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Merge pull request #393 from smowton/smowton/fix/cfg-assignment-underscores

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CFG: fix lastNode relating to assignments with underscores on the LHS
This commit is contained in:
Chris Smowton
2020-11-03 14:32:57 +00:00
committed by GitHub
parent 3c84f11d5b 3b927f3b6b
commit 582f8e444b
6 changed files with 114 additions and 24 deletions
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40
ql/src/semmle/go/controlflow/ControlFlowGraphImpl.qll
View File

@@ -759,18 +759,11 @@ module CFG {
override predicate lastNode(ControlFlow::Node last, Completion cmpl) {
ControlFlowTree.super.lastNode(last, cmpl)
or
exists(int nl, int nr | nl = getNumLhs() and nr = getNumRhs() |
last = MkAssignNode(this, nl - 1)
(
last = max(int i | | epilogueNode(i) order by i)
or
not exists(MkAssignNode(this, nl - 1)) and
(
exists(ControlFlow::Node rhs | lastNode(getRhs(nr - 1), rhs, normalCompletion()) |
if nl = nr then last = rhs else last = MkExtractNode(this, nl - 1)
)
or
not exists(getRhs(nr - 1)) and
lastNode(getLhs(nl - 1), last, normalCompletion())
)
not exists(epilogueNode(_)) and
lastNode(getLastSubExprInEvalOrder(), last, normalCompletion())
) and
cmpl = Done()
}
@@ -787,7 +780,7 @@ module CFG {
firstNode(getRhs(0), succ)
or
not exists(getRhs(_)) and
succ = epilogueNodeRanked(1)
succ = epilogueNodeRanked(0)
)
)
or
@@ -796,6 +789,10 @@ module CFG {
firstNode(getRhs(i + 1), succ)
)
or
not this instanceof RecvStmt and
lastNode(getRhs(getNumRhs() - 1), pred, normalCompletion()) and
succ = epilogueNodeRanked(0)
or
exists(int i |
pred = epilogueNodeRanked(i) and
succ = epilogueNodeRanked(i + 1)
@@ -809,16 +806,17 @@ module CFG {
)
}
private Expr getSubExprInEvalOrder(int evalOrder) {
if evalOrder < getNumLhs()
then result = getLhs(evalOrder)
else result = getRhs(evalOrder - getNumLhs())
}
private Expr getLastSubExprInEvalOrder() {
result = max(int i | | getSubExprInEvalOrder(i) order by i)
}
private ControlFlow::Node epilogueNode(int i) {
not this instanceof RecvStmt and
i = -2 and
(
lastNode(getRhs(getNumRhs() - 1), result, normalCompletion())
or
not exists(getRhs(_)) and
lastNode(getLhs(getNumLhs() - 1), result, normalCompletion())
)
or
i = -1 and
result = MkCompoundAssignRhsNode(this)
or

59
ql/test/library-tests/semmle/go/controlflow/ControlFlowGraph/ControlFlowNode_getASuccessor.expected
View File

