fix zero terminated string issue
In C "strings" are zero terminated. Functions like
strcmp/strncmp/memcmp/... work on them. We have to be careful to not
ignore the last byte.
MODIFY
llvm_mode/compare-transform-pass.so.cc
llvm_mode/compare-transform-pass.so.cc
@@ -184,6 +184,7 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, const
Value *Str1P = callInst->getArgOperand(0), *Str2P = callInst->getArgOperand(1);
StringRef Str1, Str2, ConstStr;
+ std::string TmpConstStr;
Value *VarStr;
bool HasStr1 = getConstantStringInfo(Str1P, Str1);
getConstantStringInfo(Str2P, Str2);
@@ -202,21 +203,20 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, const
}
if (HasStr1) {
- ConstStr = Str1;
+ TmpConstStr = Str1.str();
VarStr = Str2P;
constLen = isMemcmp ? sizedLen : GetStringLength(Str1P);
}
else {
- ConstStr = Str2;
+ TmpConstStr = Str2.str();
VarStr = Str1P;
constLen = isMemcmp ? sizedLen : GetStringLength(Str2P);
}
- /* bugfix thanks to pbst */
- /* ignore terminating '\0' in string for strcmp */
- if (!isSizedcmp && constLen > 0) {
- constLen--;
- }
+ /* properly handle zero terminated C strings by adding the terminating 0 to
+ * the StringRef (in comparison to std::string a StringRef has built-in
+ * runtime bounds checking, which makes debugging easier) */
+ TmpConstStr.append("\0", 1); ConstStr = StringRef(TmpConstStr);
if (isSizedcmp && constLen > sizedLen) {
constLen = sizedLen;

fix zero terminated string issue

In C "strings" are zero terminated. Functions like
strcmp/strncmp/memcmp/... work on them. We have to be careful to not
ignore the last byte.