[PATCH v4] btf: Add support to BTF_KIND_ENUM64 type

["Guillermo E. Martinez" <guillermo.e.martinez@oracle.com>]

Hello,

The following is patch v4 to update BTF/CTF backend supporting
BTF_KIND_ENUM64 type. Changes from v3:

  + Remove `ctf_enum_binfo' structure.
  + Remove -m{little,big}-endian from dg-options in testcase.

Comments will be welcomed and appreciated!,

Kind regards,
guillermo
--

BTF supports 64-bits enumerators with following encoding:

  struct btf_type:
    name_off: 0 or offset to a valid C identifier
    info.kind_flag: 0 for unsigned, 1 for signed
    info.kind: BTF_KIND_ENUM64
    info.vlen: number of enum values
    size: 1/2/4/8

The btf_type is followed by info.vlen number of:

    struct btf_enum64
    {
      uint32_t name_off;   /* Offset in string section of enumerator name.  */
      uint32_t val_lo32;   /* lower 32-bit value for a 64-bit value Enumerator */
      uint32_t val_hi32;   /* high 32-bit value for a 64-bit value Enumerator */
    };

So, a new btf_enum64 structure was added to represent BTF_KIND_ENUM64
and a new field dtd_enum_unsigned in ctf_dtdef structure to distinguish
when CTF enum is a signed or unsigned type, later that information is
used to encode the BTF enum type.

gcc/ChangeLog:

	* btfout.cc (btf_calc_num_vbytes): Compute enumeration size depending of
	enumerator type btf_enum{,64}.
	(btf_asm_type): Update btf_kflag according to enumeration type sign
	using dtd_enum_unsigned field for both:  BTF_KIND_ENUM{,64}.
	(btf_asm_enum_const): New argument to represent the size of
	the BTF enum type, writing the enumerator constant value for
	32 bits, if it's 64 bits then explicitly writes lower 32-bits
	value and higher 32-bits value.
	(output_asm_btf_enum_list): Add enumeration size argument.
	* ctfc.cc (ctf_add_enum): New argument to represent CTF enum
	basic information.
	(ctf_add_generic): Use of ei_{name. size, unsigned} to build the
	dtd structure containing enumeration information.
	(ctf_add_enumerator): Update comment mention support for BTF
	enumeration in 64-bits.
	* dwarf2ctf.cc (gen_ctf_enumeration_type): Extract signedness
	for enumeration type and use it in ctf_add_enum.
	* ctfc.h (ctf_dmdef): Update dmd_value to HOST_WIDE_INT to allow
	use 32/64 bits enumerators.
	information.
	(ctf_dtdef): New field to describe enum signedness.

include/
	* btf.h (btf_enum64): Add new definition and new symbolic
	constant to BTF_KIND_ENUM64 and BTF_KF_ENUM_{UN,}SIGNED.

gcc/testsuite/ChangeLog:

	* gcc.dg/debug/btf/btf-enum-1.c: Update testcase, with correct
	info.kflags encoding.
	* gcc.dg/debug/btf/btf-enum64-1.c: New testcase.
---
 gcc/btfout.cc                                 | 30 ++++++++++---
 gcc/ctfc.cc                                   | 13 +++---
 gcc/ctfc.h                                    |  5 ++-
 gcc/dwarf2ctf.cc                              |  5 ++-
 gcc/testsuite/gcc.dg/debug/btf/btf-enum-1.c   |  2 +-
 gcc/testsuite/gcc.dg/debug/btf/btf-enum64-1.c | 44 +++++++++++++++++++
 include/btf.h                                 | 19 ++++++--
 7 files changed, 100 insertions(+), 18 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/debug/btf/btf-enum64-1.c

diff --git a/gcc/btfout.cc b/gcc/btfout.cc
index 997a33fa089..aef9fd70a28 100644
--- a/gcc/btfout.cc
+++ b/gcc/btfout.cc
@@ -223,7 +223,9 @@ btf_calc_num_vbytes (ctf_dtdef_ref dtd)
       break;
 
     case BTF_KIND_ENUM:
-      vlen_bytes += vlen * sizeof (struct btf_enum);
+      vlen_bytes += (dtd->dtd_data.ctti_size == 0x8)
+			? vlen * sizeof (struct btf_enum64)
+			: vlen * sizeof (struct btf_enum);
       break;
 
     case BTF_KIND_FUNC_PROTO:
@@ -622,6 +624,15 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
       btf_size_type = 0;
     }
 
