Update testsuite (for SIMD) (#1373)

Lots of changes necessary to make this work, as well as some bug fixes.

The main change is allowing `nan:canonical` and `nan:arithmetic` as a
possible value for each lane of a `v128`. This needs to propogate
through the parser, IR, the JSON format, and the spec interpreter.

This also changes the format of the spec JSON file, where a SIMD value
is now stored as a list of values instead of a single u128:

```
{"type": "v128", "lane_type": "i32", "value": ["0", "0", "0", "0"]}
```

Since the lane type can be `i8` and `i16`, these types can now be used
in more places (not just the decompiler). They'll be used for the GC
proposal too (for packed values), so I've updated them to use the binary
value specified for that proposal.

Here are the actual SIMD fixes:

* SIMD lanes are malformed if they don't match the binary format, but
  invalid if they are smaller than the lane width. For example,
  `i8x16.extract_lane_s` is malformed if the lane is >= 256, because the
  lane is stored as a byte. But it is invalid if the lane is >= 16.
* The `i8x16.narrow_i16x8_u`, `i16x8.narrow_i32x4_u` and
  `i64x2.load_32x2_u` instructions were not handling sign-extension
  propoerly.

TODO: This code is pretty clumsy now; it would be better to have a
universal `Value` and `ExpectedValue` that can be used everywhere, so
the logic doesn't need to be duplicated.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/type.h b/src/type.h
index 2a7597ae..fb51e013 100644
--- a/src/type.h
+++ b/src/type.h
@@ -36,6 +36,8 @@ class Type {
     F32 = -0x03,      // 0x7d
     F64 = -0x04,      // 0x7c
     V128 = -0x05,     // 0x7b
+    I8 = -0x06,       // 0x7a  : packed-type only, used in gc and as v128 lane
+    I16 = -0x07,      // 0x79  : packed-type only, used in gc and as v128 lane
     Funcref = -0x10,  // 0x70
     Anyref = -0x11,   // 0x6f
     Nullref = -0x12,  // 0x6e
@@ -48,9 +50,7 @@ class Type {
 
     Any = 0,          // Not actually specified, but useful for type-checking
     Hostref = 2,      // Not actually specified, but used in testing and type-checking
-    I8 = 3,    // Not actually specified, but used internally with load/store
     I8U = 4,   // Not actually specified, but used internally with load/store
-    I16 = 5,   // Not actually specified, but used internally with load/store
     I16U = 6,  // Not actually specified, but used internally with load/store
     I32U = 7,  // Not actually specified, but used internally with load/store
   };
@@ -78,6 +78,8 @@ class Type {
       case Type::F32:     return "f32";
       case Type::F64:     return "f64";
       case Type::V128:    return "v128";
+      case Type::I8:      return "i8";
+      case Type::I16:     return "i16";
       case Type::Funcref: return "funcref";
       case Type::Func:    return "func";
       case Type::Exnref:  return "exnref";