[AArch64] Add Missing Custom Target Operands

[lenary]

Summary

I noticed, when examining the generated Asm Matcher table, that some of
these custom immediate operands are missing, and so we are not parsing
some hint aliases into the correct MCInst.

Where this becomes apparent is when you parse e.g. hint #7 into an
MCInst - without these cases, it becomes the MCInst (HINT 17), which
will always be printed as hint #17. With these cases, it becomes the
MCInst XPACLRI, which will be printed as xpaclri with pauth, or
hint #17 without, matching how xpaclri is parsed.

We only handle some specific hint aliases in this manner, usually where
these hints have specific effects that need to be modelled for accurate
code-generation. Otherwise, we just use the normal InstAlias system
to have the aliases parsed into a (HINT N) MCInst.

[lenary]

To clarify the changes to the tests: they check that we can parse both hint #N and the mnemonic, and when printed they both print out exactly the same way, based on features (the mnemonic if you have pauth, or as hint #n otherwise).

[lenary]

This change should probably be marked [NFC] - because the disassembly output won't change in either case, and nor will the result of assembling into an object - the only difference in behaviour is if you parse assembly and then immediately print it again (like these tests do).

[tmatheson]

LGTM

llvm/test/MC/AArch64/armv8.3a-signed-pointer.s

176

These could do with being reordered numerically

[lenary]

llvm/test/MC/AArch64/armv8.3a-signed-pointer.s

176

They could, I might do that in a separate NFC change so the history is clearer.

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

case MCK_MPR:
     // If the Kind is a token for the MPR register class which has the "za"
     // register (SME accumulator array), check if the asm is a literal "za"
     // token. This is for the "smstart za" alias that defines the register
     // as a literal token.
     if (Op.isTokenEqual("za"))
       return Match_Success;
     return Match_InvalidOperand;
 
-    // If the kind is a token for a literal immediate, check if our asm
-    // operand matches. This is for InstAliases which have a fixed-value
-    // immediate in the syntax.
+    // If the kind is a token for a literal immediate, check if our asm operand
+    // matches. This is for InstAliases which have a fixed-value immediate in
+    // the asm string, such as hints which are parsed into a specific
+    // instruction definition.
 #define MATCH_HASH(N)                                                          \
   case MCK__HASH_##N:                                                          \
     return MatchesOpImmediate(N);
     MATCH_HASH(0)
     MATCH_HASH(1)
     MATCH_HASH(2)
     MATCH_HASH(3)
     MATCH_HASH(4)
     MATCH_HASH(6)
+    MATCH_HASH(7)
     MATCH_HASH(8)
+    MATCH_HASH(10)
     MATCH_HASH(12)
+    MATCH_HASH(14)
     MATCH_HASH(16)
     MATCH_HASH(24)
+    MATCH_HASH(25)
+    MATCH_HASH(26)
+    MATCH_HASH(27)
+    MATCH_HASH(28)
+    MATCH_HASH(29)
+    MATCH_HASH(30)
+    MATCH_HASH(31)
     MATCH_HASH(32)
     MATCH_HASH(40)
     MATCH_HASH(48)
     MATCH_HASH(64)
 #undef MATCH_HASH
 #define MATCH_HASH_MINUS(N)                                                    \
   case MCK__HASH__MINUS_##N:                                                   \
     return MatchesOpImmediate(-N);

llvm/test/MC/AArch64/armv8.3a-signed-pointer.s

 // CHECK-REQ-NEXT:  msr apdbkeyhi_el1, x0
 // CHECK-REQ: error: expected writable system register or pstate
 // CHECK-REQ-NEXT:  msr apgakeylo_el1, x0
 // CHECK-REQ: error: expected writable system register or pstate
 // CHECK-REQ-NEXT:  msr apgakeyhi_el1, x0
 
