[PATCH 3/3] AVR/ld: Use .avr.prop data during linker relaxation.

[Andrew Burgess <andrew dot burgess at embecosm dot com>]

Feedback welcome,

thanks,
Andrew

---
Make use of the data held within the .avr.prop section during linker
relaxation in order to maintain the properties of the .org and .align
directives.

In relation to the .align directives, if enough bytes are deleted before
a .align directive then the alignment can be moved while still
maintaining the alignment requirement.

bfd/ChangeLog:

	* elf32-avr.c (struct elf_avr_section_data): New structure.
	(struct avr_relax_info): New structure.
	(elf_avr_new_section_hook): New function.
	(struct elf_avr_section_data): Add relax_info.
	(get_avr_relax_info): New function.
	(init_avr_relax_info): New function.
	(elf32_avr_relax_delete_bytes): Find next property record before
	deleting bytes.  When deleting don't move bytes beyond the next
	property record.
	(avr_elf32_assign_records_to_section): New function.
	(avr_property_record_compare): New function.
	(avr_load_all_property_sections): New function.
	(elf32_avr_relax_section): Load property data.  After relaxing the
	section, move any .align directives that have enough deleted bytes
	before them.
	(bfd_elf32_new_section_hook): Define.

ld/testsuite/ChangeLog:

        * ld-avr/avr-prop-1.d: New file.
        * ld-avr/avr-prop-1.s: New file.
        * ld-avr/avr-prop-2.d: New file.
        * ld-avr/avr-prop-2.s: New file.
        * ld-avr/avr-prop-3.d: New file.
        * ld-avr/avr-prop-3.s: New file.
        * ld-avr/avr-prop-4.d: New file.
        * ld-avr/avr-prop-4.s: New file.
---
 bfd/elf32-avr.c                  | 321 ++++++++++++++++++++++++++++++++++++++-
 ld/testsuite/ld-avr/avr-prop-1.d |  10 ++
 ld/testsuite/ld-avr/avr-prop-1.s |   7 +
 ld/testsuite/ld-avr/avr-prop-2.d |  12 ++
 ld/testsuite/ld-avr/avr-prop-2.s |  13 ++
 ld/testsuite/ld-avr/avr-prop-3.d |  10 ++
 ld/testsuite/ld-avr/avr-prop-3.s |   8 +
 ld/testsuite/ld-avr/avr-prop-4.d |  10 ++
 ld/testsuite/ld-avr/avr-prop-4.s |   8 +
 9 files changed, 398 insertions(+), 1 deletion(-)
 create mode 100644 ld/testsuite/ld-avr/avr-prop-1.d
 create mode 100644 ld/testsuite/ld-avr/avr-prop-1.s
 create mode 100644 ld/testsuite/ld-avr/avr-prop-2.d
 create mode 100644 ld/testsuite/ld-avr/avr-prop-2.s
 create mode 100644 ld/testsuite/ld-avr/avr-prop-3.d
 create mode 100644 ld/testsuite/ld-avr/avr-prop-3.s
 create mode 100644 ld/testsuite/ld-avr/avr-prop-4.d
 create mode 100644 ld/testsuite/ld-avr/avr-prop-4.s

diff --git a/bfd/elf32-avr.c b/bfd/elf32-avr.c
index af5fd8a..17991f9 100644
--- a/bfd/elf32-avr.c
+++ b/bfd/elf32-avr.c
@@ -708,6 +708,83 @@ static bfd_vma avr_pc_wrap_around = 0x10000000;
    instruction. This option could be switched off by a linker switch.  */
 static int avr_replace_call_ret_sequences = 1;
 
