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Add support for C bitfields #4165

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7 changes: 7 additions & 0 deletions src-self-hosted/clang.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ pub const struct_ZigClangAPInt = @OpaqueType();
pub const struct_ZigClangAPSInt = @OpaqueType();
pub const struct_ZigClangAPFloat = @OpaqueType();
pub const struct_ZigClangASTContext = @OpaqueType();
pub const struct_ZigClangASTRecordLayout = @OpaqueType();
pub const struct_ZigClangASTUnit = @OpaqueType();
pub const struct_ZigClangArraySubscriptExpr = @OpaqueType();
pub const struct_ZigClangArrayType = @OpaqueType();
Expand Down Expand Up @@ -757,6 +758,9 @@ pub extern fn ZigClangSourceManager_getSpellingLineNumber(self: ?*const struct_Z
pub extern fn ZigClangSourceManager_getSpellingColumnNumber(self: ?*const struct_ZigClangSourceManager, Loc: struct_ZigClangSourceLocation) c_uint;
pub extern fn ZigClangSourceManager_getCharacterData(self: ?*const struct_ZigClangSourceManager, SL: struct_ZigClangSourceLocation) [*:0]const u8;
pub extern fn ZigClangASTContext_getPointerType(self: ?*const struct_ZigClangASTContext, T: struct_ZigClangQualType) struct_ZigClangQualType;
pub extern fn ZigClangASTContext_getASTRecordLayout(self: ?*const struct_ZigClangASTContext, D: ?*const struct_ZigClangRecordDecl) ?*const struct_ZigClangASTRecordLayout;
pub extern fn ZigClangASTRecordLayout_getFieldCount(self: ?*const struct_ZigClangASTRecordLayout) c_uint;
pub extern fn ZigClangASTRecordLayout_getFieldOffset(self: ?*const struct_ZigClangASTRecordLayout, field_no: c_uint) u64;
pub extern fn ZigClangASTUnit_getASTContext(self: ?*struct_ZigClangASTUnit) ?*struct_ZigClangASTContext;
pub extern fn ZigClangASTUnit_getSourceManager(self: *struct_ZigClangASTUnit) *struct_ZigClangSourceManager;
pub extern fn ZigClangASTUnit_visitLocalTopLevelDecls(self: *struct_ZigClangASTUnit, context: ?*c_void, Fn: ?extern fn (?*c_void, *const struct_ZigClangDecl) bool) bool;
Expand Down Expand Up @@ -1072,6 +1076,9 @@ pub extern fn ZigClangParenExpr_getSubExpr(*const ZigClangParenExpr) *const ZigC

pub extern fn ZigClangFieldDecl_isAnonymousStructOrUnion(*const struct_ZigClangFieldDecl) bool;
pub extern fn ZigClangFieldDecl_isBitField(*const struct_ZigClangFieldDecl) bool;
pub extern fn ZigClangFieldDecl_isUnnamedBitfield(*const struct_ZigClangFieldDecl) bool;
pub extern fn ZigClangFieldDecl_getFieldIndex(*const struct_ZigClangFieldDecl) c_uint;
pub extern fn ZigClangFieldDecl_getBitWidthValue(*const struct_ZigClangFieldDecl, *const struct_ZigClangASTContext) c_uint;
pub extern fn ZigClangFieldDecl_getType(*const struct_ZigClangFieldDecl) struct_ZigClangQualType;
pub extern fn ZigClangFieldDecl_getLocation(*const struct_ZigClangFieldDecl) struct_ZigClangSourceLocation;

Expand Down
44 changes: 21 additions & 23 deletions src-self-hosted/translate_c.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -751,7 +751,8 @@ fn transRecordDecl(c: *Context, record_decl: *const ZigClangRecordDecl) Error!?*
break :blk opaque;
};

const layout_tok = try if (ZigClangRecordDecl_getPackedAttribute(record_decl))
const is_packed = ZigClangRecordDecl_getPackedAttribute(record_decl);
const layout_tok = try if (is_packed)
appendToken(c, .Keyword_packed, "packed")
else
appendToken(c, .Keyword_extern, "extern");
Expand All @@ -768,33 +769,39 @@ fn transRecordDecl(c: *Context, record_decl: *const ZigClangRecordDecl) Error!?*
.rbrace_token = undefined,
};

