[PATCH 3/5] Use x constraints for operands to vfmaddss and vfmaddsd

[Ondřej Bílka]

On Mon, May 13, 2013 at 08:36:10AM -0700, Peter Collingbourne wrote:
> While these instructions accept memory operands, only one operand
> may be a memory operand.  Giving two operands xm constraints gives
> the compiler the option of using memory for both operands, which
> would result in invalid assembly code.  Using x for all operands is
> more appropriate, as most x86_64 calling conventions will pass the
> arguments in registers anyway.
> 
Not in all cases. When you must spill registers it is advantageous to
access loop invariants with memory operand. Give one multiplication
operand xm constraint and x to other.