[RFC] LoongArch: Adjust addends for relaxed section-symbol relocations

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 1a2b3b0399e..e7318dea71b 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -177,6 +177,10 @@  loongarch_elf_new_section_hook (bfd *abfd, asection *sec)
 #define loongarch_elf_hash_table(p)					\
     ((struct loongarch_elf_link_hash_table *) ((p)->hash))		\
 
+/* True if a local STT_SECTION relocation against SEC has a nonzero
+   addend.  */
+#define loongarch_sec_has_nonzero_addend_reloc(sec) ((sec)->sec_flg1)
+
 /* During linker relaxation, indicates whether the section has already
    undergone alignment processing and no more byte deletion is permitted.  */
 #define loongarch_sec_closed_for_deletion(sec) ((sec)->sec_flg0)
@@ -1186,6 +1190,21 @@  loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	  is_abs_symbol = bfd_is_abs_symbol (&h->root);
 	}
 
+      /* Mark the target section so relaxation can skip sections without
+	 such relocations.  */
+      if (r_symndx < symtab_hdr->sh_info
+	  && rel->r_addend != 0
+	  && r_type != R_LARCH_ALIGN
+	  && ELF_ST_TYPE (isym->st_info) == STT_SECTION
+	  && isym->st_shndx < elf_numsections (abfd)
+	  && elf_elfsections (abfd)[isym->st_shndx] != NULL)
+	{
+	  asection *sym_sec
+	      = elf_elfsections (abfd)[isym->st_shndx]->bfd_section;
+	  if (sym_sec != NULL)
+	    loongarch_sec_has_nonzero_addend_reloc (sym_sec) = true;
+	}
+
       /* It is referenced by a non-shared object.  */
       if (h != NULL)
 	h->ref_regular = 1;
@@ -5056,9 +5075,9 @@  loongarch_calc_relaxed_addr (struct bfd_link_info *info, bfd_vma offset)
   struct pending_delete_op *op;
   splay_tree_node node;
 
+  /* A NULL pdops means the byte-deletion stage has passed, so offset
+     is unchanged .  */
   if (!pdops)
-    /* Currently this means we are past the stages where byte deletion could
-       possibly happen.  */
     return offset;
 
   /* Find the op that starts just before the given address.  */
@@ -5070,7 +5089,7 @@  loongarch_calc_relaxed_addr (struct bfd_link_info *info, bfd_vma offset)
   op = (struct pending_delete_op *)node->value;
 
   /* If offset is inside this op's range, it is actually one of the deleted
-     bytes, so the adjusted node->key should be returned in this case.  */
+     bytes, return the previous node->value in this case.  */
   bfd_vma op_end_off = (bfd_vma)node->key + op->size;
   if (offset < op_end_off)
     {
@@ -5219,7 +5238,62 @@  loongarch_relax_resize_symbol (bfd_size_type *size, bfd_vma orig_value,
     }
 }
 
