[binutils-gdb/binutils-2_43-branch] LoongArch: Fix broken DESC => IE transition for 2.43 branch

[liu & zhensong]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a8563dba75c92e04dbc63bdbee03b0ebc8889fa8

commit a8563dba75c92e04dbc63bdbee03b0ebc8889fa8
Author: Xi Ruoyao <xry111@xry111.site>
Date:   Fri Dec 27 16:26:28 2024 +0800

    LoongArch: Fix broken DESC => IE transition for 2.43 branch
    
    If code compiled with -fPIC -mtls-dialect=desc is linked into a PDE or
    PIE, and the code refers to external DSO symbols, we can produce broken
    link unit as check_relocs expects DESC => IE transition to happen and
    emits a TLS IE entry in the GOT, but a too early "continue" in
    relax_section actually jumps over the DESC => IE transition so the code
    sequence is unchanged and still expecting a TLS descriptor (instead of
    an IE entry) in the GOT.
    
    The bug is already fixed in master branch by commit 5c3d09c1855b
    ("LoongArch: Optimize the relaxation process") so this fix is only
    needed for the 2.43 branch.
    
    Reported-by: Icenowy Zheng <uwu@icenowy.me>
    Closes: https://gcc.gnu.org/PR118114
    Tested-by: Icenowy Zheng <uwu@icenowy.me>
    Signed-off-by: Xi Ruoyao <xry111@xry111.site>

Diff:
---
 bfd/elfnn-loongarch.c | 45 +++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 312707bb00b..7760b5279f8 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -5325,8 +5325,8 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
   for (unsigned int i = 0; i < sec->reloc_count; i++)
     {
       char symtype;
-      bfd_vma symval;
-      asection *sym_sec;
+      bfd_vma symval = 0; /* "= 0" for https://gcc.gnu.org/PR118216 */
+      asection *sym_sec = NULL;
       bool local_got = false;
       Elf_Internal_Rela *rel = relocs + i;
       struct elf_link_hash_entry *h = NULL;
@@ -5418,14 +5418,33 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
 	      symval = h->root.u.def.value;
 	      sym_sec = h->root.u.def.section;
 	    }
-	  else
-	    continue;
 
 	  if (h && LARCH_REF_LOCAL (info, h))
 	    local_got = true;
 	  symtype = h->type;
 	}
 
+      /* If the conditions for tls type transition are met, type
+	 transition is performed instead of relax.
+	 During the transition from DESC->IE/LE, there are 2 situations
+	 depending on the different configurations of the relax/norelax
+	 option.
+	 If the -relax option is used, the extra nops will be removed,
+	 and this transition is performed in pass 0.
+	 If the --no-relax option is used, nop will be retained, and
+	 this transition is performed in pass 1.  */
+      if (IS_LOONGARCH_TLS_TRANS_RELOC (r_type)
+	  && (i + 1 != sec->reloc_count)
+	  && ELFNN_R_TYPE (rel[1].r_info) == R_LARCH_RELAX
+	  && loongarch_can_trans_tls (abfd, info, h, r_symndx, r_type))
+	{
+	  loongarch_tls_perform_trans (abfd, sec, rel, h, info);
+	  r_type = ELFNN_R_TYPE (rel->r_info);
+	}
+
+      if (!sym_sec)
+	continue;
+
       if (sym_sec->sec_info_type == SEC_INFO_TYPE_MERGE
 	   && (sym_sec->flags & SEC_MERGE))
 	{
@@ -5453,24 +5472,6 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
 
       symval += sec_addr (sym_sec);
 
-      /* If the conditions for tls type transition are met, type
-	 transition is performed instead of relax.
-	 During the transition from DESC->IE/LE, there are 2 situations
-	 depending on the different configurations of the relax/norelax
-	 option.
-	 If the -relax option is used, the extra nops will be removed,
-	 and this transition is performed in pass 0.
-	 If the --no-relax option is used, nop will be retained, and
-	 this transition is performed in pass 1.  */
-      if (IS_LOONGARCH_TLS_TRANS_RELOC (r_type)
-	  && (i + 1 != sec->reloc_count)
-	  && ELFNN_R_TYPE (rel[1].r_info) == R_LARCH_RELAX
-	  && loongarch_can_trans_tls (abfd, info, h, r_symndx, r_type))
-	{
-	  loongarch_tls_perform_trans (abfd, sec, rel, h, info);
-	  r_type = ELFNN_R_TYPE (rel->r_info);
-	}
-
       switch (r_type)
 	{
 	case R_LARCH_ALIGN: