C++: Don't limit instruction and operand reuse to those cases where we have a result for 'isUseImpl'.

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll

@@ -220,9 +220,10 @@ private module IndirectOperands {
     int indirectionIndex;
 
     IndirectOperandFromIRRepr() {
-      exists(Operand repr |
-        repr = Ssa::getIRRepresentationOfIndirectOperand(operand, indirectionIndex) and
-        nodeHasOperand(this, repr, indirectionIndex - 1)
+      exists(Operand repr, int indirectionIndexRepr |
+        Ssa::hasIRRepresentationOfIndirectOperand(operand, indirectionIndex, repr,
+          indirectionIndexRepr) and
+        nodeHasOperand(this, repr, indirectionIndexRepr)
       )
     }
 
@@ -262,9 +263,10 @@ private module IndirectInstructions {
     int indirectionIndex;
 
     IndirectInstructionFromIRRepr() {
-      exists(Instruction repr |
-        repr = Ssa::getIRRepresentationOfIndirectInstruction(instr, indirectionIndex) and
-        nodeHasInstruction(this, repr, indirectionIndex - 1)
+      exists(Instruction repr, int indirectionIndexRepr |
+        Ssa::hasIRRepresentationOfIndirectInstruction(instr, indirectionIndex, repr,
+          indirectionIndexRepr) and
+        nodeHasInstruction(this, repr, indirectionIndexRepr)
       )
     }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternals.qll

@@ -74,7 +74,7 @@ predicate hasRawIndirectOperand(Operand op, int indirectionIndex) {
     type = getLanguageType(op) and
     m = countIndirectionsForCppType(type) and
     indirectionIndex = [1 .. m] and
-    not exists(getIRRepresentationOfIndirectOperand(op, indirectionIndex))
+    not hasIRRepresentationOfIndirectOperand(op, indirectionIndex, _, _)
   )
 }
 
@@ -88,7 +88,7 @@ predicate hasRawIndirectInstruction(Instruction instr, int indirectionIndex) {
     type = getResultLanguageType(instr) and
     m = countIndirectionsForCppType(type) and
     indirectionIndex = [1 .. m] and
-    not exists(getIRRepresentationOfIndirectInstruction(instr, indirectionIndex))
+    not hasIRRepresentationOfIndirectInstruction(instr, indirectionIndex, _, _)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternalsCommon.qll

@@ -781,11 +781,14 @@ private module Cached {
    * instead associated with the operand returned by this predicate.
    */
   cached
-  Operand getIRRepresentationOfIndirectOperand(Operand operand, int indirectionIndex) {
+  predicate hasIRRepresentationOfIndirectOperand(
+    Operand operand, int indirectionIndex, Operand operandRepr, int indirectionIndexRepr
+  ) {
+    indirectionIndex = [1 .. countIndirectionsForCppType(getLanguageType(operand))] and
     exists(Instruction load |
       isDereference(load, operand) and
-      result = unique( | | getAUse(load)) and
-      isUseImpl(operand, _, indirectionIndex - 1)
+      operandRepr = unique( | | getAUse(load)) and
+      indirectionIndexRepr = indirectionIndex - 1
     )
   }
 
@@ -797,12 +800,15 @@ private module Cached {
    * instead associated with the instruction returned by this predicate.
    */
   cached
-  Instruction getIRRepresentationOfIndirectInstruction(Instruction instr, int indirectionIndex) {
+  predicate hasIRRepresentationOfIndirectInstruction(
+    Instruction instr, int indirectionIndex, Instruction instrRepr, int indirectionIndexRepr
+  ) {
+    indirectionIndex = [1 .. countIndirectionsForCppType(getResultLanguageType(instr))] and
     exists(Instruction load, Operand address |
       address.getDef() = instr and
       isDereference(load, address) and
-      isUseImpl(address, _, indirectionIndex - 1) and
-      result = load
+      instrRepr = load and
+      indirectionIndexRepr = indirectionIndex - 1
     )
   }