[InstCombine] generalize reassociated Demorgan folds

This updates the recent D112108 / b92412fb286be26d
to handle the flipped logic ('or') sibling:
https://alive2.llvm.org/ce/z/Y2L6Ch

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index df2595a..015a52f 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1521,27 +1521,45 @@ static Instruction *reassociateFCmps(BinaryOperator &BO,
   return BinaryOperator::Create(Opcode, NewFCmp, BO11);
 }
 
-/// Match De Morgan's Laws:
+/// Match variations of De Morgan's Laws:
 /// (~A & ~B) == (~(A | B))
 /// (~A | ~B) == (~(A & B))
 static Instruction *matchDeMorgansLaws(BinaryOperator &I,
                                        InstCombiner::BuilderTy &Builder) {
-  auto Opcode = I.getOpcode();
+  const Instruction::BinaryOps Opcode = I.getOpcode();
   assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&
          "Trying to match De Morgan's Laws with something other than and/or");
 
   // Flip the logic operation.
-  Opcode = (Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
+  const Instruction::BinaryOps FlippedOpcode =
+      (Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
 
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
   Value *A, *B;
-  if (match(I.getOperand(0), m_OneUse(m_Not(m_Value(A)))) &&
-      match(I.getOperand(1), m_OneUse(m_Not(m_Value(B)))) &&
+  if (match(Op0, m_OneUse(m_Not(m_Value(A)))) &&
+      match(Op1, m_OneUse(m_Not(m_Value(B)))) &&
       !InstCombiner::isFreeToInvert(A, A->hasOneUse()) &&
       !InstCombiner::isFreeToInvert(B, B->hasOneUse())) {
-    Value *AndOr = Builder.CreateBinOp(Opcode, A, B, I.getName() + ".demorgan");
+    Value *AndOr =
+        Builder.CreateBinOp(FlippedOpcode, A, B, I.getName() + ".demorgan");
     return BinaryOperator::CreateNot(AndOr);
   }
 
+  // The 'not' ops may require reassociation.
+  // (A & ~B) & ~C --> A & ~(B | C)
+  // (~B & A) & ~C --> A & ~(B | C)
+  // (A | ~B) | ~C --> A | ~(B & C)
+  // (~B | A) | ~C --> A | ~(B & C)
+  BinaryOperator *BO;
+  if (match(Op0, m_OneUse(m_BinOp(BO))) && BO->getOpcode() == Opcode) {
+    Value *C;
+    if (match(BO, m_c_BinOp(m_Value(A), m_Not(m_Value(B)))) &&
+        match(Op1, m_Not(m_Value(C)))) {
+      Value *FlippedBO = Builder.CreateBinOp(FlippedOpcode, B, C);
+      return BinaryOperator::Create(Opcode, A, Builder.CreateNot(FlippedBO));
+    }
+  }
+
   return nullptr;
 }
 
@@ -2012,13 +2030,6 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
     if (match(Op0, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
         match(Op1, m_c_Or(m_Specific(A), m_Specific(B))))
       return BinaryOperator::CreateAnd(A, B);
-
-    // (A & ~B) & ~C -> A & ~(B | C)
-    // (~B & A) & ~C -> A & ~(B | C)
-    if (match(Op0, m_OneUse(m_c_And(m_Value(A), m_Not(m_Value(B))))) &&
-        match(Op1, m_Not(m_Value(C))))
-      return BinaryOperator::CreateAnd(
-          A, Builder.CreateNot(Builder.CreateOr(B, C)));
   }
 
   {

diff --git a/llvm/test/Transforms/InstCombine/and-xor-or.ll b/llvm/test/Transforms/InstCombine/and-xor-or.ll
index 63bc69b..c206c54 100644 (file)
--- a/llvm/test/Transforms/InstCombine/and-xor-or.ll
+++ b/llvm/test/Transforms/InstCombine/and-xor-or.ll
@@ -614,10 +614,9 @@ define i32 @not_and_and_not_extra_and1_use(i32 %a0, i32 %b, i32 %c) {
 define i32 @not_or_or_not(i32 %a0, i32 %b, i32 %c) {
 ; CHECK-LABEL: @not_or_or_not(
 ; CHECK-NEXT:    [[A:%.*]] = sdiv i32 42, [[A0:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[B:%.*]], -1
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[C:%.*]], -1
-; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[A]], [[NOT1]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[OR1]], [[NOT2]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[B:%.*]], [[C:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[A]], [[TMP2]]
 ; CHECK-NEXT:    ret i32 [[OR2]]
 ;
   %a = sdiv i32 42, %a0 ; thwart complexity-based canonicalization
@@ -631,10 +630,9 @@ define i32 @not_or_or_not(i32 %a0, i32 %b, i32 %c) {
 define <2 x i6> @not_or_or_not_2i6(<2 x i6> %a0, <2 x i6> %b, <2 x i6> %c) {
 ; CHECK-LABEL: @not_or_or_not_2i6(
 ; CHECK-NEXT:    [[A:%.*]] = sdiv <2 x i6> <i6 3, i6 3>, [[A0:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor <2 x i6> [[B:%.*]], <i6 -1, i6 -1>
-; CHECK-NEXT:    [[NOT2:%.*]] = xor <2 x i6> [[C:%.*]], <i6 -1, i6 undef>
-; CHECK-NEXT:    [[OR1:%.*]] = or <2 x i6> [[A]], [[NOT1]]
-; CHECK-NEXT:    [[OR2:%.*]] = or <2 x i6> [[OR1]], [[NOT2]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and <2 x i6> [[B:%.*]], [[C:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = xor <2 x i6> [[TMP1]], <i6 -1, i6 -1>
+; CHECK-NEXT:    [[OR2:%.*]] = or <2 x i6> [[A]], [[TMP2]]
 ; CHECK-NEXT:    ret <2 x i6> [[OR2]]
 ;
   %a = sdiv <2 x i6> <i6 3, i6 3>, %a0 ; thwart complexity-based canonicalization
@@ -649,10 +647,9 @@ define <2 x i6> @not_or_or_not_2i6(<2 x i6> %a0, <2 x i6> %b, <2 x i6> %c) {
 
 define i32 @not_or_or_not_commute1(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @not_or_or_not_commute1(
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[B:%.*]], -1
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[C:%.*]], -1
-; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[NOT1]], [[A:%.*]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[OR1]], [[NOT2]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[B:%.*]], [[C:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[TMP2]], [[A:%.*]]
 ; CHECK-NEXT:    ret i32 [[OR2]]
 ;
   %not1 = xor i32 %b, -1
@@ -667,10 +664,10 @@ define i32 @not_or_or_not_commute1(i32 %a, i32 %b, i32 %c) {
 define i32 @not_or_or_not_commute2_extra_not_use(i32 %a0, i32 %b, i32 %c) {
 ; CHECK-LABEL: @not_or_or_not_commute2_extra_not_use(
 ; CHECK-NEXT:    [[A:%.*]] = sdiv i32 42, [[A0:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[B:%.*]], -1
 ; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[C:%.*]], -1
-; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[A]], [[NOT1]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[OR1]], [[NOT2]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[B:%.*]], [[C]]
+; CHECK-NEXT:    [[TMP2:%.*]] = xor i32 [[TMP1]], -1
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[A]], [[TMP2]]
 ; CHECK-NEXT:    call void @use(i32 [[NOT2]])
 ; CHECK-NEXT:    ret i32 [[OR2]]
 ;