-static void
+/* Adjust relocations that refer to SEC through a local section symbol.
+   The section symbol value is zero, so the offset into SEC is stored in
+   the addend.  Such relocations may be in any section of ABFD.  */
+static bool
+loongarch_relax_adjust_reloc_addends (bfd *abfd, asection *sec,
+				      struct bfd_link_info *link_info)
+{
+  asection *relsec;
+  Elf_Internal_Shdr *symtab_hdr = &elf_symtab_hdr (abfd);
+  Elf_Internal_Sym *local_syms = (Elf_Internal_Sym *) symtab_hdr->contents;
+  unsigned int sec_shndx = _bfd_elf_section_from_bfd_section (abfd, sec);
+
+  for (relsec = abfd->sections; relsec != NULL; relsec = relsec->next)
+    {
+      Elf_Internal_Rela *relocs;
+      unsigned int i;
+
+      if (relsec->reloc_count == 0)
+	continue;
+
+      relocs = elf_section_data (relsec)->relocs;
+      if (relocs == NULL)
+	{
+	  /* Keep addend updates for later relaxation passes.  */
+	  relocs = _bfd_elf_link_read_relocs (abfd, relsec, NULL, NULL,
+					      true);
+	  if (relocs == NULL)
+	    return false;
+	}
+
+      for (i = 0; i < relsec->reloc_count; i++)
+	{
+	  Elf_Internal_Rela *rel = relocs + i;
+	  if (rel->r_addend == 0)
+	    continue;
+
+	  unsigned int r_symndx = ELFNN_R_SYM (rel->r_info);
+	  unsigned int r_type = ELFNN_R_TYPE (rel->r_info);
+
+	  /* R_LARCH_ALIGN stores alignment information in r_addend.  */
+	  if (r_symndx >= symtab_hdr->sh_info
+	      || r_type == R_LARCH_ALIGN)
+	    continue;
+
+	  Elf_Internal_Sym *sym = local_syms + r_symndx;
+	  if (ELF_ST_TYPE (sym->st_info) == STT_SECTION
+	      && sym->st_shndx == sec_shndx)
+	    rel->r_addend = loongarch_calc_relaxed_addr (link_info,
+							 rel->r_addend);
+	}
+    }
+
+  return true;
+}
+
+static bool
 loongarch_relax_perform_deletes (bfd *abfd, asection *sec,
 				 struct bfd_link_info *link_info)
 {
@@ -5245,7 +5319,7 @@  loongarch_relax_perform_deletes (bfd *abfd, asection *sec,
 
   if (node1 == NULL)
     /* No pending delete ops, nothing to do.  */
-    return;
+    return true;
 
   /* Actually delete the bytes.  For each delete op the pointer arithmetics
      look like this:
@@ -5293,9 +5367,11 @@  loongarch_relax_perform_deletes (bfd *abfd, asection *sec,
 	sec->size -= op1->cumulative_offset;
     }
 
-  /* Adjust the location of all of the relocs.  Note that we need not
-     adjust the addends, since all PC-relative references must be against
-     symbols, which we will adjust below.  */
+  if (loongarch_sec_has_nonzero_addend_reloc (sec))
+      if (! loongarch_relax_adjust_reloc_addends (abfd, sec, link_info))
+	return false;
+
+  /* Adjust the location of all of the relocs.  */
   for (i = 0; i < sec->reloc_count; i++)
     if (data->relocs[i].r_offset < toaddr)
       data->relocs[i].r_offset = loongarch_calc_relaxed_addr (
@@ -5374,6 +5450,8 @@  loongarch_relax_perform_deletes (bfd *abfd, asection *sec,
 	    loongarch_relax_resize_symbol (&sym_hash->size, orig_value, pdops);
 	}
     }
+
+  return true;
 }
 
 /* Start perform TLS type transition.
@@ -6382,9 +6460,11 @@  loongarch_elf_relax_section (bfd *abfd, asection *sec,
 
   if (pdops)
     {
-      loongarch_relax_perform_deletes (abfd, sec, info);
+      bool ok = loongarch_relax_perform_deletes (abfd, sec, info);
       htab->pending_delete_ops = NULL;
       splay_tree_delete (pdops);
+      if (!ok)
+	return false;
     }
 