+
+/* Per-section relaxation related information for avr.  */
+
+struct avr_relax_info
+{
+  /* Track the avr property records that apply to this section.  */
+
+  struct
+  {
+    /* Number of records in the list.  */
+    unsigned count;
+
+    /* How many records worth of space have we allocated.  */
+    unsigned allocated;
+
+    /* The records, only COUNT records are initialised.  */
+    struct avr_property_record *items;
+  } records;
+};
+
+/* Per section data, specialised for avr.  */
+
+struct elf_avr_section_data
+{
+  /* The standard data must appear first.  */
+  struct bfd_elf_section_data elf;
+
+  /* Relaxation related information.  */
+  struct avr_relax_info relax_info;
+};
+
+/* Possibly initialise avr specific data for new section SEC from ABFD.  */
+
+static bfd_boolean
+elf_avr_new_section_hook (bfd *abfd, asection *sec)
+{
+  if (!sec->used_by_bfd)
+    {
+      struct elf_avr_section_data *sdata;
+      bfd_size_type amt = sizeof (*sdata);
+
+      sdata = bfd_zalloc (abfd, amt);
+      if (sdata == NULL)
+	return FALSE;
+      sec->used_by_bfd = sdata;
+    }
+
+  return _bfd_elf_new_section_hook (abfd, sec);
+}
+
+/* Return a pointer to the relaxation information for SEC.  */
+
+static struct avr_relax_info *
+get_avr_relax_info (asection *sec)
+{
+  struct elf_avr_section_data *section_data;
+
+  /* No info available if no section or if it is an output section.  */
+  if (!sec || sec == sec->output_section)
+    return NULL;
+
+  section_data = (struct elf_avr_section_data *) elf_section_data (sec);
+  return &section_data->relax_info;
+}
+
+/* Initialise the per section relaxation information for SEC.  */
+
+static void
+init_avr_relax_info (asection *sec)
+{
+  struct avr_relax_info *relax_info = get_avr_relax_info (sec);
+
+  relax_info->records.count = 0;
+  relax_info->records.allocated = 0;
+  relax_info->records.items = NULL;
+}
+
 /* Initialize an entry in the stub hash table.  */
 
 static struct bfd_hash_entry *
@@ -1738,13 +1815,38 @@ elf32_avr_relax_delete_bytes (bfd *abfd,
   struct elf_link_hash_entry **sym_hashes;
   struct elf_link_hash_entry **end_hashes;
   unsigned int symcount;
+  struct avr_relax_info *relax_info;
+  struct avr_property_record *prop_record = NULL;
 
   symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
   sec_shndx = _bfd_elf_section_from_bfd_section (abfd, sec);
   contents = elf_section_data (sec)->this_hdr.contents;
+  relax_info = get_avr_relax_info (sec);
 
   toaddr = sec->size;
 
+  if (relax_info->records.count > 0)
+    {
+      /* There should be no property record within the range of deleted
+         bytes, however, there might be a property record for ADDR, this is
+         how we handle alignment directives.
+         Find the next (if any) property record after the deleted bytes.  */
+      unsigned int i;
+
+      for (i = 0; i < relax_info->records.count; ++i)
+        {
+          bfd_vma offset = relax_info->records.items [i].offset;
+
+          BFD_ASSERT (offset <= addr || offset >= (addr + count));
+          if (offset >= (addr + count))
+            {
+              prop_record = &relax_info->records.items [i];
+              toaddr = offset;
+              break;
+            }
+        }
+    }
+
   irel = elf_section_data (sec)->relocs;
   irelend = irel + sec->reloc_count;
 
@@ -1752,7 +1854,32 @@ elf32_avr_relax_delete_bytes (bfd *abfd,
   if (toaddr - addr - count > 0)
     memmove (contents + addr, contents + addr + count,
              (size_t) (toaddr - addr - count));
-  sec->size -= count;
+  if (prop_record == NULL)
+    sec->size -= count;
+  else
+    {
+      /* Use the property record to fill in the bytes we've opened up.  */
+      int fill = 0;
+      switch (prop_record->type)
+        {
+        case RECORD_ORG_AND_FILL:
+          fill = prop_record->data.org.fill;
+          /* Fall through.  */
+        case RECORD_ORG:
+          break;
+        case RECORD_ALIGN_AND_FILL:
+          fill = prop_record->data.align.fill;
+          /* Fall through.  */
+        case RECORD_ALIGN:
+          prop_record->data.align.preceding_deleted += count;
+          break;
+        };
+      memset (contents + toaddr - count, fill, count);
+
+      /* Adjust the TOADDR to avoid moving symbols located at the address
+         of the property record, which has not moved.  */
+      toaddr -= count;
+    }
 
