diff --git a/src/clang.zig b/src/clang.zig index 40dacc5df8d3..7c9d67984ffe 100644 --- a/src/clang.zig +++ b/src/clang.zig @@ -470,6 +470,9 @@ pub const FieldDecl = opaque { pub const getAlignedAttribute = ZigClangFieldDecl_getAlignedAttribute; extern fn ZigClangFieldDecl_getAlignedAttribute(*const FieldDecl, *const ASTContext) c_uint; + pub const getPackedAttribute = ZigClangFieldDecl_getPackedAttribute; + extern fn ZigClangFieldDecl_getPackedAttribute(*const FieldDecl, *const ASTContext) bool; + pub const isAnonymousStructOrUnion = ZigClangFieldDecl_isAnonymousStructOrUnion; extern fn ZigClangFieldDecl_isAnonymousStructOrUnion(*const FieldDecl) bool; @@ -1015,6 +1018,9 @@ pub const VarDecl = opaque { pub const getAlignedAttribute = ZigClangVarDecl_getAlignedAttribute; extern fn ZigClangVarDecl_getAlignedAttribute(*const VarDecl, *const ASTContext) c_uint; + pub const getPackedAttribute = ZigClangVarDecl_getPackedAttribute; + extern fn ZigClangVarDecl_getPackedAttribute(*const VarDecl, *const ASTContext) bool; + pub const getCleanupAttribute = ZigClangVarDecl_getCleanupAttribute; extern fn ZigClangVarDecl_getCleanupAttribute(*const VarDecl) ?*const FunctionDecl; diff --git a/src/translate_c.zig b/src/translate_c.zig index faa8a456f584..bfd2be958727 100644 --- a/src/translate_c.zig +++ b/src/translate_c.zig @@ -878,7 +878,7 @@ fn visitVarDecl(c: *Context, var_decl: *const clang.VarDecl, mangled_name: ?[]co .is_export = is_export, .is_threadlocal = is_threadlocal, .linksection_string = linksection_string, - .alignment = zigAlignment(var_decl.getAlignedAttribute(c.clang_context)), + .alignment = ClangAlignment.forVar(c, var_decl).zigAlignment(), .name = var_name, .type = type_node, .init = init_node, @@ -1153,7 +1153,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD const alignment = if (has_flexible_array and field_decl.getFieldIndex() == 0) @intCast(c_uint, record_alignment) else - zigAlignment(field_decl.getAlignedAttribute(c.clang_context)); + ClangAlignment.forField(c, field_decl, record_def).zigAlignment(); if (is_anon) { try c.decl_table.putNoClobber(c.gpa, @ptrToInt(field_decl.getCanonicalDecl()), field_name); @@ -1851,12 +1851,62 @@ fn transCStyleCastExprClass( return maybeSuppressResult(c, scope, result_used, cast_node); } -/// Clang reports the alignment in bits, we use bytes -/// Clang uses 0 for "no alignment specified", we use null -fn zigAlignment(bit_alignment: c_uint) ?c_uint { - if (bit_alignment == 0) return null; - return bit_alignment / 8; -} +/// The alignment of a variable or field +const ClangAlignment = struct { + /// Clang reports the alignment in bits, we use bytes + /// Clang uses 0 for "no alignment specified", we use null + bit_alignment: c_uint, + /// If the field or variable is marked as 'packed' + /// + /// According to the GCC variable attribute docs, this impacts alignment + /// https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html + /// + /// > The packed attribute specifies that a structure member + /// > should have the smallest possible alignment + /// + /// Note also that specifying the 'packed' attribute on a structure + /// implicitly packs all its fields (making their alignment 1). + /// + /// This will be null if the AST node doesn't support packing (functions) + is_packed: ?bool, + + /// Get the alignment for a field, optionally taking into account the parent record + pub fn forField(c: *const Context, field: *const clang.FieldDecl, parent: ?