const layout = ZigClangASTContext_getASTRecordLayout(c.clang_context, record_def);
var it = ZigClangRecordDecl_field_begin(record_def);
const end_it = ZigClangRecordDecl_field_end(record_def);
while (ZigClangRecordDecl_field_iterator_neq(it, end_it)) : (it = ZigClangRecordDecl_field_iterator_next(it)) {
const field_decl = ZigClangRecordDecl_field_iterator_deref(it);
const field_loc = ZigClangFieldDecl_getLocation(field_decl);

if (ZigClangFieldDecl_isBitField(field_decl)) {
const opaque = try transCreateNodeOpaqueType(c);
semicolon = try appendToken(c, .Semicolon, ";");
try emitWarning(c, field_loc, "{} demoted to opaque type - has bitfield", .{container_kind_name});
break :blk opaque;
}
const is_bitfield = ZigClangFieldDecl_isBitField(field_decl);
const offset = ZigClangASTRecordLayout_getFieldOffset(layout, ZigClangFieldDecl_getFieldIndex(field_decl));

var is_anon = false;
var raw_name = try c.str(ZigClangNamedDecl_getName_bytes_begin(@ptrCast(*const ZigClangNamedDecl, field_decl)));
if (ZigClangFieldDecl_isAnonymousStructOrUnion(field_decl)) {
if (ZigClangFieldDecl_isAnonymousStructOrUnion(field_decl) or (is_bitfield and ZigClangFieldDecl_isUnnamedBitfield(field_decl))) {
raw_name = try std.fmt.allocPrint(c.a(), "unnamed_{}", .{c.getMangle()});
is_anon = true;
}
const field_name = try appendIdentifier(c, raw_name);
_ = try appendToken(c, .Colon, ":");
const field_type = transQualType(rp, ZigClangFieldDecl_getType(field_decl), field_loc) catch |err| switch (err) {
error.UnsupportedType => {
try failDecl(c, record_loc, name, "unable to translate {} member type", .{container_kind_name});
return null;
},
else => |e| return e,

const field_type = if (is_bitfield) ty: {
const field_qt = ZigClangFieldDecl_getType(field_decl);
const sign = if (cIsSignedInteger(field_qt)) "i" else "u";
const bit_width = ZigClangFieldDecl_getBitWidthValue(field_decl, c.clang_context);
const type_name = try std.fmt.allocPrint(c.a(), "{}{}", .{ sign, bit_width });
break :ty try transCreateNodeIdentifier(c, type_name);
} else ty: {
break :ty transQualType(rp, ZigClangFieldDecl_getType(field_decl), field_loc) catch |err| switch (err) {
error.UnsupportedType => {
try failDecl(c, record_loc, name, "unable to translate {} member type", .{container_kind_name});
return null;
},
else => |e| return e,
};
};

const field_node = try c.a().create(ast.Node.ContainerField);
Expand Down Expand Up @@ -3459,15 +3466,6 @@ fn typeIsOpaque(c: *Context, ty: *const ZigClangType, loc: ZigClangSourceLocatio
const record_decl = ZigClangRecordType_getDecl(record_ty);
const record_def = ZigClangRecordDecl_getDefinition(record_decl) orelse
return true;
var it = ZigClangRecordDecl_field_begin(record_def);
const end_it = ZigClangRecordDecl_field_end(record_def);
while (ZigClangRecordDecl_field_iterator_neq(it, end_it)) : (it = ZigClangRecordDecl_field_iterator_next(it)) {
const field_decl = ZigClangRecordDecl_field_iterator_deref(it);

if (ZigClangFieldDecl_isBitField(field_decl)) {
return true;
}
}
return false;
},
.Elaborated => {
Expand Down
16 changes: 5 additions & 11 deletions src/analyze.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1682,18 +1682,12 @@ Error type_allowed_in_extern(CodeGen *g, ZigType *type_entry, bool *result) {
*result = true;
return ErrorNone;
case ZigTypeIdInt:
switch (type_entry->data.integral.bit_count) {
case 8:
case 16:
case 32:
case 64:
case 128:
*result = true;
return ErrorNone;
default:
*result = false;
return ErrorNone;
if (type_entry->data.integral.bit_count <= 128) {
*result = true;
} else {
*result = false;
}
return ErrorNone;
case ZigTypeIdVector:
return type_allowed_in_extern(g, type_entry->data.vector.elem_type, result);
case ZigTypeIdFloat:
Expand Down
31 changes: 31 additions & 0 deletions src/zig_clang.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include <clang/Frontend/CompilerInstance.h>
#include <clang/AST/APValue.h>
#include <clang/AST/Expr.h>
#include <clang/AST/RecordLayout.h>

