Add enum {} default mapping to integer type

[ctf.git] / common-trace-format-proposal.txt

diff --git a/common-trace-format-proposal.txt b/common-trace-format-proposal.txt
index 361c2ec39c21f35ceb06363b218b0c683113d284..d61b58c0fd73cc0856562db4b7c211e2ae338070 100644 (file)
--- a/common-trace-format-proposal.txt
+++ b/common-trace-format-proposal.txt
@@ -68,14 +68,10 @@ A metadata event stream contains information on trace event types. It describes:
 3. Event stream
 
 An event stream is divided in contiguous event packets of variable size. These
 3. Event stream
 
 An event stream is divided in contiguous event packets of variable size. These

-subdivisions have a variable size. An event packet can contain a certain amount
-of padding at the end. The rationale for the event stream design choices is
-explained in Appendix B. Stream Header Rationale.
-
-An event stream is divided in contiguous event packets of variable size. These
-subdivisions have a variable size. An event packet can contain a certain amount
-of padding at the end.  The stream header is repeated at the beginning of each
-event packet.
+subdivisions have a variable size. An event packet can contain a certain
+amount of padding at the end. The stream header is repeated at the
+beginning of each event packet. The rationale for the event stream
+design choices is explained in Appendix B. Stream Header Rationale.

 
 The event stream header will therefore be referred to as the "event packet
 header" throughout the rest of this document.
 
 The event stream header will therefore be referred to as the "event packet
 header" throughout the rest of this document.


@@ -103,15 +99,16 @@ types, but must be derived into a type to be usable in an event field.
 
 We define "byte-packed" types as aligned on the byte size, namely 8-bit.
 We define "bit-packed" types as following on the next bit, as defined by the
 
 We define "byte-packed" types as aligned on the byte size, namely 8-bit.
 We define "bit-packed" types as following on the next bit, as defined by the

-"bitfields" section.
+"Integers" section.

 
 All basic types, except bitfields, are either aligned on an architecture-defined
 specific alignment or byte-packed, depending on the architecture preference.
 Architectures providing fast unaligned write byte-packed basic types to save
 space, aligning each type on byte boundaries (8-bit). Architectures with slow
 unaligned writes align types on specific alignment values. If no specific
 
 All basic types, except bitfields, are either aligned on an architecture-defined
 specific alignment or byte-packed, depending on the architecture preference.
 Architectures providing fast unaligned write byte-packed basic types to save
 space, aligning each type on byte boundaries (8-bit). Architectures with slow
 unaligned writes align types on specific alignment values. If no specific

-alignment is declared for a type nor its parents, it is assumed to be bit-packed
-for bitfields and byte-packed for other types.
+alignment is declared for a type, it is assumed to be bit-packed for
+integers with size not multiple of 8 bits and for gcc bitfields. All
+other types are byte-packed.

 
 Metadata attribute representation of a specific alignment:
 
 
 Metadata attribute representation of a specific alignment:
 


@@ -189,7 +186,7 @@ typealias integer {
   size = 32;
   signed = false;
   align = 32;
   size = 32;
   signed = false;
   align = 32;

-} : uint32_t;
+} := uint32_t;

 
 Definition of a named 5-bit signed bitfield:
 
 
 Definition of a named 5-bit signed bitfield:
 


@@ -197,7 +194,7 @@ typealias integer {
   size = 5;
   signed = true;
   align = 1;
   size = 5;
   signed = true;
   align = 1;

-} : int5_t;
+} := int5_t;

 
 4.1.6 GNU/C bitfields
 
 
 4.1.6 GNU/C bitfields
 


@@ -256,7 +253,7 @@ typealias floating_point {
   exp_dig = 8;         /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
   mant_dig = 24;       /* FLT_MANT_DIG */
   byte_order = native;
   exp_dig = 8;         /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
   mant_dig = 24;       /* FLT_MANT_DIG */
   byte_order = native;

-} : float;
+} := float;

 
 TODO: define NaN, +inf, -inf behavior.
 
 
 TODO: define NaN, +inf, -inf behavior.
 


