1 files changed, 19 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 0751078e01d..3b874e4b457 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -916,7 +916,9 @@ static Value *optimizeMemCmpConstantSize(CallInst *CI, Value *LHS, Value *RHS,
   return nullptr;
 }
 
-Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilder<> &B) {
+// Most simplifications for memcmp also apply to bcmp.
+Value *LibCallSimplifier::optimizeMemCmpBCmpCommon(CallInst *CI,
+                                                   IRBuilder<> &B) {
   Value *LHS = CI->getArgOperand(0), *RHS = CI->getArgOperand(1);
   Value *Size = CI->getArgOperand(2);
 
@@ -929,16 +931,30 @@ Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilder<> &B) {
                                                 LenC->getZExtValue(), B, DL))
       return Res;
 
+  return nullptr;
+}
+
+Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilder<> &B) {
+  if (Value *V = optimizeMemCmpBCmpCommon(CI, B))
+    return V;
+
   // memcmp(x, y, Len) == 0 -> bcmp(x, y, Len) == 0
   // `bcmp` can be more efficient than memcmp because it only has to know that
   // there is a difference, not where it is.
   if (isOnlyUsedInZeroEqualityComparison(CI) && TLI->has(LibFunc_bcmp)) {
+    Value *LHS = CI->getArgOperand(0);
+    Value *RHS = CI->getArgOperand(1);
+    Value *Size = CI->getArgOperand(2);
     return emitBCmp(LHS, RHS, Size, B, DL, TLI);
   }
 
   return nullptr;
 }
 
+Value *LibCallSimplifier::optimizeBCmp(CallInst *CI, IRBuilder<> &B) {
+  return optimizeMemCmpBCmpCommon(CI, B);
+}
+
 Value *LibCallSimplifier::optimizeMemCpy(CallInst *CI, IRBuilder<> &B) {
   // memcpy(x, y, n) -> llvm.memcpy(align 1 x, align 1 y, n)
   B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(1), 1,
@@ -2512,6 +2528,8 @@ Value *LibCallSimplifier::optimizeStringMemoryLibCall(CallInst *CI,
       return optimizeStrStr(CI, Builder);
     case LibFunc_memchr:
       return optimizeMemChr(CI, Builder);
+    case LibFunc_bcmp:
+      return optimizeBCmp(CI, Builder);
     case LibFunc_memcmp:
       return optimizeMemCmp(CI, Builder);
     case LibFunc_memcpy: