
1851 return maybeSuppressResult(c, scope, result_used, cast_node);1846 return maybeSuppressResult(c, scope, result_used, cast_node);
1852}1847}
18531848
1854/// Clang reports the alignment in bits, we use bytes1849/// The alignment of a variable or field
1855/// Clang uses 0 for "no alignment specified", we use null1850const ClangAlignment = struct {
1856fn zigAlignment(bit_alignment: c_uint) ?c_uint {1851 /// Clang reports the alignment in bits, we use bytes
1857 if (bit_alignment == 0) return null;1852 /// Clang uses 0 for "no alignment specified", we use null
1858 return bit_alignment / 8;1853 bit_alignment: c_uint,
1859}1854 /// If the field or variable is marked as 'packed'
1855 ///
1856 /// According to the GCC variable attribute docs, this impacts alignment
1857 /// https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
1858 ///
1859 /// > The packed attribute specifies that a structure member
1860 /// > should have the smallest possible alignment
1861 ///
1862 /// Note also that specifying the 'packed' attribute on a structure
1863 /// implicitly packs all its fields (making their alignment 1).
1864 ///
1865 /// This will be null if the AST node doesn't support packing (functions)
1866 is_packed: ?bool,
1867
1868 /// Get the alignment for a field, optionally taking into account the parent record
1869 pub fn forField(c: *const Context, field: *const clang.FieldDecl, parent: ?*const clang.RecordDecl) ClangAlignment {
1870 const parent_packed = if (parent) |record| record.getPackedAttribute() else false;
1871 // NOTE: According to GCC docs, parent attribute packed implies child attribute packed
1872 return ClangAlignment{
1873 .bit_alignment = field.getAlignedAttribute(c.clang_context),
1874 .is_packed = field.getPackedAttribute() or parent_packed,
1875 };
1876 }
1877
1878 pub fn forVar(c: *const Context, var_decl: *const clang.VarDecl) ClangAlignment {
1879 return ClangAlignment{
1880 .bit_alignment = var_decl.getAlignedAttribute(c.clang_context),
1881 .is_packed = var_decl.getPackedAttribute(),
1882 };
1883 }
1884
1885 pub fn forFunc(c: *const Context, fun: *const clang.FunctionDecl) ClangAlignment {
1886 return ClangAlignment{
1887 .bit_alignment = fun.getAlignedAttribute(c.clang_context),
1888 .is_packed = null, // not supported by GCC/clang (or meaningful),
1889 };
1890 }
1891
1892 /// Translate the clang alignment info into a zig alignment
1893 ///
1894 /// Returns null if there is no special alignment info
1895 pub fn zigAlignment(self: ClangAlignment) ?c_uint {
1896 if (self.bit_alignment != 0) {
1897 return self.bit_alignment / 8;
1898 } else if (self.is_packed orelse false) {
1899 return 1;
1900 } else {
1901 return null;
1902 }
1903 }
1904};
18601905
1861fn transDeclStmtOne(1906fn transDeclStmtOne(
1862 c: *Context,1907 c: *Context,
...@@ -1910,7 +1955,7 @@ fn transDeclStmtOne(...@@ -1910,7 +1955,7 @@ fn transDeclStmtOne(
1910 .is_export = false,1955 .is_export = false,
1911 .is_threadlocal = var_decl.getTLSKind() != .None,1956 .is_threadlocal = var_decl.getTLSKind() != .None,
1912 .linksection_string = null,1957 .linksection_string = null,
1913 .alignment = zigAlignment(var_decl.getAlignedAttribute(c.clang_context)),1958 .alignment = ClangAlignment.forVar(c, var_decl).zigAlignment(),
1914 .name = var_name,1959 .name = var_name,
1915 .type = type_node,1960 .type = type_node,
1916 .init = init_node,1961 .init = init_node,
...@@ -5054,7 +5099,7 @@ fn finishTransFnProto(...@@ -5054,7 +5099,7 @@ fn finishTransFnProto(
5054 break :blk null;5099 break :blk null;
5055 };5100 };
50565101
5057 const alignment = if (fn_decl) |decl| zigAlignment(decl.getAlignedAttribute(c.clang_context)) else null;5102 const alignment = if (fn_decl) |decl| ClangAlignment.forFunc(c, decl).zigAlignment() else null;
50585103
5059 const explicit_callconv = if ((is_inline or is_export or is_extern) and cc == .C) null else cc;5104 const explicit_callconv = if ((is_inline or is_export or is_extern) and cc == .C) null else cc;
50605105
src/zig_clang.cpp+11-4
