vsavchenko updated this revision to Diff 335795. vsavchenko added a comment.
Support nested init lists Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D99262/new/ https://reviews.llvm.org/D99262 Files: clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp clang/test/Analysis/dead-stores.c
Index: clang/test/Analysis/dead-stores.c =================================================================== --- clang/test/Analysis/dead-stores.c +++ clang/test/Analysis/dead-stores.c @@ -635,3 +635,44 @@ volatile int v; v = 0; // no warning } + +struct Foo { + int x; + int y; +}; + +struct Foo rdar34122265_getFoo(void); + +int rdar34122265_test(int input) { + // This is allowed for defensive programming. + struct Foo foo = {0, 0}; + if (input > 0) { + foo = rdar34122265_getFoo(); + } else { + return 0; + } + return foo.x + foo.y; +} + +void rdar34122265_test_cast() { + // This is allowed for defensive programming. + struct Foo foo = {0, 0}; + (void)foo; +} + +struct Bar { + struct Foo x, y; +}; + +struct Bar rdar34122265_getBar(void); + +int rdar34122265_test_nested(int input) { + // This is allowed for defensive programming. + struct Bar bar = {{0, 0}, {0, 0}}; + if (input > 0) { + bar = rdar34122265_getBar(); + } else { + return 0; + } + return bar.x.x + bar.y.y; +} Index: clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp =================================================================== --- clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp +++ clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp @@ -11,17 +11,18 @@ // //===----------------------------------------------------------------------===// -#include "clang/Lex/Lexer.h" -#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" #include "clang/AST/ASTContext.h" #include "clang/AST/Attr.h" #include "clang/AST/ParentMap.h" #include "clang/AST/RecursiveASTVisitor.h" #include "clang/Analysis/Analyses/LiveVariables.h" +#include "clang/Lex/Lexer.h" +#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h" #include "clang/StaticAnalyzer/Core/Checker.h" #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h" #include "llvm/ADT/BitVector.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallString.h" #include "llvm/Support/SaveAndRestore.h" @@ -408,15 +409,17 @@ // Special case: check for initializations with constants. // // e.g. : int x = 0; + // struct A = {0, 1}; + // struct B = {{0}, {1, 2}}; // // If x is EVER assigned a new value later, don't issue // a warning. This is because such initialization can be // due to defensive programming. - if (E->isEvaluatable(Ctx)) + if (isConstant(E)) return; if (const DeclRefExpr *DRE = - dyn_cast<DeclRefExpr>(E->IgnoreParenCasts())) + dyn_cast<DeclRefExpr>(E->IgnoreParenCasts())) if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) { // Special case: check for initialization from constant // variables. @@ -444,6 +447,29 @@ } } } + +private: + /// Return true if the given init list can be interpreted as constant + bool isConstant(const InitListExpr *Candidate) const { + // We consider init list to be constant if each member of the list can be + // interpreted as constant. + return llvm::all_of(Candidate->inits(), + [this](const Expr *Init) { return isConstant(Init); }); + } + + /// Return true if the given expression can be interpreted as constant + bool isConstant(const Expr *E) const { + // It looks like E itself is a constant + if (E->isEvaluatable(Ctx)) + return true; + + // We should also allow defensive initialization of structs, i.e. { 0 } + if (const auto *ILE = dyn_cast<InitListExpr>(E->IgnoreParenCasts())) { + return isConstant(ILE); + } + + return false; + } }; } // end anonymous namespace
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