[PATCH v1] aarch64: Fix assembler internal error for %dtprel relocations

[srinath.parvathaneni@arm.com]

From: Srinath Parvathaneni <srinath.parvathaneni@arm.com>

The current implementation creates the DTPREL fixup before reserving
the storage for the corresponding ".xword". GCC's "%dtprel" support
for TLS DWARF debug information exposed this during an AArch64 bootstrap,
where the libsanitizer/tsan DWARF layout places the DTPREL fixup at a
frag boundary. Reserving the storage before creating the fixup avoids
this corner case.

The simplest reproducer (tsan_interceptors_posix-bad.s from libsanitizer/tsan)
is 50k lines and I'm avoid attaching that hugh testfile to this patch.

gas/
	PR binutils/34357
	* config/tc-aarch64.c (s_aarch64_cons) : Fix the storage order for
	DTPREL.

Regression tested on aarch64-linux-gnu and found no regressions.

Ok for master?

Regards,
Srinath
---
 gas/config/tc-aarch64.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index 715df4de4bf..2da5139d8af 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -2244,15 +2244,13 @@ s_aarch64_cons (int nbytes)
 		  return;
 		}
 
-	      addressT where = frag_now_fix ();
-	      fix_new_exp (frag_now, where, nbytes, &exp, 0,
-			   BFD_RELOC_AARCH64_TLS_DTPREL);
-
 	      char *dest = frag_more (nbytes);
 	      memset (dest, 0, nbytes);
+
+	      fix_new_exp (frag_now, dest - frag_now->fr_literal, nbytes,
+			   &exp, 0, BFD_RELOC_AARCH64_TLS_DTPREL);
 	      continue;
 	    }
-
 	  else
 	    {
 	      as_bad (_("unknown relocation operator"));
-- 
2.43.0