C++: Adapt to parameterized SSA implementation

Author: hvitved

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

@@ -4,7 +4,7 @@
  */
 
 /** Provides the input specification of the SSA implementation. */
-signature module SsaInputSig {
+signature module InputSig {
   /**
    * A basic block, that is, a maximal straight-line sequence of control flow nodes
    * without branches or joins.
@@ -28,7 +28,7 @@ signature module SsaInputSig {
    * ```
    *
    * The basic block starting on line 2 is an immediate dominator of
-   * the basic block online 4 (all paths from the entry point of `M`
+   * the basic block on line 4 (all paths from the entry point of `M`
    * to `return s.Length;` must go through the null check.
    */
   BasicBlock getImmediateBasicBlockDominator(BasicBlock bb);
@@ -82,7 +82,7 @@ signature module SsaInputSig {
  * NB: If this predicate is exposed, it should be cached.
  * ```
  */
-module Make<SsaInputSig Input> {
+module Make<InputSig Input> {
   private import Input
 
   private BasicBlock getABasicBlockPredecessor(BasicBlock bb) {

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

@@ -1,10 +1,10 @@
-import SsaImplCommon
 private import cpp as Cpp
 private import semmle.code.cpp.ir.IR
 private import DataFlowUtil
 private import DataFlowImplCommon as DataFlowImplCommon
 private import semmle.code.cpp.models.interfaces.Allocation as Alloc
 private import semmle.code.cpp.models.interfaces.DataFlow as DataFlow
+private import SsaImplCommon as SsaImplCommon
 
 private module SourceVariables {
   private newtype TSourceVariable =
@@ -38,8 +38,6 @@ private module SourceVariables {
   }
 }
 
-import SourceVariables
-
 cached
 private newtype TDefOrUse =
   TExplicitDef(Instruction store) { explicitWrite(_, store, _) } or
@@ -86,7 +84,7 @@ abstract class Def extends DefOrUse {
   Instruction getInstruction() { result = store }
 
   /** Gets the variable that is defined by this definition. */
-  abstract SourceVariable getSourceVariable();
+  abstract SourceVariables::SourceVariable getSourceVariable();
 
   /** Holds if this definition is guaranteed to happen. */
   abstract predicate isCertain();
@@ -103,10 +101,10 @@ abstract class Def extends DefOrUse {
 private class ExplicitDef extends Def, TExplicitDef {
   ExplicitDef() { this = TExplicitDef(store) }
 
-  override SourceVariable getSourceVariable() {
+  override SourceVariables::SourceVariable getSourceVariable() {
     exists(VariableInstruction var |
       explicitWrite(_, this.getInstruction(), var) and
-      result.(SourceIRVariable).getIRVariable() = var.getIRVariable()
+      result.(SourceVariables::SourceIRVariable).getIRVariable() = var.getIRVariable()
     )
   }
 
@@ -116,11 +114,11 @@ private class ExplicitDef extends Def, TExplicitDef {
 private class ParameterDef extends Def, TInitializeParam {
   ParameterDef() { this = TInitializeParam(store) }
 
-  override SourceVariable getSourceVariable() {
-    result.(SourceIRVariable).getIRVariable() =
+  override SourceVariables::SourceVariable getSourceVariable() {
+    result.(SourceVariables::SourceIRVariable).getIRVariable() =
       store.(InitializeParameterInstruction).getIRVariable()
     or
-    result.(SourceIRVariableIndirection).getUnderlyingIRVariable() =
+    result.(SourceVariables::SourceIRVariableIndirection).getUnderlyingIRVariable() =
       store.(InitializeIndirectionInstruction).getIRVariable()
   }
 
@@ -138,7 +136,7 @@ abstract class Use extends DefOrUse {
   override string toString() { result = "Use" }
 
   /** Gets the variable that is used by this use. */
-  abstract SourceVariable getSourceVariable();
+  abstract SourceVariables::SourceVariable getSourceVariable();
 
   override IRBlock getBlock() { result = use.getUse().getBlock() }
 
