[InstCombine] Fold bitwise logic with intrinsics (#77460)

This patch does the following folds:
```
bitwise(fshl (A, B, ShAmt), fshl(C, D, ShAmt)) -> fshl(bitwise(A, C), bitwise(B, D), ShAmt)
bitwise(fshr (A, B, ShAmt), fshr(C, D, ShAmt)) -> fshr(bitwise(A, C), bitwise(B, D), ShAmt)
bitwise(bswap(A), bswap(B)) -> bswap(bitwise(A, B))
bitwise(bswap(A), C) -> bswap(bitwise(A, bswap(C)))
bitwise(bitreverse(A), bitreverse(B)) -> bitreverse(bitwise(A, B))
bitwise(bitreverse(A), C) -> bitreverse(bitwise(A, bitreverse(C)))
```
Alive2: https://alive2.llvm.org/ce/z/iZN_TL

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

@@ -46,44 +46,6 @@ static Value *getFCmpValue(unsigned Code, Value *LHS, Value *RHS,
   return Builder.CreateFCmp(NewPred, LHS, RHS);
 }
 
-/// Transform BITWISE_OP(BSWAP(A),BSWAP(B)) or
-/// BITWISE_OP(BSWAP(A), Constant) to BSWAP(BITWISE_OP(A, B))
-/// \param I Binary operator to transform.
-/// \return Pointer to node that must replace the original binary operator, or
-///         null pointer if no transformation was made.
-static Value *SimplifyBSwap(BinaryOperator &I,
-                            InstCombiner::BuilderTy &Builder) {
-  assert(I.isBitwiseLogicOp() && "Unexpected opcode for bswap simplifying");
-
-  Value *OldLHS = I.getOperand(0);
-  Value *OldRHS = I.getOperand(1);
-
-  Value *NewLHS;
-  if (!match(OldLHS, m_BSwap(m_Value(NewLHS))))
-    return nullptr;
-
-  Value *NewRHS;
-  const APInt *C;
-
-  if (match(OldRHS, m_BSwap(m_Value(NewRHS)))) {
-    // OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) )
-    if (!OldLHS->hasOneUse() && !OldRHS->hasOneUse())
-      return nullptr;
-    // NewRHS initialized by the matcher.
-  } else if (match(OldRHS, m_APInt(C))) {
-    // OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) )
-    if (!OldLHS->hasOneUse())
-      return nullptr;
-    NewRHS = ConstantInt::get(I.getType(), C->byteSwap());
-  } else
-    return nullptr;
-
-  Value *BinOp = Builder.CreateBinOp(I.getOpcode(), NewLHS, NewRHS);
-  Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::bswap,
-                                          I.getType());
-  return Builder.CreateCall(F, BinOp);
-}
-
 /// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise
 /// (V < Lo || V >= Hi). This method expects that Lo < Hi. IsSigned indicates
 /// whether to treat V, Lo, and Hi as signed or not.
@@ -2159,6 +2121,64 @@ Instruction *InstCombinerImpl::foldBinOpOfDisplacedShifts(BinaryOperator &I) {
   return BinaryOperator::Create(ShiftOp, NewC, ShAmt);
 }
 
