feat(gnovm): implement overflow checking at VM level (#3250)

I propose that we implement overflow checking directly in gnovm opcodes,
and that gnovm always enforces overflow checking. Overflow checking
becomes a capacity of the Gno language and the Gno virtual machine.

It's important for a smart contract platform to offer by default, and
without user or developer effort, the strongest guarantees on numerical
operations.

In that topic, Gno would be superior to the standard Go runtime which,
like C and most other languages, don't address this internally beside
constants (to preserve the best possible native performances), and rely
on external user code.

It would also simplify the user code and avoid to use specific
libraries.
For example, in `gnovm/stdlibs/std/coins.go`, for the `Coin.Add` method:

Before:

```go
import "math/overflow"

func (c Coin) Add(other Coin) Coin {
    mustMatchDenominations(c.Denom, other.Denom)
 
    sum, ok := overflow.Add64(c.Amount, other.Amount)
    if !ok {
        panic("coin add overflow/underflow: " +
              strconv.Itoa(int(c.Amount)) + " +/- " +
              strconv.Itoa(int(other.Amount)))
    }

    c.Amount = sum
    return c
}
```

After:

```go
func (c Coin) Add(other Coin) Coin {
    mustMatchDenominations(c.Denom, other.Denom)
    c.Amount += other.Amount
    return c
} 
```
with the same behaviour for overflow checking. Note also that the new
version, is not only simpler, but also faster, because overflow checking
is performed natively, and not interpreted.

Integer overflow handling is only implemented for signed integers.
Unsigned integers, on purpose, just wrap around when reaching their
maximum or minimum values. This is intended to support all crypto, hash
and bitwise operations which may rely on that wrap around property.
Division by zero is still handled both in signed and unsigned integers.

Note: from now, on security level, the use of unsigned integers for
standard numeric operations should be probably considered suspicious.

## Benchmark

To measure the impact of overflow, I execute the following benchmarks:

First a micro benchmark comparing an addition of 2 ints, with and
without overflow:


```go
//go:noinline
func AddNoOverflow(x, y int) int { return x + y }

func BenchmarkAddNoOverflow(b *testing.B) {
    x, y := 4, 3
    c := 0
    for range b.N {
        c = AddNoOverflow(x, y)
    }
    if c != 7 {
        b.Error("invalid result")
    }
}

func BenchmarkAddOverflow(b *testing.B) {
    x, y := 4, 3
    c := 0
    for range b.N {
        c = overflow.Addp(x, y)
    }
    if c != 7 {
        b.Error("invalid result")
    }
}
```

The implementation of overflow checking is taken from
http://github.com/gnolang/overflow, already used in tm2.

It gives the following results:

```console
$ go test -v- run=^# -benchmem -bench=Overflow
goos: darwin
goarch: arm64
pkg: github.com/gnolang/gno/gnovm/pkg/gnolang
cpu: Apple M1
BenchmarkAddNoOverflow
BenchmarkAddNoOverflow-8    1000000000           0.9392 ns/op          0 B/op          0 allocs/op
BenchmarkAddOverflow
BenchmarkAddOverflow-8      568881582            2.101 ns/op           0 B/op          0 allocs/op
PASS
ok      github.com/gnolang/gno/gnovm/pkg/gnolang    2.640s
```

Checking overflow doubles the execution time of an addition from 1 ns/op
to 2 ns/op.

But at 2 ns, the total time is still an order of magnitude lower than
the cost of running the VM.
The impact of overflow check doesn't even appear when benchmarking at VM
level with the following:

```go
func BenchmarkOpAdd(b *testing.B) {
    m := NewMachine("bench", nil)
    x := TypedValue{T: IntType}
    x.SetInt(4)
    y := TypedValue{T: IntType}
    y.SetInt(3)

    b.ResetTimer()

    for range b.N {
        m.PushOp(OpHalt)
        m.PushExpr(&BinaryExpr{})
        m.PushValue(x)
        m.PushValue(y)
        m.PushOp(OpAdd)
        m.Run()
    }
}
```

Which gives something like:

```console
$ go test -v -benchmem -bench=OpAdd -run=^#
goos: darwin
goarch: arm64
pkg: github.com/gnolang/gno/gnovm/pkg/gnolang
cpu: Apple M1
BenchmarkOpAdd
BenchmarkOpAdd-8    16069832            74.41 ns/op      163 B/op          1 allocs/op
PASS
ok      github.com/gnolang/gno/gnovm/pkg/gnolang    1.526
```

Where the execution time varie from 60 ns/op to 100 ns/op for both
versions of addition, with or without overflow.

