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Avoid calling std::memcmp with nullptr 

Summary:
UBSAN complains that this is undefined behavior.

We can assume that empty substring (N==1) always satisfy conditions. So
std::memcmp will be called only only for N > 1 and Str.size() > 0.

Reviewers: ruiu, zturner

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D26646

llvm-svn: 286910
This commit is contained in:
Vitaly Buka 2016-11-15 00:01:40 +00:00
parent 18270a843a
commit 3ee54a6933
1 changed files with 6 additions and 3 deletions
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9
llvm/include/llvm/ADT/StringSwitch.h
View File

@ -72,8 +72,9 @@ public:
template<unsigned N>
LLVM_ATTRIBUTE_ALWAYS_INLINE
StringSwitch& Case(const char (&S)[N], const T& Value) {
assert(N);
if (!Result && N-1 == Str.size() &&
(std::memcmp(S, Str.data(), N-1) == 0)) {
(N == 1 || std::memcmp(S, Str.data(), N-1) == 0)) {
Result = &Value;
}
return *this;
@ -82,8 +83,9 @@ public:
template<unsigned N>
LLVM_ATTRIBUTE_ALWAYS_INLINE
StringSwitch& EndsWith(const char (&S)[N], const T &Value) {
assert(N);
if (!Result && Str.size() >= N-1 &&
std::memcmp(S, Str.data() + Str.size() + 1 - N, N-1) == 0) {
(N == 1 || std::memcmp(S, Str.data() + Str.size() + 1 - N, N-1) == 0)) {
Result = &Value;
}
return *this;
@ -92,8 +94,9 @@ public:
template<unsigned N>
LLVM_ATTRIBUTE_ALWAYS_INLINE
StringSwitch& StartsWith(const char (&S)[N], const T &Value) {
assert(N);
if (!Result && Str.size() >= N-1 &&
std::memcmp(S, Str.data(), N-1) == 0) {
(N == 1 || std::memcmp(S, Str.data(), N-1) == 0)) {
Result = &Value;
}
return *this;