RFR: 8257137: Revise smov and umov in aarch64 assembler.

[Hao Sun]

1. Both smov and umov lack of checking the register type validity.
   Register type must be 'B', 'H' or 'S' for smov [1].
   Register type can NOT be 'Q' for umov [2].
   Such checks are added.

2. smov and umov have different explanations on 'Q' field, i.e. bit 30
of the insturction, but current assembler implementation mixed it up.
   For umov, 'Q' field can only be set when register type 'D' is given
   [2]. However, this field of smov must be set for register type 'S'
   [1], that is, 'Q' field can be optional for register type 'B' or 'H'.

   Current implementation only took the umov scenario into account. As a
   result, runtime error ILL_ILLOPN would occur if 'smov(Register,
		   FloatRegister, S, index)' is used.

   We put them into two separate functions and make 'Q' field always set
   for smov. That means 'SMOVX' (64-bit register variant) is generated
   for all cases since it's compatible with our current usages of 'SMOVW'.
   Existing usages of smov have been double checked and this patch does
   not affect them.

3. Smoke tests are also added.

[1]. https://developer.arm.com/docs/ddi0602/f/simd-and-floating-point-instructions-alphabetic-order/smov-signed-move-vector-element-to-general-purpose-register
[2]. https://developer.arm.com/docs/ddi0602/f/simd-and-floating-point-instructions-alphabetic-order/umov-unsigned-move-vector-element-to-general-purpose-register


Note that Jtreg tier1 and jdk::tier3 have been tested and all tests passed without new failures.

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Commit messages:
 - 8257137: Revise smov and umov in aarch64 assembler.

Changes: https://git.openjdk.java.net/jdk/pull/1586/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1586&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257137
  Stats: 99 lines in 3 files changed: 20 ins; 0 del; 79 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1586.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1586/head:pull/1586

PR: https://git.openjdk.java.net/jdk/pull/1586