[PATCH] MIPS/GAS: Complete constant JMP relocs straight away

["Maciej W. Rozycki" <macro at codesourcery dot com>]

Hi,

 In the unlikely case a constant is used as the argument of a jump 
instruction, e.g.

	j	0xbfc00000

the associated JMP relocation is resolved straight away in append_insn and 
the instruction's immediate field initialised while the instruction is 
being assembled, just as in the case of several other relocs.  However 
unlike with most other relocs the JMP relocation is not marked as complete 
and a fixup is created.

 That fixup then has another chance for resolution at the final fix-up 
phase, in md_apply_fix.  Nothing is done there for JMP relocations though 
and owing to the lack of an associated symbol (as the expression is 
constant and therefore refers to none) the relocation decays to nil (and 
the instruction's argument has already been initialised).  There is no 
other processing between append_insn and md_apply_fix applied to such 
relocations either.

 I suspect there might have been an additional check intended, to see if 
the final destination of any jump instruction concerned matches the 
segment the instruction will appear in.  However I am not really sure if 
that makes sense at all as the ultimate segment will only be known to the 
linker anyway.  And the current arrangement makes it impossible to detect 
a case where the expression used as the argument to a jump instruction is 
only resolved in the fix-up phase, which we do not currently handle at 
all -- and should warn about.

 I have therefore decided to remove that special arrangement and let 
append_insn complete constant JMP relocations.  No regressions with this 
change in MIPS testing.  OK to apply?

2012-09-21  Maciej W. Rozycki  <macro@codesourcery.com>

	gas/
	* config/tc-mips.c (append_insn) <BFD_RELOC_MIPS_JMP>: Don't
	mark as incomplete for constant expressions.
	<BFD_RELOC_MIPS16_JMP>: Likewise.

  Maciej

binutils-gas-mips-jmp-reloc-complete.diff
Index: binutils-fsf-trunk-quilt/gas/config/tc-mips.c
===================================================================
--- binutils-fsf-trunk-quilt.orig/gas/config/tc-mips.c	2012-09-17 22:17:26.250930536 +0100
+++ binutils-fsf-trunk-quilt/gas/config/tc-mips.c	2012-09-17 22:18:33.511052691 +0100
@@ -4062,7 +4062,6 @@ append_insn (struct mips_cl_insn *ip, ex
 		      (unsigned long) address_expr->X_add_number);
 	    ip->insn_opcode |= ((address_expr->X_add_number >> shift)
 				& 0x3ffffff);
-	    ip->complete_p = 0;
 	  }
 	  break;
 
@@ -4074,7 +4073,6 @@ append_insn (struct mips_cl_insn *ip, ex
 	    (((address_expr->X_add_number & 0x7c0000) << 3)
 	       | ((address_expr->X_add_number & 0xf800000) >> 7)
 	       | ((address_expr->X_add_number & 0x3fffc) >> 2));
-	  ip->complete_p = 0;
 	  break;
 
 	case BFD_RELOC_16_PCREL_S2: