Java: Minor fix to modulus analysis to handle constant expressions and not only compile time constants

Author: tamasvajk

java/ql/src/semmle/code/java/dataflow/ModulusAnalysis.qll

@@ -68,11 +68,11 @@ private Expr modExpr(Expr arg, int mod) {
   exists(RemExpr rem |
     result = rem and
     arg = rem.getLeftOperand() and
-    rem.getRightOperand().(CompileTimeConstantExpr).getIntValue() = mod and
+    rem.getRightOperand().(ConstantIntegerExpr).getIntValue() = mod and
     mod >= 2
   )
   or
-  exists(CompileTimeConstantExpr c |
+  exists(ConstantIntegerExpr c |
     mod = 2.pow([1 .. 30]) and
     c.getIntValue() = mod - 1 and
     result.(AndBitwiseExpr).hasOperands(arg, c)
@@ -84,7 +84,7 @@ private Expr modExpr(Expr arg, int mod) {
  * its `testIsTrue` branch.
  */
 private Guard moduloCheck(SsaVariable v, int val, int mod, boolean testIsTrue) {
-  exists(Expr rem, CompileTimeConstantExpr c, int r, boolean polarity |
+  exists(Expr rem, ConstantIntegerExpr c, int r, boolean polarity |
     result.isEquality(rem, c, polarity) and
     c.getIntValue() = r and
     rem = modExpr(v.getAUse(), mod) and

java/ql/test/library-tests/dataflow/modulus-analysis/ModulusAnalysis.expected

@@ -22,6 +22,7 @@
 | ModulusAnalysis.java:12:25:12:29 | seven | 0 | 7 | 0 |
 | ModulusAnalysis.java:12:25:12:29 | seven | SSA def(seven) | 0 | 0 |
 | ModulusAnalysis.java:13:32:13:34 | mul | 0 | 3 | 42 |
+| ModulusAnalysis.java:13:32:13:34 | mul | 0 | 7 | 43 |
 | ModulusAnalysis.java:13:32:13:34 | mul | SSA def(mul) | 0 | 0 |
 | ModulusAnalysis.java:16:17:18:23 | ...?...:... | 0 | 3 | 4 |
 | ModulusAnalysis.java:17:15:17:15 | i | SSA init(i) | 0 | 0 |

java/ql/test/library-tests/dataflow/modulus-analysis/ModulusAnalysis.java

@@ -10,7 +10,7 @@ void m(int i, boolean cond, int x, int y, int[] arr) {
 
         int seven = 7;
         if (mul % c2 == seven) {
-            System.out.println(mul); // congruent 3 mod 42
+            System.out.println(mul); // congruent 3 mod 42, 7 mod 43
         }
 
         int j = cond