#if __GNUC__ >= 8
#pragma GCC diagnostic pop
Expand Down Expand Up @@ -1504,6 +1505,20 @@ ZigClangQualType ZigClangASTContext_getPointerType(const ZigClangASTContext* sel
return bitcast(reinterpret_cast<const clang::ASTContext *>(self)->getPointerType(bitcast(T)));
}

const ZigClangASTRecordLayout *ZigClangASTContext_getASTRecordLayout(const ZigClangASTContext* self, const ZigClangRecordDecl *D) {
const clang::RecordDecl *record_decl = reinterpret_cast<const clang::RecordDecl *>(D);
const clang::ASTRecordLayout *result = &reinterpret_cast<const clang::ASTContext *>(self)->getASTRecordLayout(record_decl);
return reinterpret_cast<const ZigClangASTRecordLayout *>(result);
}

unsigned ZigClangASTRecordLayout_getFieldCount(const struct ZigClangASTRecordLayout *self) {
return reinterpret_cast<const clang::ASTRecordLayout *>(self)->getFieldCount();
}

uint64_t ZigClangASTRecordLayout_getFieldOffset(const ZigClangASTRecordLayout *self, unsigned field_no) {
return reinterpret_cast<const clang::ASTRecordLayout *>(self)->getFieldOffset(field_no);
}

unsigned ZigClangASTContext_getTypeAlign(const ZigClangASTContext* self, ZigClangQualType T) {
return reinterpret_cast<const clang::ASTContext *>(self)->getTypeAlign(bitcast(T));
}
Expand Down Expand Up @@ -2748,6 +2763,22 @@ bool ZigClangFieldDecl_isAnonymousStructOrUnion(const ZigClangFieldDecl *field_d
return reinterpret_cast<const clang::FieldDecl*>(field_decl)->isAnonymousStructOrUnion();
}

bool ZigClangFieldDecl_isUnnamedBitfield(const struct ZigClangFieldDecl *self) {
auto casted = reinterpret_cast<const clang::FieldDecl *>(self);
return casted->isUnnamedBitfield();
}

unsigned ZigClangFieldDecl_getFieldIndex(const struct ZigClangFieldDecl *self) {
auto casted = reinterpret_cast<const clang::FieldDecl *>(self);
return casted->getFieldIndex();
}

unsigned ZigClangFieldDecl_getBitWidthValue(const struct ZigClangFieldDecl *self, const struct ZigClangASTContext *ctx) {
auto casted = reinterpret_cast<const clang::FieldDecl *>(self);
auto casted_ctx = reinterpret_cast<const clang::ASTContext *>(ctx);
return casted->getBitWidthValue(*casted_ctx);
}

ZigClangSourceLocation ZigClangFieldDecl_getLocation(const struct ZigClangFieldDecl *self) {
auto casted = reinterpret_cast<const clang::FieldDecl *>(self);
return bitcast(casted->getLocation());
Expand Down
7 changes: 7 additions & 0 deletions src/zig_clang.h
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,7 @@ struct ZigClangAPInt;
struct ZigClangAPSInt;
struct ZigClangAPValue;
struct ZigClangASTContext;
struct ZigClangASTRecordLayout;
struct ZigClangASTUnit;
struct ZigClangArraySubscriptExpr;
struct ZigClangArrayType;
Expand Down Expand Up @@ -831,7 +832,10 @@ ZIG_EXTERN_C const char* ZigClangSourceManager_getCharacterData(const struct Zig
struct ZigClangSourceLocation SL);

ZIG_EXTERN_C struct ZigClangQualType ZigClangASTContext_getPointerType(const struct ZigClangASTContext*, struct ZigClangQualType T);
ZIG_EXTERN_C const ZigClangASTRecordLayout *ZigClangASTContext_getASTRecordLayout(const struct ZigClangASTContext* self, const ZigClangRecordDecl *D);

