Ruby: Fix two join orders

`getExplicitVisibilityModifier`

Before
[2022-08-17 09:03:16] (186s) Tuple counts for quick_eval#ff/2@2005f7ku after 113ms:
                      39910   ~0%     {2} r1 = SCAN Method#8b49e67f::Method#ff OUTPUT 0, In.0 'this'
                      39910   ~0%     {2} r2 = STREAM DEDUP r1
                      135     ~2%     {2} r3 = JOIN r2 WITH Call#ee92d596::CallImpl::getArgumentImpl#dispred#fbb_120#join_rhs ON FIRST 2 OUTPUT Rhs.2 'result', Lhs.1 'this'
                      134     ~0%     {2} r4 = JOIN r3 WITH Method#8b49e67f::VisibilityModifier#f ON FIRST 1 OUTPUT Lhs.1 'this', Lhs.0 'result'

                      39910   ~0%     {1} r5 = SCAN Method#8b49e67f::Method#ff OUTPUT In.0 'this'
                      39910   ~0%     {1} r6 = STREAM DEDUP r5
                      39910   ~0%     {2} r7 = JOIN r6 WITH Method#8b49e67f::Method::getName#dispred#ff ON FIRST 1 OUTPUT Lhs.0 'this', Rhs.1
                      39770   ~1%     {3} r8 = JOIN r7 WITH AST#a6718388::AstNode::getEnclosingModule#dispred#ff ON FIRST 1 OUTPUT Rhs.1, Lhs.0 'this', Lhs.1
                      1859722 ~0%     {3} r9 = JOIN r8 WITH project#Method#8b49e67f::isDeclaredIn#fff#2_10#join_rhs ON FIRST 1 OUTPUT Rhs.1 'result', Lhs.1 'this', Lhs.2
                      11757   ~0%     {4} r10 = JOIN r9 WITH Method#8b49e67f::VisibilityModifier::getMethodArgument#dispred#bf ON FIRST 1 OUTPUT Lhs.2, Lhs.1 'this', Lhs.0 'result', Rhs.1
                      24206   ~0%     {4} r11 = JOIN r10 WITH Constant#54e8b051::ConstantValue::getStringlikeValue#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.3, Rhs.1, Lhs.1 'this', Lhs.2 'result'
                      292     ~0%     {2} r12 = JOIN r11 WITH Expr#6fb2af19::Expr::getConstantValue#dispred#ff ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.3 'result'

                      426     ~0%     {2} r13 = r4 UNION r12
                                      return r13

After
[2022-08-17 09:30:31] (0s) Tuple counts for quick_eval#ff/2@e014fd45 after 5ms:
                      39910 ~0%     {1} r1 = SCAN Method#8b49e67f::Method#ff OUTPUT In.0 'this'
                      39910 ~0%     {1} r2 = STREAM DEDUP r1

                      134   ~1%     {2} r3 = JOIN r2 WITH Method#8b49e67f::VisibilityModifier::getMethodArgument#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.0 'this', Rhs.1 'result'

                      37225 ~1%     {3} r4 = JOIN r2 WITH project#Method#8b49e67f::methodIsDeclaredIn#ffff ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.0 'this'
                      382   ~1%     {2} r5 = JOIN r4 WITH Method#8b49e67f::modifiesIn#fff_120#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Rhs.2 'result'

                      516   ~0%     {2} r6 = r3 UNION r5
                                    return r6

`getVisibilityModifier()`

Before
[2022-08-17 09:16:18] (1s) Tuple counts for quick_eval#ff/2@0e9b6ctl after 52ms:
                      39910   ~0%     {1} r1 = SCAN Method#8b49e67f::Method#ff OUTPUT In.0 'this'
                      39910   ~0%     {1} r2 = STREAM DEDUP r1
                      424     ~0%     {2} r3 = JOIN r2 WITH Method#8b49e67f::Method::getExplicitVisibilityModifier#dispred#ff ON FIRST 1 OUTPUT Lhs.0 'this', Rhs.1 'result'

                      34953   ~0%     {3} r4 = JOIN quick_eval#ff#shared WITH Method#8b49e67f::isDeclaredIn#fff ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.0 'this'
                      2338    ~0%     {2} r5 = JOIN r4 WITH quick_eval#ff#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Rhs.2 'result'

                      3861    ~0%     {1} r6 = SCAN Method#8b49e67f::SingletonMethod#ff OUTPUT In.0 'this'
                      3861    ~0%     {1} r7 = STREAM DEDUP r6
                      3859    ~6%     {2} r8 = JOIN r7 WITH AST#a6718388::AstNode::getEnclosingModule#dispred#ff ON FIRST 1 OUTPUT Lhs.0 'this', Rhs.1
                      3859    ~6%     {2} r9 = JOIN r8 WITH Method#8b49e67f::SingletonMethod#ff ON FIRST 1 OUTPUT Lhs.0 'this', Lhs.1

                      0       ~0%     {3} r10 = JOIN r9 WITH Method#8b49e67f::VisibilityModifier::getMethodArgument#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1 'result', Lhs.1, Lhs.0 'this'