+  if (btf_kind == BTF_KIND_ENUM)
+    {
+      btf_kflag = dtd->dtd_enum_unsigned
+		    ? BTF_KF_ENUM_UNSIGNED
+		    : BTF_KF_ENUM_SIGNED;
+      if (dtd->dtd_data.ctti_size == 0x8)
+	btf_kind = BTF_KIND_ENUM64;
+   }
+
   dw2_asm_output_data (4, dtd->dtd_data.ctti_name, "btt_name");
   dw2_asm_output_data (4, BTF_TYPE_INFO (btf_kind, btf_kflag, btf_vlen),
 		       "btt_info: kind=%u, kflag=%u, vlen=%u",
@@ -634,6 +645,7 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
     case BTF_KIND_UNION:
     case BTF_KIND_ENUM:
     case BTF_KIND_DATASEC:
+    case BTF_KIND_ENUM64:
       dw2_asm_output_data (4, dtd->dtd_data.ctti_size, "btt_size: %uB",
 			   dtd->dtd_data.ctti_size);
       return;
@@ -707,13 +719,19 @@ btf_asm_sou_member (ctf_container_ref ctfc, ctf_dmdef_t * dmd)
     }
 }
 
-/* Asm'out an enum constant following a BTF_KIND_ENUM.  */
+/* Asm'out an enum constant following a BTF_KIND_ENUM{,64}.  */
 
 static void
-btf_asm_enum_const (ctf_dmdef_t * dmd)
+btf_asm_enum_const (unsigned int size, ctf_dmdef_t * dmd)
 {
   dw2_asm_output_data (4, dmd->dmd_name_offset, "bte_name");
-  dw2_asm_output_data (4, dmd->dmd_value, "bte_value");
+  if (size == 4)
+    dw2_asm_output_data (size, dmd->dmd_value, "bte_value");
+  else
+    {
+      dw2_asm_output_data (4, dmd->dmd_value & 0xffffffff, "bte_value_lo32");
+      dw2_asm_output_data (4, (dmd->dmd_value >> 32) & 0xffffffff, "bte_value_hi32");
+    }
 }
 
 /* Asm'out a function parameter description following a BTF_KIND_FUNC_PROTO.  */
@@ -871,7 +889,7 @@ output_asm_btf_sou_fields (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
       btf_asm_sou_member (ctfc, dmd);
 }
 
-/* Output all enumerator constants following a BTF_KIND_ENUM.  */
+/* Output all enumerator constants following a BTF_KIND_ENUM{,64}.  */
 
 static void
 output_asm_btf_enum_list (ctf_container_ref ARG_UNUSED (ctfc),
@@ -881,7 +899,7 @@ output_asm_btf_enum_list (ctf_container_ref ARG_UNUSED (ctfc),
 
   for (dmd = dtd->dtd_u.dtu_members;
        dmd != NULL; dmd = (ctf_dmdef_t *) ctf_dmd_list_next (dmd))
-    btf_asm_enum_const (dmd);
+    btf_asm_enum_const (dtd->dtd_data.ctti_size, dmd);
 }
 
 /* Output all function arguments following a BTF_KIND_FUNC_PROTO.  */
diff --git a/gcc/ctfc.cc b/gcc/ctfc.cc
index 9773358a475..34030cbaa49 100644
--- a/gcc/ctfc.cc
+++ b/gcc/ctfc.cc
@@ -577,7 +577,7 @@ ctf_add_array (ctf_container_ref ctfc, uint32_t flag, const ctf_arinfo_t * arp,
 
 ctf_id_t
 ctf_add_enum (ctf_container_ref ctfc, uint32_t flag, const char * name,
-	      HOST_WIDE_INT size, dw_die_ref die)
+	      HOST_WIDE_INT size, bool eunsigned, dw_die_ref die)
 {
   ctf_dtdef_ref dtd;
   ctf_id_t type;
@@ -604,6 +604,7 @@ ctf_add_enum (ctf_container_ref ctfc, uint32_t flag, const char * name,
   gcc_assert (size <= CTF_MAX_SIZE);
 
   dtd->dtd_data.ctti_size = size;
+  dtd->dtd_enum_unsigned = eunsigned;
 
   ctfc->ctfc_num_stypes++;
 
@@ -630,10 +631,12 @@ ctf_add_enumerator (ctf_container_ref ctfc, ctf_id_t enid, const char * name,
 
   gcc_assert (kind == CTF_K_ENUM && vlen < CTF_MAX_VLEN);
 
