[PatternMatch] Use m_Not instead of m_c_Xor with m_AllOnes()

[AreaZR]

No description provided.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms
@llvm/pr-subscribers-backend-x86

@llvm/pr-subscribers-llvm-ir

Author: AtariDreams (AtariDreams)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/96837.diff

3 Files Affected:

• (modified) llvm/include/llvm/IR/PatternMatch.h (+1-1)
• (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+1-1)
• (modified) llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp (+1-1)

diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 526b7258b8ab7..7a096530a7ef1 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -2343,7 +2343,7 @@ struct UAddWithOverflow_match {
         return L.match(AddLHS) && R.match(AddRHS) && S.match(ICmpRHS);
 
     Value *Op1;
-    auto XorExpr = m_OneUse(m_Xor(m_Value(Op1), m_AllOnes()));
+    auto XorExpr = m_OneUse(m_Not(m_Value(Op1)));
     // (a ^ -1) <u b
     if (Pred == ICmpInst::ICMP_ULT) {
       if (XorExpr.match(ICmpLHS))
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index b9148999ff395..f917e93493950 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -30557,7 +30557,7 @@ static std::pair<Value *, BitTestKind> FindSingleBitChange(Value *V) {
     bool Not = false;
     // Check if we have a NOT
     Value *PeekI;
-    if (match(I, m_c_Xor(m_Value(PeekI), m_AllOnes())) ||
+    if (match(I, m_Not(m_Value(PeekI))) ||
         match(I, m_Sub(m_AllOnes(), m_Value(PeekI)))) {
       Not = true;
       I = dyn_cast<Instruction>(PeekI);
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 06b434857c657..38f8a41214b68 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -216,7 +216,7 @@ dropRedundantMaskingOfLeftShiftInput(BinaryOperator *OuterShift,
   // ((1 << MaskShAmt) - 1)
   auto MaskA = m_Add(m_Shl(m_One(), m_Value(MaskShAmt)), m_AllOnes());
   // (~(-1 << maskNbits))
-  auto MaskB = m_Xor(m_Shl(m_AllOnes(), m_Value(MaskShAmt)), m_AllOnes());
+  auto MaskB = m_Not(m_Shl(m_AllOnes(), m_Value(MaskShAmt)));
   // (-1 l>> MaskShAmt)
   auto MaskC = m_LShr(m_AllOnes(), m_Value(MaskShAmt));
   // ((-1 << MaskShAmt) l>> MaskShAmt)

[nikic]

LGTM, but this is not entirely NFC because it replaces some cases that use m_Xor rather than m_c_Xor.