IBM Z: Use the dedicated NOP instructions for "nop"

IBM Z: Use the dedicated NOP instructions for "nop"

We still use lr r0,r0 as a NOP instruction although we have some kind
of dedicated NOP instruction (nopr) which maps to a "branch never".

As a side-effect this fixes testcases scanning for NOPs
e.g. patchable_function_entry-*.

As another side-effect this makes it difficult to distingiush NOPs
generated for hotpatching from NOPs added when using -O0 to attach
location information to it.  Hence I had to make sure that the hotpatch
testcases get skipped when compiling without optimization.

gcc/ChangeLog:

2018-04-06  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/s390.c (s390_z10_optimize_cmp): Expand dedicated NOP
	instructions.
	* config/s390/s390.md (UNSPECV_NOP_LR_0, UNSPECV_NOP_LR_1): New
	constant definitions.
	("nop"): lr 0,0 -> nopr r0
	("nop_lr0", "nop_lr1"): New insn definitions.

gcc/testsuite/ChangeLog:

2018-04-06  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.target/s390/s390.exp: Remove -O0 from list of torture
	options.
	* gcc.target/s390/hotpatch-1.c: Skip when building without
	optimization.
	* gcc.target/s390/hotpatch-10.c: Likewise.
	* gcc.target/s390/hotpatch-11.c: Likewise.
	* gcc.target/s390/hotpatch-12.c: Likewise.
	* gcc.target/s390/hotpatch-13.c: Likewise.
	* gcc.target/s390/hotpatch-14.c: Likewise.
	* gcc.target/s390/hotpatch-15.c: Likewise.
	* gcc.target/s390/hotpatch-16.c: Likewise.
	* gcc.target/s390/hotpatch-17.c: Likewise.
	* gcc.target/s390/hotpatch-18.c: Likewise.
	* gcc.target/s390/hotpatch-19.c: Likewise.
	* gcc.target/s390/hotpatch-2.c: Likewise.
	* gcc.target/s390/hotpatch-3.c: Likewise.
	* gcc.target/s390/hotpatch-4.c: Likewise.
	* gcc.target/s390/hotpatch-5.c: Likewise.
	* gcc.target/s390/hotpatch-6.c: Likewise.
	* gcc.target/s390/hotpatch-7.c: Likewise.
	* gcc.target/s390/hotpatch-8.c: Likewise.
	* gcc.target/s390/hotpatch-9.c: Likewise.

From-SVN: r259164