@@ -274,10 +271,7 @@ this format by having the same start_value and end_value for each element, which
 is in fact a range of size 1. This single-value range is supported without
 repeating the start and end values with the value = string declaration.
 
 is in fact a range of size 1. This single-value range is supported without
 repeating the start and end values with the value = string declaration.
 

-If a numeric value is encountered between < >, it represents the integer type
-size used to hold the enumeration, in bits.
-
-enum name <integer_type OR size> {
+enum name : integer_type {

   somestring          = start_value1 ... end_value1,
   "other string"      = start_value2 ... end_value2,
   yet_another_string,  /* will be assigned to end_value2 + 1 */
   somestring          = start_value1 ... end_value1,
   "other string"      = start_value2 ... end_value2,
   yet_another_string,  /* will be assigned to end_value2 + 1 */


@@ -288,7 +282,7 @@ enum name <integer_type OR size> {
 If the values are omitted, the enumeration starts at 0 and increment of 1 for
 each entry:
 
 If the values are omitted, the enumeration starts at 0 and increment of 1 for
 each entry:
 

-enum name <32> {
+enum name : unsigned int {

   ZERO,
   ONE,
   TWO,
   ZERO,
   ONE,
   TWO,


@@ -300,7 +294,17 @@ Overlapping ranges within a single enumeration are implementation defined.
 
 A nameless enumeration can be declared as a field type or as part of a typedef:
 
 
 A nameless enumeration can be declared as a field type or as part of a typedef:
 

-enum <integer_type> {
+enum : integer_type {
+  ...
+}
+
+Enumerations omitting the container type ": integer_type" use the "int"
+type (for compatibility with C99). The "int" type must be previously
+declared. E.g.:
+
+typealias integer { size = 32; align = 32; signed = true } := int;
+
+enum {

   ...
 }
 
   ...
 }
 


@@ -374,7 +378,7 @@ variant name {
 };
 
 struct {
 };
 
 struct {

-  enum <integer_type or size> { sel1, sel2, sel3, ... } tag_field;
+  enum : integer_type { sel1, sel2, sel3, ... } tag_field;

   ...
   variant name <tag_field> v;
 }
   ...
   variant name <tag_field> v;
 }


@@ -383,7 +387,7 @@ An unnamed variant definition within a structure is expressed by the following
 metadata:
 
 struct {
 metadata:
 
 struct {

-  enum <integer_type or size> { sel1, sel2, sel3, ... } tag_field;
+  enum : integer_type { sel1, sel2, sel3, ... } tag_field;

   ...
   variant <tag_field> {
     field_type sel1;
   ...
   variant <tag_field> {
     field_type sel1;


@@ -402,14 +406,14 @@ variant example {
 };
 
 struct {
 };
 
 struct {

-  enum <uint2_t> { a, b, c } choice;
+  enum : uint2_t { a, b, c } choice;

   variant example <choice> v[unsigned int];
 }
 
 Example of an unnamed variant:
 
 struct {
   variant example <choice> v[unsigned int];
 }
 
 Example of an unnamed variant:
 
 struct {

-  enum <uint2_t> { a, b, c, d } choice;
+  enum : uint2_t { a, b, c, d } choice;

   /* Unrelated fields can be added between the variant and its tag */
   int32_t somevalue;
   variant <choice> {
   /* Unrelated fields can be added between the variant and its tag */
   int32_t somevalue;
   variant <choice> {


@@ -426,7 +430,7 @@ struct {
 Example of an unnamed variant within an array:
 
 struct {
 Example of an unnamed variant within an array:
 
 struct {

-  enum <uint2_t> { a, b, c } choice;
+  enum : uint2_t { a, b, c } choice;

   variant <choice> {
     uint32_t a;
     uint64_t b;
   variant <choice> {
     uint32_t a;
     uint64_t b;


@@ -441,7 +445,7 @@ type definition referring to the tag "x" uses the closest preceding field from
 the lexical scope of the type definition.
 
 struct {
 the lexical scope of the type definition.
 
 struct {

-  enum <uint2_t> { a, b, c, d } x;
+  enum : uint2_t { a, b, c, d } x;

 
   typedef variant <x> {        /*
                         * "x" refers to the preceding "x" enumeration in the
 
   typedef variant <x> {        /*
                         * "x" refers to the preceding "x" enumeration in the


