CTF/BTF debug formats

This commit introduces support for generating CTF debugging
information and BTF debugging information from GCC.

2021-06-28  Indu Bhagat  <indu.bhagat@oracle.com>
	    David Faust  <david.faust@oracle.com>
	    Jose E. Marchesi  <jose.marchesi@oracle.com>
	    Weimin Pan  <weimin.pan@oracle.com>

gcc/

	* Makefile.in: Add ctfc.*, ctfout.c and btfout.c files to
	GTFILES.  Add new object files.
	* common.opt: Add CTF and BTF debug info options.
	* btfout.c: New file.
	* ctfc.c: Likewise.
	* ctfc.h: Likewise.
	* ctfout.c: Likewise.
	* dwarf2ctf.c: Likewise.
	* dwarf2ctf.h: Likewise.
	* dwarf2cfi.c (dwarf2out_do_frame): Acknowledge CTF_DEBUG and
	BTF_DEBUG.
	* dwarf2out.c (dwarf2out_source_line): Likewise.
	(dwarf2out_finish): Skip emitting DWARF if CTF or BTF are to
	be generated.
	(debug_format_do_cu): New function.
	(dwarf2out_early_finish): Traverse DIEs and emit CTF/BTF for
	them if	requested.
	Include dwarf2ctf.c.
	* final.c (dwarf2_debug_info_emitted_p): Acknowledge DWARF-based debug
	formats.
	* flag-types.h (enum debug_info_type): Add CTF_DEBUG and BTF_DEBUG.
	(CTF_DEBUG): New bitmask.
	(BTF_DEBUG): Likewise.
	(enum ctf_debug_info_levels): New enum.
	* gengtype.c (open_base_files): Handle ctfc.h.
	(main): Handle uint32_t type.
	* flags.h (btf_debuginfo_p): New definition.
	(dwarf_based_debuginfo_p): Likewise.
	* opts.c (debug_type_names): Add entries for CTF and BTF.
	(btf_debuginfo_p): New function.
	(dwarf_based_debuginfo_p): Likewise.
	(common_handle_option): Handle -gctfN and -gbtf options.
	(set_debug_level): Set CTF_DEBUG, BTF_DEBUG whenever appropriate.
	* toplev.c (process_options): Inform the user and ignore -gctfLEVEL if
	frontend is not C.

include/

	* ctf.h: New file.
	* btf.h: Likewise.

libiberty/

	* simple-object.c (handle_lto_debug_sections): Copy over .ctf
	sections.

