[KnownBits] Add wrapper methods for setting and clear all bits in the underlying...

This adds routines for reseting KnownBits to unknown, making the value all zeros or all ones. It also adds methods for querying if the value is zero, all ones or unknown.

Differential Revision: https://reviews.llvm.org/D32637

llvm-svn: 302262

diff --git a/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h b/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h
index 14ee501..e7544bd 100644 (file)
--- a/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h
+++ b/llvm/include/llvm/CodeGen/FunctionLoweringInfo.h
@@ -249,7 +249,7 @@ public:
   void AddLiveOutRegInfo(unsigned Reg, unsigned NumSignBits,
                          const KnownBits &Known) {
     // Only install this information if it tells us something.
-    if (NumSignBits == 1 && Known.Zero == 0 && Known.One == 0)
+    if (NumSignBits == 1 && Known.isUnknown())
       return;
 
     LiveOutRegInfo.grow(Reg);

diff --git a/llvm/include/llvm/Support/KnownBits.h b/llvm/include/llvm/Support/KnownBits.h
index 0765fe0..3d38cf8 100644 (file)
--- a/llvm/include/llvm/Support/KnownBits.h
+++ b/llvm/include/llvm/Support/KnownBits.h
@@ -59,6 +59,39 @@ public:
     return One;
   }
 
+  /// Returns true if we don't know any bits.
+  bool isUnknown() const { return Zero.isNullValue() && One.isNullValue(); }
+
+  /// Resets the known state of all bits.
+  void resetAll() {
+    Zero.clearAllBits();
+    One.clearAllBits();
+  }
+
+  /// Returns true if value is all zero.
+  bool isZero() const {
+    assert(!hasConflict() && "KnownBits conflict!");
+    return Zero.isAllOnesValue();
+  }
+
+  /// Returns true if value is all one bits.
+  bool isAllOnes() const {
+    assert(!hasConflict() && "KnownBits conflict!");
+    return One.isAllOnesValue();
+  }
+
+  /// Make all bits known to be zero and discard any previous information.
+  void setAllZero() {
+    Zero.setAllBits();
+    One.clearAllBits();
+  }
+
+  /// Make all bits known to be one and discard any previous information.
+  void setAllOnes() {
+    Zero.clearAllBits();
+    One.setAllBits();
+  }
+
   /// Returns true if this value is known to be negative.
   bool isNegative() const { return One.isSignBitSet(); }
 

diff --git a/llvm/lib/Analysis/Lint.cpp b/llvm/lib/Analysis/Lint.cpp
index 5981382..471ccb6 100644 (file)
--- a/llvm/lib/Analysis/Lint.cpp
+++ b/llvm/lib/Analysis/Lint.cpp
@@ -537,7 +537,7 @@ static bool isZero(Value *V, const DataLayout &DL, DominatorTree *DT,
     unsigned BitWidth = V->getType()->getIntegerBitWidth();
     KnownBits Known(BitWidth);
     computeKnownBits(V, Known, DL, 0, AC, dyn_cast<Instruction>(V), DT);
-    return Known.Zero.isAllOnesValue();
+    return Known.isZero();
   }
 
   // Per-component check doesn't work with zeroinitializer
@@ -558,7 +558,7 @@ static bool isZero(Value *V, const DataLayout &DL, DominatorTree *DT,
 
     KnownBits Known(BitWidth);
     computeKnownBits(Elem, Known, DL);
-    if (Known.Zero.isAllOnesValue())
+    if (Known.isZero())
       return true;
   }
 

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index e33e081..a7f3ff6 100644 (file)
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -342,7 +342,6 @@ static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW,
   // Also compute a conservative estimate for high known-0 bits.
   // More trickiness is possible, but this is sufficient for the
   // interesting case of alignment computation.
-  Known.One.clearAllBits();
   unsigned TrailZ = Known.Zero.countTrailingOnes() +
                     Known2.Zero.countTrailingOnes();
   unsigned LeadZ =  std::max(Known.Zero.countLeadingOnes() +
@@ -351,7 +350,7 @@ static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW,
 
   TrailZ = std::min(TrailZ, BitWidth);
   LeadZ = std::min(LeadZ, BitWidth);
-  Known.Zero.clearAllBits();
+  Known.resetAll();
   Known.Zero.setLowBits(TrailZ);
   Known.Zero.setHighBits(LeadZ);
 
@@ -529,15 +528,13 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
 
     if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
       assert(BitWidth == 1 && "assume operand is not i1?");
-      Known.Zero.clearAllBits();
-      Known.One.setAllBits();
+      Known.setAllOnes();
       return;
     }
     if (match(Arg, m_Not(m_Specific(V))) &&
         isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
       assert(BitWidth == 1 && "assume operand is not i1?");
-      Known.Zero.setAllBits();
-      Known.One.clearAllBits();
+      Known.setAllZero();
       return;
     }
 
@@ -719,7 +716,7 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
       KnownBits RHSKnown(BitWidth);
       computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
 
-      if (RHSKnown.One.isAllOnesValue() || RHSKnown.isNonNegative()) {
+      if (RHSKnown.isAllOnes() || RHSKnown.isNonNegative()) {
         // We know that the sign bit is zero.
         Known.makeNonNegative();
       }
@@ -741,7 +738,7 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
       KnownBits RHSKnown(BitWidth);
       computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
 
-      if (RHSKnown.Zero.isAllOnesValue() || RHSKnown.isNegative()) {
+      if (RHSKnown.isZero() || RHSKnown.isNegative()) {
         // We know that the sign bit is one.
         Known.makeNegative();
       }
@@ -776,8 +773,7 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
   // behavior, or we might have a bug in the compiler. We can't assert/crash, so
   // clear out the known bits, try to warn the user, and hope for the best.
   if (Known.Zero.intersects(Known.One)) {
-    Known.Zero.clearAllBits();
-    Known.One.clearAllBits();
+    Known.resetAll();
 
     if (Q.ORE) {
       auto *CxtI = const_cast<Instruction *>(Q.CxtI);
@@ -813,10 +809,8 @@ static void computeKnownBitsFromShiftOperator(
     // If there is conflict between Known.Zero and Known.One, this must be an
     // overflowing left shift, so the shift result is undefined. Clear Known
     // bits so that other code could propagate this undef.
-    if ((Known.Zero & Known.One) != 0) {
-      Known.Zero.clearAllBits();
-      Known.One.clearAllBits();
-    }
+    if ((Known.Zero & Known.One) != 0)
+      Known.resetAll();
 
     return;
   }
@@ -826,8 +820,7 @@ static void computeKnownBitsFromShiftOperator(
   // If the shift amount could be greater than or equal to the bit-width of the LHS, the
   // value could be undef, so we don't know anything about it.
   if ((~Known.Zero).uge(BitWidth)) {
-    Known.Zero.clearAllBits();
-    Known.One.clearAllBits();
+    Known.resetAll();
     return;
   }
 
@@ -839,8 +832,7 @@ static void computeKnownBitsFromShiftOperator(
 
   // It would be more-clearly correct to use the two temporaries for this
   // calculation. Reusing the APInts here to prevent unnecessary allocations.
-  Known.Zero.clearAllBits();
-  Known.One.clearAllBits();
+  Known.resetAll();
 
   // If we know the shifter operand is nonzero, we can sometimes infer more
   // known bits. However this is expensive to compute, so be lazy about it and
@@ -886,10 +878,8 @@ static void computeKnownBitsFromShiftOperator(
   // return anything we'd like, but we need to make sure the sets of known bits
   // stay disjoint (it should be better for some other code to actually
   // propagate the undef than to pick a value here using known bits).
-  if (Known.Zero.intersects(Known.One)) {
-    Known.Zero.clearAllBits();
-    Known.One.clearAllBits();
-  }
+  if (Known.Zero.intersects(Known.One))
+    Known.resetAll();
 }
 
 static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known,
@@ -924,7 +914,7 @@ static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known,
                                        m_Value(Y))) ||
          match(I->getOperand(1), m_Add(m_Specific(I->getOperand(0)),
                                        m_Value(Y))))) {
-      Known2.Zero.clearAllBits(); Known2.One.clearAllBits();
+      Known2.resetAll();
       computeKnownBits(Y, Known2, Depth + 1, Q);
       if (Known2.One.countTrailingOnes() > 0)
         Known.Zero.setBit(0);
@@ -965,8 +955,7 @@ static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known,
     computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
     unsigned LeadZ = Known2.Zero.countLeadingOnes();
 
-    Known2.One.clearAllBits();
-    Known2.Zero.clearAllBits();
+    Known2.resetAll();
     computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
     unsigned RHSUnknownLeadingOnes = Known2.One.countLeadingZeros();
     if (RHSUnknownLeadingOnes != BitWidth)
@@ -1198,8 +1187,7 @@ static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known,
 
     unsigned Leaders = std::max(Known.Zero.countLeadingOnes(),
                                 Known2.Zero.countLeadingOnes());
-    Known.One.clearAllBits();
-    Known.Zero.clearAllBits();
+    Known.resetAll();
     Known.Zero.setHighBits(Leaders);
     break;
   }
@@ -1500,8 +1488,7 @@ void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
   }
   // Null and aggregate-zero are all-zeros.
   if (isa<ConstantPointerNull>(V) || isa<ConstantAggregateZero>(V)) {
-    Known.One.clearAllBits();
-    Known.Zero.setAllBits();
+    Known.setAllZero();
     return;
   }
   // Handle a constant vector by taking the intersection of the known bits of
@@ -1528,8 +1515,7 @@ void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
       Constant *Element = CV->getAggregateElement(i);
       auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element);
       if (!ElementCI) {
-        Known.Zero.clearAllBits();
-        Known.One.clearAllBits();
+        Known.resetAll();
         return;
       }
       Elt = ElementCI->getValue();
@@ -1540,7 +1526,7 @@ void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
   }
 
   // Start out not knowing anything.
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
 
   // We can't imply anything about undefs.
   if (isa<UndefValue>(V))

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index efcb615..d605a1d 100644 (file)
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2044,8 +2044,7 @@ void SelectionDAG::computeKnownBits(SDValue Op, KnownBits &Known,
       if (M < 0) {
         // For UNDEF elements, we don't know anything about the common state of
         // the shuffle result.
-        Known.One.clearAllBits();
-        Known.Zero.clearAllBits();
+        Known.resetAll();
         DemandedLHS.clearAllBits();
         DemandedRHS.clearAllBits();
         break;
@@ -2218,14 +2217,13 @@ void SelectionDAG::computeKnownBits(SDValue Op, KnownBits &Known,
     // Also compute a conservative estimate for high known-0 bits.
     // More trickiness is possible, but this is sufficient for the
     // interesting case of alignment computation.
-    Known.One.clearAllBits();
     unsigned TrailZ = Known.Zero.countTrailingOnes() +
                       Known2.Zero.countTrailingOnes();
     unsigned LeadZ =  std::max(Known.Zero.countLeadingOnes() +
                                Known2.Zero.countLeadingOnes(),
                                BitWidth) - BitWidth;
 
-    Known.Zero.clearAllBits();
+    Known.resetAll();
     Known.Zero.setLowBits(std::min(TrailZ, BitWidth));
     Known.Zero.setHighBits(std::min(LeadZ, BitWidth));
     break;
@@ -2598,8 +2596,7 @@ void SelectionDAG::computeKnownBits(SDValue Op, KnownBits &Known,
 
     uint32_t Leaders = std::max(Known.Zero.countLeadingOnes(),
                                 Known2.Zero.countLeadingOnes());
-    Known.One.clearAllBits();
-    Known.Zero.clearAllBits();
+    Known.resetAll();
     Known.Zero.setHighBits(Leaders);
     break;
   }

diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index cf3eed8..23f597d 100644 (file)
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1303,7 +1303,7 @@ void TargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
           Op.getOpcode() == ISD::INTRINSIC_VOID) &&
          "Should use MaskedValueIsZero if you don't know whether Op"
          " is a target node!");
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
 }
 
 /// This method can be implemented by targets that want to expose additional

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp b/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
index 64e1b8f..915d1d9 100644 (file)
--- a/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
@@ -3580,7 +3580,7 @@ void AMDGPUTargetLowering::computeKnownBitsForTargetNode(
     const SDValue Op, KnownBits &Known,
     const APInt &DemandedElts, const SelectionDAG &DAG, unsigned Depth) const {
 
-  Known.Zero.clearAllBits(); Known.One.clearAllBits(); // Don't know anything.
+  Known.resetAll(); // Don't know anything.
 
