JIT: Model GetFfr* with a special side effect and handle it in VN (#105973)

- Add `HW_Flag_SpecialSideEffect_Other` to GetFfr* HW intrinsics. These intrinsics essentially read memory from memory that we do not model, so we have to treat them conservatively.
- Add `GTF_CALL` and `GTF_GLOB_REF` to `GetFfr*` HW intrinsics. We have to give these a conservative set of a flag to disallow the rest of the JIT from potentially reordering them with `SetFfr`.
- Teach VN to give all HW intrinsics with any special side effect a unique VN

Fix #105944

In the test case head-merging reorders a `SetFfr` with a `GetFfr` since `GetFfr` is not given appropriately conservative side effect flags:
```
*************** Starting PHASE Head and tail merge
Both succs of BB01 start with the same tree
STMT00006 ( 0x02F[E-] ... 0x03C )
               [000039] --C-G------                         *  HWINTRINSIC void   ubyte SetFfr
               [000037] -----------                         \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000036] -----------                            \--*  CNS_INT   int    31
Checking if we can move it into the predecessor...
We can; moving statement

unlinking STMT00006 ( 0x02F[E-] ... 0x03C )
               [000039] --C-G------                         *  HWINTRINSIC void   ubyte SetFfr
               [000037] -----------                         \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000036] -----------                            \--*  CNS_INT   int    31
 from BB02

unlinking STMT00004 ( 0x03D[E-] ... 0x04A )
               [000031] --C-G------                         *  HWINTRINSIC void   ubyte SetFfr
               [000029] -----------                         \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000028] -----------                            \--*  CNS_INT   int    31
 from BB03
Did 1 head merges in BB01
...
------------ BB01 [0000] [000..02F) -> BB03(0.5),BB02(0.5) (cond), preds={} succs={BB02,BB03}

***** BB01 [0000]
STMT00000 ( 0x000[E-] ... 0x01B )
               [000003] --C-G------                         *  HWINTRINSIC void   ubyte SetFfr
               [000001] -----------                         \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000000] -----------                            \--*  CNS_INT   int    31

***** BB01 [0000]
STMT00001 ( 0x00C[E-] ... ??? )
               [000016] DA-XG------                         *  STORE_LCL_VAR simd16 V02 tmp1         
               [000013] ---XG------                         \--*  HWINTRINSIC simd16 ubyte LoadVectorFirstFaulting
               [000015] -----------                            +--*  HWINTRINSIC mask   ubyte ConvertVectorToMask
               [000014] -----------                            |  +--*  HWINTRINSIC mask   ubyte CreateTrueMaskAll
               [000008] -----------                            |  \--*  HWINTRINSIC simd16 ubyte ConvertMaskToVector
               [000007] -----------                            |     \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000006] -----------                            |        \--*  CNS_INT   int    31
               [000012] -----------                            \--*  ADD       long  
               [000009] -----------                               +--*  LCL_VAR   long   V00 arg0         
               [000011] -----------                               \--*  CAST      long <- int
               [000010] -----------                                  \--*  CNS_INT   int    1

***** BB01 [0000]
STMT00002 ( ??? ... ??? )
               [000018] -----------                         *  NOP       void  

***** BB01 [0000]
STMT00006 ( 0x02F[E-] ... 0x03C )
               [000039] --C-G------                         *  HWINTRINSIC void   ubyte SetFfr                                ; head-merging moved this from the then/else blocks
               [000037] -----------                         \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000036] -----------                            \--*  CNS_INT   int    31

***** BB01 [0000]
STMT00003 ( 0x01C[E-] ... 0x02D )
               [000027] -----------                         *  JTRUE     void  
               [000026] -----------                         \--*  EQ        int   
               [000024] -----------                            +--*  HWINTRINSIC int    ubyte op_Equality
               [000020] -----------                            |  +--*  HWINTRINSIC simd16 ubyte ConvertMaskToVector
               [000019] -----------                            |  |  \--*  HWINTRINSIC mask   ubyte GetFfrByte
               [000023] -----------                            |  \--*  HWINTRINSIC simd16 ubyte ConvertMaskToVector
               [000022] -----------                            |     \--*  HWINTRINSIC mask   ubyte CreateTrueMaskByte
               [000021] -----------                            |        \--*  CNS_INT   int    31
               [000025] -----------                            \--*  CNS_INT   int    0
```

Author: jakobbotsch

src/coreclr/jit/fgdiagnostic.cpp

@@ -3436,6 +3436,14 @@ void Compiler::fgDebugCheckFlags(GenTree* tree, BasicBlock* block)
                     case NI_Sve_PrefetchInt16:
                     case NI_Sve_PrefetchInt32:
                     case NI_Sve_PrefetchInt64:
+                    case NI_Sve_GetFfrByte:
+                    case NI_Sve_GetFfrInt16:
+                    case NI_Sve_GetFfrInt32:
+                    case NI_Sve_GetFfrInt64:
+                    case NI_Sve_GetFfrSByte:
+                    case NI_Sve_GetFfrUInt16:
+                    case NI_Sve_GetFfrUInt32:
+                    case NI_Sve_GetFfrUInt64:
                     case NI_Sve_SetFfr:
                     {
                         assert(tree->OperRequiresCallFlag(this));

src/coreclr/jit/gentree.cpp

@@ -27268,6 +27268,14 @@ bool GenTreeHWIntrinsic::OperRequiresCallFlag() const
             case NI_Sve_GatherPrefetch32Bit:
             case NI_Sve_GatherPrefetch64Bit:
             case NI_Sve_GatherPrefetch8Bit:
+            case NI_Sve_GetFfrByte:
+            case NI_Sve_GetFfrInt16:
+            case NI_Sve_GetFfrInt32:
+            case NI_Sve_GetFfrInt64:
+            case NI_Sve_GetFfrSByte:
+            case NI_Sve_GetFfrUInt16:
+            case NI_Sve_GetFfrUInt32:
+            case NI_Sve_GetFfrUInt64:
             case NI_Sve_SetFfr:
             {
                 return true;
@@ -27459,6 +27467,14 @@ void GenTreeHWIntrinsic::Initialize(NamedIntrinsic intrinsicId)
             case NI_Sve_PrefetchInt16:
             case NI_Sve_PrefetchInt32:
             case NI_Sve_PrefetchInt64:
+            case NI_Sve_GetFfrByte:
+            case NI_Sve_GetFfrInt16:
+            case NI_Sve_GetFfrInt32:
+            case NI_Sve_GetFfrInt64:
+            case NI_Sve_GetFfrSByte:
+            case NI_Sve_GetFfrUInt16:
+            case NI_Sve_GetFfrUInt32:
+            case NI_Sve_GetFfrUInt64:
             case NI_Sve_SetFfr:
             {
                 // Mark as a call and global reference, much as is done for GT_KEEPALIVE