[InstCombine] (~(a | b) & c) | ~(c | (a ^ b)) -> ~((a | b) & (c | (b ^ a)))

```
----------------------------------------
define i3 @src(i3 %a, i3 %b, i3 %c) {
%0:
  %or1 = or i3 %b, %c
  %not1 = xor i3 %or1, 7
  %and1 = and i3 %a, %not1
  %xor1 = xor i3 %b, %c
  %or2 = or i3 %xor1, %a
  %not2 = xor i3 %or2, 7
  %or3 = or i3 %and1, %not2
  ret i3 %or3
}
=>
define i3 @tgt(i3 %a, i3 %b, i3 %c) {
%0:
  %obc = or i3 %b, %c
  %xbc = xor i3 %b, %c
  %o = or i3 %a, %xbc
  %and = and i3 %obc, %o
  %r = xor i3 %and, 7
  ret i3 %r
}
Transformation seems to be correct!
```

Differential Revision: https://reviews.llvm.org/D112955

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 15f1d8790a7fe37ce970cdf87c7d431cf692e24f..6d3b228e7d7f3387599a3d454e67d5638182a3da 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1727,16 +1727,18 @@ static Instruction *foldComplexAndOrPatterns(BinaryOperator &I,
       (Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
 
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  Value *A, *B, *C;
+  Value *A, *B, *C, *X, *Y;
 
   // (~(A | B) & C) | ... --> ...
   // (~(A & B) | C) & ... --> ...
   // TODO: One use checks are conservative. We just need to check that a total
   //       number of multiple used values does not exceed reduction
   //       in operations.
-  if (match(Op0, m_c_BinOp(FlippedOpcode,
-                           m_Not(m_BinOp(Opcode, m_Value(A), m_Value(B))),
-                           m_Value(C)))) {
+  if (match(Op0,
+            m_c_BinOp(FlippedOpcode,
+                      m_CombineAnd(m_Value(X), m_Not(m_BinOp(Opcode, m_Value(A),
+                                                             m_Value(B)))),
+                      m_Value(C)))) {
     // (~(A | B) & C) | (~(A | C) & B) --> (B ^ C) & ~A
     // (~(A & B) | C) & (~(A & C) | B) --> ~((B ^ C) & A)
     if (match(Op1,
@@ -1776,6 +1778,21 @@ static Instruction *foldComplexAndOrPatterns(BinaryOperator &I,
                        m_c_BinOp(Opcode, m_Specific(B), m_Specific(C)))))))
       return BinaryOperator::CreateNot(Builder.CreateBinOp(
           Opcode, Builder.CreateBinOp(FlippedOpcode, A, C), B));
+
+    // (~(A | B) & C) | ~(C | (A ^ B)) --> ~((A | B) & (C | (A ^ B)))
+    // Note, the pattern with swapped and/or is not handled because the
+    // result is more undefined than a source:
+    // (~(A & B) | C) & ~(C & (A ^ B)) --> (A ^ B ^ C) | ~(A | C) is invalid.
+    if (Opcode == Instruction::Or && Op0->hasOneUse() &&
+        match(Op1, m_OneUse(m_Not(m_CombineAnd(
+                       m_Value(Y),
+                       m_c_BinOp(Opcode, m_Specific(C),
+                                 m_c_Xor(m_Specific(A), m_Specific(B)))))))) {
+      // X = ~(A | B)
+      // Y = (C | (A ^ B)
+      Value *Or = cast<BinaryOperator>(X)->getOperand(0);
+      return BinaryOperator::CreateNot(Builder.CreateAnd(Or, Y));
+    }
   }
 
   return nullptr;

