[ValueTracking] Consistently propagate DemandedElts is isKnownNonZero

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Differential Revision: https://phabricator.intern.facebook.com/D60250837

Author: goldsteinn

llvm/lib/Analysis/ValueTracking.cpp

@@ -303,15 +303,21 @@ bool llvm::isKnownNegative(const Value *V, const SimplifyQuery &SQ,
   return computeKnownBits(V, Depth, SQ).isNegative();
 }
 
-static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth,
+static bool isKnownNonEqual(const Value *V1, const Value *V2,
+                            const APInt &DemandedElts, unsigned Depth,
                             const SimplifyQuery &Q);
 
 bool llvm::isKnownNonEqual(const Value *V1, const Value *V2,
                            const DataLayout &DL, AssumptionCache *AC,
                            const Instruction *CxtI, const DominatorTree *DT,
                            bool UseInstrInfo) {
+  assert(V1->getType() == V2->getType() &&
+         "Testing equality of non-equal types!");
+  auto *FVTy = dyn_cast<FixedVectorType>(V1->getType());
+  APInt DemandedElts =
+      FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
   return ::isKnownNonEqual(
-      V1, V2, 0,
+      V1, V2, DemandedElts, 0,
       SimplifyQuery(DL, DT, AC, safeCxtI(V2, V1, CxtI), UseInstrInfo));
 }
 
@@ -2654,7 +2660,7 @@ static bool isNonZeroSub(const APInt &DemandedElts, unsigned Depth,
     if (C->isNullValue() && isKnownNonZero(Y, DemandedElts, Q, Depth))
       return true;
 
-  return ::isKnownNonEqual(X, Y, Depth, Q);
+  return ::isKnownNonEqual(X, Y, DemandedElts, Depth, Q);
 }
 
 static bool isNonZeroMul(const APInt &DemandedElts, unsigned Depth,
@@ -2778,8 +2784,11 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
     //    This all implies the 2 i16 elements are non-zero.
     Type *FromTy = I->getOperand(0)->getType();
     if ((FromTy->isIntOrIntVectorTy() || FromTy->isPtrOrPtrVectorTy()) &&
-        (BitWidth % getBitWidth(FromTy->getScalarType(), Q.DL)) == 0)
+        (BitWidth % getBitWidth(FromTy->getScalarType(), Q.DL)) == 0) {
+      if (match(I, m_ElementWiseBitCast(m_Value())))
+        return isKnownNonZero(I->getOperand(0), DemandedElts, Q, Depth);
       return isKnownNonZero(I->getOperand(0), Q, Depth);
+    }
   } break;
   case Instruction::IntToPtr:
     // Note that we have to take special care to avoid looking through
@@ -2788,21 +2797,21 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
     if (!isa<ScalableVectorType>(I->getType()) &&
         Q.DL.getTypeSizeInBits(I->getOperand(0)->getType()).getFixedValue() <=
             Q.DL.getTypeSizeInBits(I->getType()).getFixedValue())
-      return isKnownNonZero(I->getOperand(0), Q, Depth);
+      return isKnownNonZero(I->getOperand(0), DemandedElts, Q, Depth);
     break;
   case Instruction::PtrToInt:
     // Similar to int2ptr above, we can look through ptr2int here if the cast
     // is a no-op or an extend and not a truncate.
     if (!isa<ScalableVectorType>(I->getType()) &&
         Q.DL.getTypeSizeInBits(I->getOperand(0)->getType()).getFixedValue() <=
             Q.DL.getTypeSizeInBits(I->getType()).getFixedValue())
-      return isKnownNonZero(I->getOperand(0), Q, Depth);
+      return isKnownNonZero(I->getOperand(0), DemandedElts, Q, Depth);
     break;
   case Instruction::Trunc:
     // nuw/nsw trunc preserves zero/non-zero status of input.
     if (auto *TI = dyn_cast<TruncInst>(I))
       if (TI->hasNoSignedWrap() || TI->hasNoUnsignedWrap())
-        return isKnownNonZero(TI->getOperand(0), Q, Depth);
+        return isKnownNonZero(TI->getOperand(0), DemandedElts, Q, Depth);
     break;
 
   case Instruction::Sub:
@@ -2823,13 +2832,13 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
   case Instruction::SExt:
   case Instruction::ZExt:
     // ext X != 0 if X != 0.
-    return isKnownNonZero(I->getOperand(0), Q, Depth);
+    return isKnownNonZero(I->getOperand(0), DemandedElts, Q, Depth);
 
   case Instruction::Shl: {
     // shl nsw/nuw can't remove any non-zero bits.
     const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(I);
     if (Q.IIQ.hasNoUnsignedWrap(BO) || Q.IIQ.hasNoSignedWrap(BO))
-      return isKnownNonZero(I->getOperand(0), Q, Depth);
+      return isKnownNonZero(I->getOperand(0), DemandedElts, Q, Depth);
 
     // shl X, Y != 0 if X is odd.  Note that the value of the shift is undefined
     // if the lowest bit is shifted off the end.
@@ -2845,7 +2854,7 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
     // shr exact can only shift out zero bits.
     const PossiblyExactOperator *BO = cast<PossiblyExactOperator>(I);
     if (BO->isExact())
-      return isKnownNonZero(I->getOperand(0), Q, Depth);
+      return isKnownNonZero(I->getOperand(0), DemandedElts, Q, Depth);
 
     // shr X, Y != 0 if X is negative.  Note that the value of the shift is not
     // defined if the sign bit is shifted off the end.
@@ -3100,6 +3109,8 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
                             /*NSW=*/true, /* NUW=*/false);
         // Vec reverse preserves zero/non-zero status from input vec.
       case Intrinsic::vector_reverse:
+        return isKnownNonZero(II->getArgOperand(0), DemandedElts.reverseBits(),
+                              Q, Depth);
         // umin/smin/smax/smin/or of all non-zero elements is always non-zero.
       case Intrinsic::vector_reduce_or:
       case Intrinsic::vector_reduce_umax:
@@ -3424,7 +3435,8 @@ getInvertibleOperands(const Operator *Op1,
 /// Only handle a small subset of binops where (binop V2, X) with non-zero X
 /// implies V2 != V1.
 static bool isModifyingBinopOfNonZero(const Value *V1, const Value *V2,
-                                      unsigned Depth, const SimplifyQuery &Q) {
+                                      const APInt &DemandedElts, unsigned Depth,
+                                      const SimplifyQuery &Q) {
   const BinaryOperator *BO = dyn_cast<BinaryOperator>(V1);
   if (!BO)
     return false;
@@ -3444,39 +3456,43 @@ static bool isModifyingBinopOfNonZero(const Value *V1, const Value *V2,
       Op = BO->getOperand(0);
     else
       return false;
-    return isKnownNonZero(Op, Q, Depth + 1);
+    return isKnownNonZero(Op, DemandedElts, Q, Depth + 1);
   }
   return false;
 }
 
 /// Return true if V2 == V1 * C, where V1 is known non-zero, C is not 0/1 and
 /// the multiplication is nuw or nsw.
-static bool isNonEqualMul(const Value *V1, const Value *V2, unsigned Depth,
+static bool isNonEqualMul(const Value *V1, const Value *V2,
+                          const APInt &DemandedElts, unsigned Depth,
                           const SimplifyQuery &Q) {
   if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) {
     const APInt *C;
     return match(OBO, m_Mul(m_Specific(V1), m_APInt(C))) &&
            (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) &&
-           !C->isZero() && !C->isOne() && isKnownNonZero(V1, Q, Depth + 1);
+           !C->isZero() && !C->isOne() &&
+           isKnownNonZero(V1, DemandedElts, Q, Depth + 1);
   }
   return false;
 }
 
