Re: Fix offset for ia64 PCREL60B relocation on HP-UX

PR 25599
	* config/tc-ia64.c (emit_one_bundle): Expand comment for HP-UX
	adjustment.  Add assertion.
	* testsuite/gas/ia64/reloc-mlx.d: Pass when slot 2 specified
	for PCREL60B.

gas/ChangeLog

@@ -1,3 +1,11 @@
+2021-05-22  Alan Modra  <amodra@gmail.com>
+
+	PR 25599
+	* config/tc-ia64.c (emit_one_bundle): Expand comment for HP-UX
+	adjustment.  Add assertion.
+	* testsuite/gas/ia64/reloc-mlx.d: Pass when slot 2 specified
+	for PCREL60B.
+
 2021-05-20  Sergey Belyashov  <sergey.belyashov@gmail.com>
 
 	* config/tc-z80.c (emit_data_val): Warn on constant overflow.

gas/config/tc-ia64.c

@@ -6892,9 +6892,15 @@ emit_one_bundle (void)
 	  ifix = md.slot[curr].fixup + j;
 	  where = frag_now_fix () - 16 + i;
 #ifdef TE_HPUX
-	  /* Fix offset for PCREL60B relocation on HP-UX.  */
+	  /* Relocations for instructions specify the slot in the
+	     bottom two bits of r_offset.  The IA64 HP-UX linker
+	     expects PCREL60B relocations to specify slot 2 of an
+	     instruction.  gas generates PCREL60B against slot 1.  */
 	  if (ifix->code == BFD_RELOC_IA64_PCREL60B)
-	    ++where;
+	    {
+	      know (i == 1);
+	      ++where;
+	    }
 #endif
 
 	  fix = fix_new_exp (frag_now, where, 8,

gas/testsuite/gas/ia64/reloc-mlx.d

@@ -5,4 +5,4 @@
 
 RELOCATION RECORDS FOR \[\.text\]:
 OFFSET[[:space:]]+TYPE[[:space:]]+VALUE[[:space:]]*
-0+1[[:space:]]+PCREL60B[[:space:]]+bar
+0+[12][[:space:]]+PCREL60B[[:space:]]+bar