feat(dataflow): Add initial dataflow lib

Author: GeekMasher

ql/lib/codeql/bicep/DataFlow.qll

@@ -0,0 +1,16 @@
+/**
+ * Provides classes for performing local (intra-procedural) and
+ * global (inter-procedural) data flow analyses.
+ */
+
+ import codeql.Locations
+
+ /**
+  * Provides classes for performing local (intra-procedural) and
+  * global (inter-procedural) data flow analyses.
+  */
+ module DataFlow {
+   private import codeql.dataflow.DataFlow
+   import DataFlowMake<Location, BicepDataFlow>
+   import Public
+ }

ql/lib/codeql/bicep/dataflow/DataFlow.qll

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+private import codeql.dataflow.DataFlow
+private import codeql.bicep.AST
+private import codeql.bicep.CFG as Cfg
+private import codeql.bicep.dataflow.Ssa as Ssa
+private import codeql.Locations

ql/lib/codeql/bicep/dataflow/Ssa.qll

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+/**
+ * Provides the module `Ssa` for working with static single assignment (SSA) form.
+ */
+
+/**
+ * Provides classes for working with static single assignment (SSA) form.
+ */
+module Ssa {
+  private import bicep
+  private import codeql.bicep.controlflow.BasicBlocks
+  private import codeql.bicep.controlflow.ControlFlowGraph
+  private import codeql.bicep.controlflow.internal.ControlFlowGraphImpl as CfgImpl
+  private import internal.SsaImpl as SsaImpl
+
+  class Variable = SsaImpl::SsaInput::SourceVariable;
+
+  class Definition extends SsaImpl::Definition {
+    final CfgNode getControlFlowNode() {
+      exists(BasicBlock bb, int i | this.definesAt(_, bb, i) | result = bb.getNode(i))
+    }
+
+    final CfgNode getARead() { result = SsaImpl::getARead(this) }
+
+    final CfgNode getAFirstRead() { SsaImpl::firstRead(this, result) }
+  }
+
+  class WriteDefinition extends Definition, SsaImpl::WriteDefinition {
+    final CfgNode getControlFlowNode() {
+      exists(BasicBlock bb, int i | this.definesAt(_, bb, i) | result = bb.getNode(i))
+    }
+
+    final CfgNode getARead() { result = SsaImpl::getARead(this) }
+
+    cached
+    override Location getLocation() {
+      exists(BasicBlock bb, int i |
+        this.definesAt(_, bb, i) and
+        result = bb.getNode(i).getLocation()
+      )
+    }
+  }
+}