Merge lto branch into trunk.

From-SVN: r152434

1 files changed, 674 insertions, 0 deletions

diff --git a/gcc/lto/lto-elf.c b/gcc/lto/lto-elf.c
new file mode 100644
index 0000000..f678348
--- /dev/null
+++ b/gcc/lto/lto-elf.c
@@ -0,0 +1,674 @@
+/* LTO routines for ELF object files.
+   Copyright 2009 Free Software Foundation, Inc.
+   Contributed by CodeSourcery, 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/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "toplev.h"
+#include <gelf.h>
+#include "lto.h"
+#include "tm.h"
+#include "libiberty.h"
+#include "ggc.h"
+#include "lto-streamer.h"
+
+
+/* Initialize FILE, an LTO file object for FILENAME.  */
+static void
+lto_file_init (lto_file *file, const char *filename)
+{
+  file->filename = filename;
+}
+
+/* An ELF file.  */
+struct lto_elf_file 
+{
+  /* The base information.  */
+  lto_file base;
+
+  /* The system file descriptor for the file.  */
+  int fd;
+
+  /* The libelf descriptor for the file.  */
+  Elf *elf;
+
+  /* Section number of string table used for section names.  */
+  size_t sec_strtab;
+
+  /* Writable file members.  */
+
+  /* The currently active section.  */
+  Elf_Scn *scn;
+
+  /* The output stream for section header names.  */
+  struct lto_output_stream *shstrtab_stream;
+
+  /* Linked list of data which must be freed *after* the file has been
+     closed.  This is an annoying limitation of libelf.  */
+  struct lto_char_ptr_base *data;
+};
+typedef struct lto_elf_file lto_elf_file;
+
+/* Stores executable header attributes which must be shared by all ELF files.
+   This is used for validating input files and populating output files.  */
+static struct {
+  bool initialized;
+  /* 32 or 64 bits?  */
+  size_t bits;
+  unsigned char elf_ident[EI_NIDENT];
+  Elf64_Half elf_machine;
+} cached_file_attrs;
+
+
+/* Return the section header for SECTION.  The return value is never
+   NULL.  Call lto_elf_free_shdr to release the memory allocated.  */
+
+static Elf64_Shdr *
+lto_elf_get_shdr (Elf_Scn *section)
+{
+  Elf64_Shdr *shdr;
+
+  switch (cached_file_attrs.bits)
+    {
+    case 32:
+      {
+	Elf32_Shdr *shdr32;
+
+	/* Read the 32-bit section header.  */
+	shdr32 = elf32_getshdr (section);
+	if (!shdr32)
+	  fatal_error ("could not read section header: %s", elf_errmsg (0));
+
+	/* Transform it into a 64-bit section header.  */
+	shdr = XNEW (Elf64_Shdr);
+	shdr->sh_name = shdr32->sh_name;
+	shdr->sh_type = shdr32->sh_type;
+	shdr->sh_flags = shdr32->sh_flags;
+	shdr->sh_addr = shdr32->sh_addr;
+	shdr->sh_offset = shdr32->sh_offset;
+	shdr->sh_size = shdr32->sh_size;
+	shdr->sh_link = shdr32->sh_link;
+	shdr->sh_info = shdr32->sh_info;
+	shdr->sh_addralign = shdr32->sh_addralign;
+	shdr->sh_entsize  = shdr32->sh_entsize;
+	break;
+      }
+      break;
+
+    case 64:
+      shdr = elf64_getshdr (section);
+      if (!shdr)
+	fatal_error ("could not read section header: %s", elf_errmsg (0));
+      break;
+
+    default:
+      gcc_unreachable ();
+    }
+
+  return shdr;
+}
+
+/* Free SHDR, previously allocated by lto_elf_get_shdr.  */
+static void
+lto_elf_free_shdr (Elf64_Shdr *shdr)
+{
+  if (cached_file_attrs.bits != 64)
+    free (shdr);
+}
+
+
+/* Returns a hash code for P.  */
+
+static hashval_t
+hash_name (const void *p)
+{
+  const struct lto_section_slot *ds = (const struct lto_section_slot *) p;
+  return (hashval_t) htab_hash_string (ds->name);
+}
+
+
+/* Returns nonzero if P1 and P2 are equal.  */
+
+static int
+eq_name (const void *p1, const void *p2)
+{
+  const struct lto_section_slot *s1 =
+    (const struct lto_section_slot *) p1;
+  const struct lto_section_slot *s2 =
+    (const struct lto_section_slot *) p2;
+
+  return strcmp (s1->name, s2->name) == 0;
+}
+
+
+/* Build a hash table whose key is the section names and whose data is
+   the start and size of each section in the .o file.  */
+
+htab_t
+lto_elf_build_section_table (lto_file *lto_file) 
+{
+  lto_elf_file *elf_file = (lto_elf_file *)lto_file;
+  htab_t section_hash_table;
+  Elf_Scn *section;
+
+  section_hash_table = htab_create (37, hash_name, eq_name, free);
+
+  for (section = elf_getscn (elf_file->elf, 0);
+       section;
+       section = elf_nextscn (elf_file->elf, section)) 
+    {
+      Elf64_Shdr *shdr;
+      const char *name;
+      size_t offset;
+      char *new_name;
+      void **slot;
+      struct lto_section_slot s_slot;
+
+      /* Get the name of this section.  */
+      shdr = lto_elf_get_shdr (section);
+      offset = shdr->sh_name;
+      name = elf_strptr (elf_file->elf, 
+			 elf_file->sec_strtab,
+			 offset);
+
+      /* Only put lto stuff into the symtab.  */
+      if (strncmp (name, LTO_SECTION_NAME_PREFIX, 
+		   strlen (LTO_SECTION_NAME_PREFIX)) != 0)
+	{
+	  lto_elf_free_shdr (shdr);
+	  continue;
+	}
+
+      new_name = XNEWVEC (char, strlen (name) + 1);
+      strcpy (new_name, name);
+      s_slot.name = new_name;
+      slot = htab_find_slot (section_hash_table, &s_slot, INSERT);
+      if (*slot == NULL)
+	{
+	  struct lto_section_slot *new_slot = XNEW (struct lto_section_slot);
+
+	  new_slot->name = new_name;
+	  /* The offset into the file for this section.  */
+	  new_slot->start = shdr->sh_offset;
+	  new_slot->len = shdr->sh_size;
+	  *slot = new_slot;
+	}
+      else
+	{
+	  error ("two or more sections for %s:", new_name);
+	  return NULL;
+	}
+
+      lto_elf_free_shdr (shdr);
+    }
+
+  return section_hash_table;
+}
+
+
+/* Initialize the section header of section SCN.  SH_NAME is the section name
+   as an index into the section header string table.  SH_TYPE is the section
+   type, an SHT_* macro from libelf headers.  */
+
+#define DEFINE_INIT_SHDR(BITS)					      \
+static void							      \
+init_shdr##BITS (Elf_Scn *scn, size_t sh_name, size_t sh_type)	      \
+{								      \
+  Elf##BITS##_Shdr *shdr;					      \
+								      \
+  shdr = elf##BITS##_getshdr (scn);				      \
+  if (!shdr)							      \
+    fatal_error ("elf"#BITS"_getshdr() failed: %s.", elf_errmsg (-1));\
+								      \
+  shdr->sh_name = sh_name;					      \
+  shdr->sh_type = sh_type;					      \
+  shdr->sh_addralign = POINTER_SIZE / BITS_PER_UNIT;		      \
+  shdr->sh_flags = 0;						      \
+  shdr->sh_entsize = 0;						      \
+}
+
+DEFINE_INIT_SHDR (32)
+DEFINE_INIT_SHDR (64)
+
+static bool first_data_block;
+
+/* Begin a new ELF section named NAME with type TYPE in the current output
+   file.  TYPE is an SHT_* macro from the libelf headers.  */
+
+static void
+lto_elf_begin_section_with_type (const char *name, size_t type)
+{
+  lto_elf_file *file;
+  Elf_Scn *scn;
+  size_t sh_name;
+
+  /* Grab the current output file and do some basic assertion checking.  */
+  file = (lto_elf_file *) lto_get_current_out_file (),
+  gcc_assert (file);
+  gcc_assert (file->elf);