 /// Return true if V2 == V1 << C, where V1 is known non-zero, C is not 0 and
 /// the shift is nuw or nsw.
-static bool isNonEqualShl(const Value *V1, const Value *V2, unsigned Depth,
+static bool isNonEqualShl(const Value *V1, const Value *V2,
+                          const APInt &DemandedElts, unsigned Depth,
                           const SimplifyQuery &Q) {
   if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) {
     const APInt *C;
     return match(OBO, m_Shl(m_Specific(V1), m_APInt(C))) &&
            (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) &&
-           !C->isZero() && isKnownNonZero(V1, Q, Depth + 1);
+           !C->isZero() && isKnownNonZero(V1, DemandedElts, Q, Depth + 1);
   }
   return false;
 }
 
 static bool isNonEqualPHIs(const PHINode *PN1, const PHINode *PN2,
-                           unsigned Depth, const SimplifyQuery &Q) {
+                           const APInt &DemandedElts, unsigned Depth,
+                           const SimplifyQuery &Q) {
   // Check two PHIs are in same block.
   if (PN1->getParent() != PN2->getParent())
     return false;
@@ -3498,14 +3514,15 @@ static bool isNonEqualPHIs(const PHINode *PN1, const PHINode *PN2,
 
     SimplifyQuery RecQ = Q;
     RecQ.CxtI = IncomBB->getTerminator();
-    if (!isKnownNonEqual(IV1, IV2, Depth + 1, RecQ))
+    if (!isKnownNonEqual(IV1, IV2, DemandedElts, Depth + 1, RecQ))
       return false;
     UsedFullRecursion = true;
   }
   return true;
 }
 
-static bool isNonEqualSelect(const Value *V1, const Value *V2, unsigned Depth,
+static bool isNonEqualSelect(const Value *V1, const Value *V2,
+                             const APInt &DemandedElts, unsigned Depth,
                              const SimplifyQuery &Q) {
   const SelectInst *SI1 = dyn_cast<SelectInst>(V1);
   if (!SI1)
@@ -3516,12 +3533,12 @@ static bool isNonEqualSelect(const Value *V1, const Value *V2, unsigned Depth,
     const Value *Cond2 = SI2->getCondition();
     if (Cond1 == Cond2)
       return isKnownNonEqual(SI1->getTrueValue(), SI2->getTrueValue(),
-                             Depth + 1, Q) &&
+                             DemandedElts, Depth + 1, Q) &&
              isKnownNonEqual(SI1->getFalseValue(), SI2->getFalseValue(),
-                             Depth + 1, Q);
+                             DemandedElts, Depth + 1, Q);
   }
-  return isKnownNonEqual(SI1->getTrueValue(), V2, Depth + 1, Q) &&
-         isKnownNonEqual(SI1->getFalseValue(), V2, Depth + 1, Q);
+  return isKnownNonEqual(SI1->getTrueValue(), V2, DemandedElts, Depth + 1, Q) &&
+         isKnownNonEqual(SI1->getFalseValue(), V2, DemandedElts, Depth + 1, Q);
 }
 
 // Check to see if A is both a GEP and is the incoming value for a PHI in the
@@ -3577,7 +3594,8 @@ static bool isNonEqualPointersWithRecursiveGEP(const Value *A, const Value *B,
 }
 
 /// Return true if it is known that V1 != V2.
-static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth,
+static bool isKnownNonEqual(const Value *V1, const Value *V2,
+                            const APInt &DemandedElts, unsigned Depth,
                             const SimplifyQuery &Q) {
   if (V1 == V2)
     return false;
@@ -3595,40 +3613,44 @@ static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth,
   auto *O2 = dyn_cast<Operator>(V2);
   if (O1 && O2 && O1->getOpcode() == O2->getOpcode()) {
     if (auto Values = getInvertibleOperands(O1, O2))
-      return isKnownNonEqual(Values->first, Values->second, Depth + 1, Q);
+      return isKnownNonEqual(Values->first, Values->second, DemandedElts,
+                             Depth + 1, Q);
 
     if (const PHINode *PN1 = dyn_cast<PHINode>(V1)) {
       const PHINode *PN2 = cast<PHINode>(V2);
       // FIXME: This is missing a generalization to handle the case where one is
       // a PHI and another one isn't.
-      if (isNonEqualPHIs(PN1, PN2, Depth, Q))
+      if (isNonEqualPHIs(PN1, PN2, DemandedElts, Depth, Q))
         return true;
     };
   }
 
