[AggressiveInstCombine] Inline strcmp/strncmp

llvm/include/llvm/Analysis/ValueTracking.h

@@ -116,6 +116,8 @@ bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL,
                             const DominatorTree *DT = nullptr,
                             bool UseInstrInfo = true);
 
+bool isOnlyUsedInZeroComparison(const Instruction *CxtI);
+
 bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI);
 
 /// Return true if the given value is known to be non-zero when defined. For

llvm/include/llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h

@@ -8,7 +8,7 @@
 /// \file
 ///
 /// AggressiveInstCombiner - Combine expression patterns to form expressions
-/// with fewer, simple instructions. This pass does not modify the CFG.
+/// with fewer, simple instructions.
 ///
 //===----------------------------------------------------------------------===//
 

llvm/lib/Analysis/ValueTracking.cpp

@@ -252,6 +252,13 @@ bool llvm::haveNoCommonBitsSet(const WithCache<const Value *> &LHSCache,
                                         RHSCache.getKnownBits(SQ));
 }
 
+bool llvm::isOnlyUsedInZeroComparison(const Instruction *I) {
+  return !I->user_empty() && all_of(I->users(), [](const User *U) {
+    ICmpInst::Predicate P;
+    return match(U, m_ICmp(P, m_Value(), m_Zero()));
+  });
+}
+
 bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *I) {
   return !I->user_empty() && all_of(I->users(), [](const User *U) {
     ICmpInst::Predicate P;