   KnownBits Known2;
   unsigned Opc = Op.getOpcode();

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 932ab9d..f248a82 100644 (file)
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -12640,7 +12640,7 @@ void ARMTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
                                                       const SelectionDAG &DAG,
                                                       unsigned Depth) const {
   unsigned BitWidth = Known.getBitWidth();
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
   switch (Op.getOpcode()) {
   default: break;
   case ARMISD::ADDC:
@@ -12655,7 +12655,8 @@ void ARMTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
   case ARMISD::CMOV: {
     // Bits are known zero/one if known on the LHS and RHS.
     DAG.computeKnownBits(Op.getOperand(0), Known, Depth+1);
-    if (Known.Zero == 0 && Known.One == 0) return;
+    if (Known.isUnknown())
+      return;
 
     KnownBits KnownRHS;
     DAG.computeKnownBits(Op.getOperand(1), KnownRHS, Depth+1);

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 483e9b1..685f24c 100644 (file)
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -12031,7 +12031,7 @@ void PPCTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
                                                       const APInt &DemandedElts,
                                                       const SelectionDAG &DAG,
                                                       unsigned Depth) const {
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
   switch (Op.getOpcode()) {
   default: break;
   case PPCISD::LBRX: {

diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index c44e371..acb34d5 100644 (file)
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -1881,7 +1881,7 @@ void SparcTargetLowering::computeKnownBitsForTargetNode
                                  const SelectionDAG &DAG,
                                  unsigned Depth) const {
   KnownBits Known2;
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
 
   switch (Op.getOpcode()) {
   default: break;

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index b5d1962..a1ade43 100644 (file)
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -26614,7 +26614,7 @@ void X86TargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
          "Should use MaskedValueIsZero if you don't know whether Op"
          " is a target node!");
 
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
   switch (Opc) {
   default: break;
   case X86ISD::ADD:
@@ -26644,7 +26644,7 @@ void X86TargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
   case X86ISD::VSRLI: {
     if (auto *ShiftImm = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
       if (ShiftImm->getAPIntValue().uge(VT.getScalarSizeInBits())) {
-        Known.Zero.setAllBits();
+        Known.setAllZero();
         break;
       }
 

diff --git a/llvm/lib/Target/XCore/XCoreISelLowering.cpp b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
index 4d3ecf2..b874268 100644 (file)
--- a/llvm/lib/Target/XCore/XCoreISelLowering.cpp
+++ b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
@@ -1825,7 +1825,7 @@ void XCoreTargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
                                                         const APInt &DemandedElts,
                                                         const SelectionDAG &DAG,
                                                         unsigned Depth) const {
-  Known.Zero.clearAllBits(); Known.One.clearAllBits();
+  Known.resetAll();
   switch (Op.getOpcode()) {
   default: break;
   case XCoreISD::LADD:

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 4fd90d7..6989d67 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3619,7 +3619,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
     // then this one is redundant, and should be removed.
     KnownBits Known(1);
     computeKnownBits(IIOperand, Known, 0, II);
-    if (Known.One.isAllOnesValue())
+    if (Known.isAllOnes())
       return eraseInstFromFunction(*II);
 
     // Update the cache of affected values for this assumption (we might be

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 6097077..34ce235 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4050,7 +4050,7 @@ Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
     // is set. If the comparison is against zero, then this is a check to see if
     // *that* bit is set.
     APInt Op0KnownZeroInverted = ~Op0Known.Zero;
-    if (~Op1Known.Zero == 0) {
+    if (Op1Known.isZero()) {
       // If the LHS is an AND with the same constant, look through it.
       Value *LHS = nullptr;
       const APInt *LHSC;

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index c42c76a..05b0177 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -120,8 +120,7 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     return nullptr;
   }
 
-  Known.Zero.clearAllBits();
-  Known.One.clearAllBits();
+  Known.resetAll();
   if (DemandedMask == 0)     // Not demanding any bits from V.
     return UndefValue::get(VTy);