-  if (isModifyingBinopOfNonZero(V1, V2, Depth, Q) ||
-      isModifyingBinopOfNonZero(V2, V1, Depth, Q))
+  if (isModifyingBinopOfNonZero(V1, V2, DemandedElts, Depth, Q) ||
+      isModifyingBinopOfNonZero(V2, V1, DemandedElts, Depth, Q))
     return true;
 
-  if (isNonEqualMul(V1, V2, Depth, Q) || isNonEqualMul(V2, V1, Depth, Q))
+  if (isNonEqualMul(V1, V2, DemandedElts, Depth, Q) ||
+      isNonEqualMul(V2, V1, DemandedElts, Depth, Q))
     return true;
 
-  if (isNonEqualShl(V1, V2, Depth, Q) || isNonEqualShl(V2, V1, Depth, Q))
+  if (isNonEqualShl(V1, V2, DemandedElts, Depth, Q) ||
+      isNonEqualShl(V2, V1, DemandedElts, Depth, Q))
     return true;
 
   if (V1->getType()->isIntOrIntVectorTy()) {
     // Are any known bits in V1 contradictory to known bits in V2? If V1
     // has a known zero where V2 has a known one, they must not be equal.
-    KnownBits Known1 = computeKnownBits(V1, Depth, Q);
+    KnownBits Known1 = computeKnownBits(V1, DemandedElts, Depth, Q);
     if (!Known1.isUnknown()) {
-      KnownBits Known2 = computeKnownBits(V2, Depth, Q);
+      KnownBits Known2 = computeKnownBits(V2, DemandedElts, Depth, Q);
       if (Known1.Zero.intersects(Known2.One) ||
           Known2.Zero.intersects(Known1.One))
         return true;
     }
   }
 
-  if (isNonEqualSelect(V1, V2, Depth, Q) || isNonEqualSelect(V2, V1, Depth, Q))
+  if (isNonEqualSelect(V1, V2, DemandedElts, Depth, Q) ||
+      isNonEqualSelect(V2, V1, DemandedElts, Depth, Q))
     return true;
 
   if (isNonEqualPointersWithRecursiveGEP(V1, V2, Q) ||
@@ -3640,7 +3662,7 @@ static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth,
   // Check PtrToInt type matches the pointer size.
   if (match(V1, m_PtrToIntSameSize(Q.DL, m_Value(A))) &&
       match(V2, m_PtrToIntSameSize(Q.DL, m_Value(B))))
-    return isKnownNonEqual(A, B, Depth + 1, Q);
+    return isKnownNonEqual(A, B, DemandedElts, Depth + 1, Q);
 
   return false;
 }

llvm/test/Analysis/ValueTracking/known-non-zero.ll

@@ -1522,11 +1522,7 @@ define <4 x i1> @vec_reverse_non_zero_fail(<4 x i8> %xx) {
 
 define i1 @vec_reverse_non_zero_demanded(<4 x i8> %xx) {
 ; CHECK-LABEL: @vec_reverse_non_zero_demanded(
-; CHECK-NEXT:    [[X:%.*]] = add nuw <4 x i8> [[XX:%.*]], <i8 1, i8 0, i8 0, i8 0>
-; CHECK-NEXT:    [[REV:%.*]] = call <4 x i8> @llvm.vector.reverse.v4i8(<4 x i8> [[X]])
-; CHECK-NEXT:    [[ELE:%.*]] = extractelement <4 x i8> [[REV]], i64 3
-; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[ELE]], 0
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 false
 ;
   %x = add nuw <4 x i8> %xx, <i8 1, i8 0, i8 0, i8 0>
   %rev = call <4 x i8> @llvm.vector.reverse(<4 x i8> %x)