[PATCH] LoongArch: only insert align section for ld -r if an input has R_LARCH_ALIGN

[Xi Ruoyao]

Commit 8bf4b69718d4 ("LoongArch: Fix relaxation alignment with ld -r (PR
33236)") has broken the kernel modules on Debian sid.  The expectation
of the kernel is all the source files which would be linked into a
module are compiled with -mno-relax so the module should not contain
R_LARCH_ALIGN, thus the module loader rejects any module containing
R_LARCH_ALIGN.

To restore the correctness of the expectation, only insert the align
section if an input has R_LARCH_ALIGN.  It also does not make too much
sense to bloat the output with NOPs and R_LARCH_ALIGN if no input
contains R_LARCH_ALIGN anyway (regardless the kernel stuff).

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---

I remember I've tested the ld -r against this vector when I reviewed
that, but somehow I didn't catch the breakage...

 bfd/elfnn-loongarch.c                         | 25 +++++++++++++++++--
 .../relax-align-ld-r-norelax.d                |  9 +++++++
 ld/testsuite/ld-loongarch-elf/relax.exp       |  1 +
 3 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 ld/testsuite/ld-loongarch-elf/relax-align-ld-r-norelax.d

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 03b0eb40ac7..a8e52da80bd 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -139,6 +139,9 @@ struct loongarch_elf_link_hash_table
   /* Pending relaxation (byte deletion) operations meant for roughly
      sequential access.  */
   splay_tree pending_delete_ops;
+
+  /* If any input contains R_LARCH_ALIGN.  */
+  bool has_align_reloc;
 };
 
 struct loongarch_elf_section_data
@@ -1109,10 +1112,21 @@ loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
   const Elf_Internal_Rela *rel;
   asection *sreloc = NULL;
 
+  htab = loongarch_elf_hash_table (info);
+
   if (bfd_link_relocatable (info))
-    return true;
+    {
+      for (rel = relocs; rel < relocs + sec->reloc_count; rel++)
+	if (ELFNN_R_TYPE (rel->r_info) == R_LARCH_ALIGN)
+	  {
+	    htab->has_align_reloc = true;
+	    break;
+	  }
+
+      /* No need for more checks for ld -r.  */
+      return true;
+    }
 
-  htab = loongarch_elf_hash_table (info);
   symtab_hdr = &elf_symtab_hdr (abfd);
   sym_hashes = elf_sym_hashes (abfd);
 
@@ -7098,7 +7112,14 @@ elfNN_loongarch_size_aligns (bfd *output_bfd,
 					  (const char *, asection *),
 			     void (*layout_sections_again) (void))
 {
+
+  struct loongarch_elf_link_hash_table *htab;
   bool need_laying_out = false;
+
+  htab = loongarch_elf_hash_table (info);
+  if (!htab->has_align_reloc)
+    return true;
+
   for (bfd *input_bfd = info->input_bfds; input_bfd != NULL;
        input_bfd = input_bfd->link.next)
     {
diff --git a/ld/testsuite/ld-loongarch-elf/relax-align-ld-r-norelax.d b/ld/testsuite/ld-loongarch-elf/relax-align-ld-r-norelax.d
new file mode 100644
index 00000000000..5f33b8b4d89
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-align-ld-r-norelax.d
@@ -0,0 +1,9 @@
+#source: relax-align-ld-r.s
+#as: -mno-relax
+#ld: -r
+#objdump: -Dr
+
+#failif
+#...
+.*R_LARCH_ALIGN.*
+#...
diff --git a/ld/testsuite/ld-loongarch-elf/relax.exp b/ld/testsuite/ld-loongarch-elf/relax.exp
index bb8429ab515..bf4955f4c62 100644
--- a/ld/testsuite/ld-loongarch-elf/relax.exp
+++ b/ld/testsuite/ld-loongarch-elf/relax.exp
@@ -49,6 +49,7 @@ proc run_partial_linking_align_test {} {
 if [istarget loongarch*-*-*] {
   run_dump_test "relax-align-1"
   run_dump_test "relax-align-ld-r"
+  run_dump_test "relax-align-ld-r-norelax"
 }
 
 if [istarget loongarch64-*-*] {
-- 
2.55.0