instcombine: Migrate memcmp optimizations

[oota-llvm.git] / lib / Transforms / Scalar / SimplifyLibCalls.cpp

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 3f39df94560353b9f952d6d9ef0873d588024b2b..4d54e13c7714d1c4a276b04559136ef3ea71551a 100644 (file)
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -104,54 +104,6 @@ static bool CallHasFloatingPointArgument(const CallInst *CI) {
 //===----------------------------------------------------------------------===//
 
 namespace {
-//===---------------------------------------===//
-// 'memcmp' Optimizations
-
-struct MemCmpOpt : public LibCallOptimization {
-  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    FunctionType *FT = Callee->getFunctionType();
-    if (FT->getNumParams() != 3 || !FT->getParamType(0)->isPointerTy() ||
-        !FT->getParamType(1)->isPointerTy() ||
-        !FT->getReturnType()->isIntegerTy(32))
-      return 0;
-
-    Value *LHS = CI->getArgOperand(0), *RHS = CI->getArgOperand(1);
-
-    if (LHS == RHS)  // memcmp(s,s,x) -> 0
-      return Constant::getNullValue(CI->getType());
-
-    // Make sure we have a constant length.
-    ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
-    if (!LenC) return 0;
-    uint64_t Len = LenC->getZExtValue();
-
-    if (Len == 0) // memcmp(s1,s2,0) -> 0
-      return Constant::getNullValue(CI->getType());
-
-    // memcmp(S1,S2,1) -> *(unsigned char*)LHS - *(unsigned char*)RHS
-    if (Len == 1) {
-      Value *LHSV = B.CreateZExt(B.CreateLoad(CastToCStr(LHS, B), "lhsc"),
-                                 CI->getType(), "lhsv");
-      Value *RHSV = B.CreateZExt(B.CreateLoad(CastToCStr(RHS, B), "rhsc"),
-                                 CI->getType(), "rhsv");
-      return B.CreateSub(LHSV, RHSV, "chardiff");
-    }
-
-    // Constant folding: memcmp(x, y, l) -> cnst (all arguments are constant)
-    StringRef LHSStr, RHSStr;
-    if (getConstantStringInfo(LHS, LHSStr) &&
-        getConstantStringInfo(RHS, RHSStr)) {
-      // Make sure we're not reading out-of-bounds memory.
-      if (Len > LHSStr.size() || Len > RHSStr.size())
-        return 0;
-      uint64_t Ret = memcmp(LHSStr.data(), RHSStr.data(), Len);
-      return ConstantInt::get(CI->getType(), Ret);
-    }
-
-    return 0;
-  }
-};
-
 //===---------------------------------------===//
 // 'memcpy' Optimizations
 
@@ -887,7 +839,7 @@ namespace {
 
     StringMap<LibCallOptimization*> Optimizations;
     // Memory LibCall Optimizations
-    MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
+    MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
     // Math Library Optimizations
     CosOpt Cos; PowOpt Pow; Exp2Opt Exp2;
     UnaryDoubleFPOpt UnaryDoubleFP, UnsafeUnaryDoubleFP;
@@ -954,7 +906,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
 /// we know.
 void SimplifyLibCalls::InitOptimizations() {
   // Memory LibCall Optimizations
-  Optimizations["memcmp"] = &MemCmp;
   AddOpt(LibFunc::memcpy, &MemCpy);
   Optimizations["memmove"] = &MemMove;
   AddOpt(LibFunc::memset, &MemSet);