[PATCH][AArch64][PR20319] Prevent undefined FMOV instructions.

[Egeyar Bagcioglu]

Hello,

The attached patch is essentially the patch Nick proposed two years ago 
to fix pr 20319: https://sourceware.org/bugzilla/show_bug.cgi?id=20319

It introduces QL_INT2FP_FMOV and QL_FP2INT_FMOV to be used with fmov 
rather than QL_INT2FP and QL_FP2INT so that the instructions of the form

fmov    x0, s0
fmov    s0, x0
fmov    w0, d0
fmov    d0, w0

are not accepted by the assembler.

The differences with the originally proposed patch:
I picked Nick's patch up, re-based it, completed the missing parts of 
"verify_fmov" function according to the now-available ARMv8.2 
documentation. I've also added the test cases that this function was 
checking. As a result, I realized that most of the test-cases already 
pass before the patch. Therefore, I trimmed that patch accordingly, down 
to the attached patch. It now makes only the necessary changes in the 
code; however, preserves the newly-added already-passing test cases.


 Â Â Â  [AArch64][PR20319] Prevent undefined FMOV instructions.

 Â Â Â  Detect illegal FMOV instructions that changes the size from 32 bits 
to 64
 Â Â Â  bits and vice versa. Add tests for these and other undefined FMOV
 Â Â Â  instructions.

 Â Â Â  gas/ChangeLog:

 Â Â Â Â Â Â Â  PR 20319
 Â Â Â Â Â Â Â  * testsuite/gas/aarch64/illegal-3.s: Test if unallocated FMOV 
encodings
 Â Â Â Â Â Â Â  are detected as undefined.
 Â Â Â Â Â Â Â  * testsuite/gas/aarch64/illegal-3.d: Likewise.
 Â Â Â Â Â Â Â  * testsuite/gas/aarch64/illegal.s: Test if FMOV instructions 
that are
 Â Â Â Â Â Â Â  changing the size from 32 bits to 64 bits and vice versa 
trigger an
 Â Â Â Â Â Â Â  error.
 Â Â Â Â Â Â Â  * testsuite/gas/aarch64/illegal.l: Likewise.

 Â Â Â  opcodes/ChangeLog:

 Â Â Â Â Â Â Â  PR 20319
 Â Â Â Â Â Â Â  * aarch64-tbl.h: Introduce QL_INT2FP_FMOV and QL_FP2INT_FMOV.
 Â Â Â Â Â Â Â  (aarch64_opcode_table) : Use QL_INT2FP_FMOV and QL_FP2INT_FMOV.


The patch is tested on aarch64-unknown-linux-gnu and introduced no 
regressions.

Please take a look and apply if legitimate.

Regards,
Egeyar
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