[ConstantRange] Add getNonEmpty() constructor

ConstantRanges have an annoying special case: If upper and lower are
the same, it can be either an empty or a full set. When constructing
constant ranges nearly always a full set is intended, but this still
requires an explicit check in many places.

This revision adds a getNonEmpty() constructor that disambiguates this
case: If upper and lower are the same, a full set is created.

Differential Revision: https://reviews.llvm.org/D60947

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358854 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/ConstantRange.h b/include/llvm/IR/ConstantRange.h
index ec57e08..6dbe405 100644 (file)
--- a/include/llvm/IR/ConstantRange.h
+++ b/include/llvm/IR/ConstantRange.h
@@ -79,6 +79,14 @@ public:
     return ConstantRange(BitWidth, true);
   }
 
+  /// Create non-empty constant range with the given bounds. If Lower and
+  /// Upper are the same, a full range is returned.
+  static ConstantRange getNonEmpty(APInt Lower, APInt Upper) {
+    if (Lower == Upper)
+      return getFull(Lower.getBitWidth());
+    return ConstantRange(std::move(Lower), std::move(Upper));
+  }
+
   /// Initialize a range based on a known bits constraint. The IsSigned flag
   /// indicates whether the constant range should not wrap in the signed or
   /// unsigned domain.

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 01b4019..1f69bc8 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -5808,12 +5808,8 @@ static ConstantRange getRangeForAffineARHelper(APInt Step,
       Descending ? std::move(StartUpper) : std::move(MovedBoundary);
   NewUpper += 1;
 
-  // If we end up with full range, return a proper full range.
-  if (NewLower == NewUpper)
-    return ConstantRange::getFull(BitWidth);
-
   // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
-  return ConstantRange(std::move(NewLower), std::move(NewUpper));
+  return ConstantRange::getNonEmpty(std::move(NewLower), std::move(NewUpper));
 }
 
 ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 9c7b0fa..3b08a2d 100644 (file)
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -5726,8 +5726,7 @@ ConstantRange llvm::computeConstantRange(const Value *V, bool UseInstrInfo) {
   else if (auto *SI = dyn_cast<SelectInst>(V))
     setLimitsForSelectPattern(*SI, Lower, Upper);
 
-  ConstantRange CR = Lower != Upper ? ConstantRange(Lower, Upper)
-                                    : ConstantRange::getFull(BitWidth);
+  ConstantRange CR = ConstantRange::getNonEmpty(Lower, Upper);
 
   if (auto *I = dyn_cast<Instruction>(V))
     if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range))

diff --git a/lib/IR/ConstantRange.cpp b/lib/IR/ConstantRange.cpp
index 87b66fa..7bd14e6 100644 (file)
--- a/lib/IR/ConstantRange.cpp
+++ b/lib/IR/ConstantRange.cpp
@@ -101,18 +101,10 @@ ConstantRange ConstantRange::makeAllowedICmpRegion(CmpInst::Predicate Pred,
       return getEmpty(W);
     return ConstantRange(APInt::getSignedMinValue(W), std::move(SMax));
   }
-  case CmpInst::ICMP_ULE: {
-    APInt UMax(CR.getUnsignedMax());
-    if (UMax.isMaxValue())
-      return getFull(W);
-    return ConstantRange(APInt::getMinValue(W), std::move(UMax) + 1);
-  }
-  case CmpInst::ICMP_SLE: {
-    APInt SMax(CR.getSignedMax());
-    if (SMax.isMaxSignedValue())
-      return getFull(W);
-    return ConstantRange(APInt::getSignedMinValue(W), std::move(SMax) + 1);
-  }
+  case CmpInst::ICMP_ULE:
+    return getNonEmpty(APInt::getMinValue(W), CR.getUnsignedMax() + 1);
+  case CmpInst::ICMP_SLE:
+    return getNonEmpty(APInt::getSignedMinValue(W), CR.getSignedMax() + 1);
   case CmpInst::ICMP_UGT: {
     APInt UMin(CR.getUnsignedMin());
     if (UMin.isMaxValue())
@@ -125,18 +117,10 @@ ConstantRange ConstantRange::makeAllowedICmpRegion(CmpInst::Predicate Pred,
       return getEmpty(W);
     return ConstantRange(std::move(SMin) + 1, APInt::getSignedMinValue(W));
   }
-  case CmpInst::ICMP_UGE: {
-    APInt UMin(CR.getUnsignedMin());
-    if (UMin.isMinValue())
-      return getFull(W);
-    return ConstantRange(std::move(UMin), APInt::getNullValue(W));
-  }
-  case CmpInst::ICMP_SGE: {
-    APInt SMin(CR.getSignedMin());
-    if (SMin.isMinSignedValue())
-      return getFull(W);
-    return ConstantRange(std::move(SMin), APInt::getSignedMinValue(W));
-  }
+  case CmpInst::ICMP_UGE:
+    return getNonEmpty(CR.getUnsignedMin(), APInt::getNullValue(W));
+  case CmpInst::ICMP_SGE:
+    return getNonEmpty(CR.getSignedMin(), APInt::getSignedMinValue(W));
   }
 }
 
