C#: Replace Ssa::PhiNode with SsaPhiDefinition.

Author: aschackmull

csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll

@@ -186,7 +186,7 @@ private predicate defMaybeNull(SsaDefinition def, ControlFlowNode node, string m
       de.guardSuggestsMaybeNull(reason) and
       msg = "as suggested by $@ null check" and
       node = def.getControlFlowNode() and
-      not de = any(Ssa::PhiNode phi).getARead() and
+      not de = any(SsaPhiDefinition phi).getARead() and
       // Don't use a check as reason if there is a `null` assignment
       // or argument
       not def.(SsaExplicitWrite).getValue() instanceof MaybeNullExpr and
@@ -213,22 +213,22 @@ private predicate defMaybeNull(SsaDefinition def, ControlFlowNode node, string m
     exists(Dereference d | dereferenceAt(def, d) |
       node = def.getControlFlowNode() and
       d.hasNullableType() and
-      not def instanceof Ssa::PhiNode and
+      not def instanceof SsaPhiDefinition and
       reason = def.getSourceVariable().getAssignable() and
       msg = "because it has a nullable type"
     )
   )
 }
 
 private SsaDefinition getAPseudoInput(SsaDefinition def) {
-  result = def.(Ssa::PhiNode).getAnInput()
+  result = def.(SsaPhiDefinition).getAnInput()
 }
 
 // `def.getAnUltimateDefinition()` includes inputs into uncertain
 // definitions, but we only want inputs into pseudo nodes
 private SsaDefinition getAnUltimateDefinition(SsaDefinition def) {
   result = getAPseudoInput*(def) and
-  not result instanceof Ssa::PhiNode
+  not result instanceof SsaPhiDefinition
 }
 
 /**

csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll

@@ -357,7 +357,7 @@ module Ssa {
      * includes inputs to phi nodes and the prior definitions of uncertain writes.
      */
     private Definition getAPhiInputOrPriorDefinition() {
-      result = this.(PhiNode).getAnInput() or
+      result = this.(SsaPhiDefinition).getAnInput() or
       result = this.(UncertainDefinition).getPriorDefinition()
     }
 
@@ -392,7 +392,7 @@ module Ssa {
      */
     final Definition getAnUltimateDefinition() {
       result = this.getAPhiInputOrPriorDefinition*() and
-      not result instanceof PhiNode
+      not result instanceof SsaPhiDefinition
     }
 
     /**
@@ -646,11 +646,13 @@ module Ssa {
   }
 
   /**
+   * DEPRECATED: Use `SsaPhiDefinition` instead.
+   *
    * An SSA phi node, that is, a pseudo definition for a variable at a point
    * in the flow graph where otherwise two or more definitions for the variable
    * would be visible.
    */
-  class PhiNode extends Definition, SsaImpl::PhiNode {
+  deprecated class PhiNode extends Definition, SsaImpl::PhiNode {
     /**
      * Gets an input of this phi node. Example:
      *

csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll

@@ -873,7 +873,7 @@ private module Cached {
   }
 
   cached
-  Definition phiHasInputFromBlock(Ssa::PhiNode phi, BasicBlock bb) {
+  deprecated Definition phiHasInputFromBlock(Ssa::PhiNode phi, BasicBlock bb) {
     Impl::phiHasInputFromBlock(phi, result, bb)
   }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/ModulusAnalysisSpecific.qll

@@ -9,7 +9,7 @@ module Private {
 
   class SsaVariable = SU::SsaVariable;
 
-  class SsaPhiNode = CS::Ssa::PhiNode;
+  class SsaPhiNode = CS::SsaPhiDefinition;
 
   class Expr = CS::ControlFlowNodes::ExprNode;
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/SignAnalysisSpecific.qll

@@ -15,7 +15,7 @@ module Private {
 
   class SsaVariable = CS::SsaDefinition;
 
-  class SsaPhiNode = CS::Ssa::PhiNode;
+  class SsaPhiNode = CS::SsaPhiDefinition;
 
   class VarAccess = RU::ExprNode::AssignableAccess;
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/SsaReadPositionSpecific.qll

@@ -7,7 +7,7 @@ private import SsaReadPositionCommon
 
 class SsaVariable = CS::SsaDefinition;
 
-class SsaPhiNode = CS::Ssa::PhiNode;
+class SsaPhiNode = CS::SsaPhiDefinition;
 
 class BasicBlock = CS::BasicBlock;
 

csharp/ql/test/library-tests/dataflow/defuse/useUseEquivalence.ql

@@ -32,7 +32,7 @@ private TLocalScopeVariableReadOrSsaDef getANextReadOrDef(TLocalScopeVariableRea
     result = TLocalScopeVariableRead(read.getANextRead())
     or
     not exists(read.getANextRead()) and
-    exists(SsaDefinition ssaDef, Ssa::PhiNode phi, BasicBlock bb |
+    exists(SsaDefinition ssaDef, SsaPhiDefinition phi, BasicBlock bb |
       ssaDef.getARead() = read and
       phi.getAnInput() = ssaDef and
       phi.definesAt(_, bb, _) and
@@ -45,7 +45,7 @@ private TLocalScopeVariableReadOrSsaDef getANextReadOrDef(TLocalScopeVariableRea
     result = TLocalScopeVariableRead(Ssa::ssaGetAFirstUse(ssaDef))
     or
     not exists(Ssa::ssaGetAFirstUse(ssaDef)) and
-    exists(Ssa::PhiNode phi |
+    exists(SsaPhiDefinition phi |
       phi.getAnInput() = ssaDef and
       result = TSsaDefinition(phi)
     )

csharp/ql/test/library-tests/dataflow/ssa/SSAPhi.ql

@@ -1,6 +1,6 @@
 import csharp
 
-from Ssa::SourceVariable v, Ssa::PhiNode phi, SsaDefinition input
+from Ssa::SourceVariable v, SsaPhiDefinition phi, SsaDefinition input
 where
   phi.getAnInput() = input and
   v = phi.getSourceVariable()