Merge pull request #8859 from tausbn/python-fix-bad-essa-joins

Python: Fix a bunch of bad joins

Author: yoff

python/ql/lib/semmle/python/essa/Essa.qll

@@ -498,13 +498,13 @@ private EssaVariable potential_input(EssaNodeRefinement ref) {
 
 /** An assignment to a variable `v = val` */
 class AssignmentDefinition extends EssaNodeDefinition {
+  ControlFlowNode value;
+
   AssignmentDefinition() {
-    SsaSource::assignment_definition(this.getSourceVariable(), this.getDefiningNode(), _)
+    SsaSource::assignment_definition(this.getSourceVariable(), this.getDefiningNode(), value)
   }
 
-  ControlFlowNode getValue() {
-    SsaSource::assignment_definition(this.getSourceVariable(), this.getDefiningNode(), result)
-  }
+  ControlFlowNode getValue() { result = value }
 
   override string getRepresentation() { result = this.getValue().getNode().toString() }
 

python/ql/lib/semmle/python/essa/SsaCompute.qll

@@ -496,8 +496,8 @@ private module SsaComputeImpl {
     predicate firstUse(EssaDefinition def, ControlFlowNode use) {
       exists(SsaSourceVariable v, BasicBlock b1, int i1, BasicBlock b2, int i2 |
         adjacentVarRefs(v, b1, i1, b2, i2) and
-        definesAt(def, v, b1, i1) and
-        variableSourceUse(v, use, b2, i2)
+        definesAt(def, pragma[only_bind_into](v), b1, i1) and
+        variableSourceUse(pragma[only_bind_into](v), use, b2, i2)
       )
       or
       exists(

python/ql/src/Numerics/Pythagorean.ql

@@ -10,36 +10,30 @@
  */
 
 import python
+import semmle.python.dataflow.new.DataFlow
+import semmle.python.ApiGraphs
 
-predicate squareOp(BinaryExpr e) {
-  e.getOp() instanceof Pow and e.getRight().(IntegerLiteral).getN() = "2"
-}
-
-predicate squareMul(BinaryExpr e) {
-  e.getOp() instanceof Mult and e.getRight().(Name).getId() = e.getLeft().(Name).getId()
+DataFlow::ExprNode squareOp() {
+  exists(BinaryExpr e | e = result.asExpr() |
+    e.getOp() instanceof Pow and e.getRight().(IntegerLiteral).getN() = "2"
+  )
 }
 
-predicate squareRef(Name e) {
-  e.isUse() and
-  exists(SsaVariable v, Expr s | v.getVariable() = e.getVariable() |
-    s = v.getDefinition().getNode().getParentNode().(AssignStmt).getValue() and
-    square(s)
+DataFlow::ExprNode squareMul() {
+  exists(BinaryExpr e | e = result.asExpr() |
+    e.getOp() instanceof Mult and e.getRight().(Name).getId() = e.getLeft().(Name).getId()
   )
 }
 
-predicate square(Expr e) {
-  squareOp(e)
-  or
-  squareMul(e)
-  or
-  squareRef(e)
-}
+DataFlow::ExprNode square() { result in [squareOp(), squareMul()] }
 
-from Call c, BinaryExpr s
+from DataFlow::CallCfgNode c, BinaryExpr s, DataFlow::ExprNode left, DataFlow::ExprNode right
 where
-  c.getFunc().toString() = "sqrt" and
-  c.getArg(0) = s and
+  c = API::moduleImport("math").getMember("sqrt").getACall() and
+  c.getArg(0).asExpr() = s and
   s.getOp() instanceof Add and
-  square(s.getLeft()) and
-  square(s.getRight())
+  left.asExpr() = s.getLeft() and
+  right.asExpr() = s.getRight() and
+  left.getALocalSource() = square() and
+  right.getALocalSource() = square()
 select c, "Pythagorean calculation with sub-optimal numerics"

python/ql/test/query-tests/Numerics/Pythagorean.expected

@@ -1,3 +1,3 @@
-| pythagorean_test.py:6:12:6:28 | sqrt() | Pythagorean calculation with sub-optimal numerics |
-| pythagorean_test.py:9:12:9:26 | sqrt() | Pythagorean calculation with sub-optimal numerics |
-| pythagorean_test.py:14:12:14:24 | sqrt() | Pythagorean calculation with sub-optimal numerics |
+| pythagorean_test.py:6:12:6:28 | ControlFlowNode for sqrt() | Pythagorean calculation with sub-optimal numerics |
+| pythagorean_test.py:9:12:9:26 | ControlFlowNode for sqrt() | Pythagorean calculation with sub-optimal numerics |
+| pythagorean_test.py:14:12:14:24 | ControlFlowNode for sqrt() | Pythagorean calculation with sub-optimal numerics |