[clang-tools-extra] r213155 - [clang-tidy] Add a checker for zero-length memset.
Benjamin Kramer
benny.kra at googlemail.com
Wed Jul 16 07:30:21 PDT 2014
Author: d0k
Date: Wed Jul 16 09:30:19 2014
New Revision: 213155
URL: http://llvm.org/viewvc/llvm-project?rev=213155&view=rev
Log:
[clang-tidy] Add a checker for zero-length memset.
If there's memset(x, y, 0) in the code it's most likely a mistake. The
checker suggests a fix-it to swap 'y' and '0'.
I think this has the potential to be promoted into a general clang warning
after some testing in clang-tidy.
Differential Revision: http://reviews.llvm.org/D4535
Added:
clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.cpp
clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.h
clang-tools-extra/trunk/test/clang-tidy/google-memset-zero-length.cpp
Modified:
clang-tools-extra/trunk/clang-tidy/google/CMakeLists.txt
clang-tools-extra/trunk/clang-tidy/google/GoogleTidyModule.cpp
Modified: clang-tools-extra/trunk/clang-tidy/google/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/google/CMakeLists.txt?rev=213155&r1=213154&r2=213155&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/google/CMakeLists.txt (original)
+++ clang-tools-extra/trunk/clang-tidy/google/CMakeLists.txt Wed Jul 16 09:30:19 2014
@@ -5,6 +5,7 @@ add_clang_library(clangTidyGoogleModule
ExplicitConstructorCheck.cpp
ExplicitMakePairCheck.cpp
GoogleTidyModule.cpp
+ MemsetZeroLengthCheck.cpp
NamedParameterCheck.cpp
OverloadedUnaryAndCheck.cpp
StringReferenceMemberCheck.cpp
Modified: clang-tools-extra/trunk/clang-tidy/google/GoogleTidyModule.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/google/GoogleTidyModule.cpp?rev=213155&r1=213154&r2=213155&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/google/GoogleTidyModule.cpp (original)
+++ clang-tools-extra/trunk/clang-tidy/google/GoogleTidyModule.cpp Wed Jul 16 09:30:19 2014
@@ -13,6 +13,7 @@
#include "AvoidCStyleCastsCheck.h"
#include "ExplicitConstructorCheck.h"
#include "ExplicitMakePairCheck.h"
+#include "MemsetZeroLengthCheck.h"
#include "NamedParameterCheck.h"
#include "OverloadedUnaryAndCheck.h"
#include "StringReferenceMemberCheck.h"
@@ -46,6 +47,9 @@ public:
"google-runtime-member-string-references",
new ClangTidyCheckFactory<runtime::StringReferenceMemberCheck>());
CheckFactories.addCheckFactory(
+ "google-runtime-memset",
+ new ClangTidyCheckFactory<runtime::MemsetZeroLengthCheck>());
+ CheckFactories.addCheckFactory(
"google-readability-casting",
new ClangTidyCheckFactory<readability::AvoidCStyleCastsCheck>());
CheckFactories.addCheckFactory(
Added: clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.cpp?rev=213155&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.cpp (added)
+++ clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.cpp Wed Jul 16 09:30:19 2014
@@ -0,0 +1,85 @@
+//===--- MemsetZeroLengthCheck.cpp - clang-tidy -------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MemsetZeroLengthCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace runtime {
+
+void
+MemsetZeroLengthCheck::registerMatchers(ast_matchers::MatchFinder *Finder) {
+ auto InTemplateInstantiation = hasAncestor(
+ decl(anyOf(recordDecl(ast_matchers::isTemplateInstantiation()),
+ functionDecl(ast_matchers::isTemplateInstantiation()))));
+ // Look for memset(x, y, 0) as those is most likely an argument swap.
+ // TODO: Also handle other standard functions that suffer from the same
+ // problem, e.g. memchr.
+ Finder->addMatcher(
+ callExpr(callee(functionDecl(hasName("::memset"))), argumentCountIs(3),
+ unless(InTemplateInstantiation)).bind("decl"),
+ this);
+}
+
+/// \brief Get a StringRef representing a SourceRange.
+static StringRef getAsString(const MatchFinder::MatchResult &Result,
+ SourceRange R) {
+ const SourceManager &SM = *Result.SourceManager;
+ // Don't even try to resolve macro or include contraptions. Not worth emitting
+ // a fixit for.