@@ -635,7 +635,7 @@
| main.go:79:2:79:13 | call to Print | main.go:80:1:80:1 | exit |
| main.go:79:12:79:12 | z | main.go:79:2:79:13 | call to Print |
| main.go:82:1:82:1 | entry | main.go:82:18:82:18 | zero value for a |
| main.go:82:1:86:1 | function declaration | main.go:0:0:0:0 | exit |
| main.go:82:1:86:1 | function declaration | main.go:88:6:88:23 | skip |
| main.go:82:6:82:13 | skip | main.go:82:1:86:1 | function declaration |
| main.go:82:18:82:18 | implicit read of a | main.go:82:25:82:25 | implicit read of b |
| main.go:82:18:82:18 | initialization of a | main.go:82:25:82:25 | zero value for b |
@@ -655,6 +655,36 @@
| main.go:84:11:84:12 | 19 | main.go:84:9:84:12 | ...+... |
| main.go:84:15:84:15 | x | main.go:84:2:84:2 | assignment to x |
| main.go:85:2:85:7 | return statement | main.go:82:18:82:18 | implicit read of a |
| main.go:88:1:88:1 | entry | main.go:88:25:88:25 | argument corresponding to x |
| main.go:88:1:96:1 | function declaration | main.go:0:0:0:0 | exit |
| main.go:88:6:88:23 | skip | main.go:88:1:96:1 | function declaration |
| main.go:88:25:88:25 | argument corresponding to x | main.go:88:25:88:25 | initialization of x |
| main.go:88:25:88:25 | initialization of x | main.go:89:2:89:2 | skip |
| main.go:89:2:89:2 | assignment to a | main.go:89:5:89:5 | assignment to b |
| main.go:89:2:89:2 | skip | main.go:89:5:89:5 | skip |
| main.go:89:5:89:5 | assignment to b | main.go:90:5:90:8 | cond |
| main.go:89:5:89:5 | skip | main.go:89:10:89:10 | x |
| main.go:89:10:89:10 | x | main.go:89:13:89:13 | 0 |
| main.go:89:13:89:13 | 0 | main.go:89:2:89:2 | assignment to a |
| main.go:90:5:90:8 | cond | main.go:90:5:90:10 | call to cond |
| main.go:90:5:90:10 | call to cond | main.go:90:10:90:10 | call to cond is false |
| main.go:90:5:90:10 | call to cond | main.go:90:10:90:10 | call to cond is true |
| main.go:90:5:90:10 | call to cond | main.go:96:1:96:1 | exit |
| main.go:90:10:90:10 | call to cond is false | main.go:93:3:93:3 | skip |
| main.go:90:10:90:10 | call to cond is true | main.go:91:3:91:3 | skip |
| main.go:91:3:91:3 | assignment to a | main.go:95:9:95:9 | a |
| main.go:91:3:91:3 | skip | main.go:91:6:91:6 | skip |
| main.go:91:6:91:6 | skip | main.go:91:10:91:10 | b |
| main.go:91:10:91:10 | b | main.go:91:13:91:13 | a |
| main.go:91:13:91:13 | a | main.go:91:3:91:3 | assignment to a |
| main.go:93:3:93:3 | skip | main.go:93:6:93:6 | skip |
| main.go:93:6:93:6 | assignment to b | main.go:95:9:95:9 | a |
| main.go:93:6:93:6 | skip | main.go:93:10:93:10 | b |
| main.go:93:10:93:10 | b | main.go:93:13:93:13 | a |
| main.go:93:13:93:13 | a | main.go:93:6:93:6 | assignment to b |
| main.go:95:2:95:12 | return statement | main.go:96:1:96:1 | exit |
| main.go:95:9:95:9 | a | main.go:95:12:95:12 | b |
| main.go:95:12:95:12 | b | main.go:95:2:95:12 | return statement |
| noretfunctions.go:0:0:0:0 | entry | noretfunctions.go:3:1:6:1 | skip |
| noretfunctions.go:3:1:6:1 | skip | noretfunctions.go:8:6:8:12 | skip |
| noretfunctions.go:8:1:8:1 | entry | noretfunctions.go:9:2:9:8 | selection of Exit |
@@ -734,7 +764,7 @@
| stmts2.go:12:9:12:13 | ...+... | stmts2.go:12:2:12:13 | return statement |
| stmts2.go:12:13:12:13 | y | stmts2.go:12:9:12:13 | ...+... |
| stmts2.go:15:1:15:1 | entry | stmts2.go:15:13:15:14 | argument corresponding to ch |
| stmts2.go:15:1:28:1 | function declaration | stmts2.go:0:0:0:0 | exit |
| stmts2.go:15:1:28:1 | function declaration | stmts2.go:30:6:30:12 | skip |
| stmts2.go:15:6:15:11 | skip | stmts2.go:15:1:28:1 | function declaration |
| stmts2.go:15:13:15:14 | argument corresponding to ch | stmts2.go:15:13:15:14 | initialization of ch |
| stmts2.go:15:13:15:14 | initialization of ch | stmts2.go:17:13:17:14 | ch |
@@ -778,6 +808,29 @@
| stmts2.go:25:16:25:17 | ch | stmts2.go:16:2:26:2 | select statement |
| stmts2.go:27:2:27:9 | return statement | stmts2.go:28:1:28:1 | exit |
| stmts2.go:27:9:27:9 | 1 | stmts2.go:27:2:27:9 | return statement |
| stmts2.go:30:1:30:1 | entry | stmts2.go:31:2:31:2 | skip |
| stmts2.go:30:1:34:1 | function declaration | stmts2.go:0:0:0:0 | exit |
| stmts2.go:30:6:30:12 | skip | stmts2.go:30:1:34:1 | function declaration |
| stmts2.go:31:2:31:2 | assignment to x | stmts2.go:31:2:31:14 | ... := ...[1] |
| stmts2.go:31:2:31:2 | skip | stmts2.go:31:5:31:5 | skip |
| stmts2.go:31:2:31:14 | ... := ...[0] | stmts2.go:31:2:31:2 | assignment to x |
| stmts2.go:31:2:31:14 | ... := ...[1] | stmts2.go:32:6:32:6 | skip |
| stmts2.go:31:5:31:5 | skip | stmts2.go:31:10:31:12 | gen |
| stmts2.go:31:10:31:12 | gen | stmts2.go:31:10:31:14 | call to gen |
| stmts2.go:31:10:31:14 | call to gen | stmts2.go:31:2:31:14 | ... := ...[0] |
| stmts2.go:31:10:31:14 | call to gen | stmts2.go:34:1:34:1 | exit |
| stmts2.go:32:6:32:6 | assignment to y | stmts2.go:32:6:32:17 | value declaration specifier[1] |
| stmts2.go:32:6:32:6 | skip | stmts2.go:32:9:32:9 | skip |
| stmts2.go:32:6:32:17 | value declaration specifier[0] | stmts2.go:32:6:32:6 | assignment to y |
| stmts2.go:32:6:32:17 | value declaration specifier[1] | stmts2.go:33:9:33:9 | x |
| stmts2.go:32:9:32:9 | skip | stmts2.go:32:13:32:15 | gen |
| stmts2.go:32:13:32:15 | gen | stmts2.go:32:13:32:17 | call to gen |
| stmts2.go:32:13:32:17 | call to gen | stmts2.go:32:6:32:17 | value declaration specifier[0] |
| stmts2.go:32:13:32:17 | call to gen | stmts2.go:34:1:34:1 | exit |
| stmts2.go:33:2:33:13 | return statement | stmts2.go:34:1:34:1 | exit |
| stmts2.go:33:9:33:9 | x | stmts2.go:33:13:33:13 | y |
| stmts2.go:33:9:33:13 | ...+... | stmts2.go:33:2:33:13 | return statement |
| stmts2.go:33:13:33:13 | y | stmts2.go:33:9:33:13 | ...+... |
| stmts3.go:0:0:0:0 | entry | stmts3.go:3:1:3:13 | skip |
| stmts3.go:3:1:3:13 | skip | stmts3.go:5:6:5:11 | skip |
| stmts3.go:5:1:5:1 | entry | stmts3.go:7:3:7:5 | skip |
@@ -814,7 +867,7 @@
| stmts3.go:19:22:19:23 | skip | stmts3.go:19:23:19:23 | exit |
| stmts4.go:0:0:0:0 | entry | stmts4.go:3:5:3:5 | skip |
| stmts4.go:3:5:3:5 | skip | stmts4.go:3:5:3:5 | zero value for _ |
| stmts4.go:3:5:3:5 | skip | stmts4.go:5:6:5:11 | skip |
| stmts4.go:3:5:3:5 | zero value for _ | stmts4.go:5:6:5:11 | skip |
| stmts4.go:5:1:5:26 | function declaration | stmts4.go:0:0:0:0 | exit |
| stmts4.go:5:6:5:11 | skip | stmts4.go:5:1:5:26 | function declaration |
| stmts5.go:0:0:0:0 | entry | stmts5.go:3:1:5:1 | skip |

