LoongArch: Remove "elf_seg_map (info->output_bfd) == NULL" relaxation…

… condition

Previously the condition prevented shared objects from being relaxed.
To remove the limitation, we need to update program header size and
.eh_frame_hdr size before relaxation.

bfd/elfnn-loongarch.c

@@ -3738,7 +3738,7 @@ loongarch_relax_delete_bytes (bfd *abfd,
 
 /* Relax pcalau12i,addi.d => pcaddi.  */
 static bool
-loongarch_relax_pcala_addi (bfd *abfd, asection *sec,
+loongarch_relax_pcala_addi (bfd *abfd, asection *sec, asection *sym_sec,
 		       Elf_Internal_Rela *rel_hi, bfd_vma symval,
 		       struct bfd_link_info *info, bool *again)
 {
@@ -3747,7 +3747,24 @@ loongarch_relax_pcala_addi (bfd *abfd, asection *sec,
   uint32_t pca = bfd_get (32, abfd, contents + rel_hi->r_offset);
   uint32_t add = bfd_get (32, abfd, contents + rel_lo->r_offset);
   uint32_t rd = pca & 0x1f;
+
+  /* This section's output_offset need to subtract the bytes of instructions
+     relaxed by the previous sections, so it needs to be updated beforehand.
+     size_input_section already took care of updating it after relaxation,
+     so we additionally update once here.  */
+  sec->output_offset = sec->output_section->size;
   bfd_vma pc = sec_addr (sec) + rel_hi->r_offset;
+
+  /* If pc and symbol not in the same segment, add/sub segment alignment.
+     FIXME: if there are multiple readonly segments?  */
+  if (!(sym_sec->flags & SEC_READONLY))
+    {
+      if (symval > pc)
+	pc -= info->maxpagesize;
+      else if (symval < pc)
+	pc += info->maxpagesize;
+    }
+
   const uint32_t addi_d = 0x02c00000;
   const uint32_t pcaddi = 0x18000000;
 
@@ -3889,7 +3906,6 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
       || sec->sec_flg0
       || (sec->flags & SEC_RELOC) == 0
       || sec->reloc_count == 0
-      || elf_seg_map (info->output_bfd) == NULL
       || (info->disable_target_specific_optimizations
 	  && info->relax_pass == 0)
       /* The exp_seg_relro_adjust is enum phase_enum (0x4),
@@ -4009,14 +4025,15 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
 	  break;
 	case R_LARCH_PCALA_HI20:
 	  if (0 == info->relax_pass && (i + 4) <= sec->reloc_count)
-	    loongarch_relax_pcala_addi (abfd, sec, rel, symval, info, again);
+	    loongarch_relax_pcala_addi (abfd, sec, sym_sec, rel, symval,
+					info, again);
 	  break;
 	case R_LARCH_GOT_PC_HI20:
 	  if (local_got && 0 == info->relax_pass
 	      && (i + 4) <= sec->reloc_count)
 	    {
 	      if (loongarch_relax_pcala_ld (abfd, sec, rel))
-		loongarch_relax_pcala_addi (abfd, sec, rel, symval,
+		loongarch_relax_pcala_addi (abfd, sec, sym_sec, rel, symval,
 					    info, again);
 	    }
 	  break;

ld/emultempl/loongarchelf.em

@@ -62,6 +62,24 @@ gld${EMULATION_NAME}_after_allocation (void)
 	}
     }
 
+  /* The program header size of executable file may increase.  */
+  if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour
+      && !bfd_link_relocatable (&link_info))
+    {
+      if (lang_phdr_list == NULL)
+        elf_seg_map (link_info.output_bfd) = NULL;
+      if (!_bfd_elf_map_sections_to_segments (link_info.output_bfd,
+					      &link_info,
+					      NULL))
+        einfo (_("%F%P: map sections to segments failed: %E\n"));
+    }
+
+  /* Adjust program header size and .eh_frame_hdr size before
+     lang_relax_sections. Without it, the vma of data segment may increase.  */
+  lang_do_assignments (lang_allocating_phase_enum);
+  lang_reset_memory_regions ();
+  lang_size_sections (NULL, true);
+
   enum phase_enum *phase = &(expld.dataseg.phase);
   bfd_elf${ELFSIZE}_loongarch_set_data_segment_info (&link_info, (int *) phase);
   /* gld${EMULATION_NAME}_map_segments (need_layout); */