...@@ -1941,10 +1941,7 @@ const char* ZigClangVarDecl_getSectionAttribute(const struct ZigClangVarDecl *se...@@ -1941,10 +1941,7 @@ const char* ZigClangVarDecl_getSectionAttribute(const struct ZigClangVarDecl *se
19411941
1942bool ZigClangRecordDecl_getPackedAttribute(const ZigClangRecordDecl *zig_record_decl) {1942bool ZigClangRecordDecl_getPackedAttribute(const ZigClangRecordDecl *zig_record_decl) {
1943 const clang::RecordDecl *record_decl = reinterpret_cast<const clang::RecordDecl *>(zig_record_decl);1943 const clang::RecordDecl *record_decl = reinterpret_cast<const clang::RecordDecl *>(zig_record_decl);
1944 if (record_decl->getAttr<clang::PackedAttr>()) {1944 return record_decl->hasAttr<clang::PackedAttr>();
1945 return true;
1946 }
1947 return false;
1948}1945}
19491946
1950unsigned ZigClangVarDecl_getAlignedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx) {1947unsigned ZigClangVarDecl_getAlignedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx) {
...@@ -1985,6 +1982,16 @@ unsigned ZigClangFunctionDecl_getAlignedAttribute(const struct ZigClangFunctionD...@@ -1985,6 +1982,16 @@ unsigned ZigClangFunctionDecl_getAlignedAttribute(const struct ZigClangFunctionD
1985 return 0;1982 return 0;
1986}1983}
19871984
1985bool ZigClangVarDecl_getPackedAttribute(const struct ZigClangVarDecl *self) {
1986 auto casted_self = reinterpret_cast<const clang::VarDecl *>(self);
1987 return casted_self->hasAttr<clang::PackedAttr>();
1988}
1989
1990bool ZigClangFieldDecl_getPackedAttribute(const struct ZigClangFieldDecl *self) {
1991 auto casted_self = reinterpret_cast<const clang::FieldDecl *>(self);
1992 return casted_self->hasAttr<clang::PackedAttr>();
1993}
1994
1988ZigClangQualType ZigClangParmVarDecl_getOriginalType(const struct ZigClangParmVarDecl *self) {1995ZigClangQualType ZigClangParmVarDecl_getOriginalType(const struct ZigClangParmVarDecl *self) {
1989 return bitcast(reinterpret_cast<const clang::ParmVarDecl *>(self)->getOriginalType());1996 return bitcast(reinterpret_cast<const clang::ParmVarDecl *>(self)->getOriginalType());
1990}1997}
src/zig_clang.h+2
...@@ -1101,6 +1101,8 @@ ZIG_EXTERN_C const struct ZigClangFunctionDecl *ZigClangVarDecl_getCleanupAttrib...@@ -1101,6 +1101,8 @@ ZIG_EXTERN_C const struct ZigClangFunctionDecl *ZigClangVarDecl_getCleanupAttrib
1101ZIG_EXTERN_C unsigned ZigClangVarDecl_getAlignedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx);1101ZIG_EXTERN_C unsigned ZigClangVarDecl_getAlignedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx);
1102ZIG_EXTERN_C unsigned ZigClangFunctionDecl_getAlignedAttribute(const struct ZigClangFunctionDecl *self, const ZigClangASTContext* ctx);1102ZIG_EXTERN_C unsigned ZigClangFunctionDecl_getAlignedAttribute(const struct ZigClangFunctionDecl *self, const ZigClangASTContext* ctx);
1103ZIG_EXTERN_C unsigned ZigClangFieldDecl_getAlignedAttribute(const struct ZigClangFieldDecl *self, const ZigClangASTContext* ctx);1103ZIG_EXTERN_C unsigned ZigClangFieldDecl_getAlignedAttribute(const struct ZigClangFieldDecl *self, const ZigClangASTContext* ctx);
1104ZIG_EXTERN_C bool ZigClangVarDecl_getPackedAttribute(const struct ZigClangVarDecl *self);
1105ZIG_EXTERN_C bool ZigClangFieldDecl_getPackedAttribute(const struct ZigClangFieldDecl *self);
11041106
1105ZIG_EXTERN_C const struct ZigClangStringLiteral *ZigClangFileScopeAsmDecl_getAsmString(const struct ZigClangFileScopeAsmDecl *self);1107ZIG_EXTERN_C const struct ZigClangStringLiteral *ZigClangFileScopeAsmDecl_getAsmString(const struct ZigClangFileScopeAsmDecl *self);
11061108
test/run_translated_c.zig+12-14
...@@ -250,20 +250,18 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {...@@ -250,20 +250,18 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {
250 \\}250 \\}
251 , "");251 , "");
252252
253 if (@import("builtin").zig_backend == .stage1) {253 cases.add("struct initializer - packed",
254 cases.add("struct initializer - packed",254 \\#define _NO_CRT_STDIO_INLINE 1
255 \\#define _NO_CRT_STDIO_INLINE 1255 \\#include <stdint.h>
256 \\#include <stdint.h>256 \\#include <stdlib.h>
