JavaScript: Make implicit inits of module and exports source nodes.

Max Schaefer · Max Schaefer · commit 702192c316ce · 2020-09-02T19:52:13.000+01:00
This is instead of making every access to those variables source nodes, and fixes a regression in `DeadStoreOfProperty`.
diff --git a/javascript/ql/src/ApiGraphs.qll b/javascript/ql/src/ApiGraphs.qll
@@ -334,8 +334,7 @@ module API {
           exports(m, _, _)
           or
           exists(NodeModule nm | nm = mod |
-            exists(nm.getModuleVariable().getAnAccess()) or
-            exists(nm.getExportsVariable().getAnAccess())
+            exists(SSA::implicitInit([nm.getModuleVariable(), nm.getExportsVariable()]))
           )
         )
       } or
@@ -529,13 +528,13 @@ module API {
     cached
     predicate use(Feature nd, DataFlow::SourceNode ref) {
       exists(string m, Module mod | nd = MkModule(m) and mod = importableModule(m) |
-        ref = mod.(NodeModule).getModuleVariable().getAnAccess().flow()
+        ref = DataFlow::ssaDefinitionNode(SSA::implicitInit(mod.(NodeModule).getModuleVariable()))
         or
         ref = DataFlow::parameterNode(mod.(AmdModule).getDefine().getModuleParameter())
       )
       or
       exists(string m, Module mod | nd = MkModuleExport(m) and mod = importableModule(m) |
-        ref = mod.(NodeModule).getExportsVariable().getAnAccess().flow()
+        ref = DataFlow::ssaDefinitionNode(SSA::implicitInit(mod.(NodeModule).getExportsVariable()))
         or
         ref = DataFlow::parameterNode(mod.(AmdModule).getDefine().getExportsParameter())
       )
@@ -753,14 +752,14 @@ private module Label {
   string promised() { result = "promised" }
 }
 
+/**
+ * A CommonJS `module` or `exports` variable, considered as a source node.
+ */
 private class AdditionalSourceNode extends DataFlow::SourceNode::Range {
   AdditionalSourceNode() {
-    exists(NodeModule m, RValue v |
-      v = m.getModuleVariable().getAnAccess()
-      or
-      v = m.getExportsVariable().getAnAccess()
-    |
-      this = v.flow()
+    exists(NodeModule m, Variable v |
+      v in [m.getModuleVariable(), m.getExportsVariable()] and
+      this = DataFlow::ssaDefinitionNode(SSA::implicitInit(v))
     )
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -334,8 +334,7 @@ module API {`
`334`	`334`	`exports(m, _, _)`
`335`	`335`	`or`
`336`	`336`	`exists(NodeModule nm \| nm = mod \|`
`337`		`- exists(nm.getModuleVariable().getAnAccess()) or`
`338`		`- exists(nm.getExportsVariable().getAnAccess())`
	`337`	`+ exists(SSA::implicitInit([nm.getModuleVariable(), nm.getExportsVariable()]))`
`339`	`338`	`)`
`340`	`339`	`)`
`341`	`340`	`} or`
`@@ -529,13 +528,13 @@ module API {`
`529`	`528`	`cached`
`530`	`529`	`predicate use(Feature nd, DataFlow::SourceNode ref) {`
`531`	`530`	`exists(string m, Module mod \| nd = MkModule(m) and mod = importableModule(m) \|`
`532`		`- ref = mod.(NodeModule).getModuleVariable().getAnAccess().flow()`
	`531`	`+ ref = DataFlow::ssaDefinitionNode(SSA::implicitInit(mod.(NodeModule).getModuleVariable()))`
`533`	`532`	`or`
`534`	`533`	`ref = DataFlow::parameterNode(mod.(AmdModule).getDefine().getModuleParameter())`
`535`	`534`	`)`
`536`	`535`	`or`
`537`	`536`	`exists(string m, Module mod \| nd = MkModuleExport(m) and mod = importableModule(m) \|`
`538`		`- ref = mod.(NodeModule).getExportsVariable().getAnAccess().flow()`
	`537`	`+ ref = DataFlow::ssaDefinitionNode(SSA::implicitInit(mod.(NodeModule).getExportsVariable()))`
`539`	`538`	`or`
`540`	`539`	`ref = DataFlow::parameterNode(mod.(AmdModule).getDefine().getExportsParameter())`
`541`	`540`	`)`
`@@ -753,14 +752,14 @@ private module Label {`
`753`	`752`	`string promised() { result = "promised" }`
`754`	`753`	`}`
`755`	`754`
	`755`	`+/**`
	`756`	+ * A CommonJS `module` or `exports` variable, considered as a source node.
	`757`	`+ */`
`756`	`758`	`private class AdditionalSourceNode extends DataFlow::SourceNode::Range {`
`757`	`759`	`AdditionalSourceNode() {`
`758`		`- exists(NodeModule m, RValue v \|`
`759`		`- v = m.getModuleVariable().getAnAccess()`
`760`		`- or`
`761`		`- v = m.getExportsVariable().getAnAccess()`
`762`		`- \|`
`763`		`- this = v.flow()`
	`760`	`+ exists(NodeModule m, Variable v \|`
	`761`	`+ v in [m.getModuleVariable(), m.getExportsVariable()] and`
	`762`	`+ this = DataFlow::ssaDefinitionNode(SSA::implicitInit(v))`
`764`	`763`	`)`
`765`	`764`	`}`
`766`	`765`	`}`