Author: Valeriy Savchenko Date: 2020-04-23T19:52:45+03:00 New Revision: a88025672f89374bfa584e2179a557f44d86da11
URL: https://github.com/llvm/llvm-project/commit/a88025672f89374bfa584e2179a557f44d86da11 DIFF: https://github.com/llvm/llvm-project/commit/a88025672f89374bfa584e2179a557f44d86da11.diff LOG: [analyzer] Consider array subscripts to be interesting lvalues. Static analyzer has a mechanism of clearing redundant nodes when analysis hits a certain threshold with a number of nodes in exploded graph (default is 1000). It is similar to GC and aims removing nodes not useful for analysis. Unfortunately nodes corresponding to array subscript expressions (that actively participate in data propagation) get removed during the cleanup. This might prevent the analyzer from generating useful notes about where it thinks the data came from. This fix is pretty much consistent with the way analysis works already. Lvalue "interestingness" stands for the analyzer's possibility of tracking values through them. Differential Revision: https://reviews.llvm.org/D78638 Added: clang/test/Analysis/CheckThatArraySubsciptNodeIsNotCollected.cpp Modified: clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp Removed: ################################################################################ diff --git a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp index c4838492271c..635495e9bf60 100644 --- a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp +++ b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp @@ -50,9 +50,8 @@ ExplodedGraph::~ExplodedGraph() = default; bool ExplodedGraph::isInterestingLValueExpr(const Expr *Ex) { if (!Ex->isLValue()) return false; - return isa<DeclRefExpr>(Ex) || - isa<MemberExpr>(Ex) || - isa<ObjCIvarRefExpr>(Ex); + return isa<DeclRefExpr>(Ex) || isa<MemberExpr>(Ex) || + isa<ObjCIvarRefExpr>(Ex) || isa<ArraySubscriptExpr>(Ex); } bool ExplodedGraph::shouldCollect(const ExplodedNode *node) { diff --git a/clang/test/Analysis/CheckThatArraySubsciptNodeIsNotCollected.cpp b/clang/test/Analysis/CheckThatArraySubsciptNodeIsNotCollected.cpp new file mode 100644 index 000000000000..b1c0f339bd56 --- /dev/null +++ b/clang/test/Analysis/CheckThatArraySubsciptNodeIsNotCollected.cpp @@ -0,0 +1,40 @@ +// RUN: %clang_analyze_cc1 -analyzer-checker=core -analyzer-output=text -verify %s + +class A { +public: + int method(); +}; + +A *foo(); +void bar(A *); + +int index; + +// We want to check here that the notes about the origins of the null pointer +// (array[index] = foo()) will get to the final report. +// +// The analyzer used to drop exploded nodes for array subscripts when it was +// time to collect redundant nodes. This GC-like mechanism kicks in only when +// the exploded graph is large enough (>1K nodes). For this reason, 'index' +// is a global variable, and the sink point is inside of a loop. + +void test() { + A *array[42]; + A *found; + + for (index = 0; (array[index] = foo()); ++index) { // expected-note {{Loop condition is false. Execution continues on line 34}} + // expected-note@-1 {{Value assigned to 'index'}} + // expected-note@-2 {{Assigning value}} + // expected-note@-3 {{Assuming pointer value is null}} + if (array[0]) + break; + } + + do { + found = array[index]; // expected-note {{Null pointer value stored to 'found'}} + + if (found->method()) // expected-warning {{Called C++ object pointer is null [core.CallAndMessage]}} + // expected-note@-1 {{Called C++ object pointer is null}} + bar(found); + } while (--index); +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
