func()

in go/ssa/sanity.go [90:211]

• 100 lines of code
• 55 McCabe index (conditional complexity)

func (s *sanity) checkInstr(idx int, instr Instruction) {
	switch instr := instr.(type) {
	case *If, *Jump, *Return, *Panic:
		s.errorf("control flow instruction not at end of block")
	case *Phi:
		if idx == 0 {
			// It suffices to apply this check to just the first phi node.
			if dup := findDuplicate(s.block.Preds); dup != nil {
				s.errorf("phi node in block with duplicate predecessor %s", dup)
			}
		} else {
			prev := s.block.Instrs[idx-1]
			if _, ok := prev.(*Phi); !ok {
				s.errorf("Phi instruction follows a non-Phi: %T", prev)
			}
		}
		if ne, np := len(instr.Edges), len(s.block.Preds); ne != np {
			s.errorf("phi node has %d edges but %d predecessors", ne, np)

		} else {
			for i, e := range instr.Edges {
				if e == nil {
					s.errorf("phi node '%s' has no value for edge #%d from %s", instr.Comment, i, s.block.Preds[i])
				}
			}
		}

	case *Alloc:
		if !instr.Heap {
			found := false
			for _, l := range s.fn.Locals {
				if l == instr {
					found = true
					break
				}
			}
			if !found {
				s.errorf("local alloc %s = %s does not appear in Function.Locals", instr.Name(), instr)
			}
		}

	case *BinOp:
	case *Call:
	case *ChangeInterface:
	case *ChangeType:
	case *SliceToArrayPointer:
	case *Convert:
		if _, ok := instr.X.Type().Underlying().(*types.Basic); !ok {
			if _, ok := instr.Type().Underlying().(*types.Basic); !ok {
				s.errorf("convert %s -> %s: at least one type must be basic", instr.X.Type(), instr.Type())
			}
		}

	case *Defer:
	case *Extract:
	case *Field:
	case *FieldAddr:
	case *Go:
	case *Index:
	case *IndexAddr:
	case *Lookup:
	case *MakeChan:
	case *MakeClosure:
		numFree := len(instr.Fn.(*Function).FreeVars)
		numBind := len(instr.Bindings)
		if numFree != numBind {
			s.errorf("MakeClosure has %d Bindings for function %s with %d free vars",
				numBind, instr.Fn, numFree)

		}
		if recv := instr.Type().(*types.Signature).Recv(); recv != nil {
			s.errorf("MakeClosure's type includes receiver %s", recv.Type())
		}

	case *MakeInterface:
	case *MakeMap:
	case *MakeSlice:
	case *MapUpdate:
	case *Next:
	case *Range:
	case *RunDefers:
	case *Select:
	case *Send:
	case *Slice:
	case *Store:
	case *TypeAssert:
	case *UnOp:
	case *DebugRef:
		// TODO(adonovan): implement checks.
	default:
		panic(fmt.Sprintf("Unknown instruction type: %T", instr))
	}

	if call, ok := instr.(CallInstruction); ok {
		if call.Common().Signature() == nil {
			s.errorf("nil signature: %s", call)
		}
	}

	// Check that value-defining instructions have valid types
	// and a valid referrer list.
	if v, ok := instr.(Value); ok {
		t := v.Type()
		if t == nil {
			s.errorf("no type: %s = %s", v.Name(), v)
		} else if t == tRangeIter {
			// not a proper type; ignore.
		} else if b, ok := t.Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
			s.errorf("instruction has 'untyped' result: %s = %s : %s", v.Name(), v, t)
		}
		s.checkReferrerList(v)
	}

	// Untyped constants are legal as instruction Operands(),
	// for example:
	//   _ = "foo"[0]
	// or:
	//   if wordsize==64 {...}

	// All other non-Instruction Values can be found via their
	// enclosing Function or Package.
}