+  gcc_assert (!file->scn);
+
+  /* Create a new section.  */
+  scn = elf_newscn (file->elf);
+  if (!scn)
+    fatal_error ("could not create a new ELF section: %s.", elf_errmsg (-1));
+  file->scn = scn;
+
+  /* Add a string table entry and record the offset.  */
+  gcc_assert (file->shstrtab_stream);
+  sh_name = file->shstrtab_stream->total_size;
+  lto_output_data_stream (file->shstrtab_stream, name, strlen (name) + 1);
+
+  /* Initialize the section header.  */
+  switch (cached_file_attrs.bits)
+    {
+    case 32:
+      init_shdr32 (scn, sh_name, type);
+      break;
+
+    case 64:
+      init_shdr64 (scn, sh_name, type);
+      break;
+
+    default:
+      gcc_unreachable ();
+    }
+
+  first_data_block = true;
+}
+
+
+/* Begin a new ELF section named NAME in the current output file.  */
+
+void
+lto_elf_begin_section (const char *name)
+{
+  lto_elf_begin_section_with_type (name, SHT_PROGBITS);
+}
+
+
+/* Append DATA of length LEN to the current output section.  BASE is a pointer
+   to the output page containing DATA.  It is freed once the output file has
+   been written.  */
+
+void
+lto_elf_append_data (const void *data, size_t len, void *block)
+{
+  lto_elf_file *file;
+  Elf_Data *elf_data;
+  struct lto_char_ptr_base *base = (struct lto_char_ptr_base *) block;
+
+  /* Grab the current output file and do some basic assertion checking.  */
+  file = (lto_elf_file *) lto_get_current_out_file ();
+  gcc_assert (file);
+  gcc_assert (file->scn);
+
+  elf_data = elf_newdata (file->scn);
+  if (!elf_data)
+    fatal_error ("could not append data to ELF section: %s", elf_errmsg (-1));
+
+  if (first_data_block)
+    {
+      elf_data->d_align = POINTER_SIZE / BITS_PER_UNIT;
+      first_data_block = false;
+    }
+  else
+    elf_data->d_align = 1;
+  elf_data->d_buf = CONST_CAST (void *, data);
+  elf_data->d_off = 0LL;
+  elf_data->d_size = len;
+  elf_data->d_type = ELF_T_BYTE;
+  elf_data->d_version = EV_CURRENT;
+
+  base->ptr = (char *)file->data;
+  file->data = base;
+}
+
+
+/* End the current output section.  This just does some assertion checking
+   and sets the current output file's scn member to NULL.  */
+
+void
+lto_elf_end_section (void)
+{
+  lto_elf_file *file;
+
+  /* Grab the current output file and validate some basic assertions.  */
+  file = (lto_elf_file *) lto_get_current_out_file ();
+  gcc_assert (file);
+  gcc_assert (file->scn);
+
+  file->scn = NULL;
+}
+
+
+/* Validate's ELF_FILE's executable header and, if cached_file_attrs is
+   uninitialized, caches the architecture.  */
+
+#define DEFINE_VALIDATE_EHDR(BITS)				\
+static bool							\
+validate_ehdr##BITS (lto_elf_file *elf_file)			\
+{								\
+  Elf##BITS##_Ehdr *elf_header;					\
+								\
+  elf_header = elf##BITS##_getehdr (elf_file->elf);		\
+  if (!elf_header)						\
+    {								\
+      error ("could not read ELF header: %s", elf_errmsg (0));	\
+      return false;						\
+    }								\
+								\
+  if (elf_header->e_type != ET_REL)				\
+    {								\
+      error ("not a relocatable ELF object file");		\
+      return false;						\
+    }								\
+								\
+  if (!cached_file_attrs.initialized)				\
+    cached_file_attrs.elf_machine = elf_header->e_machine;	\
+								\
+  if (cached_file_attrs.elf_machine != elf_header->e_machine)	\
+    {								\
+      error ("inconsistent file architecture detected");	\
+      return false;						\
+    }								\
+								\
+  return true;							\
+}
+
+DEFINE_VALIDATE_EHDR (32)
+DEFINE_VALIDATE_EHDR (64)
+
+
+/* Validate's ELF_FILE's executable header and, if cached_file_attrs is
+   uninitialized, caches the results.  Also records the section header string
+   table's section index.  Returns true on success or false on failure.  */
+
+static bool
+validate_file (lto_elf_file *elf_file)
+{
+  const char *elf_ident;
+
+  /* Some aspects of the libelf API are dependent on whether the
+     object file is a 32-bit or 64-bit file.  Determine which kind of
+     file this is now.  */
+  elf_ident = elf_getident (elf_file->elf, NULL);
+  if (!elf_ident)
+    {
+      error ("could not read ELF identification information: %s",
+	      elf_errmsg (0));
+      return false;
+	     
+    }
+
+  if (!cached_file_attrs.initialized)
+    {
+      switch (elf_ident[EI_CLASS])
+	{
+	case ELFCLASS32:
+	  cached_file_attrs.bits = 32;
+	  break;
+
+	case ELFCLASS64:
+	  cached_file_attrs.bits = 64;
+	  break;
+
+	default:
+	  error ("unsupported ELF file class");
+	  return false;
+	}
+
+      memcpy (cached_file_attrs.elf_ident, elf_ident,
+	      sizeof cached_file_attrs.elf_ident);
+    }
+
+  if (memcmp (elf_ident, cached_file_attrs.elf_ident,
+	      sizeof cached_file_attrs.elf_ident))
+    return false;
+
+  /* Check that the input file is a relocatable object file with the correct
+     architecture.  */
+  switch (cached_file_attrs.bits)
+    {
+    case 32:
+      if (!validate_ehdr32 (elf_file))
+	return false;
+      break;
+
+    case 64:
+      if (!validate_ehdr64 (elf_file))
+	return false;
+      break;
+
+    default:
+      gcc_unreachable ();
+    }
+
+  /* Read the string table used for section header names.  */
+  if (elf_getshdrstrndx (elf_file->elf, &elf_file->sec_strtab) == -1)
+    {
+      error ("could not locate ELF string table: %s", elf_errmsg (0));
+      return false;
+    }
+
+  cached_file_attrs.initialized = true;
+  return true;
+}
+
+
+/* Helper functions used by init_ehdr.  Initialize ELF_FILE's executable
+   header using cached data from previously read files.  */
+
+#define DEFINE_INIT_EHDR(BITS)					      \
+static void							      \
+init_ehdr##BITS (lto_elf_file *elf_file)			      \
+{								      \
+  Elf##BITS##_Ehdr *ehdr;					      \
+								      \
+  gcc_assert (cached_file_attrs.bits);				      \
+								      \
+  ehdr = elf##BITS##_newehdr (elf_file->elf);			      \
+  if (!ehdr)							      \
+    fatal_error ("elf"#BITS"_newehdr() failed: %s.", elf_errmsg (-1));\
+								      \
+  memcpy (ehdr->e_ident, cached_file_attrs.elf_ident,		      \
+	  sizeof cached_file_attrs.elf_ident);			      \
+  ehdr->e_type = ET_REL;					      \
+  ehdr->e_version = EV_CURRENT;					      \
+  ehdr->e_machine = cached_file_attrs.elf_machine;		      \
+}
+
+DEFINE_INIT_EHDR (32)
+DEFINE_INIT_EHDR (64)
+
+
+/* Initialize ELF_FILE's executable header using cached data from previously
+   read files.  */
+
+static void
+init_ehdr (lto_elf_file *elf_file)
+{
+  switch (cached_file_attrs.bits)
+    {
+    case 32:
+      init_ehdr32 (elf_file);
+      break;
+
+    case 64:
+      init_ehdr64 (elf_file);
+      break;
+
+    default:
+      gcc_unreachable ();
+    }
+}
+
+
+/* Open ELF file FILENAME.  If WRITABLE is true, the file is opened for write
+   and, if necessary, created.  Otherwise, the file is opened for reading.