                      3859    ~0%     {3} r11 = JOIN r9 WITH Method#8b49e67f::SingletonMethod::getName#dispred#ff ON FIRST 1 OUTPUT Rhs.1, Lhs.0 'this', Lhs.1
                      7731    ~0%     {3} r12 = JOIN r11 WITH Constant#54e8b051::ConstantValue::getStringlikeValue#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2
                      1343055 ~1%     {3} r13 = JOIN r12 WITH Expr#6fb2af19::Expr::getConstantValue#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2
                      6546    ~2%     {3} r14 = JOIN r13 WITH Method#8b49e67f::VisibilityModifier::getMethodArgument#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1 'result', Lhs.2, Lhs.1 'this'

                      6546    ~2%     {3} r15 = r10 UNION r14
                      120     ~2%     {2} r16 = JOIN r15 WITH AST#a6718388::AstNode::getEnclosingModule#dispred#ff ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.0 'result'

                      2458    ~0%     {2} r17 = r5 UNION r16
                      2882    ~0%     {2} r18 = r3 UNION r17
                                      return r18

After
[2022-08-17 09:29:42] (2s) Tuple counts for quick_eval#ff/2@77b18cdg after 5ms:
                      39910 ~0%     {1} r1 = SCAN Method#8b49e67f::Method#ff OUTPUT In.0 'this'
                      39910 ~0%     {1} r2 = STREAM DEDUP r1
                      516   ~0%     {2} r3 = JOIN r2 WITH Method#8b49e67f::Method::getExplicitVisibilityModifier#dispred#ff ON FIRST 1 OUTPUT Lhs.0 'this', Rhs.1 'result'

                      3861  ~0%     {1} r4 = SCAN Method#8b49e67f::SingletonMethod#ff OUTPUT In.0 'this'
                      3861  ~0%     {1} r5 = STREAM DEDUP r4

                      0     ~0%     {2} r6 = JOIN r5 WITH Method#8b49e67f::VisibilityModifier::getMethodArgument#dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.0 'this', Rhs.1 'result'

                      516   ~0%     {2} r7 = r3 UNION r6

                      36845 ~0%     {3} r8 = JOIN quick_eval#ff#shared WITH Method#8b49e67f::isDeclaredIn#fff ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.0 'this'
                      2421  ~0%     {2} r9 = JOIN r8 WITH quick_eval#ff#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Rhs.2 'result'

                      2584  ~0%     {3} r10 = JOIN r5 WITH project#Method#8b49e67f::methodIsDeclaredIn#ffff ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.0 'this'
                      39    ~0%     {2} r11 = JOIN r10 WITH Method#8b49e67f::modifiesIn#fff_120#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Rhs.2 'result'

                      2460  ~1%     {2} r12 = r9 UNION r11
                      2976  ~0%     {2} r13 = r7 UNION r12
                                    return r13

Author: hvitved

ruby/ql/lib/codeql/ruby/ast/Method.qll

@@ -173,7 +173,7 @@ class Method extends MethodBase, TMethod {
     result = this.getExplicitVisibilityModifier()
     or
     not exists(this.getExplicitVisibilityModifier()) and
-    exists(Namespace n, int methodPos | isDeclaredIn(this, n, methodPos) |
+    exists(ModuleBase n, int methodPos | isDeclaredIn(this, n, methodPos) |
       // The relevant visibility modifier is the closest call that occurs before
       // the definition of `m` (typically this means higher up the file).
       result =
@@ -204,18 +204,35 @@ class Method extends MethodBase, TMethod {
   VisibilityModifier getExplicitVisibilityModifier() {
     result.getMethodArgument() = this
     or
-    isDeclaredIn(result, this.getEnclosingModule(), _) and
-    result.getMethodArgument().getConstantValue().getStringlikeValue() = this.getName()
+    exists(ModuleBase n, string name |
+      methodIsDeclaredIn(this, n, name) and
+      modifiesIn(result, n, name)
+    )
   }
 }
 
+pragma[nomagic]
+private predicate modifiesIn(VisibilityModifier vm, ModuleBase n, string name) {
+  n = vm.getEnclosingModule() and
+  name = vm.getMethodArgument().getConstantValue().getStringlikeValue()
+}
+
 /**
- * Holds if statement `m` is declared in namespace `n` at position `pos`.
+ * Holds if statement `s` is declared in namespace `n` at position `pos`.
  */
-pragma[noinline]
-private predicate isDeclaredIn(Stmt m, Namespace n, int pos) {
-  n = m.getEnclosingModule() and
-  n.getStmt(pos) = m
+pragma[nomagic]
+private predicate isDeclaredIn(Stmt s, ModuleBase n, int pos) {
+  n = s.getEnclosingModule() and
+  n.getStmt(pos) = s
+}
+
+/**
+ * Holds if method `m` with name `name` is declared in namespace `n`.
+ */
+pragma[nomagic]
+private predicate methodIsDeclaredIn(MethodBase m, ModuleBase n, string name) {
+  isDeclaredIn(m, n, _) and
+  name = m.getName()
 }
 
 /** A singleton method. */
@@ -273,11 +290,11 @@ class SingletonMethod extends MethodBase, TSingletonMethod {
   override predicate isPrivate() { super.isPrivate() }
 
   override VisibilityModifier getVisibilityModifier() {
-    result.getEnclosingModule() = this.getEnclosingModule() and
-    (
-      result.getMethodArgument() = this
-      or
-      result.getMethodArgument().getConstantValue().getStringlikeValue() = this.getName()
+    result.getMethodArgument() = this
+    or
+    exists(ModuleBase n, string name |
+      methodIsDeclaredIn(this, n, name) and
+      modifiesIn(result, n, name)
     )
   }
 }