C++: Drive-by join order fix. Before:

```
Evaluated relational algebra for predicate SsaInternals::getDefImpl/1#1ed4f567@65628fbv with tuple counts:
          4935102  ~5%    {4} r1 = SCAN `SsaInternals::SsaImpl::Definition.definesAt/3#dispred#7eea4c8f` OUTPUT In.2, In.3, In.0, In.1
        104274503  ~1%    {3}    | JOIN WITH `SsaInternals::DefImpl.hasIndexInBlock/2#dispred#30a6c29f_120#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.3, Lhs.2
          4921319  ~2%    {2}    | JOIN WITH `SsaInternals::DefImpl.getSourceVariable/0#dispred#72437659` ON FIRST 2 OUTPUT Lhs.2, Lhs.0
                          return r1
```
After:
```
Evaluated relational algebra for predicate SsaInternals::SsaImpl::Definition.definesAt/3#dispred#7eea4c8f_1230#join_rhs@b280fb5h with tuple counts:
        4935102  ~3%    {4} r1 = SCAN `SsaInternals::SsaImpl::Definition.definesAt/3#dispred#7eea4c8f` OUTPUT In.1, In.2, In.3, In.0
                        return r1

Evaluated relational algebra for predicate SsaInternals::DefImpl.hasIndexInBlock/3#dispred#31d295aa_1230#join_rhs@2be655s4 with tuple counts:
        5634706  ~1%    {4} r1 = SCAN `SsaInternals::DefImpl.hasIndexInBlock/3#dispred#31d295aa` OUTPUT In.1, In.2, In.3, In.0
                        return r1

Evaluated relational algebra for predicate SsaInternals::getDefImpl/1#1ed4f567@8afa36uu with tuple counts:
        4921319  ~2%    {2} r1 = JOIN `SsaInternals::SsaImpl::Definition.definesAt/3#dispred#7eea4c8f_1230#join_rhs` WITH `SsaInternals::DefImpl.hasIndexInBlock/3#dispred#31d295aa_1230#join_rhs` ON FIRST 3 OUTPUT Lhs.3, Rhs.3
                        return r1
```

Author: MathiasVP

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

@@ -1567,7 +1567,7 @@ private int countNumberOfBranchesUsingParameter(SwitchInstruction switch, Parame
         |
           exists(Ssa::UseImpl use | use.hasIndexInBlock(useblock, _, sv))
           or
-          exists(Ssa::DefImpl def | def.hasIndexInBlock(useblock, _, sv))
+          exists(Ssa::DefImpl def | def.hasIndexInBlock(sv, useblock, _))
         )
       )
   )
@@ -1814,7 +1814,7 @@ module IteratorFlow {
      */
     private predicate isIteratorWrite(Instruction write, Operand address) {
       exists(Ssa::DefImpl writeDef, IRBlock bb, int i |
-        writeDef.hasIndexInBlock(bb, i, _) and
+        writeDef.hasIndexInBlock(_, bb, i) and
         bb.getInstruction(i) = write and
         address = writeDef.getAddressOperand()
       )

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

@@ -191,7 +191,7 @@ abstract class DefImpl extends TDefImpl {
    * Holds if this definition (or use) has index `index` in block `block`,
    * and is a definition (or use) of the variable `sv`
    */
-  final predicate hasIndexInBlock(IRBlock block, int index, SourceVariable sv) {
+  final predicate hasIndexInBlock(SourceVariable sv, IRBlock block, int index) {
     this.hasIndexInBlock(block, index) and
     sv = this.getSourceVariable()
   }
@@ -891,12 +891,12 @@ private module SsaInput implements SsaImplCommon::InputSig<Location> {
   predicate variableWrite(BasicBlock bb, int i, SourceVariable v, boolean certain) {
     DataFlowImplCommon::forceCachingInSameStage() and
     (
-      exists(DefImpl def | def.hasIndexInBlock(bb, i, v) |
+      exists(DefImpl def | def.hasIndexInBlock(v, bb, i) |
         if def.isCertain() then certain = true else certain = false
       )
       or
       exists(GlobalDefImpl global |
-        global.hasIndexInBlock(bb, i, v) and
+        global.hasIndexInBlock(v, bb, i) and
         certain = true
       )
     )
@@ -934,10 +934,11 @@ module SsaCached {
 }
 
 /** Gets the `DefImpl` corresponding to `def`. */
+pragma[nomagic]
 private DefImpl getDefImpl(SsaImpl::Definition def) {
   exists(SourceVariable sv, IRBlock bb, int i |
     def.definesAt(sv, bb, i) and
-    result.hasIndexInBlock(bb, i, sv)
+    result.hasIndexInBlock(sv, bb, i)
   )
 }