+// Fold and/or/xor with two equal intrinsic IDs:
+// bitwise(fshl (A, B, ShAmt), fshl(C, D, ShAmt))
+// -> fshl(bitwise(A, C), bitwise(B, D), ShAmt)
+// bitwise(fshr (A, B, ShAmt), fshr(C, D, ShAmt))
+// -> fshr(bitwise(A, C), bitwise(B, D), ShAmt)
+// bitwise(bswap(A), bswap(B)) -> bswap(bitwise(A, B))
+// bitwise(bswap(A), C) -> bswap(bitwise(A, bswap(C)))
+// bitwise(bitreverse(A), bitreverse(B)) -> bitreverse(bitwise(A, B))
+// bitwise(bitreverse(A), C) -> bitreverse(bitwise(A, bitreverse(C)))
+static Instruction *
+foldBitwiseLogicWithIntrinsics(BinaryOperator &I,
+                               InstCombiner::BuilderTy &Builder) {
+  assert(I.isBitwiseLogicOp() && "Should and/or/xor");
+  if (!I.getOperand(0)->hasOneUse())
+    return nullptr;
+  IntrinsicInst *X = dyn_cast<IntrinsicInst>(I.getOperand(0));
+  if (!X)
+    return nullptr;
+
+  IntrinsicInst *Y = dyn_cast<IntrinsicInst>(I.getOperand(1));
+  if (Y && (!Y->hasOneUse() || X->getIntrinsicID() != Y->getIntrinsicID()))
+    return nullptr;
+
+  Intrinsic::ID IID = X->getIntrinsicID();
+  const APInt *RHSC;
+  // Try to match constant RHS.
+  if (!Y && (!(IID == Intrinsic::bswap || IID == Intrinsic::bitreverse) ||
+             !match(I.getOperand(1), m_APInt(RHSC))))
+    return nullptr;
+
+  switch (IID) {
+  case Intrinsic::fshl:
+  case Intrinsic::fshr: {
+    if (X->getOperand(2) != Y->getOperand(2))
+      return nullptr;
+    Value *NewOp0 =
+        Builder.CreateBinOp(I.getOpcode(), X->getOperand(0), Y->getOperand(0));
+    Value *NewOp1 =
+        Builder.CreateBinOp(I.getOpcode(), X->getOperand(1), Y->getOperand(1));
+    Function *F = Intrinsic::getDeclaration(I.getModule(), IID, I.getType());
+    return CallInst::Create(F, {NewOp0, NewOp1, X->getOperand(2)});
+  }
+  case Intrinsic::bswap:
+  case Intrinsic::bitreverse: {
+    Value *NewOp0 = Builder.CreateBinOp(
+        I.getOpcode(), X->getOperand(0),
+        Y ? Y->getOperand(0)
+          : ConstantInt::get(I.getType(), IID == Intrinsic::bswap
+                                              ? RHSC->byteSwap()
+                                              : RHSC->reverseBits()));
+    Function *F = Intrinsic::getDeclaration(I.getModule(), IID, I.getType());
+    return CallInst::Create(F, {NewOp0});
+  }
+  default:
+    return nullptr;
+  }
+}
+
 // FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
 // here. We should standardize that construct where it is needed or choose some
 // other way to ensure that commutated variants of patterns are not missed.
@@ -2194,9 +2214,6 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
   if (Value *V = foldUsingDistributiveLaws(I))
     return replaceInstUsesWith(I, V);
 
-  if (Value *V = SimplifyBSwap(I, Builder))
-    return replaceInstUsesWith(I, V);
-
   if (Instruction *R = foldBinOpShiftWithShift(I))
     return R;
 
@@ -2688,6 +2705,9 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
   if (Instruction *Res = foldBinOpOfDisplacedShifts(I))
     return Res;
 
+  if (Instruction *Res = foldBitwiseLogicWithIntrinsics(I, Builder))
+    return Res;
+
   return nullptr;
 }
 
@@ -3347,9 +3367,6 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
   if (Value *V = foldUsingDistributiveLaws(I))
     return replaceInstUsesWith(I, V);
 
-  if (Value *V = SimplifyBSwap(I, Builder))
-    return replaceInstUsesWith(I, V);
-
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
   Type *Ty = I.getType();
   if (Ty->isIntOrIntVectorTy(1)) {
@@ -3884,6 +3901,9 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
       return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, *C1 | *C2));
   }
 
+  if (Instruction *Res = foldBitwiseLogicWithIntrinsics(I, Builder))
+    return Res;
+
   return nullptr;
 }
 
@@ -4507,9 +4527,6 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   if (SimplifyDemandedInstructionBits(I))
     return &I;
 
-  if (Value *V = SimplifyBSwap(I, Builder))
-    return replaceInstUsesWith(I, V);
-
   if (Instruction *R = foldNot(I))
     return R;
 
@@ -4799,5 +4816,8 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   if (Instruction *Res = foldBinOpOfDisplacedShifts(I))
     return Res;
 
+  if (Instruction *Res = foldBitwiseLogicWithIntrinsics(I, Builder))
+    return Res;
+
   return nullptr;
 }

llvm/test/Transforms/InstCombine/bitreverse-known-bits.ll

@@ -46,9 +46,8 @@ define i1 @test3(i32 %arg) {
 
 define i8 @add_bitreverse(i8 %a) {
 ; CHECK-LABEL: @add_bitreverse(
-; CHECK-NEXT:    [[B:%.*]] = and i8 [[A:%.*]], -4
-; CHECK-NEXT:    [[REVERSE:%.*]] = call i8 @llvm.bitreverse.i8(i8 [[B]]), !range [[RNG0:![0-9]+]]
-; CHECK-NEXT:    [[C:%.*]] = or disjoint i8 [[REVERSE]], -16
+; CHECK-NEXT:    [[TMP1:%.*]] = or i8 [[A:%.*]], 15
+; CHECK-NEXT:    [[C:%.*]] = call i8 @llvm.bitreverse.i8(i8 [[TMP1]])
 ; CHECK-NEXT:    ret i8 [[C]]
 ;
   %b = and i8 %a, 252