feat: add stack trace on machine

gno.land/cmd/gnoland/testdata/panic1.txtar

@@ -0,0 +1,26 @@
+# test recursion 
+
+## start a new node
+gnoland start
+
+gnokey maketx addpkg -pkgdir $WORK -pkgpath gno.land/r/demo/panic -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1
+
+! gnokey maketx call -pkgpath gno.land/r/demo/panic --func Trigger --gas-fee 1000000ugnot --gas-wanted 2000000 --broadcast -chainid=tendermint_test test1
+
+stderr 'panic\(i\<VPBlock\(1\,0\)\>\)'
+stderr 'gno.land/r/demo/panic:5'
+stderr 'p\<VPBlock\(3\,0\)\>\(\)'
+stderr 'gno.land/r/demo/panic:9'
+
+-- panic.gno --
+package main
+
+func p() {
+   i := "here"
+	panic(i)
+}
+
+func Trigger() {
+	p()
+}
+

gno.land/cmd/gnoland/testdata/panic2.txtar

@@ -0,0 +1,34 @@
+# test panic recursion
+## start a new node
+gnoland start
+
+gnokey maketx addpkg -pkgdir $WORK -pkgpath gno.land/r/demo/panic -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1
+
+! gnokey maketx call -pkgpath gno.land/r/demo/panic --func Trigger --gas-fee 1000000ugnot --gas-wanted 2000000 --broadcast -chainid=tendermint_test test1
+
+
+stderr 'panic\(\(const \(\"here\" \<untyped\> string\)\)\)'
+stderr 'gno.land/r/demo/panic:5'
+stderr 'p\<VPBlock\(3\,0\)\>\(i\<VPBlock\(1\,0\)\> \+ \(const \(1 int\)\)\)'
+stderr 'gno.land/r/demo/panic:7'
+stderr 'p\<VPBlock\(3\,0\)\>\(i\<VPBlock\(1\,0\)\> \+ \(const \(1 int\)\)\)'
+stderr 'gno.land/r/demo/panic:7'
+stderr 'p\<VPBlock\(3\,0\)\>\(i\<VPBlock\(1\,0\)\> \+ \(const \(1 int\)\)\)'
+stderr 'gno.land/r/demo/panic:7'
+stderr 'p\<VPBlock\(3\,0\)\>\(\(const \(0 int\)\)\)'
+stderr 'gno.land/r/demo/panic:11'
+
+-- panic.gno --
+package main
+
+func p(i int) {
+	if i == 3 {
+		panic("here")
+	}
+	p(i+1)
+}
+
+func Trigger() {
+	p(0)
+}
+

gno.land/pkg/sdk/vm/keeper.go

@@ -303,7 +303,7 @@ func (vm *VMKeeper) Call(ctx sdk.Context, msg MsgCall) (res string, err error) {
 				panic(r)
 			default:
 				err = errors.Wrap(fmt.Errorf("%v", r), "VM call panic: %v\n%s\n",
-					r, m.String())
+					r, m.Stacktrace())
 				return
 			}
 		}

gnovm/pkg/gnolang/machine.go

@@ -25,6 +25,8 @@ type Exception struct {
 	// Frame is used to reference the frame a panic occurred in so that recover() knows if the
 	// currently executing deferred function is able to recover from the panic.
 	Frame *Frame
+
+	Stack *Stack
 }
 
 func (e Exception) Sprint(m *Machine) string {
@@ -47,6 +49,7 @@ type Machine struct {
 	Package    *PackageValue // active package
 	Realm      *Realm        // active realm
 	Alloc      *Allocator    // memory allocations
+	Stack      *Stack        // stack of expressions
 	Exceptions []Exception
 	NumResults int   // number of results returned
 	Cycles     int64 // number of "cpu" cycles
@@ -164,6 +167,7 @@ func NewMachineWithOptions(opts MachineOptions) *Machine {
 	mm.Store = store
 	mm.Context = context
 	mm.GasMeter = vmGasMeter
+	mm.Stack = NewStack()
 	mm.Debugger.enabled = opts.Debug
 	mm.Debugger.in = opts.Input
 	mm.Debugger.out = output
@@ -1539,12 +1543,13 @@ func (m *Machine) PopStmt() Stmt {
 		m.Printf("-s %v\n", s)
 	}
 	if bs, ok := s.(*bodyStmt); ok {
-		return bs.PopActiveStmt()
+		s = bs.PopActiveStmt()
 	} else {
-		// general case.
 		m.Stmts = m.Stmts[:numStmts-1]
-		return s
 	}
+
+	m.Stack.onStmtPopped(s)
+	return s
 }
 
 func (m *Machine) ForcePopStmt() (s Stmt) {
@@ -1740,6 +1745,7 @@ func (m *Machine) PushFrameCall(cx *CallExpr, fv *FuncValue, recv TypedValue) {
 	if rlm != nil && m.Realm != rlm {
 		m.Realm = rlm // enter new realm
 	}
+	m.Stack.OnFramePushed(fr)
 }
 
 func (m *Machine) PushFrameGoNative(cx *CallExpr, fv *NativeValue) {
@@ -1774,6 +1780,7 @@ func (m *Machine) PopFrame() Frame {
 		m.Printf("-F %#v\n", f)
 	}
 	m.Frames = m.Frames[:numFrames-1]
+	m.Stack.OnFramePopped(f)
 	return *f
 }
 
@@ -2004,6 +2011,7 @@ func (m *Machine) Panic(ex TypedValue) {
 		Exception{
 			Value: ex,
 			Frame: m.MustLastCallFrame(1),
+			Stack: m.Stack.Copy(),
 		},
 	)
 
@@ -2148,6 +2156,22 @@ func (m *Machine) String() string {
 	return builder.String()
 }
 
+func (m *Machine) Stacktrace() string {
+	var builder strings.Builder
+	builder.WriteString("Stacktrace:\n")
+	for i, ex := range m.Exceptions {
+		builder.WriteString(fmt.Sprintf("    Exception %d: \n ", i))
+
+		for i := len(ex.Stack.Execs) - 1; i >= 0; i-- {
+			exec := ex.Stack.Execs[i]
+			builder.WriteString(fmt.Sprintf("        %v\n", exec.Stmt))
+			builder.WriteString(fmt.Sprintf("            %v:%d\n", exec.Fun.PkgPath, exec.Stmt.GetLine()))
+		}
+	}
+
+	return builder.String()
+}
+
 //----------------------------------------
 // utility
 

gnovm/pkg/gnolang/stack.go

@@ -0,0 +1,40 @@
+package gnolang
+
+type execution struct {
+	Stmt Stmt
+	Fun  *FuncValue
+}
+type Stack struct {
+	Execs []execution
+}
+
+func NewStack() *Stack {
+	return &Stack{
+		Execs: make([]execution, 0),
+	}
+}
+
+func (s *Stack) onStmtPopped(stmt Stmt) {
+	if len(s.Execs) > 0 {
+		s.Execs[len(s.Execs)-1].Stmt = stmt
+	}
+}
+
+func (s *Stack) OnFramePushed(frame *Frame) {
+	if frame.Func != nil {
+		s.Execs = append(s.Execs, execution{Fun: frame.Func})
+	}
+}
+
+func (s *Stack) OnFramePopped(frame *Frame) {
+	if frame.Func != nil {
+		s.Execs = s.Execs[:len(s.Execs)-1]
+	}
+}
+
+func (s *Stack) Copy() *Stack {
+	cpy := NewStack()
+	cpy.Execs = make([]execution, len(s.Execs))
+	copy(cpy.Execs, s.Execs)
+	return cpy
+}