diff --git a/core/vm/analysis.go b/core/vm/analysis.go
index d5f048d1d0c3802d854ef6324c436d0552b323d6..f9c4298d39466ab45e78caa5309826a433cbc996 100644
--- a/core/vm/analysis.go
+++ b/core/vm/analysis.go
@@ -25,7 +25,7 @@ import (
// destinations stores one map per contract (keyed by hash of code).
// The maps contain an entry for each location of a JUMPDEST
// instruction.
-type destinations map[common.Hash][]byte
+type destinations map[common.Hash]bitvec
// has checks whether code has a JUMPDEST at dest.
func (d destinations) has(codehash common.Hash, code []byte, dest *big.Int) bool {
@@ -38,24 +38,53 @@ func (d destinations) has(codehash common.Hash, code []byte, dest *big.Int) bool
m, analysed := d[codehash]
if !analysed {
- m = jumpdests(code)
+ m = codeBitmap(code)
d[codehash] = m
}
- return (m[udest/8] & (1 << (udest % 8))) != 0
+ return OpCode(code[udest]) == JUMPDEST && m.codeSegment(udest)
}
-// jumpdests creates a map that contains an entry for each
-// PC location that is a JUMPDEST instruction.
-func jumpdests(code []byte) []byte {
- m := make([]byte, len(code)/8+1)
- for pc := uint64(0); pc < uint64(len(code)); pc++ {
+// bitvec is a bit vector which maps bytes in a program.
+// An unset bit means the byte is an opcode, a set bit means
+// it's data (i.e. argument of PUSHxx).
+type bitvec []byte
+
+func (bits *bitvec) set(pos uint64) {
+ (*bits)[pos/8] |= 0x80 >> (pos % 8)
+}
+func (bits *bitvec) set8(pos uint64) {
+ (*bits)[pos/8] |= 0xFF >> (pos % 8)
+ (*bits)[pos/8+1] |= ^(0xFF >> (pos % 8))
+}
+
+// codeSegment checks if the position is in a code segment.
+func (bits *bitvec) codeSegment(pos uint64) bool {
+ return ((*bits)[pos/8] & (0x80 >> (pos % 8))) == 0
+}
+
+// codeBitmap collects data locations in code.
+func codeBitmap(code []byte) bitvec {
+ // The bitmap is 4 bytes longer than necessary, in case the code
+ // ends with a PUSH32, the algorithm will push zeroes onto the
+ // bitvector outside the bounds of the actual code.
+ bits := make(bitvec, len(code)/8+1+4)
+ for pc := uint64(0); pc < uint64(len(code)); {
op := OpCode(code[pc])
- if op == JUMPDEST {
- m[pc/8] |= 1 << (pc % 8)
- } else if op >= PUSH1 && op <= PUSH32 {
- a := uint64(op) - uint64(PUSH1) + 1
- pc += a
+
+ if op >= PUSH1 && op <= PUSH32 {
+ numbits := op - PUSH1 + 1
+ pc++
+ for ; numbits >= 8; numbits -= 8 {
+ bits.set8(pc) // 8
+ pc += 8
+ }
+ for ; numbits > 0; numbits-- {
+ bits.set(pc)
+ pc++
+ }
+ } else {
+ pc++
}
}
- return m
+ return bits
}
diff --git a/core/vm/analysis_test.go b/core/vm/analysis_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..a64f90ed9c0b1ecab4b9f1eb34c409a5327282bc
--- /dev/null
+++ b/core/vm/analysis_test.go
@@ -0,0 +1,53 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import "testing"
+
+func TestJumpDestAnalysis(t *testing.T) {
+ tests := []struct {
+ code []byte
+ exp byte
+ which int
+ }{
+ {[]byte{byte(PUSH1), 0x01, 0x01, 0x01}, 0x40, 0},
+ {[]byte{byte(PUSH1), byte(PUSH1), byte(PUSH1), byte(PUSH1)}, 0x50, 0},
+ {[]byte{byte(PUSH8), byte(PUSH8), byte(PUSH8), byte(PUSH8), byte(PUSH8), byte(PUSH8), byte(PUSH8), byte(PUSH8), 0x01, 0x01, 0x01}, 0x7F, 0},
+ {[]byte{byte(PUSH8), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0x80, 1},
+ {[]byte{0x01, 0x01, 0x01, 0x01, 0x01, byte(PUSH2), byte(PUSH2), byte(PUSH2), 0x01, 0x01, 0x01}, 0x03, 0},
+ {[]byte{0x01, 0x01, 0x01, 0x01, 0x01, byte(PUSH2), 0x01, 0x01, 0x01, 0x01, 0x01}, 0x00, 1},
+ {[]byte{byte(PUSH3), 0x01, 0x01, 0x01, byte(PUSH1), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0x74, 0},
+ {[]byte{byte(PUSH3), 0x01, 0x01, 0x01, byte(PUSH1), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0x00, 1},
+ {[]byte{0x01, byte(PUSH8), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0x3F, 0},
+ {[]byte{0x01, byte(PUSH8), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0xC0, 1},
+ {[]byte{byte(PUSH16), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0x7F, 0},
+ {[]byte{byte(PUSH16), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0xFF, 1},
+ {[]byte{byte(PUSH16), 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01}, 0x80, 2},
+ {[]byte{byte(PUSH8), 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, byte(PUSH1), 0x01}, 0x7f, 0},
+ {[]byte{byte(PUSH8), 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, byte(PUSH1), 0x01}, 0xA0, 1},
+ {[]byte{byte(PUSH32)}, 0x7F, 0},
+ {[]byte{byte(PUSH32)}, 0xFF, 1},
+ {[]byte{byte(PUSH32)}, 0xFF, 2},
+ }
+ for _, test := range tests {
+ ret := codeBitmap(test.code)
+ if ret[test.which] != test.exp {
+ t.Fatalf("expected %x, got %02x", test.exp, ret[test.which])
+ }
+ }
+
+}