+ if (R.getBegin().isMacroID() ||
+ !SM.isWrittenInSameFile(R.getBegin(), R.getEnd()))
+ return StringRef();
+
+ const char *Begin = SM.getCharacterData(R.getBegin());
+ const char *End = SM.getCharacterData(Lexer::getLocForEndOfToken(
+ R.getEnd(), 0, SM, Result.Context->getLangOpts()));
+
+ return StringRef(Begin, End - Begin);
+}
+
+void MemsetZeroLengthCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *Call = Result.Nodes.getNodeAs<CallExpr>("decl");
+
+ const Expr *Arg1 = Call->getArg(1);
+ const Expr *Arg2 = Call->getArg(2);
+
+ // Try to evaluate the second argument so we can also find values that are not
+ // just literals. We don't emit a warning if the second argument also
+ // evaluates to zero.
+ llvm::APSInt Value1, Value2;
+ if (!Arg2->EvaluateAsInt(Value2, *Result.Context) || Value2 != 0 ||
+ (Arg1->EvaluateAsInt(Value1, *Result.Context) && Value1 == 0))
+ return;
+
+ // Emit a warning and fix-its to swap the arguments.
+ auto D = diag(Call->getLocStart(),
+ "memset of size zero, potentially swapped arguments");
+ SourceRange LHSRange = Arg1->getSourceRange();
+ SourceRange RHSRange = Arg2->getSourceRange();
+ StringRef RHSString = getAsString(Result, RHSRange);
+ StringRef LHSString = getAsString(Result, LHSRange);
+ if (LHSString.empty() || RHSString.empty())
+ return;
+
+ D << FixItHint::CreateReplacement(CharSourceRange::getTokenRange(LHSRange),
+ RHSString)
+ << FixItHint::CreateReplacement(CharSourceRange::getTokenRange(RHSRange),
+ LHSString);
+}
+
+} // namespace runtime
+} // namespace tidy
+} // namespace clang
Added: clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.h
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.h?rev=213155&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.h (added)
+++ clang-tools-extra/trunk/clang-tidy/google/MemsetZeroLengthCheck.h Wed Jul 16 09:30:19 2014
@@ -0,0 +1,35 @@
+//===--- MemsetZeroLengthCheck.h - clang-tidy ---------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_MEMSET_ZERO_LENGTH_CHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_MEMSET_ZERO_LENGTH_CHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace runtime {
+
+/// \brief Finds calls to memset with a literal zero in the length argument.
+///
+/// This is most likely unintended and the length and value arguments are
+/// swapped.
+///
+/// Corresponding cpplint.py check name: 'runtime/memset'.
+class MemsetZeroLengthCheck : public ClangTidyCheck {
+public:
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace runtime
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_MEMSET_ZERO_LENGTH_CHECK_H
Added: clang-tools-extra/trunk/test/clang-tidy/google-memset-zero-length.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/google-memset-zero-length.cpp?rev=213155&view=auto
==============================================================================
--- clang-tools-extra/trunk/test/clang-tidy/google-memset-zero-length.cpp (added)
+++ clang-tools-extra/trunk/test/clang-tidy/google-memset-zero-length.cpp Wed Jul 16 09:30:19 2014
@@ -0,0 +1,51 @@
+// RUN: $(dirname %s)/check_clang_tidy_fix.sh %s google-runtime-memset %t
+// REQUIRES: shell
+
+void *memset(void *, int, __SIZE_TYPE__);
+
+namespace std {
+ using ::memset;
+}
+
+template <int i>
+void memtmpl() {
+ memset(0, sizeof(int), i);
+ memset(0, sizeof(int), 0);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(0, 0, sizeof(int));
+}
+
+void foo(void *a, int xsize, int ysize) {
+ memset(a, sizeof(int), 0);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(a, 0, sizeof(int));
+#define M memset(a, sizeof(int), 0);
+ M
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: #define M memset(a, sizeof(int), 0);
+ ::memset(a, xsize *
+ ysize, 0);
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: ::memset(a, 0, xsize *
+// CHECK-FIXES-NEXT: ysize);
+ std::memset(a, sizeof(int), 0x00);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: std::memset(a, 0x00, sizeof(int));
+
+ const int v = 0;
+ memset(a, sizeof(int), v);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(a, v, sizeof(int));
+
+ memset(a, sizeof(int), v + v);
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: memset of size zero, potentially swapped argument
+// CHECK-FIXES: memset(a, v + v, sizeof(int));
+
+ memset(a, sizeof(int), v + 1);
+
+ memset(a, -1, sizeof(int));
+ memset(a, 0xcd, 1);
+ memset(a, v, 0);
+
+ memtmpl<0>();
+}
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