Middle-end might come up with hard registers as operands for expanders which 
clobber respective hard regs.  This patch uses freshly created pseudos for 
respective expander operands and emits pseudo <-> hard move insn.

Ok for 4.9.2?

It's not yet for trunk because avr trunk backend is currently broken.

Johann

gcc/
	PR63633
	* config/avr/avr-protos.h (regmask): New inline function.
	(avr_fix_inputs, avr_emit3_fix_outputs): New protos.
	* config/avr/avr.c (avr_fix_operands, avr_move_fixed_operands)
	(avr_fix_inputs, avr_emit3_fix_outputs): New functions.
	* config/avr/avr-fixed.md (mulqq3_nomul, muluqq3_nomul)
	(mul<ALL2QA>3, mul<ALL4A>3, <usdiv><ALL1Q>3, <usdiv><ALL2QA>3)
	(<usdiv><ALL4A>3, round<ALL124QA>3): Fix input operands.
	* config/avr/avr-dimode.md (add<ALL8>3, sub<ALL8>3)
	(<ss_addsub><ALL8S>3, <us_addsub><ALL8U>3, cbranch<ALL8>4)
	(<di_shifts><ALL8>3, <any_extend>mulsidi3): Fix input operands.
	* config/avr/avr.md (mulqi3_call, mulhi3_call, mulsi3, mulpsi3)
	(mulu<QIHI>si3, muls<QIHI>si3, mulohisi3, <any_extend>mulhisi3)
	(usmulhisi3, <any_extend>mulhi3_highpart, mulsqipsi3)
	(fmul, fmuls, fmulsu): Fix operands.  Turn insn into expander as
	needed.

gcc/testsuite/
	PR63633
	* gcc.target/avr/torture/pr63633-ice-mult.c: New test.