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[PATCH] bfd: xtensa: ignore overflow in hight part of const16 relocation


32-bit constants loaded by two const16 opcodes that involve relocation
(e.g. calculated as a sum of a symbol and a constant) may overflow,
resulting in linking error with the following message:

  dangerous relocation: const16: cannot encode: (_start+0x70000000)

They whould wrap around instead.

bfd/
2018-12-07  Max Filippov  <jcmvbkbc@gmail.com>

	* elf32-xtensa.c (elf_xtensa_do_reloc): Only use bits 16..31 of
	the relocated value for the high part const16 immediate.
---
 bfd/elf32-xtensa.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/bfd/elf32-xtensa.c b/bfd/elf32-xtensa.c
index cf085b7b0751..de960cd3b8fc 100644
--- a/bfd/elf32-xtensa.c
+++ b/bfd/elf32-xtensa.c
@@ -1957,8 +1957,9 @@ elf_xtensa_do_reloc (reloc_howto_type *howto,
 	}
       else if (opcode == get_const16_opcode ())
 	{
-	  /* ALT used for high 16 bits.  */
-	  newval = relocation >> 16;
+	  /* ALT used for high 16 bits.
+	     Ignore 32-bit overflow.  */
+	  newval = (relocation >> 16) & 0xffff;
 	  opnd = 1;
 	}
       else
-- 
2.11.0


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