1 files changed, 436 insertions, 0 deletions

diff --git a/gcc/ctfc.h b/gcc/ctfc.h
new file mode 100644
index 0000000..39c5270
--- /dev/null
+++ b/gcc/ctfc.h
@@ -0,0 +1,436 @@
+/* ctfc.h - Declarations and definitions related to the CTF container.
+   Copyright (C) 2019,2021 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+/* This file defines the data structures and functions used by the compiler
+   to generate the CTF debug info.  The definitions below are compiler internal
+   representations and closely reflect the CTF format requirements in <ctf.h>.
+
+   The contents of the CTF container are used eventually for emission of both
+   CTF (ctfout.c) and BTF debug info (btfout.c), as the two type debug formats
+   are close cousins.  */
+
+#ifndef GCC_CTFC_H
+#define GCC_CTFC_H 1
+
+#include "config.h"
+#include "system.h"
+#include "tree.h"
+#include "fold-const.h"
+#include "dwarf2ctf.h"
+#include "ctf.h"
+#include "btf.h"
+
+/* Invalid CTF type ID definition.  */
+
+#define CTF_NULL_TYPEID 0
+
+/* Value to start generating the CTF type ID from.  */
+
+#define CTF_INIT_TYPEID 1
+
+/* CTF type ID.  */
+
+typedef uint64_t ctf_id_t;
+
+/* CTF string table element (list node).  */
+
+typedef struct GTY ((chain_next ("%h.cts_next"))) ctf_string
+{
+  const char * cts_str;		  /* CTF string.  */
+  struct ctf_string * cts_next;   /* A list node.  */
+} ctf_string_t;
+
+/* Internal representation of CTF string table.  */
+
+typedef struct GTY (()) ctf_strtable
+{
+  ctf_string_t * ctstab_head;	    /* Head str ptr.  */
+  ctf_string_t * ctstab_tail;	    /* Tail.  new str appended to tail.  */
+  int ctstab_num;		    /* Number of strings in the table.  */
+  size_t ctstab_len;		    /* Size of string table in bytes.  */
+  const char * ctstab_estr;	    /* Empty string "".  */
+} ctf_strtable_t;
+
+/* Encoding information for integers, floating-point values etc.  The flags
+   field will contain values appropriate for the type defined in <ctf.h>.  */
+
+typedef struct GTY (()) ctf_encoding
+{
+  unsigned int cte_format;  /* Data format (CTF_INT_* or CTF_FP_* flags).  */
+  unsigned int cte_offset;  /* Offset of value in bits.  */
+  unsigned int cte_bits;    /* Size of storage in bits.  */
+} ctf_encoding_t;
+
+/* Array information for CTF generation.  */
+
+typedef struct GTY (()) ctf_arinfo
+{
+  ctf_id_t ctr_contents;	/* Type of array contents.  */
+  ctf_id_t ctr_index;		/* Type of array index.  */
+  unsigned int ctr_nelems;	/* Number of elements.  */
+} ctf_arinfo_t;
+
+/* Function information for CTF generation.  */
+
+typedef struct GTY (()) ctf_funcinfo
+{
+  ctf_id_t ctc_return;		/* Function return type.  */
+  unsigned int ctc_argc;	/* Number of typed arguments to function.  */
+  unsigned int ctc_flags;	/* Function attributes (see below).  */
+} ctf_funcinfo_t;
+
+typedef struct GTY (()) ctf_sliceinfo
+{
+  unsigned int cts_type;	/* Reference CTF type.  */
+  unsigned short cts_offset;	/* Offset in bits of the first bit.  */
+  unsigned short cts_bits;	/* Size in bits.  */
+} ctf_sliceinfo_t;
+
+/* CTF type representation internal to the compiler.  It closely reflects the
+   ctf_type_t type node in <ctf.h> except the GTY (()) tags.  */
+
+typedef struct GTY (()) ctf_itype
+{
+  uint32_t ctti_name;		/* Reference to name in string table.  */
+  uint32_t ctti_info;		/* Encoded kind, variant length (see below).  */
+  union GTY ((desc ("0")))
+  {
+    uint32_t GTY ((tag ("0"))) _size;/* Size of entire type in bytes.  */
+    uint32_t GTY ((tag ("1"))) _type;/* Reference to another type.  */
+  } _u;
+  uint32_t ctti_lsizehi;	/* High 32 bits of type size in bytes.  */
+  uint32_t ctti_lsizelo;	/* Low 32 bits of type size in bytes.  */
+} ctf_itype_t;
+
+#define ctti_size _u._size
+#define ctti_type _u._type
+
+/* Function arguments end with varargs.  */
+
+#define CTF_FUNC_VARARG 0x1
+
+/* Struct/union/enum member definition for CTF generation.  */
+
+typedef struct GTY ((chain_next ("%h.dmd_next"))) ctf_dmdef
+{
+  const char * dmd_name;	/* Name of this member.  */
+  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).  */
+  struct ctf_dmdef * dmd_next;	/* A list node.  */
+} ctf_dmdef_t;
+
+#define ctf_dmd_list_next(elem) ((ctf_dmdef_t *)((elem)->dmd_next))
+
+/* Function Argument.  */
+
+typedef struct GTY (()) ctf_func_arg
+{
+  ctf_id_t farg_type;		  /* Type identifier of the argument.  */
+  const char * farg_name;	  /* Name of the the argument.  */
+  uint32_t farg_name_offset;	  /* Offset of the name in str table.  */
+  struct ctf_func_arg * farg_next;/* A list node.  */
+} ctf_func_arg_t;
+
+#define ctf_farg_list_next(elem) ((ctf_func_arg_t *)((elem)->farg_next))
+
+/* Type definition for CTF generation.  */
+
+struct GTY ((for_user)) ctf_dtdef
+{
+  dw_die_ref dtd_key;	      /* Type key for hashing.  */
+  const char * dtd_name;      /* Name associated with definition (if any).  */
+  ctf_id_t dtd_type;	      /* Type identifier for this definition.  */
+  ctf_itype_t dtd_data;	      /* Type node.  */
+  bool from_global_func; /* Whether this type was added from a global
+			    function.  */
+  union GTY ((desc ("ctf_dtu_d_union_selector (&%1)")))
+  {
+    /* struct, union, or enum.  */
+    ctf_dmdef_t * GTY ((tag ("CTF_DTU_D_MEMBERS"))) dtu_members;
+    /* array.  */
+    ctf_arinfo_t GTY ((tag ("CTF_DTU_D_ARRAY"))) dtu_arr;
+    /* integer or float.  */
+    ctf_encoding_t GTY ((tag ("CTF_DTU_D_ENCODING"))) dtu_enc;
+    /* function.  */
+    ctf_func_arg_t * GTY ((tag ("CTF_DTU_D_ARGUMENTS"))) dtu_argv;
+    /* slice.  */
+    ctf_sliceinfo_t GTY ((tag ("CTF_DTU_D_SLICE"))) dtu_slice;
+  } dtd_u;
+};
+
+typedef struct ctf_dtdef ctf_dtdef_t;
+
+/* Variable definition for CTF generation.  */
+
+struct GTY ((for_user)) ctf_dvdef
+{
+  dw_die_ref dvd_key;		/* DWARF DIE corresponding to the variable.  */
+  const char * dvd_name;	/* Name associated with variable.  */
+  uint32_t dvd_name_offset;	/* Offset of the name in str table.  */
+  unsigned int dvd_visibility;	/* External visibility.  0=static,1=global.  */
+  ctf_id_t dvd_type;		/* Type of variable.  */
+};
+
+typedef struct ctf_dvdef ctf_dvdef_t;
+
+typedef ctf_dvdef_t * ctf_dvdef_ref;
+typedef ctf_dtdef_t * ctf_dtdef_ref;
+
+/* Location information for CTF Types and CTF Variables.  */
+
+typedef struct GTY (()) ctf_srcloc
+{
+  const char * ctsloc_file;
+  unsigned int ctsloc_line;
+  unsigned int ctsloc_col;
+} ctf_srcloc_t;
+
+typedef ctf_srcloc_t * ctf_srcloc_ref;
+
+/* Helper enum and api for the GTY machinery to work on union dtu_d.  */
+
+enum ctf_dtu_d_union_enum {
+  CTF_DTU_D_MEMBERS,
+  CTF_DTU_D_ARRAY,
+  CTF_DTU_D_ENCODING,
+  CTF_DTU_D_ARGUMENTS,
+  CTF_DTU_D_SLICE,
+};
+
+enum ctf_dtu_d_union_enum
+ctf_dtu_d_union_selector (ctf_dtdef_ref);
+
+struct ctfc_dtd_hasher : ggc_ptr_hash <ctf_dtdef_t>
+{
+  typedef ctf_dtdef_ref compare_type;
+
+  static hashval_t hash (ctf_dtdef_ref);
+  static bool equal (ctf_dtdef_ref, ctf_dtdef_ref);
+};
+
+inline hashval_t
+ctfc_dtd_hasher::hash (ctf_dtdef_ref dtd)
+{
+  return htab_hash_pointer (dtd->dtd_key);
+}
+
+inline bool
+ctfc_dtd_hasher::equal (ctf_dtdef_ref dtd, ctf_dtdef_ref dtd2)
+{
+  return (dtd->dtd_key == dtd2->dtd_key);
+}
+
+struct ctfc_dvd_hasher : ggc_ptr_hash <ctf_dvdef_t>
+{
+  typedef ctf_dvdef_ref compare_type;
+
+  static hashval_t hash (ctf_dvdef_ref);
+  static bool equal (ctf_dvdef_ref, ctf_dvdef_ref);
+};
+
+inline hashval_t
+ctfc_dvd_hasher::hash (ctf_dvdef_ref dvd)
+{
+  return htab_hash_pointer (dvd->dvd_key);
+}
+
+inline bool
+ctfc_dvd_hasher::equal (ctf_dvdef_ref dvd, ctf_dvdef_ref dvd2)
+{
+  return (dvd->dvd_key == dvd2->dvd_key);
+}
+
+/* CTF container structure.
+   It is the context passed around when generating ctf debug info.  There is
+   one container per translation unit.  */
+
+typedef struct GTY (()) ctf_container
+{
+  /* CTF Preamble.  */
+  unsigned short ctfc_magic;
+  unsigned char ctfc_version;
+  unsigned char ctfc_flags;
+  uint32_t ctfc_cuname_offset;
+
+  /* CTF types.  */
+  hash_table <ctfc_dtd_hasher> * GTY (()) ctfc_types;
+  /* CTF variables.  */
+  hash_table <ctfc_dvd_hasher> * GTY (()) ctfc_vars;
+
+  /* CTF string table.  */
+  ctf_strtable_t ctfc_strtable;
+  /* Auxilliary string table.  At this time, used for keeping func arg names
+     for BTF.  */
+  ctf_strtable_t ctfc_aux_strtable;
+
+  uint64_t ctfc_num_types;
+  uint64_t ctfc_num_stypes;
+  uint64_t ctfc_num_global_funcs;
+  uint64_t ctfc_num_global_objts;
+
+  /* Number of vlen bytes - the variable length portion after ctf_type_t and
+     ctf_stype_t in the CTF section.  This is used to calculate the offsets in
+     the CTF header.  */
+  uint64_t ctfc_num_vlen_bytes;
+
+  /* Next CTF type id to assign.  */
+  ctf_id_t ctfc_nextid;
+
+  /* Specify an explicit length of 0 so that the GC marking routines steer
+     clear of marking the CTF vars and CTF types twice. These lists below do
+     not own the pointed to objects, they simply hold references to them.  */
+
+  /* List of pre-processed CTF Variables.  CTF requires that the variables
+     appear in the sorted order of their names.  */
+  ctf_dvdef_t ** GTY ((length ("0"))) ctfc_vars_list;
+  /* List of pre-processed CTF types.  CTF requires that a shared type must
+     appear before the type that uses it.  For the compiler, this means types
+     are emitted in sorted order of their type IDs.  */
+  ctf_dtdef_t ** GTY ((length ("0"))) ctfc_types_list;
+  /* List of CTF function types for global functions.  The order of global
+     function entries in the CTF funcinfo section is undefined by the
+     compiler.  */
+  ctf_dtdef_t ** GTY ((length ("0"))) ctfc_gfuncs_list;
+  /* List of CTF variables at global scope.  The order of global object entries
+     in the CTF objinfo section is undefined by the  compiler.  */
+  ctf_dvdef_t ** GTY ((length ("0"))) ctfc_gobjts_list;
+
+  /* Following members are for debugging only.  They do not add functional
+     value to the task of CTF creation.  These can be cleaned up once CTF
+     generation stabilizes.  */
+
+  /* Keep a count of the number of bytes dumped in asm for debugging
+     purposes.  */
+  uint64_t ctfc_numbytes_asm;
+   /* Total length of all strings in CTF.  */
+  size_t ctfc_strlen;
+  /* Total length of all strings in aux string table.  */
+  size_t ctfc_aux_strlen;
+
+} ctf_container_t;
+
+/* Markers for which string table from the CTF container to use.  */
+
+#define CTF_STRTAB 0	    /* CTF string table.  */
+#define CTF_AUX_STRTAB 1    /* CTF auxilliary string table.  */
+
+typedef ctf_container_t * ctf_container_ref;
+
+extern GTY (()) ctf_container_ref tu_ctfc;
+
+extern void ctfc_delete_container (ctf_container_ref);
+
+/* If the next ctf type id is still set to the init value, no ctf records to
+   report.  */
+extern bool ctfc_is_empty_container (ctf_container_ref);
+
+/* Get the total number of CTF types in the container.  */
