C++: 'origDelta' should always be 'odLeft' when deriving subtraction ranges.

Author: MathiasVP

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/analysis/RangeAnalysisStage.qll

@@ -1106,12 +1106,9 @@ module RangeStage<
         b = bRight and origdelta = odRight and reason = rRight and bLeft instanceof SemZeroBound
       )
       or
-      exists(
-        D::Delta dLeft, D::Delta dRight, boolean fbeLeft, boolean fbeRight, D::Delta odLeft,
-        D::Delta odRight, SemReason rLeft, SemReason rRight
-      |
-        boundedSubOperandLeft(e, upper, b, dLeft, fbeLeft, odLeft, rLeft) and
-        boundedSubOperandRight(e, upper, dRight, fbeRight, odRight, rRight) and
+      exists(D::Delta dLeft, D::Delta dRight, boolean fbeLeft, boolean fbeRight |
+        boundedSubOperandLeft(e, upper, b, dLeft, fbeLeft, origdelta, reason) and
+        boundedSubOperandRight(e, upper, dRight, fbeRight, _, _) and
         // when `upper` is `true` we have:
         // left <= b + dLeft
         // right >= 0 + dRight
@@ -1124,10 +1121,6 @@ module RangeStage<
         //               = b + (dLeft - dRight)
         delta = D::fromFloat(D::toFloat(dLeft) - D::toFloat(dRight)) and
         fromBackEdge = fbeLeft.booleanOr(fbeRight)
-      |
-        origdelta = odLeft and reason = rLeft
-        or
-        origdelta = odRight and reason = rRight
       )
       or
       exists(