[PATCH] D42266: [analyzer] Prevent AnalyzerStatsChecker from crash

[Peter Szecsi via Phabricator via cfe-commits]

szepet created this revision.
szepet added reviewers: NoQ, dcoughlin, xazax.hun.
Herald added subscribers: dkrupp, a.sidorin, rnkovacs, baloghadamsoftware, whisperity.

The checker marks the locations where the analyzer creates sinks. However, it can happen that the sink was created because of a loop which does not contain condition statement, only breaks in the body. The `exhausted block` is the block which should contain the condition but empty, in this case.
This change only emits this marking in order to avoid the undefined behavior.


Repository:
  rC Clang

https://reviews.llvm.org/D42266

Files:
  lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
  test/Analysis/analyzer-stats.c


Index: test/Analysis/analyzer-stats.c
===================================================================
--- test/Analysis/analyzer-stats.c
+++ test/Analysis/analyzer-stats.c
@@ -1,4 +1,4 @@
-// RUN: %clang_analyze_cc1 -analyzer-checker=core,deadcode.DeadStores,debug.Stats -verify -Wno-unreachable-code -analyzer-opt-analyze-nested-blocks %s
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,deadcode.DeadStores,debug.Stats -verify -Wno-unreachable-code -analyzer-opt-analyze-nested-blocks -analyzer-max-loop 4 %s
 
 int foo();
 
@@ -12,3 +12,19 @@
   a /= 4;
   return a;
 }
+
+
+int sink() // expected-warning-re{{sink -> Total CFGBlocks: {{[0-9]+}} | Unreachable CFGBlocks: 1 | Exhausted Block: yes | Empty WorkList: yes}}
+{
+  for (int i = 0; i < 10; ++i) // expected-warning {{(sink): The analyzer generated a sink at this point}}
+    ++i;
+
+  return 0;
+}
+
+int emptyConditionLoop() // expected-warning-re{{emptyConditionLoop -> Total CFGBlocks: {{[0-9]+}} | Unreachable CFGBlocks: 0 | Exhausted Block: yes | Empty WorkList: yes}}
+{
+  int num = 1;
+  for (;;)
+    num++;
+}
Index: lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
+++ lib/StaticAnalyzer/Checkers/AnalyzerStatsChecker.cpp
@@ -122,6 +122,8 @@
       E = CE.blocks_exhausted_end(); I != E; ++I) {
     const BlockEdge &BE =  I->first;
     const CFGBlock *Exit = BE.getDst();
+    if (Exit->empty())
+      continue;
     const CFGElement &CE = Exit->front();
     if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
       SmallString<128> bufI;


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