@@ -453,9 +457,9 @@ struct {
   } example_variant;
 
   struct {
   } example_variant;
 
   struct {

-    enum <int> { x, y, z } x;  /* This enumeration is not used by "v". */
+    enum : int { x, y, z } x;  /* This enumeration is not used by "v". */

     example_variant v;                 /*
     example_variant v;                 /*

-                                * "v" uses the "enum <uint2_t> { a, b, c, d }"
+                                * "v" uses the "enum : uint2_t { a, b, c, d }"

                                 * tag.
                                 */
   } a[10];
                                 * tag.
                                 */
   } a[10];


@@ -504,7 +508,7 @@ Metadata representation of a named string type:
 
 typealias string {
   encoding = UTF8 OR ASCII;
 
 typealias string {
   encoding = UTF8 OR ASCII;

-} : name;
+} := name;

 
 A nameless string type can be declared as a field type:
 
 
 A nameless string type can be declared as a field type:
 


@@ -657,7 +661,7 @@ struct event_header_1 {
    * id: range: 0 - 30.
    * id 31 is reserved to indicate an extended header.
    */
    * id: range: 0 - 30.
    * id 31 is reserved to indicate an extended header.
    */

-  enum <uint5_t> { compact = 0 ... 30, extended = 31 } id;
+  enum : uint5_t { compact = 0 ... 30, extended = 31 } id;

   variant <id> {
     struct {
       uint27_t timestamp;
   variant <id> {
     struct {
       uint27_t timestamp;


@@ -685,7 +689,7 @@ struct event_header_2 {
    * id: range: 0 - 65534.
    * id 65535 is reserved to indicate an extended header.
    */
    * id: range: 0 - 65534.
    * id 65535 is reserved to indicate an extended header.
    */

-  enum <uint16_t> { compact = 0 ... 65534, extended = 65535 } id;
+  enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;

   variant <id> {
     struct {
       uint32_t timestamp;
   variant <id> {
     struct {
       uint32_t timestamp;


@@ -765,20 +769,23 @@ contained within the payload. (This follows the ISO/C standard for structures)
 
 7. Metadata
 
 
 7. Metadata
 

-The meta-data is located in a stream named "metadata". It is made of "event
-packets", which each start with an event packet header. The event type within
-the metadata stream have no event header nor event context. Each event only
-contains a null-terminated "string" payload, which is a metadata description
-entry. The events are packed one next to another. Each event packet start with
-an event packet header, which contains, amongst other fields, the magic number
-and trace UUID. The trace UUID is represented as a string of hexadecimal digits
-and dashes "-".
-
-The metadata can be parsed by reading through the metadata strings, skipping
-newlines and null-characters. Type names are made of a single identifier, and
-can be surrounded by prefix/postfix. Text contained within "/*" and "*/", as
-well as within "//" and end of line, are treated as comments. Boolean values can
-be represented as true, TRUE, or 1 for true, and false, FALSE, or 0 for false.
+The meta-data is located in a stream identified by its name: "metadata".
+It is made of "event packets", which each start with an event packet
+header. The event type within the metadata stream have no event header
+nor event context. Each event only contains a null-terminated "string"
+payload, which is a metadata description entry. The events are packed
+one next to another. Each event packet start with an event packet
+header, which contains, amongst other fields, the magic number and trace
+UUID. In the event packet header, the trace UUID is represented as an
+array of bytes. Within the string-based metadata description, the trace
+UUID is represented as a string of hexadecimal digits and dashes "-".
+
+The metadata can be parsed by reading through the metadata strings,
+skipping null-characters. Type names are made of a single identifier,
+and can be surrounded by prefix/postfix. Text contained within "/*" and
+"*/", as well as within "//" and end of line, are treated as comments.
+Boolean values can be represented as true, TRUE, or 1 for true, and
+false, FALSE, or 0 for false.

 
 
 7.1 Declaration vs Definition
 
 
 7.1 Declaration vs Definition


@@ -791,10 +798,13 @@ variant field), a declaration is followed by a declarator, which specify
 the newly defined type name (for typedef), or the field name (for
 declarations located within structure and variants). Array and sequence,
 declared with square brackets ("[" "]"), are part of the declarator,
 the newly defined type name (for typedef), or the field name (for
 declarations located within structure and variants). Array and sequence,
 declared with square brackets ("[" "]"), are part of the declarator,

-similarly to C99.
+similarly to C99. The enumeration base type is specified by
+": base_type", which is part of the type specifier. The variant tag
+name, specified between "<" ">", is also part of the type specifier.

 
 A definition associates a type to a location in the event structure
 
 A definition associates a type to a location in the event structure

-hierarchy (see Section 6).
+hierarchy (see Section 6). This association is denoted by ":=", as shown
+in Section 7.3.

 
 
 7.2 Metadata Scopes
 
 
 7.2 Metadata Scopes


@@ -845,8 +855,14 @@ different scopes. There is no possible conflict, because the dynamic
 scope must be specified when a variant refers to a tag field located in
 a different dynamic scope.
 
 scope must be specified when a variant refers to a tag field located in
 a different dynamic scope.
 

+The information available in the dynamic scopes can be thought of as the
+current tracing context. At trace production, information about the
+current context is saved into the specified scope field levels. At trace
+consumption, for each event, the current trace context is therefore
+readable by accessing the upper dynamic scopes.

 
 

-7.2 Metadata Examples
+
+7.3 Metadata Examples

 
 The grammar representing the CTF metadata is presented in
 Appendix C. CTF Metadata Grammar. This section presents a rather ligher
 
 The grammar representing the CTF metadata is presented in
 Appendix C. CTF Metadata Grammar. This section presents a rather ligher


@@ -891,7 +907,7 @@ event {
  * Type declarations behave similarly to the C standard.
  */
 
  * Type declarations behave similarly to the C standard.
  */
 

-typedef aliased_type_prefix aliased_type new_type aliased_type_postfix;
+typedef aliased_type_specifiers new_type_declarators;

 
 /* e.g.: typedef struct example new_type_name[10]; */
 
 
 /* e.g.: typedef struct example new_type_name[10]; */
 


@@ -899,15 +915,15 @@ typedef aliased_type_prefix aliased_type new_type aliased_type_postfix;
  * typealias
  *
  * The "typealias" declaration can be used to give a name (including
  * typealias
  *
  * The "typealias" declaration can be used to give a name (including

- * prefix/postfix) to a type. It should also be used to map basic C types
- * (float, int, unsigned long, ...) to a CTF type. Typealias is a superset of
- * "typedef": it also allows assignment of a simple variable identifier to a
- * type.
+ * pointer declarator specifier) to a type. It should also be used to
+ * map basic C types (float, int, unsigned long, ...) to a CTF type.
+ * Typealias is a superset of "typedef": it also allows assignment of a
+ * simple variable identifier to a type.

  */
 
 typealias type_class {
   ...
  */
 
 typealias type_class {
   ...

-} : new_type_prefix new_type new_type_postfix;
+} := type_specifiers type_declarator;

 
 /*
  * e.g.: 
 
 /*
  * e.g.: 


@@ -915,13 +931,13 @@ typealias type_class {
  *   size = 32;
  *   align = 32;
  *   signed = false;
  *   size = 32;
  *   align = 32;
  *   signed = false;

- * } : struct page *;
+ * } := struct page *;

  *
  * typealias integer {
  *  size = 32;
  *  align = 32;
  *  signed = true;
  *
  * typealias integer {
  *  size = 32;
  *  align = 32;
  *  signed = true;

- * } : int;
+ * } := int;

  */
 
 struct name {
  */
 
 struct name {


@@ -932,7 +948,7 @@ variant name {
   ...
 };
 
   ...
 };
 

-enum name <integer_type or size> {
+enum name : integer_type {

   ...
 };
 
   ...
 };
 


@@ -949,7 +965,7 @@ variant {
   ...
 }
 
   ...
 }
 

-enum <integer_type or size> {
+enum : integer_type {

   ...
 }
 
   ...
 }
 


@@ -1240,6 +1256,9 @@ unary-operator: one of
 assignment-operator:
        =
 
 assignment-operator:
        =
 

+type-assignment-operator:
+       :=
+

 constant-expression:
        unary-expression
 
 constant-expression:
        unary-expression
 


@@ -1249,11 +1268,11 @@ constant-expression-range:
 2.2) Declarations:
 
 declaration:
 2.2) Declarations:
 
 declaration:

-       declaration-specifiers ;
-       declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ;
+       declaration-specifiers declarator-list-opt ;

        ctf-specifier ;
 
 declaration-specifiers:
        ctf-specifier ;
 
 declaration-specifiers:

+       storage-class-specifier declaration-specifiers-opt

        type-specifier declaration-specifiers-opt
        type-qualifier declaration-specifiers-opt
 
        type-specifier declaration-specifiers-opt
        type-qualifier declaration-specifiers-opt
 


@@ -1280,6 +1299,7 @@ type-specifier:
        unsigned
        _Bool
        _Complex
        unsigned
        _Bool
        _Complex

+       _Imaginary

        struct-specifier
        variant-specifier
        enum-specifier
        struct-specifier
        variant-specifier
        enum-specifier


@@ -1297,8 +1317,8 @@ struct-or-variant-declaration-list:
 struct-or-variant-declaration:
        specifier-qualifier-list struct-or-variant-declarator-list ;
        declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ;
 struct-or-variant-declaration:
        specifier-qualifier-list struct-or-variant-declarator-list ;
        declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ;

-       typealias declaration-specifiers abstract-declarator-list : declaration-specifiers abstract-declarator-list ;
-       typealias declaration-specifiers abstract-declarator-list : declarator-list ;
+       typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ;
+       typealias declaration-specifiers abstract-declarator-list := declarator-list ;

 
 specifier-qualifier-list:
        type-specifier specifier-qualifier-list-opt
 
 specifier-qualifier-list:
        type-specifier specifier-qualifier-list-opt


@@ -1323,12 +1343,8 @@ enum-specifier:
        enum identifier-opt { enumerator-list }
        enum identifier-opt { enumerator-list , }
        enum identifier
        enum identifier-opt { enumerator-list }
        enum identifier-opt { enumerator-list , }
        enum identifier

-       enum identifier-opt < declaration-specifiers > { enumerator-list }
-       enum identifier-opt < declaration-specifiers > { enumerator-list , }
-       enum identifier < declaration-specifiers >
-       enum identifier-opt < integer-constant > { enumerator-list }
-       enum identifier-opt < integer-constant > { enumerator-list , }
-       enum identifier < integer-constant >
+       enum identifier-opt : declaration-specifiers { enumerator-list }
+       enum identifier-opt : declaration-specifiers { enumerator-list , }

 
 enumerator-list:
        enumerator
 
 enumerator-list:
        enumerator


@@ -1378,8 +1394,8 @@ ctf-specifier:
        event { ctf-assignment-expression-list-opt }
        stream { ctf-assignment-expression-list-opt }
        trace { ctf-assignment-expression-list-opt }
        event { ctf-assignment-expression-list-opt }
        stream { ctf-assignment-expression-list-opt }
        trace { ctf-assignment-expression-list-opt }

-       typealias declaration-specifiers abstract-declarator-list : declaration-specifiers abstract-declarator-list ;
-       typealias declaration-specifiers abstract-declarator-list : declarator-list ;
+       typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ;
+       typealias declaration-specifiers abstract-declarator-list := declarator-list ;

 
 ctf-type-specifier:
        floating_point { ctf-assignment-expression-list-opt }
 
 ctf-type-specifier:
        floating_point { ctf-assignment-expression-list-opt }


@@ -1394,5 +1410,5 @@ ctf-assignment-expression:
        unary-expression assignment-operator unary-expression
        unary-expression type-assignment-operator type-specifier
        declaration-specifiers storage-class-specifier declaration-specifiers declarator-list
        unary-expression assignment-operator unary-expression
        unary-expression type-assignment-operator type-specifier
        declaration-specifiers storage-class-specifier declaration-specifiers declarator-list

-       typealias declaration-specifiers abstract-declarator-list : declaration-specifiers abstract-declarator-list
-       typealias declaration-specifiers abstract-declarator-list : declarator-list
+       typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list
+       typealias declaration-specifiers abstract-declarator-list := declarator-list