 // ALL-EMPTY:
 // ALL-EMPTY:
+  hint #25
   paciasp
 // CHECK-NEXT: paciasp        // encoding: [0x3f,0x23,0x03,0xd5]
+// CHECK-NEXT: paciasp        // encoding: [0x3f,0x23,0x03,0xd5]
+// NO83-NEXT: hint #25        // encoding: [0x3f,0x23,0x03,0xd5]
 // NO83-NEXT: hint #25        // encoding: [0x3f,0x23,0x03,0xd5]
+  hint #29
   autiasp
 // CHECK-NEXT: autiasp        // encoding: [0xbf,0x23,0x03,0xd5]
+// CHECK-NEXT: autiasp        // encoding: [0xbf,0x23,0x03,0xd5]
+// NO83-NEXT: hint #29        // encoding: [0xbf,0x23,0x03,0xd5]
 // NO83-NEXT: hint #29        // encoding: [0xbf,0x23,0x03,0xd5]
+  hint #24
   paciaz
 // CHECK-NEXT: paciaz         // encoding: [0x1f,0x23,0x03,0xd5]
+// CHECK-NEXT: paciaz         // encoding: [0x1f,0x23,0x03,0xd5]
+// NO83-NEXT: hint #24        // encoding: [0x1f,0x23,0x03,0xd5]
 // NO83-NEXT: hint #24        // encoding: [0x1f,0x23,0x03,0xd5]
+  hint #28
   autiaz
 // CHECK-NEXT: autiaz         // encoding: [0x9f,0x23,0x03,0xd5]
+// CHECK-NEXT: autiaz         // encoding: [0x9f,0x23,0x03,0xd5]
 // NO83-NEXT: hint #28        // encoding: [0x9f,0x23,0x03,0xd5]
+// NO83-NEXT: hint #28        // encoding: [0x9f,0x23,0x03,0xd5]
+  hint #8
   pacia1716
 // CHECK-NEXT: pacia1716      // encoding: [0x1f,0x21,0x03,0xd5]
+// CHECK-NEXT: pacia1716      // encoding: [0x1f,0x21,0x03,0xd5]
+// NO83-NEXT: hint #8         // encoding: [0x1f,0x21,0x03,0xd5]
 // NO83-NEXT: hint #8         // encoding: [0x1f,0x21,0x03,0xd5]
+  hint #12
   autia1716
 // CHECK-NEXT: autia1716      // encoding: [0x9f,0x21,0x03,0xd5]
+// CHECK-NEXT: autia1716      // encoding: [0x9f,0x21,0x03,0xd5]
+// NO83-NEXT: hint #12        // encoding: [0x9f,0x21,0x03,0xd5]
 // NO83-NEXT: hint #12        // encoding: [0x9f,0x21,0x03,0xd5]
+  hint #27
   pacibsp
 // CHECK-NEXT: pacibsp        // encoding: [0x7f,0x23,0x03,0xd5]
+// CHECK-NEXT: pacibsp        // encoding: [0x7f,0x23,0x03,0xd5]
 // NO83-NEXT: hint #27        // encoding: [0x7f,0x23,0x03,0xd5]
+// NO83-NEXT: hint #27        // encoding: [0x7f,0x23,0x03,0xd5]
+  hint #31
   autibsp
 // CHECK-NEXT: autibsp        // encoding: [0xff,0x23,0x03,0xd5]
+// CHECK-NEXT: autibsp        // encoding: [0xff,0x23,0x03,0xd5]
 // NO83-NEXT: hint #31        // encoding: [0xff,0x23,0x03,0xd5]
+// NO83-NEXT: hint #31        // encoding: [0xff,0x23,0x03,0xd5]
+  hint #26
   pacibz
 // CHECK-NEXT: pacibz         // encoding: [0x5f,0x23,0x03,0xd5]
+// CHECK-NEXT: pacibz         // encoding: [0x5f,0x23,0x03,0xd5]
 // NO83-NEXT: hint #26        // encoding: [0x5f,0x23,0x03,0xd5]
+// NO83-NEXT: hint #26        // encoding: [0x5f,0x23,0x03,0xd5]
+  hint #30
   autibz
 // CHECK-NEXT: autibz         // encoding: [0xdf,0x23,0x03,0xd5]
+// CHECK-NEXT: autibz         // encoding: [0xdf,0x23,0x03,0xd5]
+// NO83-NEXT: hint #30        // encoding: [0xdf,0x23,0x03,0xd5]
 // NO83-NEXT: hint #30        // encoding: [0xdf,0x23,0x03,0xd5]
+  hint #10
   pacib1716
 // CHECK-NEXT: pacib1716      // encoding: [0x5f,0x21,0x03,0xd5]
+// CHECK-NEXT: pacib1716      // encoding: [0x5f,0x21,0x03,0xd5]
+// NO83-NEXT: hint #10        // encoding: [0x5f,0x21,0x03,0xd5]
 // NO83-NEXT: hint #10        // encoding: [0x5f,0x21,0x03,0xd5]
+  hint #14
   autib1716
 // CHECK-NEXT: autib1716      // encoding: [0xdf,0x21,0x03,0xd5]
+// CHECK-NEXT: autib1716      // encoding: [0xdf,0x21,0x03,0xd5]
 // NO83-NEXT: hint #14        // encoding: [0xdf,0x21,0x03,0xd5]
+// NO83-NEXT: hint #14        // encoding: [0xdf,0x21,0x03,0xd5]
+  hint #7
   xpaclri
 // CHECK-NEXT: xpaclri        // encoding: [0xff,0x20,0x03,0xd5]
+// CHECK-NEXT: xpaclri        // encoding: [0xff,0x20,0x03,0xd5]
+// NO83-NEXT: hint #7         // encoding: [0xff,0x20,0x03,0xd5]
 // NO83-NEXT: hint #7         // encoding: [0xff,0x20,0x03,0xd5]
 
 // ALL-EMPTY:
   pacia x0, x1
 // CHECK-NEXT: pacia x0, x1     // encoding: [0x20,0x00,0xc1,0xda]
 // CHECK-REQ-NEXT:      ^
 // CHECK-REQ-NEXT: error: instruction requires: pa
 // CHECK-REQ-NEXT: pacia x0, x1
   autia x0, x1