   /* Adjust all the reloc addresses.  */
   for (irel = elf_section_data (sec)->relocs; irel < irelend; irel++)
@@ -2049,6 +2176,127 @@ get_elf_r_symndx_offset (bfd *abfd, unsigned long r_symndx)
   return offset;
 }
 
+/* Iterate over the property records in R_LIST, and copy each record into
+   the list of records within the relaxation information for the section to
+   which the record applies.  */
+
+static void
+avr_elf32_assign_records_to_sections (struct avr_property_record_list *r_list)
+{
+  unsigned int i;
+
+  for (i = 0; i < r_list->record_count; ++i)
+    {
+      struct avr_relax_info *relax_info;
+
+      relax_info = get_avr_relax_info (r_list->records [i].section);
+      BFD_ASSERT (relax_info != NULL);
+
+      if (relax_info->records.count
+          == relax_info->records.allocated)
+        {
+          /* Allocate more space.  */
+          bfd_size_type size;
+
+          relax_info->records.allocated += 10;
+          size = (sizeof (struct avr_property_record)
+                  * relax_info->records.allocated);
+          relax_info->records.items
+            = bfd_realloc (relax_info->records.items, size);
+        }
+
+      memcpy (&relax_info->records.items [relax_info->records.count],
+              &r_list->records [i],
+              sizeof (struct avr_property_record));
+      relax_info->records.count++;
+    }
+}
+
+/* Compare two STRUCT AVR_PROPERTY_RECORD in AP and BP, used as the
+   ordering callback from QSORT.  */
+
+static int
+avr_property_record_compare (const void *ap, const void *bp)
+{
+  const struct avr_property_record *a
+    = (struct avr_property_record *) ap;
+  const struct avr_property_record *b
+    = (struct avr_property_record *) bp;
+
+  if (a->offset != b->offset)
+    return (a->offset - b->offset);
+
+  if (a->section != b->section)
+    return (bfd_get_section_vma (a->section->owner, a->section)
+            - bfd_get_section_vma (b->section->owner, b->section));
+
+  return (a->type - b->type);
+}
+
+/* Load all of the avr property sections from all of the bfd objects
+   referenced from LINK_INFO.  All of the records within each property
+   section are assigned to the STRUCT AVR_RELAX_INFO within the section
+   specific data of the appropriate section.  */
+
+static void
+avr_load_all_property_sections (struct bfd_link_info *link_info)
+{
+  bfd *abfd;
+  asection *sec;
+
+  /* Initialize the per-section relaxation info.  */
+  for (abfd = link_info->input_bfds; abfd != NULL; abfd = abfd->link.next)
+    for (sec = abfd->sections; sec != NULL; sec = sec->next)
+      {
+	init_avr_relax_info (sec);
+      }
+
+  /* Load the descriptor tables from .avr.prop sections.  */
+  for (abfd = link_info->input_bfds; abfd != NULL; abfd = abfd->link.next)
+    {
+      struct avr_property_record_list *r_list;
+
+      r_list = avr_elf32_load_property_records (abfd);
+      if (r_list != NULL)
+        avr_elf32_assign_records_to_sections (r_list);
+
+      free (r_list);
+    }
+
+  /* Now, for every section, ensure that the descriptor list in the
+     relaxation data is sorted by ascending offset within the section.  */
+  for (abfd = link_info->input_bfds; abfd != NULL; abfd = abfd->link.next)
+    for (sec = abfd->sections; sec != NULL; sec = sec->next)
+      {
+        struct avr_relax_info *relax_info = get_avr_relax_info (sec);
+        if (relax_info && relax_info->records.count > 0)
+          {
+            unsigned int i;
+
+            qsort (relax_info->records.items,
+                   relax_info->records.count,
+                   sizeof (struct avr_property_record),
+                   avr_property_record_compare);
+
+            /* For debug purposes, list all the descriptors.  */
+            for (i = 0; i < relax_info->records.count; ++i)
+              {
+                switch (relax_info->records.items [i].type)
+                  {
+                  case RECORD_ORG:
+                    break;
+                  case RECORD_ORG_AND_FILL:
+                    break;
+                  case RECORD_ALIGN:
+                    break;
+                  case RECORD_ALIGN_AND_FILL:
+                    break;
+                  };
+              }
+          }
+      }
+}
+
 /* This function handles relaxing for the avr.
    Many important relaxing opportunities within functions are already
    realized by the compiler itself.
@@ -2092,6 +2340,15 @@ elf32_avr_relax_section (bfd *abfd,
   bfd_byte *contents = NULL;
   Elf_Internal_Sym *isymbuf = NULL;
   struct elf32_avr_link_hash_table *htab;
+  static bfd_boolean relaxation_initialised = FALSE;
+
+  if (!relaxation_initialised)
+    {
+      relaxation_initialised = TRUE;
+
+      /* Load entries from the .avr.prop sections.  */
+      avr_load_all_property_sections (link_info);
+    }
 
   /* If 'shrinkable' is FALSE, do not shrink by deleting bytes while
      relaxing. Such shrinking can cause issues for the sections such
@@ -2695,6 +2952,67 @@ elf32_avr_relax_section (bfd *abfd,
         }
     }
 
+  if (!*again)
+    {
+      /* Look through all the property records in this section to see if
+         there's any alignment records that can be moved.  */
+      struct avr_relax_info *relax_info;
+
+      relax_info = get_avr_relax_info (sec);
+      if (relax_info->records.count > 0)
+        {
+          unsigned int i;
+
+          for (i = 0; i < relax_info->records.count; ++i)
+            {
+              switch (relax_info->records.items [i].type)
+                {
+                case RECORD_ORG:
+                case RECORD_ORG_AND_FILL:
+                  break;
+                case RECORD_ALIGN:
+                case RECORD_ALIGN_AND_FILL:
+                  {
+                    struct avr_property_record *record;
+                    unsigned long bytes_to_align;
+                    int count = 0;
+
+                    /* Look for alignment directives that have had enough
+                       bytes deleted before them, such that the directive
+                       can be moved backwards and still maintain the
+                       required alignment.  */
+                    record = &relax_info->records.items [i];
+                    bytes_to_align
+                      = (unsigned long) (1 << record->data.align.bytes);
+                    while (record->data.align.preceding_deleted >=
+                           bytes_to_align)
+                      {
+                        record->data.align.preceding_deleted
+                          -= bytes_to_align;
+                        count += bytes_to_align;
+                      }
+
+                    if (count > 0)
+                      {
+                        bfd_vma addr = record->offset;
+
+                        /* We can delete COUNT bytes and this alignment
+                           directive will still be correctly aligned.
+                           First move the alignment directive, then delete
+                           the bytes.  */
+                        record->offset -= count;
+                        elf32_avr_relax_delete_bytes (abfd, sec,
+                                                      addr - count,
+                                                      count);
+                        *again = TRUE;
+                      }
+                  }
+                  break;
+                }
+            }
+        }
+    }
+
   if (contents != NULL
       && elf_section_data (sec)->this_hdr.contents != contents)
     {
@@ -3810,5 +4128,6 @@ avr_elf32_property_record_name (struct avr_property_record *rec)
 #define bfd_elf32_bfd_relax_section elf32_avr_relax_section
 #define bfd_elf32_bfd_get_relocated_section_contents \
                                         elf32_avr_get_relocated_section_contents
+#define bfd_elf32_new_section_hook	elf_avr_new_section_hook
 
