Merge pull request #14711 from aschackmull/shared/rangeutil-share2

Java/C++/RangeAnalysis: Move a couple of utility predicates to shared qlpack

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/SemanticCFG.qll

@@ -12,9 +12,6 @@ class SemBasicBlock extends Specific::BasicBlock {
   /** Holds if this block (transitively) dominates `otherblock`. */
   final predicate bbDominates(SemBasicBlock otherBlock) { Specific::bbDominates(this, otherBlock) }
 
-  /** Holds if this block has dominance information. */
-  final predicate hasDominanceInformation() { Specific::hasDominanceInformation(this) }
-
   /** Gets an expression that is evaluated in this basic block. */
   final SemExpr getAnExpr() { result.getBasicBlock() = this }
 

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/SemanticExprSpecific.qll

@@ -122,8 +122,6 @@ module SemanticExprConfig {
     dominator.dominates(dominated)
   }
 
-  predicate hasDominanceInformation(BasicBlock block) { any() }
-
   private predicate id(Cpp::Locatable x, Cpp::Locatable y) { x = y }
 
   private predicate idOf(Cpp::Locatable x, int y) = equivalenceRelation(id/2)(x, y)

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/SemanticGuard.qll

@@ -35,32 +35,4 @@ predicate semImplies_v2(SemGuard g1, boolean b1, SemGuard g2, boolean b2) {
   Specific::implies_v2(g1, b1, g2, b2)
 }
 
-/**
- * Holds if `guard` directly controls the position `controlled` with the
- * value `testIsTrue`.
- */
-pragma[nomagic]
-predicate semGuardDirectlyControlsSsaRead(
-  SemGuard guard, SemSsaReadPosition controlled, boolean testIsTrue
-) {
-  guard.directlyControls(controlled.(SemSsaReadPositionBlock).getBlock(), testIsTrue)
-  or
-  exists(SemSsaReadPositionPhiInputEdge controlledEdge | controlledEdge = controlled |
-    guard.directlyControls(controlledEdge.getOrigBlock(), testIsTrue) or
-    guard.hasBranchEdge(controlledEdge.getOrigBlock(), controlledEdge.getPhiBlock(), testIsTrue)
-  )
-}
-
-/**
- * Holds if `guard` controls the position `controlled` with the value `testIsTrue`.
- */
-predicate semGuardControlsSsaRead(SemGuard guard, SemSsaReadPosition controlled, boolean testIsTrue) {
-  semGuardDirectlyControlsSsaRead(guard, controlled, testIsTrue)
-  or
-  exists(SemGuard guard0, boolean testIsTrue0 |
-    semImplies_v2(guard0, testIsTrue0, guard, testIsTrue) and
-    semGuardControlsSsaRead(guard0, controlled, testIsTrue0)
-  )
-}
-
 SemGuard semGetComparisonGuard(SemRelationalExpr e) { result = Specific::comparisonGuard(e) }

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/SemanticSSA.qll

@@ -63,36 +63,3 @@ class SemSsaReadPositionBlock extends SemSsaReadPosition {
 
   SemExpr getAnExpr() { result = this.getBlock().getAnExpr() }
 }
-
-/**
- * Holds if `inp` is an input to `phi` along a back edge.
- */
-predicate semBackEdge(SemSsaPhiNode phi, SemSsaVariable inp, SemSsaReadPositionPhiInputEdge edge) {
-  edge.phiInput(phi, inp) and
-  // Conservatively assume that every edge is a back edge if we don't have dominance information.
-  (
-    phi.getBasicBlock().bbDominates(edge.getOrigBlock()) or
-    irreducibleSccEdge(edge.getOrigBlock(), phi.getBasicBlock()) or
-    not edge.getOrigBlock().hasDominanceInformation()
-  )
-}
-
-/**
- * Holds if the edge from b1 to b2 is part of a multiple-entry cycle in an irreducible control flow
- * graph.
- *
- * An ireducible control flow graph is one where the usual dominance-based back edge detection does
- * not work, because there is a cycle with multiple entry points, meaning there are
- * mutually-reachable basic blocks where neither dominates the other. For such a graph, we first
- * remove all detectable back-edges using the normal condition that the predecessor block is
- * dominated by the successor block, then mark all edges in a cycle in the resulting graph as back
- * edges.
- */
-private predicate irreducibleSccEdge(SemBasicBlock b1, SemBasicBlock b2) {
-  trimmedEdge(b1, b2) and trimmedEdge+(b2, b1)
-}
-
-private predicate trimmedEdge(SemBasicBlock pred, SemBasicBlock succ) {
-  pred.getASuccessor() = succ and
-  not succ.bbDominates(pred)
-}

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/analysis/RangeAnalysisImpl.qll

@@ -72,14 +72,12 @@ module Sem implements Semantic {
 
   class BasicBlock = SemBasicBlock;
 
+  BasicBlock getABasicBlockSuccessor(BasicBlock bb) { result = bb.getASuccessor() }
+
   class Guard = SemGuard;
 
   predicate implies_v2 = semImplies_v2/4;
 
-  predicate guardDirectlyControlsSsaRead = semGuardDirectlyControlsSsaRead/3;
-
-  predicate guardControlsSsaRead = semGuardControlsSsaRead/3;
-
   class Type = SemType;
 
   class IntegerType = SemIntegerType;
@@ -100,8 +98,6 @@ module Sem implements Semantic {
 
   class SsaReadPositionBlock = SemSsaReadPositionBlock;
 
-  predicate backEdge = semBackEdge/3;
-
   predicate conversionCannotOverflow(Type fromType, Type toType) {
     SemanticType::conversionCannotOverflow(fromType, toType)
   }

cpp/ql/lib/semmle/code/cpp/rangeanalysis/new/internal/semantic/analysis/SignAnalysisCommon.qll

@@ -294,7 +294,7 @@ module SignAnalysis<DeltaSig D, UtilSig<Sem, D> Utils> {
   ) {
     exists(boolean testIsTrue, SemRelationalExpr comp |
       pos.hasReadOfVar(v) and
-      semGuardControlsSsaRead(semGetComparisonGuard(comp), pos, testIsTrue) and
+      guardControlsSsaRead(semGetComparisonGuard(comp), pos, testIsTrue) and
       not unknownSign(lowerbound)
     |
       testIsTrue = true and
@@ -318,7 +318,7 @@ module SignAnalysis<DeltaSig D, UtilSig<Sem, D> Utils> {
   ) {
     exists(boolean testIsTrue, SemRelationalExpr comp |
       pos.hasReadOfVar(v) and
-      semGuardControlsSsaRead(semGetComparisonGuard(comp), pos, testIsTrue) and
+      guardControlsSsaRead(semGetComparisonGuard(comp), pos, testIsTrue) and
       not unknownSign(upperbound)
     |
       testIsTrue = true and
@@ -343,7 +343,7 @@ module SignAnalysis<DeltaSig D, UtilSig<Sem, D> Utils> {
   private predicate eqBound(SemExpr eqbound, SemSsaVariable v, SemSsaReadPosition pos, boolean isEq) {
     exists(SemGuard guard, boolean testIsTrue, boolean polarity, SemExpr e |
       pos.hasReadOfVar(pragma[only_bind_into](v)) and
-      semGuardControlsSsaRead(guard, pragma[only_bind_into](pos), testIsTrue) and
+      guardControlsSsaRead(guard, pragma[only_bind_into](pos), testIsTrue) and
       e = ssaRead(pragma[only_bind_into](v), D::fromInt(0)) and
       guard.isEquality(eqbound, e, polarity) and
       isEq = polarity.booleanXor(testIsTrue).booleanNot() and