Update SSA interface

Author: hvitved

shared/ssa/codeql/ssa/Ssa.qll

@@ -1310,10 +1310,6 @@ module Make<LocationSig Location, InputSig<Location> Input> {
     }
 
     cached
-    private predicate ssaInputNode(SsaInputDefinitionExt def, BasicBlock input) {
-      def.hasInputFromBlock(_, _, _, _, input)
-    }
-
     private newtype TNode =
       TParamNode(DfInput::Parameter p) or
       TExprNode(DfInput::Expr e, Boolean isPost) {
@@ -1325,7 +1321,9 @@ module Make<LocationSig Location, InputSig<Location> Input> {
         isPost = false
       } or
       TSsaDefinitionNode(DefinitionExt def) or
-      TSsaInputNode(SsaInputDefinitionExt def, BasicBlock input) { ssaInputNode(def, input) }
+      TSsaInputNode(SsaInputDefinitionExt def, BasicBlock input) {
+        def.hasInputFromBlock(_, _, _, _, input)
+      }
 
     /**
      * A data flow node that we need to reference in the value step relation.
@@ -1541,33 +1539,39 @@ module Make<LocationSig Location, InputSig<Location> Input> {
     }
 
     /** Holds if there is a local flow step from `nodeFrom` to `nodeTo`. */
-    predicate localFlowStep(DefinitionExt def, Node nodeFrom, Node nodeTo) {
+    predicate localFlowStep(DefinitionExt def, Node nodeFrom, Node nodeTo, boolean isUseStep) {
       (
         // Flow from assignment into SSA definition
         DfInput::ssaDefAssigns(def, nodeFrom.(ExprNode).getExpr())
         or
         // Flow from parameter into entry definition
         DfInput::ssaDefInitializesParam(def, nodeFrom.(ParameterNode).getParameter())
       ) and
-      nodeTo.(SsaDefinitionExtNode).getDefinitionExt() = def
+      nodeTo.(SsaDefinitionExtNode).getDefinitionExt() = def and
+      isUseStep = false
       or
       // Flow from SSA definition to first read
       def = nodeFrom.(SsaDefinitionExtNode).getDefinitionExt() and
-      firstReadExt(def, nodeTo)
+      firstReadExt(def, nodeTo) and
+      isUseStep = false
       or
       // Flow from (post-update) read to next read
       adjacentReadPairExt(def, [nodeFrom, nodeFrom.(ExprPostUpdateNode).getPreUpdateNode()], nodeTo) and
-      nodeFrom != nodeTo
+      nodeFrom != nodeTo and
+      isUseStep = true
       or
       // Flow into phi (read) SSA definition node from def
-      inputFromDef(def, nodeFrom, nodeTo)
+      inputFromDef(def, nodeFrom, nodeTo) and
+      isUseStep = false
       or
       // Flow into phi (read) SSA definition node from (post-update) read
-      inputFromRead(def, [nodeFrom, nodeFrom.(ExprPostUpdateNode).getPreUpdateNode()], nodeTo)
+      inputFromRead(def, [nodeFrom, nodeFrom.(ExprPostUpdateNode).getPreUpdateNode()], nodeTo) and
+      isUseStep = true
       or
       // Flow from input node to def
       nodeTo.(SsaDefinitionExtNode).getDefinitionExt() = def and
-      def = nodeFrom.(SsaInputNode).getDefinitionExt()
+      def = nodeFrom.(SsaInputNode).getDefinitionExt() and
+      isUseStep = false
     }
 
     pragma[nomagic]