ZIG_EXTERN_C unsigned ZigClangASTRecordLayout_getFieldCount(const ZigClangASTRecordLayout *self);
ZIG_EXTERN_C uint64_t ZigClangASTRecordLayout_getFieldOffset(const ZigClangASTRecordLayout *self, unsigned field_no);

// Can return null.
ZIG_EXTERN_C struct ZigClangASTUnit *ZigClangLoadFromCommandLine(const char **args_begin, const char **args_end,
Expand Down Expand Up @@ -1130,8 +1134,11 @@ ZIG_EXTERN_C const char *ZigClangMacroDefinitionRecord_getName_getNameStart(cons
ZIG_EXTERN_C struct ZigClangSourceLocation ZigClangMacroDefinitionRecord_getSourceRange_getBegin(const struct ZigClangMacroDefinitionRecord *);
ZIG_EXTERN_C struct ZigClangSourceLocation ZigClangMacroDefinitionRecord_getSourceRange_getEnd(const struct ZigClangMacroDefinitionRecord *);

ZIG_EXTERN_C unsigned ZigClangFieldDecl_getFieldIndex(const struct ZigClangFieldDecl *self);
ZIG_EXTERN_C unsigned ZigClangFieldDecl_getBitWidthValue(const struct ZigClangFieldDecl *self, const struct ZigClangASTContext *ctx);
ZIG_EXTERN_C bool ZigClangFieldDecl_isBitField(const struct ZigClangFieldDecl *);
ZIG_EXTERN_C bool ZigClangFieldDecl_isAnonymousStructOrUnion(const ZigClangFieldDecl *);
ZIG_EXTERN_C bool ZigClangFieldDecl_isUnnamedBitfield(const ZigClangFieldDecl *);
ZIG_EXTERN_C struct ZigClangQualType ZigClangFieldDecl_getType(const struct ZigClangFieldDecl *);
ZIG_EXTERN_C struct ZigClangSourceLocation ZigClangFieldDecl_getLocation(const struct ZigClangFieldDecl *);

Expand Down
15 changes: 15 additions & 0 deletions test/stage1/c_abi/main.zig
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Expand Up @@ -261,3 +261,18 @@ export fn zig_big_struct_both(x: BigStruct) BigStruct {
};
return s;
}

test "C struct with bit fields" {
const C_struct = extern struct {
a: u4,
b: u6,
c: i2,
d: u0, // 0-width field aligns to next byte boundary
e: u1,
};
std.testing.expectEqual(0, @bitOffsetOf(C_struct, "a"));
std.testing.expectEqual(4, @bitOffsetOf(C_struct, "b"));
std.testing.expectEqual(10, @bitOffsetOf(C_struct, "c"));
std.testing.expectEqual(16, @bitOffsetOf(C_struct, "d"));
std.testing.expectEqual(16, @bitOffsetOf(C_struct, "e"));
}
37 changes: 27 additions & 10 deletions test/translate_c.zig
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Expand Up @@ -347,18 +347,35 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
\\};
});

cases.add("pointer to struct demoted to opaque due to bit fields",
\\struct Foo {
\\ unsigned int: 1;
\\};
\\struct Bar {
\\ struct Foo *foo;
cases.add("bit fields",
\\struct bitfield {
\\ unsigned int a : 3;
\\ signed int b : 6;
\\ unsigned int c : 6;
\\ unsigned int d : 6;
\\ unsigned int : 0;
\\ unsigned long long e : 22;
\\ unsigned int a2 : 3;
\\ unsigned int b2 : 6;
\\ unsigned int c2 : 6;
\\ unsigned int d2 : 6;
\\ unsigned int : 0;
\\ unsigned long long e2 : 22;
\\};
, &[_][]const u8{
\\pub const struct_Foo = @OpaqueType();
,
\\pub const struct_Bar = extern struct {
\\ foo: ?*struct_Foo,
\\pub const struct_bitfield = extern struct {
\\ a: u3,
\\ b: i6,
\\ c: u6,
\\ d: u6,
\\ unnamed_1: u0,
\\ e: u22,
\\ a2: u3,
\\ b2: u6,
\\ c2: u6,
\\ d2: u6,
\\ unnamed_2: u0,
\\ e2: u22,
\\};
});

Expand Down