C++: Make sign analysis aware of unsigned'ness and accept test changes.

Author: MathiasVP

cpp/ql/lib/experimental/semmle/code/cpp/semantic/SemanticExprSpecific.qll

@@ -216,7 +216,9 @@ module SemanticExprConfig {
     TSsaInstruction(IR::Instruction instr) { instr.hasMemoryResult() } or
     TSsaOperand(IR::Operand op) { op.isDefinitionInexact() } or
     TSsaPointerArithmeticGuard(ValueNumber instr) {
-      exists(Guard g, IR::Operand use | use = instr.getAUse() |
+      exists(Guard g, IR::Operand use |
+        use = instr.getAUse() and use.getIRType() instanceof IR::IRAddressType
+      |
         g.comparesLt(use, _, _, _, _) or
         g.comparesLt(_, use, _, _, _) or
         g.comparesEq(use, _, _, _, _) or

cpp/ql/lib/experimental/semmle/code/cpp/semantic/analysis/SignAnalysisCommon.qll

@@ -198,6 +198,16 @@ module SignAnalysis<DeltaSig D, UtilSig<D> Utils> {
     }
   }
 
+  /** An expression of an unsigned type. */
+  private class UnsignedExpr extends FlowSignExpr {
+    UnsignedExpr() { Utils::getTrackedType(this) instanceof SemUnsignedIntegerType }
+
+    override Sign getSignRestriction() {
+      result = TPos() or
+      result = TZero()
+    }
+  }
+
   pragma[nomagic]
   private predicate binaryExprOperands(SemBinaryExpr binary, SemExpr left, SemExpr right) {
     binary.getLeftOperand() = left and binary.getRightOperand() = right

cpp/ql/test/library-tests/ir/range-analysis/SimpleRangeAnalysis_tests.cpp

@@ -318,7 +318,7 @@ int test_mult01(int a, int b) {
     int r = a*b;  // -143 .. 253
     range(r);
     total += r;
-    range(total); // $ range=">=... * ...+0"
+    range(total); // $ MISSING: range=">=... * ...+0"
   }
   if (3 <= a && a <= 11 && -13 <= b && b <= 0) {
     range(a); // $ range=<=11 range=>=3
@@ -366,7 +366,7 @@ int test_mult02(int a, int b) {
     int r = a*b;  // -143 .. 253
     range(r);
     total += r;
-    range(total); // $ range=">=... * ...+0"
+    range(total); // $ MISSING: range=">=... * ...+0"
   }
   if (0 <= a && a <= 11 && -13 <= b && b <= 0) {
     range(a); // $ range=<=11 range=>=0
@@ -461,7 +461,7 @@ int test_mult04(int a, int b) {
     int r = a*b;  // -391 .. 221
     range(r);
     total += r;
-    range(total); // $ range="<=... * ...+0"
+    range(total); // $ MISSING: range="<=... * ...+0"
   }
   if (-17 <= a && a <= 0 && -13 <= b && b <= 0) {
     range(a); // $ range=<=0 range=>=-17
@@ -509,7 +509,7 @@ int test_mult05(int a, int b) {
     int r = a*b;  // -391 .. 221
     range(r);
     total += r;
-    range(total); // $ range="<=... * ...+0"
+    range(total); // $ MISSING: range="<=... * ...+0"
   }
   if (-17 <= a && a <= -2 && -13 <= b && b <= 0) {
     range(a); // $ range=<=-2 range=>=-17