gas: fix bumping to architectures >v9 in sparc64-* targets.

gas: fix bumping to architectures >v9 in sparc64-* targets.

This patch fixes two related problems:

- By default gas is supposed to bump the current architecture
  (starting with v6) as it finds "higher" instructions as the
  assembling progresses.  There are four possible cases depending on
  the usage of the -A and -bump options:

  (a) No -A and -bump are specified.  In this case max_architecture
      must be the highest architecture not conflicting with the
      default architecture.  The default opcode architecture is
      indirectly set in configure.tgt and is "v9" in sparc64 systems
      (from "v9-64").  Thus the maximum architecture in sparc64
      systems must be "v9b".  No warnings are echoed when the assembly
      of an instruction bumps the current architecture.

  (b) Only -bump is specified.  This is like (a) but warnings are
      always issued when the assembly of an instruction bumps the
      current architecture.

  (c) Only -A is specified.  In this case bumping to a new
      architecture is an error.

  (d) Both -A and -bump are specified.  In this case max_architecture
      must be the highest architecture not conflicting with the
      default architecture, but warnings are only to be issued when
      bumping to an architecture higher than the architecture selected
      in the -A option.

  `max_architecture' is a global variable defined in tc-sparc.c which
  is initialized to the opcode architecture corresponding to the
  default architecture ("sparclite" for sparc-* targets and "v9" for
  sparc64-* targets).  Then in `md_begin' it is set to the highest
  non-conflicting architecture, but only when both -A and -bump are
  specified.

  Thus (a) does not work:

    $ echo "fzero %f0" | as
    {standard input}: Assembler messages:
    {standard input}:1: Error: Architecture mismatch on "fzero".
    {standard input}:1:  (Requires v9a|v9b; requested architecture is v9.)

  Neither (b):

    $ echo "fzero %f0" | as -bump
    {standard input}: Assembler messages:
    {standard input}:1: Error: Architecture mismatch on "fzero".
    {standard input}:1:  (Requires v9a|v9b; requested architecture is v9.)

  Only (d) does:

    $ echo "fzero %f0" | as -Av9 -bump
    {standard input}: Assembler messages:
    {standard input}:1: Warning: architecture bumped from "v6" to "v9a" on "fzero"

  This patch fixes that function to "upgrade" `max_architecture' also
  in the (a) and (b) cases.

  Note that this problem becomes apparent only in sparc64-* targets
  because in sparc-* targets the default architecture is the "higher"
  among the 32bit architectures ("sparclite").

- Gas maintains a set of hardware capabilities associated with each
  gas architecture, in `sparc_arch_table'.  On the other hand
  libopcodes maintains a set of hardware capabilities needed by each
  individual sparc instruction.

  When an instruction is assembled in `sparc_ip' gas checks for the
  presence of the hardware capabilities required by the instruction,
  emitting an error if some capability is missing.

  However, this mechanism does not work properly if the current
  architecture is bumped due to an instruction requiring new hw
  capabilities not present on either the default architecture or an
  architecture specified with -A:

  $ echo "fzero %f0" | as -bump
  {standard input}: Assembler messages:
  {standard input}:1: Warning: architecture bumped from "v6" to "v9a" on "fzero"
  {standard input}:1: Error: Hardware capability "vis" not enabled for "fzero".

  This patch fixes this by adding the set of required hw caps of an
  instruction if it triggers an architecture bump.

The patch has been tested in sparc64-unknown-linux-gnu.

gas/ChangeLog:

2014-09-12  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* config/tc-sparc.c (sparc_ip): Update the set of allowed hwcaps
	when bumping the current architecture.
	(md_begin): Adjust the highetst architecture level also when a
	specific architecture is not requested.