cranelift: Remove of/nof overflow flags from icmp (#4879)

* cranelift: Remove of/nof overflow flags from icmp

Neither Wasmtime nor cg-clif use these flags under any circumstances.
From discussion on #3060 I see it's long been unclear what purpose these
flags served.

Fixes #3060, fixes #4406, and fixes #4875... by deleting all the code
that could have been buggy.

This changes the cranelift-fuzzgen input format by removing some IntCC
options, so I've gone ahead and enabled I128 icmp tests at the same
time. Since only the of/nof cases were failing before, I expect these to
work.

* Restore trapif tests

It's still useful to validate that iadd_ifcout's iflags result can be
forwarded correctly to trapif, and for that purpose it doesn't really
matter what condition code is checked.

cranelift/interpreter/src/interpreter.rs

@@ -740,7 +740,7 @@ mod tests {
     #[test]
     fn state_flags() {
         let mut state = InterpreterState::default();
-        let flag = IntCC::Overflow;
+        let flag = IntCC::UnsignedLessThan;
         assert!(!state.has_iflag(flag));
         state.set_iflag(flag);
         assert!(state.has_iflag(flag));

cranelift/interpreter/src/step.rs

@@ -1293,8 +1293,6 @@ where
                     &left.clone().convert(ValueConversionKind::ToUnsigned)?,
                     &right.clone().convert(ValueConversionKind::ToUnsigned)?,
                 )?,
-                IntCC::Overflow => Value::overflow(left, right)?,
-                IntCC::NotOverflow => !Value::overflow(left, right)?,
             },
             bool_ty,
         )?)

cranelift/interpreter/src/value.rs

@@ -46,7 +46,6 @@ pub trait Value: Clone + From<DataValue> {
         Ok(other.eq(self)? || other.gt(self)?)
     }
     fn uno(&self, other: &Self) -> ValueResult<bool>;
-    fn overflow(&self, other: &Self) -> ValueResult<bool>;
 
     // Arithmetic.
     fn add(self, other: Self) -> ValueResult<Self>;
@@ -478,17 +477,6 @@ impl Value for DataValue {
         Ok(self.is_nan()? || other.is_nan()?)
     }
 
-    fn overflow(&self, other: &Self) -> ValueResult<bool> {
-        Ok(match (self, other) {
-            (DataValue::I8(a), DataValue::I8(b)) => a.checked_sub(*b).is_none(),
-            (DataValue::I16(a), DataValue::I16(b)) => a.checked_sub(*b).is_none(),
-            (DataValue::I32(a), DataValue::I32(b)) => a.checked_sub(*b).is_none(),
-            (DataValue::I64(a), DataValue::I64(b)) => a.checked_sub(*b).is_none(),
-            (DataValue::I128(a), DataValue::I128(b)) => a.checked_sub(*b).is_none(),
-            _ => unimplemented!(),
-        })
-    }
-
     fn add(self, other: Self) -> ValueResult<Self> {
         if self.is_float() {
             binary_match!(+(self, other); [F32, F64])