10
ql/test/library-tests/semmle/go/controlflow/ControlFlowGraph/main.go
View File

@@ -84,3 +84,13 @@ func multiRes() (a int, b float32) {
x, a = x+19, x
return
}
func fooWithUnderscores(x int) (int, int) {
a, b := x, 0
if cond() {
a, _ = b, a
} else {
_, b = b, a
}
return a, b
}

6
ql/test/library-tests/semmle/go/controlflow/ControlFlowGraph/stmts2.go
View File

@@ -26,3 +26,9 @@ func test14(ch chan int) int {
}
return 1
}
func test13b() int {
x, _ := gen()
var y, _ = gen()
return x + y
}

1
ql/test/query-tests/RedundantCode/DeadStoreOfLocal/DeadStoreOfLocal.expected
View File

@@ -27,3 +27,4 @@
| testdata.go:488:3:488:3 | assignment to x | This definition of x is never used. |
| testdata.go:542:3:542:3 | assignment to x | This definition of x is never used. |
| testdata.go:580:4:580:4 | assignment to x | This definition of x is never used. |
| testdata.go:629:3:629:4 | assignment to v1 | This definition of v1 is never used. |

22
ql/test/query-tests/RedundantCode/DeadStoreOfLocal/testdata.go
View File

@@ -610,4 +610,26 @@ func _() {
_ = x
}
func _(v1, v2 int32) (int32, int32) {
if v1 > v2 {
v1, _ = v2, v1
}
return v1, v2
}
func _(v1, v2 int32) (int32, int32) {
if v1 > v2 {
_, v1 = v2, v1
}
return v1, v2
}
func _(v1, v2 int32) (int32, int32) {
if v1 > v2 {
v1, _ = v2, v1
}
v1, v2 = 0, 0
return v1, v2
}
func anyFunctionMightPanic()