## Related PRs and issues

- PRs: 
    - #3197 
    - #3192
    - #3117
    - #2983
    - #2905 
    - #2698
- Issues: 
    - #2873
    - #1844
    - #1729


<!-- please provide a detailed description of the changes made in this
pull request. -->

<details><summary>Contributors' checklist...</summary>

- [ ] Added new tests, or not needed, or not feasible
- [ ] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [ ] Updated the official documentation or not needed
- [ ] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [ ] Added references to related issues and PRs
- [ ] Provided any useful hints for running manual tests
</details>

examples/gno.land/p/demo/grc/grc20/token.gno

@@ -1,7 +1,6 @@
 package grc20
 
 import (
-	"math/overflow"
 	"std"
 	"strconv"
 
@@ -170,17 +169,24 @@ func (led *PrivateLedger) Approve(owner, spender std.Address, amount uint64) err
 }
 
 // Mint increases the total supply of the token and adds the specified amount to the specified address.
-func (led *PrivateLedger) Mint(address std.Address, amount uint64) error {
+func (led *PrivateLedger) Mint(address std.Address, amount uint64) (err error) {
 	if !address.IsValid() {
 		return ErrInvalidAddress
 	}
 
-	// XXX: math/overflow is not supporting uint64.
-	// This checks prevents overflow but makes the totalSupply limited to a uint63.
-	sum, ok := overflow.Add64(int64(led.totalSupply), int64(amount))
-	if !ok {
-		return ErrOverflow
-	}
+	defer func() {
+		if r := recover(); r != nil {
+			if r != "addition overflow" {
+				panic(r)
+			}
+			err = ErrOverflow
+		}
+	}()
+
+	// Convert amount and totalSupply to signed integers to enable
+	// overflow checking (not occuring on unsigned) when computing the sum.
+	// The maximum value for totalSupply is therefore 1<<63.
+	sum := int64(led.totalSupply) + int64(amount)
 
 	led.totalSupply = uint64(sum)
 	currentBalance := led.balanceOf(address)

gnovm/pkg/gnolang/op_bench_test.go

@@ -0,0 +1,70 @@
+package gnolang
+
+import (
+	"testing"
+
+	"github.com/gnolang/gno/tm2/pkg/overflow"
+)
+
+func BenchmarkOpAdd(b *testing.B) {
+	m := NewMachine("bench", nil)
+	x := TypedValue{T: IntType}
+	x.SetInt(4)
+	y := TypedValue{T: IntType}
+	y.SetInt(3)
+
+	b.ResetTimer()
+
+	for range b.N {
+		m.PushOp(OpHalt)
+		m.PushExpr(&BinaryExpr{})
+		m.PushValue(x)
+		m.PushValue(y)
+		m.PushOp(OpAdd)
+		m.Run()
+	}
+}
+
+//go:noinline
+func AddNoOverflow(x, y int) int { return x + y }
+
+func BenchmarkAddNoOverflow(b *testing.B) {
+	x, y := 4, 3
+	c := 0
+	for range b.N {
+		c = AddNoOverflow(x, y)
+	}
+	if c != 7 {
+		b.Error("invalid result")
+	}
+}
+
+func BenchmarkAddOverflow(b *testing.B) {
+	x, y := 4, 3
+	c := 0
+	for range b.N {
+		c = overflow.Addp(x, y)
+	}
+	if c != 7 {
+		b.Error("invalid result")
+	}
+}
+
+func TestOpAdd1(t *testing.T) {
+	m := NewMachine("test", nil)
+	a := TypedValue{T: IntType}
+	a.SetInt(4)
+	b := TypedValue{T: IntType}
+	b.SetInt(3)
+	t.Log("a:", a, "b:", b)
+
+	start := m.NumValues
+	m.PushOp(OpHalt)
+	m.PushExpr(&BinaryExpr{})
+	m.PushValue(a)
+	m.PushValue(b)
+	m.PushOp(OpAdd)
+	m.Run()
+	res := m.ReapValues(start)
+	t.Log("res:", res)
+}