diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp index 575c93b9dd3..ecca3c73b90 100644 --- a/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp +++ b/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp @@ -955,6 +955,17 @@ struct MemCmpOpt : public LibCallOptimization { return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI->getType()); } + // Constant folding: memcmp(x, y, l) -> cnst (all arguments are constant) + std::string LHSStr, RHSStr; + if (GetConstantStringInfo(LHS, LHSStr) && + GetConstantStringInfo(RHS, RHSStr)) { + // Make sure we're not reading out-of-bounds memory. + if (Len > LHSStr.length() || Len > RHSStr.length()) + return 0; + uint64_t Ret = memcmp(LHSStr.data(), RHSStr.data(), Len); + return ConstantInt::get(CI->getType(), Ret); + } + return 0; } }; @@ -2479,10 +2490,6 @@ bool SimplifyLibCalls::doInitialization(Module &M) { // lround, lroundf, lroundl: // * lround(cnst) -> cnst' // -// memcmp: -// * memcmp(x,y,l) -> cnst -// (if all arguments are constant and strlen(x) <= l and strlen(y) <= l) -// // pow, powf, powl: // * pow(exp(x),y) -> exp(x*y) // * pow(sqrt(x),y) -> pow(x,y*0.5) |