*const clang.RecordDecl) ClangAlignment { + const parent_packed = if (parent) |record| record.getPackedAttribute() else false; + // NOTE: According to GCC docs, parent attribute packed implies child attribute packed + return ClangAlignment{ + .bit_alignment = field.getAlignedAttribute(c.clang_context), + .is_packed = field.getPackedAttribute(c.clang_context) or parent_packed, + }; + } + + pub fn forVar(c: *const Context, var_decl: *const clang.VarDecl) ClangAlignment { + return ClangAlignment{ + .bit_alignment = var_decl.getAlignedAttribute(c.clang_context), + .is_packed = var_decl.getPackedAttribute(c.clang_context), + }; + } + + pub fn forFunc(c: *const Context, fun: *const clang.FunctionDecl) ClangAlignment { + return ClangAlignment{ + .bit_alignment = fun.getAlignedAttribute(c.clang_context), + .is_packed = null, // not supported by GCC/clang (or meaningful), + }; + } + + /// Translate the clang alignment info into a zig alignment + /// + /// Returns null if there is no special alignment info + pub fn zigAlignment(self: ClangAlignment) ?c_uint { + if (self.bit_alignment != 0) { + return self.bit_alignment / 8; + } else if (self.is_packed orelse false) { + return 1; + } else { + return null; + } + } +}; fn transDeclStmtOne( c: *Context, @@ -1910,7 +1960,7 @@ fn transDeclStmtOne( .is_export = false, .is_threadlocal = var_decl.getTLSKind() != .None, .linksection_string = null, - .alignment = zigAlignment(var_decl.getAlignedAttribute(c.clang_context)), + .alignment = ClangAlignment.forVar(c, var_decl).zigAlignment(), .name = var_name, .type = type_node, .init = init_node, @@ -5054,7 +5104,7 @@ fn finishTransFnProto( break :blk null; }; - const alignment = if (fn_decl) |decl| zigAlignment(decl.getAlignedAttribute(c.clang_context)) else null; + const alignment = if (fn_decl) |decl| ClangAlignment.forFunc(c, decl).zigAlignment() else null; const explicit_callconv = if ((is_inline or is_export or is_extern) and cc == .C) null else cc; diff --git a/src/zig_clang.cpp b/src/zig_clang.cpp index 7b79f8e985a2..90f4cb5f3750 100644 --- a/src/zig_clang.cpp +++ b/src/zig_clang.cpp @@ -1975,6 +1975,26 @@ unsigned ZigClangFunctionDecl_getAlignedAttribute(const struct ZigClangFunctionD return 0; } +bool ZigClangVarDecl_getPackedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx) { + auto casted_self = reinterpret_cast(self); + auto casted_ctx = const_cast(reinterpret_cast(ctx)); + if (const clang::PackedAttr *PA = casted_self->getAttr()) { + return true; + } else { + return false; + } +} + +bool ZigClangFieldDecl_getPackedAttribute(const struct ZigClangFieldDecl *self, const ZigClangASTContext* ctx) { + auto casted_self = reinterpret_cast(self); + auto casted_ctx = const_cast(reinterpret_cast(ctx)); + if (const clang::PackedAttr *PA = casted_self->getAttr()) { + return true; + } else { + return false; + } +} + ZigClangQualType ZigClangParmVarDecl_getOriginalType(const struct ZigClangParmVarDecl *self) { return bitcast(reinterpret_cast(self)->getOriginalType()); } diff --git a/src/zig_clang.h b/src/zig_clang.h index 3da57d4301cb..45e65af7a89d 100644 --- a/src/zig_clang.h +++ b/src/zig_clang.h @@ -1088,6 +1088,8 @@ ZIG_EXTERN_C const struct ZigClangFunctionDecl *ZigClangVarDecl_getCleanupAttrib ZIG_EXTERN_C unsigned ZigClangVarDecl_getAlignedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx); ZIG_EXTERN_C unsigned ZigClangFunctionDecl_getAlignedAttribute(const struct ZigClangFunctionDecl *self, const ZigClangASTContext* ctx); ZIG_EXTERN_C unsigned ZigClangFieldDecl_getAlignedAttribute(const struct ZigClangFieldDecl *self, const ZigClangASTContext* ctx); +ZIG_EXTERN_C bool ZigClangVarDecl_getPackedAttribute(const struct ZigClangVarDecl *self, const ZigClangASTContext* ctx); +ZIG_EXTERN_C bool ZigClangFieldDecl_getPackedAttribute(const struct ZigClangFieldDecl *self, const ZigClangASTContext* ctx); ZIG_EXTERN_C const struct ZigClangStringLiteral *ZigClangFileScopeAsmDecl_getAsmString(const struct ZigClangFileScopeAsmDecl *self);