[clang] a9e90f7 - [clang][dataflow] Fix a null pointer crash in `computeBlockInputState()`.

[Martin Braenne via cfe-commits]

Author: Martin Braenne
Date: 2023-05-22T12:19:55Z
New Revision: a9e90f7994222dde987154ed009504afbf3c2166

URL: https://github.com/llvm/llvm-project/commit/a9e90f7994222dde987154ed009504afbf3c2166
DIFF: https://github.com/llvm/llvm-project/commit/a9e90f7994222dde987154ed009504afbf3c2166.diff

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

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.

Reviewed By: ymandel

Differential Revision: https://reviews.llvm.org/D151071

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
index 4fc8f27ffc9b2..37dd7081ae986 100644
--- a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -216,7 +216,8 @@ computeBlockInputState(const CFGBlock &Block, AnalysisContext &AC) {
     // 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());

diff  --git a/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp b/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
index 30aef86e7a26e..5bfb9e53778b0 100644
--- a/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
@@ -296,6 +296,22 @@ TEST_F(NoreturnDestructorTest, ConditionalOperatorLeftBranchReturns) {
                                  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 @@ TEST_F(NoreturnDestructorTest, ConditionalOperatorRightBranchReturns) {
                                  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"