diff --git a/llvm/test/Transforms/InstCombine/and-xor-or.ll b/llvm/test/Transforms/InstCombine/and-xor-or.ll
index 2270fb10881dcd274b90d71588e8b643fd434aee..a07153835d8953e352e89be5f6ad2f014fc8b33b 100644 (file)
--- a/llvm/test/Transforms/InstCombine/and-xor-or.ll
+++ b/llvm/test/Transforms/InstCombine/and-xor-or.ll
@@ -2023,12 +2023,10 @@ define i32 @and_or_not_not_wrong_b(i32 %a, i32 %b, i32 %c, i32 %d) {
 define i32 @and_not_or_or_not_or_xor(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
   %or1 = or i32 %b, %c
@@ -2044,12 +2042,10 @@ define i32 @and_not_or_or_not_or_xor(i32 %a, i32 %b, i32 %c) {
 define i32 @and_not_or_or_not_or_xor_commute1(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_commute1(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[C:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
   %or1 = or i32 %c, %b
@@ -2066,12 +2062,10 @@ define i32 @and_not_or_or_not_or_xor_commute2(i32 %a0, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_commute2(
 ; CHECK-NEXT:    [[A:%.*]] = sdiv i32 42, [[A0:%.*]]
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[A]], [[NOT1]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
 ; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
   %a = sdiv i32 42, %a0 ; thwart complexity-based canonicalization
@@ -2088,12 +2082,10 @@ define i32 @and_not_or_or_not_or_xor_commute2(i32 %a0, i32 %b, i32 %c) {
 define i32 @and_not_or_or_not_or_xor_commute3(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_commute3(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[C]], [[B]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
   %or1 = or i32 %b, %c
@@ -2110,12 +2102,10 @@ define i32 @and_not_or_or_not_or_xor_commute4(i32 %a0, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_commute4(
 ; CHECK-NEXT:    [[A:%.*]] = sdiv i32 42, [[A0:%.*]]
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[A]], [[NOT1]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
 ; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[A]], [[XOR1]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
   %a = sdiv i32 42, %a0 ; thwart complexity-based canonicalization
@@ -2132,12 +2122,10 @@ define i32 @and_not_or_or_not_or_xor_commute4(i32 %a0, i32 %b, i32 %c) {
 define i32 @and_not_or_or_not_or_xor_commute5(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_commute5(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
   %or1 = or i32 %b, %c
@@ -2153,12 +2141,10 @@ define i32 @and_not_or_or_not_or_xor_commute5(i32 %a, i32 %b, i32 %c) {
 define i32 @and_not_or_or_not_or_xor_use1(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_use1(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    call void @use(i32 [[OR1]])
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
@@ -2177,11 +2163,10 @@ define i32 @and_not_or_or_not_or_xor_use2(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_use2(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
 ; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    call void @use(i32 [[NOT1]])
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
@@ -2222,12 +2207,10 @@ define i32 @and_not_or_or_not_or_xor_use3(i32 %a, i32 %b, i32 %c) {
 define i32 @and_not_or_or_not_or_xor_use4(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_use4(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    call void @use(i32 [[XOR1]])
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
@@ -2245,12 +2228,10 @@ define i32 @and_not_or_or_not_or_xor_use4(i32 %a, i32 %b, i32 %c) {
 define i32 @and_not_or_or_not_or_xor_use5(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @and_not_or_or_not_or_xor_use5(
 ; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[B:%.*]], [[C:%.*]]
-; CHECK-NEXT:    [[NOT1:%.*]] = xor i32 [[OR1]], -1
-; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[NOT1]], [[A:%.*]]
 ; CHECK-NEXT:    [[XOR1:%.*]] = xor i32 [[B]], [[C]]
-; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A]]
-; CHECK-NEXT:    [[NOT2:%.*]] = xor i32 [[OR2]], -1
-; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[AND1]], [[NOT2]]
+; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[XOR1]], [[A:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[OR1]], [[OR2]]
+; CHECK-NEXT:    [[OR3:%.*]] = xor i32 [[TMP1]], -1
 ; CHECK-NEXT:    call void @use(i32 [[OR2]])
 ; CHECK-NEXT:    ret i32 [[OR3]]
 ;
@@ -2289,6 +2270,8 @@ define i32 @and_not_or_or_not_or_xor_use6(i32 %a, i32 %b, i32 %c) {
 }
 
 ; (a | ~(b & c)) & ~(a & (b ^ c)) --> ~(a | b) | (a ^ b ^ c)
+; This pattern is not handled because the result is more undefined than a source.
+; It is invalid as is, but feezing %a and %b will make it valid.
 
 define i32 @or_not_and_and_not_and_xor(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: @or_not_and_and_not_and_xor(