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

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

1 files changed, 18 insertions, 32 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index e33e0812a08..a7f3ff672ae 100644
--- 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))