   return true;
diff --git a/ld/testsuite/ld-loongarch-elf/relax-stt-section-a.s b/ld/testsuite/ld-loongarch-elf/relax-stt-section-a.s
new file mode 100644
index 00000000000..7d7a22f1994
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-stt-section-a.s
@@ -0,0 +1,9 @@ 
+  .text
+  call36 .text
+  call36 .data
+a:
+  call36 a
+  .align 3
+
+.data
+  .4byte 0x123
diff --git a/ld/testsuite/ld-loongarch-elf/relax-stt-section-b.s b/ld/testsuite/ld-loongarch-elf/relax-stt-section-b.s
new file mode 100644
index 00000000000..d884d3ca934
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-stt-section-b.s
@@ -0,0 +1,9 @@ 
+  .text
+  call36 .text
+  call36 .data
+b:
+  call36 b
+  .align 3
+
+.data
+  .4byte 0x123
diff --git a/ld/testsuite/ld-loongarch-elf/relax-stt-section-ld-r.d b/ld/testsuite/ld-loongarch-elf/relax-stt-section-ld-r.d
new file mode 100644
index 00000000000..314bbdf0020
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-stt-section-ld-r.d
@@ -0,0 +1,19 @@ 
+#name: LoongArch relax STT_SECTION addend
+#source: relax-stt-section-a.s
+#source: relax-stt-section-b.s
+#ld: -r
+#readelf: -rW
+
+#...
+0+4[ \t]+.*R_LARCH_CALL36.*\.text \+ 4
+#...
+0+c[ \t]+.*R_LARCH_CALL36.*\.data \+ 0
+#...
+0+14[ \t]+.*R_LARCH_CALL36.*a \+ 0
+#...
+0+24[ \t]+.*R_LARCH_CALL36.*\.text \+ 24
+#...
+0+2c[ \t]+.*R_LARCH_CALL36.*\.data \+ 4
+#...
+0+34[ \t]+.*R_LARCH_CALL36.*b \+ 0
+#pass
diff --git a/ld/testsuite/ld-loongarch-elf/relax-stt-section-ld.d b/ld/testsuite/ld-loongarch-elf/relax-stt-section-ld.d
new file mode 100644
index 00000000000..23832b4996a
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-stt-section-ld.d
@@ -0,0 +1,20 @@ 
+#name: LoongArch relax STT_SECTION addend executable
+#source: relax-stt-section-a.s
+#source: relax-stt-section-b.s
+#ld: -r
+#ld_after_inputfiles: && cp tmpdir/dump tmpdir/relax-stt-section-ld-r.o && $LD -o tmpdir/dump tmpdir/relax-stt-section-ld-r.o -e 0 -T $srcdir/$subdir/relax-stt-section.ld
+#objdump: -d -M no-aliases
+
+#...
+.*[ \t]+bl[ \t]+.*# 12000000 <a-0x8>
+#...
+.*[ \t]+bl[ \t]+.*# 12010000 <b\+0xffe8>
+#...
+.*[ \t]+bl[ \t]+.*# 12000008 <a>
+#...
+.*[ \t]+bl[ \t]+.*# 12000010 <a\+0x8>
+#...
+.*[ \t]+bl[ \t]+.*# 12010004 <b\+0xffec>
+#...
+.*[ \t]+bl[ \t]+.*# 12000018 <b>
+#pass
diff --git a/ld/testsuite/ld-loongarch-elf/relax-stt-section.ld b/ld/testsuite/ld-loongarch-elf/relax-stt-section.ld
new file mode 100644
index 00000000000..cbe77d77f79
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-stt-section.ld
@@ -0,0 +1,8 @@ 
+SECTIONS
+{
+  . = 0x12000000;
+  .text : { *(.text) }
+
+  . = 0x12010000;
+  .data : { *(.data) }
+}
diff --git a/ld/testsuite/ld-loongarch-elf/relax.exp b/ld/testsuite/ld-loongarch-elf/relax.exp
index bf4955f4c62..e851367a964 100644
--- a/ld/testsuite/ld-loongarch-elf/relax.exp
+++ b/ld/testsuite/ld-loongarch-elf/relax.exp
@@ -50,6 +50,8 @@  if [istarget loongarch*-*-*] {
   run_dump_test "relax-align-1"
   run_dump_test "relax-align-ld-r"
   run_dump_test "relax-align-ld-r-norelax"
+  run_dump_test "relax-stt-section-ld-r"
+  run_dump_test "relax-stt-section-ld"
 }
 
 if [istarget loongarch64-*-*] {