@@ -148,23 +146,26 @@ abstract class Use extends DefOrUse {
 private class ExplicitUse extends Use, TExplicitUse {
   ExplicitUse() { this = TExplicitUse(use) }
 
-  override SourceVariable getSourceVariable() {
+  override SourceVariables::SourceVariable getSourceVariable() {
     exists(VariableInstruction var |
       use.getDef() = var and
       if use.getUse() instanceof ReadSideEffectInstruction
-      then result.(SourceIRVariableIndirection).getUnderlyingIRVariable() = var.getIRVariable()
-      else result.(SourceIRVariable).getIRVariable() = var.getIRVariable()
+      then
+        result.(SourceVariables::SourceIRVariableIndirection).getUnderlyingIRVariable() =
+          var.getIRVariable()
+      else result.(SourceVariables::SourceIRVariable).getIRVariable() = var.getIRVariable()
     )
   }
 }
 
 private class ReturnParameterIndirection extends Use, TReturnParamIndirection {
   ReturnParameterIndirection() { this = TReturnParamIndirection(use) }
 
-  override SourceVariable getSourceVariable() {
+  override SourceVariables::SourceVariable getSourceVariable() {
     exists(ReturnIndirectionInstruction ret |
       returnParameterIndirection(use, ret) and
-      result.(SourceIRVariableIndirection).getUnderlyingIRVariable() = ret.getIRVariable()
+      result.(SourceVariables::SourceIRVariableIndirection).getUnderlyingIRVariable() =
+        ret.getIRVariable()
     )
   }
 }
@@ -610,27 +611,45 @@ private module Cached {
 
 import Cached
 
-/**
- * Holds if the `i`'th write in block `bb` writes to the variable `v`.
- * `certain` is `true` if the write is guaranteed to overwrite the entire variable.
- */
-predicate variableWrite(IRBlock bb, int i, SourceVariable v, boolean certain) {
-  DataFlowImplCommon::forceCachingInSameStage() and
-  exists(Def def |
-    def.hasIndexInBlock(bb, i) and
-    v = def.getSourceVariable() and
-    (if def.isCertain() then certain = true else certain = false)
-  )
-}
+private module SsaInput implements SsaImplCommon::InputSig {
+  private import semmle.code.cpp.ir.IR
 
-/**
- * Holds if the `i`'th read in block `bb` reads to the variable `v`.
- * `certain` is `true` if the read is guaranteed. For C++, this is always the case.
- */
-predicate variableRead(IRBlock bb, int i, SourceVariable v, boolean certain) {
-  exists(Use use |
-    use.hasIndexInBlock(bb, i) and
-    v = use.getSourceVariable() and
-    certain = true
-  )
+  class BasicBlock = IRBlock;
+
+  class SourceVariable = SourceVariables::SourceVariable;
+
+  BasicBlock getImmediateBasicBlockDominator(BasicBlock bb) { result.immediatelyDominates(bb) }
+
+  BasicBlock getABasicBlockSuccessor(BasicBlock bb) { result = bb.getASuccessor() }
+
+  class ExitBasicBlock extends IRBlock {
+    ExitBasicBlock() { this.getLastInstruction() instanceof ExitFunctionInstruction }
+  }
+
+  /**
+   * Holds if the `i`'th write in block `bb` writes to the variable `v`.
+   * `certain` is `true` if the write is guaranteed to overwrite the entire variable.
+   */
+  predicate variableWrite(BasicBlock bb, int i, SourceVariable v, boolean certain) {
+    DataFlowImplCommon::forceCachingInSameStage() and
+    exists(Def def |
+      def.hasIndexInBlock(bb, i) and
+      v = def.getSourceVariable() and
+      (if def.isCertain() then certain = true else certain = false)
+    )
+  }
+
+  /**
+   * Holds if the `i`'th read in block `bb` reads to the variable `v`.
+   * `certain` is `true` if the read is guaranteed. For C++, this is always the case.
+   */
+  predicate variableRead(BasicBlock bb, int i, SourceVariable v, boolean certain) {
+    exists(Use use |
+      use.hasIndexInBlock(bb, i) and
+      v = use.getSourceVariable() and
+      certain = true
+    )
+  }
 }
+
+import SsaImplCommon::Make<SsaInput>