+
+extern unsigned int ctfc_get_num_ctf_types (ctf_container_ref);
+
+/* Get the total number of CTF variables in the container.  */
+
+extern unsigned int ctfc_get_num_ctf_vars (ctf_container_ref);
+
+/* Get reference to the CTF string table or the CTF auxilliary
+   string table.  */
+
+extern ctf_strtable_t * ctfc_get_strtab (ctf_container_ref, int);
+
+/* Get the length of the specified string table in the CTF container.  */
+
+extern size_t ctfc_get_strtab_len (ctf_container_ref, int);
+
+/* Get the number of bytes to represent the variable length portion of all CTF
+   types in the CTF container.  */
+
+extern size_t ctfc_get_num_vlen_bytes (ctf_container_ref);
+
+/* The compiler demarcates whether types are visible at top-level scope or not.
+   The only example so far of a type not visible at top-level scope is slices.
+   CTF_ADD_NONROOT is used to indicate the latter.  */
+#define	CTF_ADD_NONROOT	0	/* CTF type only visible in nested scope.  */
+#define	CTF_ADD_ROOT	1	/* CTF type visible at top-level scope.  */
+
+/* These APIs allow to initialize and finalize the CTF machinery and
+   to add types to the CTF container associated to the current
+   translation unit.  Used in dwarf2ctf.c.  */
+
+extern void ctf_init (void);
+extern void ctf_output (const char * filename);
+extern void ctf_finalize (void);
+
+extern void btf_output (const char * filename);
+extern void btf_init_postprocess (void);
+extern void btf_finalize (void);
+
+extern ctf_container_ref ctf_get_tu_ctfc (void);
+
+extern bool ctf_type_exists (ctf_container_ref, dw_die_ref, ctf_id_t *);
+
+extern void ctf_add_cuname (ctf_container_ref, const char *);
+
+extern ctf_dvdef_ref ctf_dvd_lookup (const ctf_container_ref, dw_die_ref);
+
+extern const char * ctf_add_string (ctf_container_ref, const char *,
+				    uint32_t *, int);
+
+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);
+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 *,
+			       const ctf_encoding_t *, dw_die_ref);
+extern ctf_id_t ctf_add_integer (ctf_container_ref, uint32_t, const char *,
+				 const ctf_encoding_t *, dw_die_ref);
+extern ctf_id_t ctf_add_unknown (ctf_container_ref, uint32_t, const char *,
+				 const ctf_encoding_t *, dw_die_ref);
+extern ctf_id_t ctf_add_pointer (ctf_container_ref, uint32_t, ctf_id_t,
+				 dw_die_ref);
+extern ctf_id_t ctf_add_array (ctf_container_ref, uint32_t,
+			       const ctf_arinfo_t *, dw_die_ref);
+extern ctf_id_t ctf_add_forward (ctf_container_ref, uint32_t, const char *,
+				 uint32_t, dw_die_ref);
+extern ctf_id_t ctf_add_typedef (ctf_container_ref, uint32_t, const char *,
+				 ctf_id_t, dw_die_ref);
+extern ctf_id_t ctf_add_function (ctf_container_ref, uint32_t, const char *,
+				  const ctf_funcinfo_t *, dw_die_ref, bool);
+extern ctf_id_t ctf_add_sou (ctf_container_ref, uint32_t, const char *,
+			     uint32_t, size_t, dw_die_ref);
+
+extern int ctf_add_enumerator (ctf_container_ref, ctf_id_t, const char *,
+			       HOST_WIDE_INT, dw_die_ref);
+extern int ctf_add_member_offset (ctf_container_ref, dw_die_ref, const char *,
+				  ctf_id_t, uint64_t);
+extern int ctf_add_function_arg (ctf_container_ref, dw_die_ref,
+				 const char *, ctf_id_t);
+extern int ctf_add_variable (ctf_container_ref, const char *, ctf_id_t,
+			     dw_die_ref, unsigned int);
+
+/* CTF section does not emit location information; at this time, location
+   information is needed for BTF CO-RE use-cases.  */
+
+extern int ctfc_get_dtd_srcloc (ctf_dtdef_ref, ctf_srcloc_ref);
+extern int ctfc_get_dvd_srcloc (ctf_dvdef_ref, ctf_srcloc_ref);
+
+#endif /* GCC_CTFC_H */