[PATCH, rs6000] PR 62195, Fix wi constraint

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

(I'm not sure if an earlier patch got mailed out, I'm sorry if there are
duplicate postings).

I had a thinko in my patch on August 11th, in that I allowed the wi constraint
to be FLOAT_REGS on a non-VSX system, but I had a pattern in movdi that
generated a VSX instruction.  I have tightened wi, so that it applies only when
VSX is used.

In addition, I had used wi for lfiwax/lfiwzx and in the case issued an ISA 2.07
(power8) instruction.  I have changed these cases to use the wj constraint
(constraint for register class under ISA 2.07 for doing move direct of
DImode).  I decided that it wasn't worth adding a new constraint for these
cases, and if the user does -mcpu=power8 -mno-move-direct, it will still
generate the lfiwax/lfiwzx instructions which target the traditional floating
point registers.  I have done bootstraps with this compiler and it had no
regressions.  Is the patch ok to check in?

2014-08-21  Michael Meissner  <meissner@linux.vnet.ibm.com>

	PR target/62195
	* doc/md.texi (Machine Constraints): Update PowerPC wi constraint
	documentation to state it is only for VSX operations.

	* config/rs6000/rs6000.c (rs6000_init_hard_regno_mode_ok): Make wi
	constraint only active if VSX.

	* config/rs6000/rs6000.md (lfiwax): Use wj constraint instead of
	wi cosntraint for ISA 2.07 lxsiwax/lxsiwzx instructions.
	(lfiwzx): Likewise.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

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