[binutils-gdb] bfd: use less memory in string merging

[Michael Matz <matz@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=21160d8a18dc21aafb8ab1026e13e5c524954a46

commit 21160d8a18dc21aafb8ab1026e13e5c524954a46
Author: Michael Matz <matz@suse.de>
Date:   Tue Nov 7 17:12:46 2023 +0100

    bfd: use less memory in string merging
    
    the offset-to-entry mappings are allocated in blocks, which may
    become a bit wasteful in case there are extremely many small
    input files or sections.  This made it so that a large project
    (Qt5WebEngine) didn't build anymore on x86 32bit due to address
    space limits.  It barely fit into address space before the new
    string merging, and then got pushed over the limit by this.
    
    So instead of leaving the waste reallocate the maps to their final
    size once known.  Now the link barely fits again.
    
    bfd/
        * merge.c (record_section): Reallocate offset maps to their
        final size.

Diff:
---
 bfd/merge.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/bfd/merge.c b/bfd/merge.c
index 61ffab4d706..eeaa1a01fe3 100644
--- a/bfd/merge.c
+++ b/bfd/merge.c
@@ -711,6 +711,7 @@ record_section (struct sec_merge_info *sinfo,
   unsigned int align;
   bfd_size_type amt;
   bfd_byte *contents;
+  void *tmpptr;
 
   amt = sec->size;
   if (sec->flags & SEC_STRINGS)
@@ -771,6 +772,19 @@ record_section (struct sec_merge_info *sinfo,
 
   free (contents);
   contents = NULL;
+
+  /* We allocate the ofsmap arrays in blocks of 2048 elements.
+     In case we have very many small input files/sections,
+     this might waste large amounts of memory, so reallocate these
+     arrays here to their true size.  */
+  amt = secinfo->noffsetmap + 1;
+  tmpptr = bfd_realloc (secinfo->map, amt * sizeof(secinfo->map[0]));
+  if (tmpptr)
+    secinfo->map = tmpptr;
+  tmpptr = bfd_realloc (secinfo->map_ofs, amt * sizeof(secinfo->map_ofs[0]));
+  if (tmpptr)
+    secinfo->map_ofs = tmpptr;
+
   /*printf ("ZZZ %s:%s %u entries\n", sec->owner->filename, sec->name,
 	  (unsigned)secinfo->noffsetmap);*/