diff options
Diffstat (limited to 'llvm_mode/compare-transform-pass.so.cc')
| -rw-r--r-- | llvm_mode/compare-transform-pass.so.cc | 79 |
1 files changed, 43 insertions, 36 deletions
diff --git a/llvm_mode/compare-transform-pass.so.cc b/llvm_mode/compare-transform-pass.so.cc index 2f5eb341..4879994a 100644 --- a/llvm_mode/compare-transform-pass.so.cc +++ b/llvm_mode/compare-transform-pass.so.cc @@ -304,17 +304,24 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, if (!(HasStr1 || HasStr2)) continue; if (isMemcmp || isStrncmp || isStrncasecmp) { - /* check if third operand is a constant integer * strlen("constStr") and sizeof() are treated as constant */ Value * op2 = callInst->getArgOperand(2); ConstantInt *ilen = dyn_cast<ConstantInt>(op2); - if (!ilen) continue; - /* final precaution: if size of compare is larger than constant - * string skip it*/ - uint64_t literalLength = HasStr1 ? Str1.size() : Str2.size(); - if (literalLength + 1 < ilen->getZExtValue()) continue; - + if (ilen) { + uint64_t len = ilen->getZExtValue(); + // if len is zero this is a pointless call but allow real + // implementation to worry about that + if (!len) continue; + + if (isMemcmp) { + // if size of compare is larger than constant string this is + // likely a bug but allow real implementation to worry about + // that + uint64_t literalLength = HasStr1 ? Str1.size() : Str2.size(); + if (literalLength + 1 < ilen->getZExtValue()) continue; + } + } else continue; } calls.push_back(callInst); @@ -341,7 +348,7 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, Value * VarStr; bool HasStr1 = getConstantStringInfo(Str1P, Str1); bool HasStr2 = getConstantStringInfo(Str2P, Str2); - uint64_t constLen, sizedLen; + uint64_t constStrLen, constSizedLen, unrollLen; bool isMemcmp = !callInst->getCalledFunction()->getName().compare(StringRef("memcmp")); bool isSizedcmp = isMemcmp || @@ -349,23 +356,12 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, StringRef("strncmp")) || !callInst->getCalledFunction()->getName().compare( StringRef("strncasecmp")); + bool isConstSized = isSizedcmp && isa<ConstantInt>(callInst->getArgOperand(2)); bool isCaseInsensitive = !callInst->getCalledFunction()->getName().compare( StringRef("strcasecmp")) || !callInst->getCalledFunction()->getName().compare( StringRef("strncasecmp")); - if (isSizedcmp) { - - Value * op2 = callInst->getArgOperand(2); - ConstantInt *ilen = dyn_cast<ConstantInt>(op2); - sizedLen = ilen->getZExtValue(); - - } else { - - sizedLen = 0; - - } - if (!(HasStr1 || HasStr2)) { // do we have a saved local or global variable initialization? @@ -389,35 +385,46 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, } + if (isConstSized) { + + Value * op2 = callInst->getArgOperand(2); + constSizedLen = dyn_cast<ConstantInt>(op2)->getZExtValue(); + + } + if (HasStr1) { TmpConstStr = Str1.str(); VarStr = Str2P; - constLen = isMemcmp ? sizedLen : TmpConstStr.length(); } else { TmpConstStr = Str2.str(); VarStr = Str1P; - constLen = isMemcmp ? sizedLen : TmpConstStr.length(); } - /* 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) */ + // add null termination character implicit in c strings TmpConstStr.append("\0", 1); - if (!sizedLen) constLen++; + + // in the unusual case the const str has embedded null + // characters, the string comparison functions should terminate + // at the first null + if (!isMemcmp) + TmpConstStr.assign(TmpConstStr, 0, TmpConstStr.find('\0') + 1); + + constStrLen = TmpConstStr.length(); + // prefer use of StringRef (in comparison to std::string a StringRef has + // built-in runtime bounds checking, which makes debugging easier) ConstStr = StringRef(TmpConstStr); - // fprintf(stderr, "issized: %d, const > sized ? %u > %u\n", isSizedcmp, - // constLen, sizedLen); - if (isSizedcmp && constLen > sizedLen && sizedLen) constLen = sizedLen; - if (constLen > TmpConstStr.length()) constLen = TmpConstStr.length(); - if (!constLen) constLen = TmpConstStr.length(); - if (!constLen) continue; + + if (isConstSized) + unrollLen = constSizedLen < constStrLen ? constSizedLen : constStrLen; + else + unrollLen = constStrLen; if (!be_quiet) - errs() << callInst->getCalledFunction()->getName() << ": len " << constLen + errs() << callInst->getCalledFunction()->getName() << ": len " << unrollLen << ": " << ConstStr << "\n"; /* split before the call instruction */ @@ -426,7 +433,7 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, BasicBlock *next_bb = BasicBlock::Create(C, "cmp_added", end_bb->getParent(), end_bb); BranchInst::Create(end_bb, next_bb); - PHINode *PN = PHINode::Create(Int32Ty, constLen + 1, "cmp_phi"); + PHINode *PN = PHINode::Create(Int32Ty, unrollLen + 1, "cmp_phi"); #if LLVM_VERSION_MAJOR < 8 TerminatorInst *term = bb->getTerminator(); @@ -436,7 +443,7 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, BranchInst::Create(next_bb, bb); term->eraseFromParent(); - for (uint64_t i = 0; i < constLen; i++) { + for (uint64_t i = 0; i < unrollLen; i++) { BasicBlock * cur_bb = next_bb; unsigned char c; @@ -473,7 +480,7 @@ bool CompareTransform::transformCmps(Module &M, const bool processStrcmp, Value *sext = IRB.CreateSExt(isub, Int32Ty); PN->addIncoming(sext, cur_bb); - if (i < constLen - 1) { + if (i < unrollLen - 1) { next_bb = BasicBlock::Create(C, "cmp_added", end_bb->getParent(), end_bb); |