[PATCH 1/3] RISC-V: Add ZCMT table jump relaxation

[Bigmagic]

--- a/bfd/elfnn-riscv.c+++ b/bfd/elfnn-riscv.c
@@ -1893,11 +1893,18 @@ riscv_elf_late_size_sections (bfd *output_bfd, struct bfd_link_info *info)
       if (s->output_section == NULL)
        return false;


-      if (!_bfd_generic_link_add_one_symbol (
-           info, output_bfd, RISCV_TABLE_JUMP_BASE_SYMBOL, BSF_GLOBAL, s,
-           (bfd_vma) 0, (const char *) NULL, true,
-           get_elf_backend_data (output_bfd)->collect, &bh))
-       return false;
+      /* Only create the symbol if it doesn't already exist (e.g. from
+        a linker script PROVIDE).  */
+      bh = bfd_link_hash_lookup (info->hash, RISCV_TABLE_JUMP_BASE_SYMBOL,
+                                false, false, false);
+      if (bh == NULL)
+       {
+         if (!_bfd_generic_link_add_one_symbol (
+               info, output_bfd, RISCV_TABLE_JUMP_BASE_SYMBOL, BSF_GLOBAL, s,
+               (bfd_vma) 0, (const char *) NULL, true,
+               get_elf_backend_data (output_bfd)->collect, &bh))
+           return false;
+       }
     }


This patch fixes an issue where the RISC-V linker would unconditionally create the __riscv_table_jump_base symbol during ZCMT relaxation, even if it was already defined in a linker script via PROVIDE.

Currently, riscv_elf_late_size_sections() always calls _bfd_generic_link_add_one_symbol() to create the __riscv_table_jump_base symbol. This overwrites any definition provided by a linker script, making it impossible for users to override this symbol with a custom address through PROVIDE.


The patch first looks up the symbol in the linker hash table using bfd_link_hash_lookup(). Only if the symbol is not found does it proceed to create it. This allows linker scripts to pre-define the symbol via PROVIDE, which will then be used by ZCMT relaxation.
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