Merge pull request github#10986 from erik-krogh/tsPerf

JS: push more context into load/store steps from the exploratory flow-analysis

Author: erik-krogh

javascript/ql/lib/semmle/javascript/dataflow/Configuration.qll

@@ -1175,6 +1175,7 @@ private predicate parameterPropReadStep(
     invk = getAwaitOperand(succ)
   ) and
   callInputStep(f, invk, arg, parm, cfg) and
+  prop = pragma[only_bind_into](getARelevantProp(cfg)) and
   (
     read = parm.getAPropertyRead(prop)
     or
@@ -1192,7 +1193,7 @@ private predicate reachesReturn(
   isRelevant(read, cfg) and
   returnExpr(f, read, _) and
   summary = PathSummary::level() and
-  callInputStep(f, _, _, _, _) // check that a relevant result can exist.
+  parameterPropReadStep(_, _, _, cfg, _, _, f, _) // check that a relevant result can exist.
   or
   exists(DataFlow::Node mid, PathSummary oldSummary, PathSummary newSummary |
     flowStep(read, cfg, mid, oldSummary) and
@@ -1202,6 +1203,33 @@ private predicate reachesReturn(
   )
 }
 
+// used in `getARelevantProp`, outlined for performance
+pragma[noinline]
+private string getARelevantStoreProp(DataFlow::Configuration cfg) {
+  exists(DataFlow::Node previous | isRelevant(previous, cfg) |
+    basicStoreStep(previous, _, result) or
+    isAdditionalStoreStep(previous, _, result, cfg)
+  )
+}
+
+// used in `getARelevantProp`, outlined for performance
+pragma[noinline]
+private string getARelevantLoadProp(DataFlow::Configuration cfg) {
+  exists(DataFlow::Node previous | isRelevant(previous, cfg) |
+    basicLoadStep(previous, _, result) or
+    isAdditionalLoadStep(previous, _, result, cfg)
+  )
+}
+
+/** Gets the name of a property that is both loaded and stored according to the exploratory analysis. */
+pragma[noinline]
+private string getARelevantProp(DataFlow::Configuration cfg) {
+  result = getARelevantStoreProp(cfg) and
+  result = getARelevantLoadProp(cfg)
+  or
+  result = getAPropertyUsedInLoadStore(cfg)
+}
+
 /**
  * Holds if the property `prop` of the object `pred` should be loaded into `succ`.
  */
@@ -1275,6 +1303,7 @@ private predicate reachableFromStoreBase(
 ) {
   exists(TPathSummary s1, TPathSummary s2, DataFlow::Node rhs |
     storeStep(rhs, nd, startProp, cfg, s2) and
+    startProp = getARelevantProp(cfg) and
     endProp = startProp and
     base = nd and
     exists(boolean hasCall, DataFlow::FlowLabel data |
@@ -1300,6 +1329,7 @@ private predicate reachableFromStoreBase(
     exists(string midProp |
       reachableFromStoreBase(startProp, midProp, base, mid, cfg, oldSummary, onlyRelevantInCall) and
       isAdditionalLoadStoreStep(mid, nd, midProp, endProp, cfg) and
+      endProp = getARelevantProp(cfg) and
       newSummary = PathSummary::level()
     )
   |