257 \\#include <stdlib.h>257 \\struct s {uint8_t x,y;
258 \\struct s {uint8_t x,y;258 \\ uint32_t z;} __attribute__((packed)) s0 = {1, 2};
259 \\ uint32_t z;} __attribute__((packed)) s0 = {1, 2};259 \\int main() {
260 \\int main() {260 \\ /* sizeof nor offsetof currently supported */
261 \\ /* sizeof nor offsetof currently supported */261 \\ if (((intptr_t)&s0.z - (intptr_t)&s0.x) != 2) abort();
262 \\ if (((intptr_t)&s0.z - (intptr_t)&s0.x) != 2) abort();262 \\ return 0;
263 \\ return 0;263 \\}
264 \\}264 , "");
265 , "");
266 }
267265
268 cases.add("cast signed array index to unsigned",266 cases.add("cast signed array index to unsigned",
269 \\#include <stdlib.h>267 \\#include <stdlib.h>
test/translate_c.zig+82-16
...@@ -728,22 +728,20 @@ pub fn addCases(cases: *tests.TranslateCContext) void {...@@ -728,22 +728,20 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
728 \\}728 \\}
729 });729 });
730730
731 if (builtin.zig_backend == .stage1) {731 cases.add("struct initializer - packed",
732 cases.add("struct initializer - packed",732 \\struct {int x,y,z;} __attribute__((packed)) s0 = {1, 2};
733 \\struct {int x,y,z;} __attribute__((packed)) s0 = {1, 2};733 , &[_][]const u8{
734 , &[_][]const u8{734 \\const struct_unnamed_1 = extern struct {
735 \\const struct_unnamed_1 = packed struct {735 \\ x: c_int align(1),
736 \\ x: c_int,736 \\ y: c_int align(1),
737 \\ y: c_int,737 \\ z: c_int align(1),
738 \\ z: c_int,738 \\};
739 \\};739 \\pub export var s0: struct_unnamed_1 = struct_unnamed_1{
740 \\pub export var s0: struct_unnamed_1 = struct_unnamed_1{740 \\ .x = @as(c_int, 1),
741 \\ .x = @as(c_int, 1),741 \\ .y = @as(c_int, 2),
742 \\ .y = @as(c_int, 2),742 \\ .z = 0,
743 \\ .z = 0,743 \\};
744 \\};744 });
745 });
746 }
747745
748 // Test case temporarily disabled:746 // Test case temporarily disabled:
749 // https://github.com/ziglang/zig/issues/12055747 // https://github.com/ziglang/zig/issues/12055
...@@ -1393,6 +1391,74 @@ pub fn addCases(cases: *tests.TranslateCContext) void {...@@ -1393,6 +1391,74 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
1393 \\pub const Foo = union_Foo;1391 \\pub const Foo = union_Foo;
1394 });1392 });
13951393
1394 cases.add("packed union - simple",
1395 \\union Foo {
1396 \\ char x;
1397 \\ double y;
1398 \\} __attribute__((packed));
1399 , &[_][]const u8{
1400 \\pub const union_Foo = extern union {
1401 \\ x: u8 align(1),
1402 \\ y: f64 align(1),
1403 \\};
1404 ,
1405 \\pub const Foo = union_Foo;
1406 });
1407
1408 cases.add("packed union - nested unpacked",
1409 \\union Foo{
1410 \\ char x;
1411 \\ double y;
1412 \\ struct {
1413 \\ char a;
1414 \\ int b;
1415 \\ } z;
1416 \\} __attribute__((packed));
1417 , &[_][]const u8{
1418 // NOTE: The nested struct is *not* packed/aligned,
1419 // even though the parent struct is
1420 // this is consistent with GCC docs
1421 \\const struct_unnamed_1 = extern struct {
1422 \\ a: u8,
1423 \\ b: c_int,
1424 \\};
1425 ,
1426 \\pub const union_Foo = extern union {
1427 \\ x: u8 align(1),
1428 \\ y: f64 align(1),
1429 \\ z: struct_unnamed_1 align(1),
1430 \\};
1431 ,
1432 \\pub const Foo = union_Foo;
1433 });
1434
1435 cases.add("packed union - nested packed",
1436 \\union Foo{
1437 \\ char x;
1438 \\ double y;
1439 \\ struct {
1440 \\ char a;
1441 \\ int b;
1442 \\ } __attribute__((packed)) z;
1443 \\} __attribute__((packed));
1444 , &[_][]const u8{
1445 // in order for the nested struct to be packed, it must
1446 // have an independent packed declaration on
1447 // the nested type (see GCC docs for details)
1448 \\const struct_unnamed_1 = extern struct {
1449 \\ a: u8 align(1),
1450 \\ b: c_int align(1),
1451 \\};
1452 ,
1453 \\pub const union_Foo = extern union {
1454 \\ x: u8 align(1),
1455 \\ y: f64 align(1),
1456 \\ z: struct_unnamed_1 align(1),
1457 \\};
1458 ,
1459 \\pub const Foo = union_Foo;
1460 });
1461
1396 cases.add("string literal",1462 cases.add("string literal",
1397 \\const char *foo(void) {1463 \\const char *foo(void) {
1398 \\ return "bar";1464 \\ return "bar";