-  /* Enum value is of type HOST_WIDE_INT in the compiler, dmd_value is int32_t
-     on the other hand.  Check bounds and skip adding this enum value if out of
-     bounds.  */
-  if ((value > INT_MAX) || (value < INT_MIN))
+  /* Enum value is of type HOST_WIDE_INT in the compiler, CTF enumerators
+     values in ctf_enum_t is limited to int32_t, BTF supports signed and
+     unsigned enumerators values of 32 and 64 bits, for both debug formats
+     we use ctf_dmdef_t.dmd_value entry of HOST_WIDE_INT type. So check
+     CTF bounds and skip adding this enum value if out of bounds.  */
+  if (!btf_debuginfo_p() && ((value > INT_MAX) || (value < INT_MIN)))
     {
       /* FIXME - Note this TBD_CTF_REPRESENTATION_LIMIT.  */
       return (1);
diff --git a/gcc/ctfc.h b/gcc/ctfc.h
index bcf3a43ae1b..48c381a008d 100644
--- a/gcc/ctfc.h
+++ b/gcc/ctfc.h
@@ -133,7 +133,7 @@ typedef struct GTY ((chain_next ("%h.dmd_next"))) ctf_dmdef
   ctf_id_t dmd_type;		/* Type of this member (for sou).  */
   uint32_t dmd_name_offset;	/* Offset of the name in str table.  */
   uint64_t dmd_offset;		/* Offset of this member in bits (for sou).  */
-  int dmd_value;		/* Value of this member (for enum).  */
+  HOST_WIDE_INT dmd_value;	/* Value of this member (for enum).  */
   struct ctf_dmdef * dmd_next;	/* A list node.  */
 } ctf_dmdef_t;
 
@@ -162,6 +162,7 @@ struct GTY ((for_user)) ctf_dtdef
   bool from_global_func; /* Whether this type was added from a global
 			    function.  */
   uint32_t linkage;           /* Used in function types.  0=local, 1=global.  */
+  bool dtd_enum_unsigned;     /* Enum signedness.  */
   union GTY ((desc ("ctf_dtu_d_union_selector (&%1)")))
   {
     /* struct, union, or enum.  */
@@ -406,7 +407,7 @@ extern const char * ctf_add_string (ctf_container_ref, const char *,
 extern ctf_id_t ctf_add_reftype (ctf_container_ref, uint32_t, ctf_id_t,
 				 uint32_t, dw_die_ref);
 extern ctf_id_t ctf_add_enum (ctf_container_ref, uint32_t, const char *,
-			      HOST_WIDE_INT, dw_die_ref);
+			      HOST_WIDE_INT, bool, dw_die_ref);
 extern ctf_id_t ctf_add_slice (ctf_container_ref, uint32_t, ctf_id_t,
 			       uint32_t, uint32_t, dw_die_ref);
 extern ctf_id_t ctf_add_float (ctf_container_ref, uint32_t, const char *,
diff --git a/gcc/dwarf2ctf.cc b/gcc/dwarf2ctf.cc
index 397100004c2..748dd0cd8af 100644
--- a/gcc/dwarf2ctf.cc
+++ b/gcc/dwarf2ctf.cc
@@ -736,6 +736,7 @@ gen_ctf_enumeration_type (ctf_container_ref ctfc, dw_die_ref enumeration)
 {
   const char *enum_name = get_AT_string (enumeration, DW_AT_name);
   unsigned int bit_size = ctf_die_bitsize (enumeration);
+  unsigned int signedness = get_AT_unsigned (enumeration, DW_AT_encoding);
   int declaration_p = get_AT_flag (enumeration, DW_AT_declaration);
 
   ctf_id_t enumeration_type_id;
@@ -759,7 +760,9 @@ gen_ctf_enumeration_type (ctf_container_ref ctfc, dw_die_ref enumeration)
 
   /* Generate a CTF type for the enumeration.  */
   enumeration_type_id = ctf_add_enum (ctfc, CTF_ADD_ROOT,
-				      enum_name, bit_size / 8, enumeration);
+				      enum_name, bit_size / 8,
+				      (signedness == DW_ATE_unsigned),
+				      enumeration);
 
   /* Process the enumerators.  */
   {
diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-enum-1.c b/gcc/testsuite/gcc.dg/debug/btf/btf-enum-1.c
index 728493b0804..7e940529f1b 100644
--- a/gcc/testsuite/gcc.dg/debug/btf/btf-enum-1.c
+++ b/gcc/testsuite/gcc.dg/debug/btf/btf-enum-1.c
@@ -4,7 +4,7 @@
 /* { dg-options "-O0 -gbtf -dA" } */
 