 #include "elf32-target.h"
diff --git a/ld/testsuite/ld-avr/avr-prop-1.d b/ld/testsuite/ld-avr/avr-prop-1.d
new file mode 100644
index 0000000..0c4ddc4
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-1.d
@@ -0,0 +1,10 @@
+#name: AVR .avr.prop, single .org test.
+#as: -mmcu=avrxmega2 -mlink-relax
+#ld: -mavrxmega2 --relax
+#source: avr-prop-1.s
+#nm: -n
+#target: avr-*-*
+
+#...
+00000020 T dest
+#...
diff --git a/ld/testsuite/ld-avr/avr-prop-1.s b/ld/testsuite/ld-avr/avr-prop-1.s
new file mode 100644
index 0000000..a287d3e
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-1.s
@@ -0,0 +1,7 @@
+        .text
+        .global _start, dest
+_start:
+        CALL    dest
+        .org    0x20
+dest:
+        nop
diff --git a/ld/testsuite/ld-avr/avr-prop-2.d b/ld/testsuite/ld-avr/avr-prop-2.d
new file mode 100644
index 0000000..a45443e
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-2.d
@@ -0,0 +1,12 @@
+#name: AVR .avr.prop, multiple .org test.
+#as: -mmcu=avrxmega2 -mlink-relax
+#ld: -mavrxmega2 --relax
+#source: avr-prop-2.s
+#nm: -n
+#target: avr-*-*
+
+#...
+00000010 T label1
+00000020 T label2
+00000030 T dest
+#...
diff --git a/ld/testsuite/ld-avr/avr-prop-2.s b/ld/testsuite/ld-avr/avr-prop-2.s
new file mode 100644
index 0000000..a36eb18
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-2.s
@@ -0,0 +1,13 @@
+        .text
+        .global _start, label1, label2, dest
+_start:
+        CALL    dest
+        .org    0x10
+label1:
+        CALL    dest
+        .org    0x20
+label2:
+        CALL    dest
+        .org    0x30
+dest:
+        nop
diff --git a/ld/testsuite/ld-avr/avr-prop-3.d b/ld/testsuite/ld-avr/avr-prop-3.d
new file mode 100644
index 0000000..0e1e271
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-3.d
@@ -0,0 +1,10 @@
+#name: AVR .avr.prop, single .align test.
+#as: -mmcu=avrxmega2 -mlink-relax
+#ld: -mavrxmega2 --relax
+#source: avr-prop-3.s
+#nm: -n
+#target: avr-*-*
+
+#...
+00000008 T dest
+#...
diff --git a/ld/testsuite/ld-avr/avr-prop-3.s b/ld/testsuite/ld-avr/avr-prop-3.s
new file mode 100644
index 0000000..bf66a45
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-3.s
@@ -0,0 +1,8 @@
+        .text
+        .global _start, dest
+_start:
+        CALL    dest
+        CALL    dest
+        .align  3
+dest:
+        NOP
diff --git a/ld/testsuite/ld-avr/avr-prop-4.d b/ld/testsuite/ld-avr/avr-prop-4.d
new file mode 100644
index 0000000..42a42c1
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-4.d
@@ -0,0 +1,10 @@
+#name: AVR .avr.prop, realign .align test.
+#as: -mmcu=avrxmega2 -mlink-relax
+#ld: -mavrxmega2 --relax
+#source: avr-prop-4.s
+#nm: -n
+#target: avr-*-*
+
+#...
+00000004 T dest
+#...
diff --git a/ld/testsuite/ld-avr/avr-prop-4.s b/ld/testsuite/ld-avr/avr-prop-4.s
new file mode 100644
index 0000000..b1d532f
--- /dev/null
+++ b/ld/testsuite/ld-avr/avr-prop-4.s
@@ -0,0 +1,8 @@
+        .text
+        .global _start, dest
+_start:
+        CALL    dest
+        CALL    dest
+        .align  2
+dest:
+        NOP
-- 
1.9.3