@@ -948,9 +932,7 @@ ConstantRange::smax(const ConstantRange &Other) const {
     return getEmpty();
   APInt NewL = APIntOps::smax(getSignedMin(), Other.getSignedMin());
   APInt NewU = APIntOps::smax(getSignedMax(), Other.getSignedMax()) + 1;
-  if (NewU == NewL)
-    return getFull();
-  return ConstantRange(std::move(NewL), std::move(NewU));
+  return getNonEmpty(std::move(NewL), std::move(NewU));
 }
 
 ConstantRange
@@ -961,9 +943,7 @@ ConstantRange::umax(const ConstantRange &Other) const {
     return getEmpty();
   APInt NewL = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
   APInt NewU = APIntOps::umax(getUnsignedMax(), Other.getUnsignedMax()) + 1;
-  if (NewU == NewL)
-    return getFull();
-  return ConstantRange(std::move(NewL), std::move(NewU));
+  return getNonEmpty(std::move(NewL), std::move(NewU));
 }
 
 ConstantRange
@@ -974,9 +954,7 @@ ConstantRange::smin(const ConstantRange &Other) const {
     return getEmpty();
   APInt NewL = APIntOps::smin(getSignedMin(), Other.getSignedMin());
   APInt NewU = APIntOps::smin(getSignedMax(), Other.getSignedMax()) + 1;
-  if (NewU == NewL)
-    return getFull();
-  return ConstantRange(std::move(NewL), std::move(NewU));
+  return getNonEmpty(std::move(NewL), std::move(NewU));
 }
 
 ConstantRange
@@ -987,9 +965,7 @@ ConstantRange::umin(const ConstantRange &Other) const {
     return getEmpty();
   APInt NewL = APIntOps::umin(getUnsignedMin(), Other.getUnsignedMin());
   APInt NewU = APIntOps::umin(getUnsignedMax(), Other.getUnsignedMax()) + 1;
-  if (NewU == NewL)
-    return getFull();
-  return ConstantRange(std::move(NewL), std::move(NewU));
+  return getNonEmpty(std::move(NewL), std::move(NewU));
 }
 
 ConstantRange
@@ -1012,13 +988,7 @@ ConstantRange::udiv(const ConstantRange &RHS) const {
   }
 
   APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;
-
-  // If the LHS is Full and the RHS is a wrapped interval containing 1 then
-  // this could occur.
-  if (Lower == Upper)
-    return getFull();
-
-  return ConstantRange(std::move(Lower), std::move(Upper));
+  return getNonEmpty(std::move(Lower), std::move(Upper));
 }
 
 ConstantRange
@@ -1029,9 +999,7 @@ ConstantRange::binaryAnd(const ConstantRange &Other) const {
   // TODO: replace this with something less conservative
 
   APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
-  if (umin.isAllOnesValue())
-    return getFull();
-  return ConstantRange(APInt::getNullValue(getBitWidth()), std::move(umin) + 1);
+  return getNonEmpty(APInt::getNullValue(getBitWidth()), std::move(umin) + 1);
 }
 
 ConstantRange
@@ -1042,9 +1010,7 @@ ConstantRange::binaryOr(const ConstantRange &Other) const {
   // TODO: replace this with something less conservative
 
   APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
-  if (umax.isNullValue())
-    return getFull();
-  return ConstantRange(std::move(umax), APInt::getNullValue(getBitWidth()));
+  return getNonEmpty(std::move(umax), APInt::getNullValue(getBitWidth()));
 }
 
 ConstantRange
@@ -1079,10 +1045,7 @@ ConstantRange::lshr(const ConstantRange &Other) const {
 
   APInt max = getUnsignedMax().lshr(Other.getUnsignedMin()) + 1;
   APInt min = getUnsignedMin().lshr(Other.getUnsignedMax());
-  if (min == max)
-    return getFull();
-
-  return ConstantRange(std::move(min), std::move(max));
+  return getNonEmpty(std::move(min), std::move(max));
 }
 
 ConstantRange
@@ -1133,10 +1096,7 @@ ConstantRange::ashr(const ConstantRange &Other) const {
     min = NegMin;
     max = PosMax;
   }
-  if (min == max)
-    return getFull();
-
-  return ConstantRange(std::move(min), std::move(max));
+  return getNonEmpty(std::move(min), std::move(max));
 }
 
 ConstantRange ConstantRange::inverse() const {