 /* { dg-final { scan-assembler-times "\[\t \]0x6000004\[\t \]+\[^\n\]*btt_info" 1 } } */
-/* { dg-final { scan-assembler-times "\[\t \]0x6000003\[\t \]+\[^\n\]*btt_info" 1 } } */
+/* { dg-final { scan-assembler-times "\[\t \]0x86000003\[\t \]+\[^\n\]*btt_info" 1 } } */
 /* { dg-final { scan-assembler-times "ascii \"QAD.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
 /* { dg-final { scan-assembler-times "ascii \"QED.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
 /* { dg-final { scan-assembler-times "ascii \"QOD.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-enum64-1.c b/gcc/testsuite/gcc.dg/debug/btf/btf-enum64-1.c
new file mode 100644
index 00000000000..e443d4c8c00
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/btf/btf-enum64-1.c
@@ -0,0 +1,44 @@
+/* Test BTF generation for 64 bits enums.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O0 -gbtf -dA" } */
+
+/* { dg-final { scan-assembler-times "\[\t \].size\[\t \]myenum1,\[\t \]8" 1 } } */
+/* { dg-final { scan-assembler-times "\[\t \].size\[\t \]myenum2,\[\t \]8" 1 } } */
+/* { dg-final { scan-assembler-times "\[\t \].size\[\t \]myenum3,\[\t \]8" 1 } } */
+/* { dg-final { scan-assembler-times "\[\t \]0x13000003\[\t \]+\[^\n\]*btt_info" 2 } } */
+/* { dg-final { scan-assembler-times "\[\t \]0x93000003\[\t \]+\[^\n\]*btt_info" 1 } } */
+/* { dg-final { scan-assembler-times "\[\t \]0xffffffaa\[\t \]+\[^\n\]*bte_value_lo32" 2 } } */
+/* { dg-final { scan-assembler-times "\[\t \]0xff\[\t \]+\[^\n\]*bte_value_hi32" 3 } } */
+/* { dg-final { scan-assembler-times "ascii \"B1.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"B2.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"B3.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"C1.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"C2.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"C3.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"D1.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"D2.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "ascii \"D3.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
+/* { dg-final { scan-assembler-times "bte_value_lo32" 9 } } */
+/* { dg-final { scan-assembler-times "bte_value_hi32" 9 } } */
+
+enum default_enum
+{
+  B1 = 0xffffffffaa,
+  B2 = 0xbbbbbbbb,
+  B3 = 0xaabbccdd,
+} myenum1 = B1;
+
+enum explicit_unsigned
+{
+  C1 = 0xffffffffbbUL,
+  C2 = 0xbbbbbbbb,
+  C3 = 0xaabbccdd,
+} myenum2 = C1;
+
+enum signed64
+{
+  D1 = 0xffffffffaa,
+  D2 = 0xbbbbbbbb,
+  D3 = -0x1,
+} myenum3 = D1;
diff --git a/include/btf.h b/include/btf.h
index 78b551ced23..eba67f9d599 100644
--- a/include/btf.h
+++ b/include/btf.h
@@ -109,7 +109,8 @@ struct btf_type
 #define BTF_KIND_VAR		14	/* Variable.  */
 #define BTF_KIND_DATASEC	15	/* Section such as .bss or .data.  */
 #define BTF_KIND_FLOAT		16	/* Floating point.  */
-#define BTF_KIND_MAX		BTF_KIND_FLOAT
+#define BTF_KIND_ENUM64 	19	/* Enumeration up to 64 bits.  */
+#define BTF_KIND_MAX		BTF_KIND_ENUM64
 #define NR_BTF_KINDS		(BTF_KIND_MAX + 1)
 
 /* For some BTF_KINDs, struct btf_type is immediately followed by
@@ -130,14 +131,17 @@ struct btf_type
 #define BTF_INT_BOOL	(1 << 2)
 
 /* BTF_KIND_ENUM is followed by VLEN struct btf_enum entries,
-   which describe the enumerators. Note that BTF currently only
-   supports signed 32-bit enumerator values.  */
+   which describe the enumerators. */
 struct btf_enum
 {
   uint32_t name_off;	/* Offset in string section of enumerator name.  */
   int32_t  val;		/* Enumerator value.  */
 };
 
+/* BTF_KF_ENUM_ holds the flags for kflags in BTF_KIND_ENUM{,64}.  */
+#define BTF_KF_ENUM_UNSIGNED	(0)
+#define BTF_KF_ENUM_SIGNED 	(1 << 0)
+
 /* BTF_KIND_ARRAY is followed by a single struct btf_array.  */
 struct btf_array
 {
@@ -190,6 +194,15 @@ struct btf_var_secinfo
   uint32_t size;	/* Size (in bytes) of variable.  */
 };
 
+/* BTF_KIND_ENUM64 is followed by VLEN struct btf_enum64 entries,
+   which describe the 64 bits enumerators.  */
+struct btf_enum64
+{
+  uint32_t name_off;	/* Offset in string section of enumerator name.  */
+  uint32_t val_lo32;	/* lower 32-bit value for a 64-bit value Enumerator */
+  uint32_t val_hi32;	/* high 32-bit value for a 64-bit value Enumerator */
+};
+
 #ifdef	__cplusplus
 }
 #endif
-- 
2.35.1