ARM: add fstmx and fldmx instructions for assembly

These instructions are deprecated oddities, but we still need to be able to
disassemble (and reassemble) them if and when they're encountered.

Patch by Amaury de la Vieuville.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183011 91177308-0d34-0410-b5e6-96231b3b80d8

test/MC/Disassembler/ARM/fp-encoding.txt

@@ -221,6 +221,20 @@
 # CHECK: vldmdbeq r5!, {s21, s22, s23}
 # CHECK: vldmdbeq r7!, {d14, d15, d16, d17}
 
+0x0d 0x4b 0x96 0x0c
+0x0f 0x3b 0xb7 0x0c
+0x09 0x1b 0x38 0xed
+# CHECK: fldmiaxeq r6, {d4, d5, d6, d7, d8, d9}
+# CHECK: fldmiaxeq r7!, {d3, d4, d5, d6, d7, d8, d9}
+# CHECK: fldmdbx   r8!, {d1, d2, d3, d4}
+
+0x07 0x2b 0x83 0xec
+0x05 0x5b 0xa3 0x0c
+0x0f 0x3b 0x20 0x1d
+# CHECK: fstmiax   r3, {d2, d3, d4}
+# CHECK: fstmiaxeq r3!, {d5, d6}
+# CHECK: fstmdbxne r0!, {d3, d4, d5, d6, d7, d8, d9}
+
 0x04 0x7a 0xa6 0x0c
 0x0c 0xfb 0xa4 0x0c
 0x03 0xaa 0xf8 0x0c

test/MC/Disassembler/ARM/invalid-FSTMX-arm.txt

@@ -0,0 +1,8 @@
+# RUN: llvm-mc --disassemble %s -triple=armv7 2>&1 | FileCheck %s -check-prefix=CHECK-WARN
+# RUN: llvm-mc --disassemble %s -triple=armv7 2>&1 | FileCheck %s
+
+# offset=1
+# CHECK-WARN: potentially undefined
+# CHECK-WARN: 0x01 0xdb 0x84 0xec
+# CHECK: fstmiax r4, {d13}
+0x01 0xdb 0x84 0xec