[PATCH] D151071: [clang][dataflow] Fix a null pointer crash in `computeBlockInputState()`.

[Martin Böhme via Phabricator via cfe-commits]

mboehme created this revision.
Herald added subscribers: martong, xazax.hun.
Herald added a reviewer: NoQ.
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mboehme requested review of this revision.
Herald added a project: clang.
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The crash was due to unconditionally calling
`Block.succ_begin()->getReachableBlock()->hasNoReturnElement()`, but
`getReachableBlock()` can return null now that we have turned
`PruneTriviallyFalseEdges` on.

This patch adds two tests that crash without the fix.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D151071

Files:
  clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
  clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp


Index: clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
+++ clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
@@ -296,6 +296,22 @@
                                  UnorderedElementsAre("foo"))))));
 }
 
+TEST_F(NoreturnDestructorTest,
+       ConditionalOperatorConstantCondition_LeftBranchReturns) {
+  std::string Code = R"(
+    #include "noreturn_destructor_test_defs.h"
+
+    void target() {
+      int value = true ? foo() : Fatal().bar();
+      (void)0;
+      // [[p]]
+    }
+  )";
+  runDataflow(Code, UnorderedElementsAre(IsStringMapEntry(
+                        "p", HoldsFunctionCallLattice(HasCalledFunctions(
+                                 UnorderedElementsAre("foo"))))));
+}
+
 TEST_F(NoreturnDestructorTest, ConditionalOperatorRightBranchReturns) {
   std::string Code = R"(
     #include "noreturn_destructor_test_defs.h"
@@ -311,6 +327,22 @@
                                  UnorderedElementsAre("foo"))))));
 }
 
+TEST_F(NoreturnDestructorTest,
+       ConditionalOperatorConstantCondition_RightBranchReturns) {
+  std::string Code = R"(
+    #include "noreturn_destructor_test_defs.h"
+
+    void target() {
+      int value = false ? Fatal().bar() : foo();
+      (void)0;
+      // [[p]]
+    }
+  )";
+  runDataflow(Code, UnorderedElementsAre(IsStringMapEntry(
+                        "p", HoldsFunctionCallLattice(HasCalledFunctions(
+                                 UnorderedElementsAre("foo"))))));
+}
+
 TEST_F(NoreturnDestructorTest, ConditionalOperatorNestedBranchesDoNotReturn) {
   std::string Code = R"(
     #include "noreturn_destructor_test_defs.h"
Index: clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -219,7 +219,8 @@
     // operator includes a branch that contains a noreturn destructor call.
     //
     // See `NoreturnDestructorTest` for concrete examples.
-    if (Block.succ_begin()->getReachableBlock()->hasNoReturnElement()) {
+    if (Block.succ_begin()->getReachableBlock() != nullptr &&
+        Block.succ_begin()->getReachableBlock()->hasNoReturnElement()) {
       auto &StmtToBlock = AC.CFCtx.getStmtToBlock();
       auto StmtBlock = StmtToBlock.find(Block.getTerminatorStmt());
       assert(StmtBlock != StmtToBlock.end());


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