+   Returns the opened file.  */
+
+lto_file *
+lto_elf_file_open (const char *filename, bool writable)
+{
+  lto_elf_file *elf_file;
+  lto_file *result;
+
+  /* Set up.  */
+  elf_file = XCNEW (lto_elf_file);
+  result = (lto_file *) elf_file;
+  lto_file_init (result, filename);
+  elf_file->fd = -1;
+
+  /* Open the file.  */
+  elf_file->fd = open (filename, writable ? O_WRONLY|O_CREAT : O_RDONLY, 0666);
+  if (elf_file->fd == -1)
+    {
+      error ("could not open file %s", filename);
+      goto fail;
+    }
+
+  /* Initialize the ELF library.  */
+  if (elf_version (EV_CURRENT) == EV_NONE)
+    {
+      error ("ELF library is older than that used when building GCC");
+      goto fail;
+    }
+
+  /* Open the ELF file descriptor.  */
+  elf_file->elf = elf_begin (elf_file->fd, writable ? ELF_C_WRITE : ELF_C_READ,
+			     NULL);
+  if (!elf_file->elf)
+    {
+      error ("could not open ELF file: %s", elf_errmsg (0));
+      goto fail;
+    }
+
+  if (writable)
+    {
+      init_ehdr (elf_file);
+      elf_file->shstrtab_stream = XCNEW (struct lto_output_stream);
+      /* Output an empty string to the section header table.  This becomes the
+	 name of the initial NULL section.  */
+      lto_output_1_stream (elf_file->shstrtab_stream, '\0');
+    }
+  else
+    if (!validate_file (elf_file))
+      goto fail;
+
+  return result;
+
+ fail:
+  lto_elf_file_close (result);
+  return NULL;
+}
+
+
+/* Close ELF file FILE and clean up any associated data structures.  If FILE
+   was opened for writing, the file's ELF data is written at this time, and
+   any cached data buffers are freed.  */
+
+void
+lto_elf_file_close (lto_file *file)
+{
+  lto_elf_file *elf_file = (lto_elf_file *) file;
+  struct lto_char_ptr_base *cur, *tmp;
+
+  /* Write the ELF section header string table.  */
+  if (elf_file->shstrtab_stream)
+    {
+      size_t strtab;
+      GElf_Ehdr *ehdr_p, ehdr_buf;
+      lto_file *old_file = lto_set_current_out_file (file);
+
+      lto_elf_begin_section_with_type (".shstrtab", SHT_STRTAB);
+      ehdr_p = gelf_getehdr (elf_file->elf, &ehdr_buf);
+      if (ehdr_p == NULL)
+	fatal_error ("gelf_getehdr() failed: %s.", elf_errmsg (-1));
+      strtab = elf_ndxscn (elf_file->scn);
+      if (strtab < SHN_LORESERVE)
+	ehdr_p->e_shstrndx = strtab;
+      else
+	{
+	  GElf_Shdr *shdr_p, shdr_buf;
+	  Elf_Scn *scn_p = elf_getscn (elf_file->elf, 0);
+	  if (scn_p == NULL)
+	    fatal_error ("elf_getscn() failed: %s.", elf_errmsg (-1));
+	  shdr_p = gelf_getshdr (scn_p, &shdr_buf);
+	  if (shdr_p == NULL)
+	    fatal_error ("gelf_getshdr() failed: %s.", elf_errmsg (-1));
+	  shdr_p->sh_link = strtab;
+	  if (gelf_update_shdr (scn_p, shdr_p) == 0)
+	    fatal_error ("gelf_update_shdr() failed: %s.", elf_errmsg (-1));
+	  ehdr_p->e_shstrndx = SHN_XINDEX;
+	}
+      if (gelf_update_ehdr (elf_file->elf, ehdr_p) == 0)
+	fatal_error ("gelf_update_ehdr() failed: %s.", elf_errmsg (-1));
+      lto_write_stream (elf_file->shstrtab_stream);
+      lto_elf_end_section ();
+
+      lto_set_current_out_file (old_file);
+      free (elf_file->shstrtab_stream);
+
+      if (elf_update (elf_file->elf, ELF_C_WRITE) < 0)
+	fatal_error ("elf_update() failed: %s.", elf_errmsg (-1));
+    }
+
+  if (elf_file->elf)
+    elf_end (elf_file->elf);
+  if (elf_file->fd != -1)
+    close (elf_file->fd);
+
+  /* Free any ELF data buffers.  */
+  cur = elf_file->data;
+  while (cur)
+    {
+      tmp = cur;
+      cur = (struct lto_char_ptr_base *) cur->ptr;
+      free (tmp);
+    }
+
+  free (file);
+}
+
+
+/* The current output file.  */
+static lto_file *current_out_file;
+
+
+/* Sets the current output file to FILE.  Returns the old output file or
+   NULL.  */
+
+lto_file *
+lto_set_current_out_file (lto_file *file)
+{
+  lto_file *old_file = current_out_file;
+  current_out_file = file;
+  return old_file;
+}
+
+
+/* Returns the current output file.  */
+
+lto_file *
+lto_get_current_out_file (void)
+{
+  return current_out_file;
+}