From c56c004e0b8030e8ca8614e7febe581221938b75 Mon Sep 17 00:00:00 2001 From: Ted Kremenek Date: Wed, 23 Feb 2011 05:11:46 +0000 Subject: Teach CFGBuilder about null pointer constants in conditionals, and how they can be used to prune branches. Fixes false null pointer dereference warning in PR 8183. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126305 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/CFG.cpp | 14 +++++++++++--- test/Sema/exprs.c | 8 ++++++++ 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp index 0957875fd2..90b3120cd2 100644 --- a/lib/Analysis/CFG.cpp +++ b/lib/Analysis/CFG.cpp @@ -17,6 +17,7 @@ #include "clang/AST/DeclCXX.h" #include "clang/AST/StmtVisitor.h" #include "clang/AST/PrettyPrinter.h" +#include "clang/AST/CharUnits.h" #include "llvm/Support/GraphWriter.h" #include "llvm/Support/Allocator.h" #include "llvm/Support/Format.h" @@ -413,9 +414,16 @@ private: Expr::EvalResult Result; if (!S->isTypeDependent() && !S->isValueDependent() && - S->Evaluate(Result, *Context) && Result.Val.isInt()) - return Result.Val.getInt().getBoolValue(); - + S->Evaluate(Result, *Context)) { + if (Result.Val.isInt()) + return Result.Val.getInt().getBoolValue(); + if (Result.Val.isLValue()) { + Expr *e = Result.Val.getLValueBase(); + const CharUnits &c = Result.Val.getLValueOffset(); + if (!e && c.isZero()) + return false; + } + } return TryResult(); } }; diff --git a/test/Sema/exprs.c b/test/Sema/exprs.c index 5917e085ea..0d6c5488de 100644 --- a/test/Sema/exprs.c +++ b/test/Sema/exprs.c @@ -18,6 +18,14 @@ int test_pr8876() { return 0; } +// PR 8183 - Handle null pointer constants on the left-side of the '&&', and reason about +// this when determining the reachability of the null pointer dereference on the right side. +void pr8183(unsigned long long test) +{ + (void)((((void*)0)) && (*((unsigned long long*)(((void*)0))) = ((unsigned long long)((test)) % (unsigned long long)((1000000000))))); // no-warning + (*((unsigned long long*)(((void*)0))) = ((unsigned long long)((test)) % (unsigned long long)((1000000000)))); // expected-warning {{indirection of non-volatile null pointer will be deleted, not trap}} expected-note {{consider using __builtin_trap() or qualifying pointer with 'volatile'}} +} + // PR1966 _Complex double test1() { return __extension__ 1.0if; -- cgit v1.2.1