Support: Extract ScaledNumbers::compare()

llvm-svn: 211507

llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h

@@ -66,19 +66,6 @@ public:
       return IsNeg ? INT64_MIN : INT64_MAX;
     return IsNeg ? -int64_t(U) : int64_t(U);
   }
-
-  static int compare(uint64_t L, uint64_t R, int Shift) {
-    assert(Shift >= 0);
-    assert(Shift < 64);
-
-    uint64_t L_adjusted = L >> Shift;
-    if (L_adjusted < R)
-      return -1;
-    if (L_adjusted > R)
-      return 1;
-
-    return L > L_adjusted << Shift ? 1 : 0;
-  }
 };
 
 /// \brief Simple representation of an unsigned floating point.
@@ -289,7 +276,9 @@ public:
     return joinSigned(scaleByInverse(Unsigned.first), Unsigned.second);
   }
 
-  int compare(const UnsignedFloat &X) const;
+  int compare(const UnsignedFloat &X) const {
+    return ScaledNumbers::compare(Digits, Exponent, X.Digits, X.Exponent);
+  }
   int compareTo(uint64_t N) const {
     UnsignedFloat Float = getFloat(N);
     int Compare = compare(Float);
@@ -605,27 +594,6 @@ void UnsignedFloat<DigitsT>::shiftRight(int32_t Shift) {
   return;
 }
 
-template <class DigitsT>
-int UnsignedFloat<DigitsT>::compare(const UnsignedFloat &X) const {
-  // Check for zero.
-  if (isZero())
-    return X.isZero() ? 0 : -1;
-  if (X.isZero())
-    return 1;
-
-  // Check for the scale.  Use lgFloor to be sure that the exponent difference
-  // is always lower than 64.
-  int32_t lgL = lgFloor(), lgR = X.lgFloor();
-  if (lgL != lgR)
-    return lgL < lgR ? -1 : 1;
-
-  // Compare digits.
-  if (Exponent < X.Exponent)
-    return UnsignedFloatBase::compare(Digits, X.Digits, X.Exponent - Exponent);
-
-  return -UnsignedFloatBase::compare(X.Digits, Digits, Exponent - X.Exponent);
-}
-
 template <class T> struct isPodLike<UnsignedFloat<T>> {
   static const bool value = true;
 };

llvm/include/llvm/Support/ScaledNumber.h

@@ -227,6 +227,40 @@ template <class DigitsT> int32_t getLgCeiling(DigitsT Digits, int16_t Scale) {
   return Lg.first + (Lg.second < 0);
 }
 
+/// \brief Implementation for comparing scaled numbers.
+///
+/// Compare two 64-bit numbers with different scales.  Given that the scale of
+/// \c L is higher than that of \c R by \c ScaleDiff, compare them.  Return -1,
+/// 1, and 0 for less than, greater than, and equal, respectively.
+///
+/// \pre 0 <= ScaleDiff < 64.
+int compareImpl(uint64_t L, uint64_t R, int ScaleDiff);
+
+/// \brief Compare two scaled numbers.
+///
+/// Compare two scaled numbers.  Returns 0 for equal, -1 for less than, and 1
+/// for greater than.
+template <class DigitsT>
+int compare(DigitsT LDigits, int16_t LScale, DigitsT RDigits, int16_t RScale) {
+  // Check for zero.
+  if (!LDigits)
+    return RDigits ? -1 : 0;
+  if (!RDigits)
+    return 1;
+
+  // Check for the scale.  Use getLgFloor to be sure that the scale difference
+  // is always lower than 64.
+  int32_t lgL = getLgFloor(LDigits, LScale), lgR = getLgFloor(RDigits, RScale);
+  if (lgL != lgR)
+    return lgL < lgR ? -1 : 1;
+
+  // Compare digits.
+  if (LScale < RScale)
+    return compareImpl(LDigits, RDigits, RScale - LScale);
+
+  return -compareImpl(RDigits, LDigits, LScale - RScale);
+}
+
 } // end namespace ScaledNumbers
 } // end namespace llvm
 

llvm/lib/Support/ScaledNumber.cpp

@@ -117,3 +117,16 @@ std::pair<uint64_t, int16_t> ScaledNumbers::divide64(uint64_t Dividend,
 
   return getRounded(Quotient, Shift, Dividend >= getHalf(Divisor));
 }
+
+int ScaledNumbers::compareImpl(uint64_t L, uint64_t R, int ScaleDiff) {
+  assert(ScaleDiff >= 0 && "wrong argument order");
+  assert(ScaleDiff < 64 && "numbers too far apart");
+
+  uint64_t L_adjusted = L >> ScaleDiff;
+  if (L_adjusted < R)
+    return -1;
+  if (L_adjusted > R)
+    return 1;
+
+  return L > L_adjusted << ScaleDiff ? 1 : 0;
+}

llvm/unittests/Support/ScaledNumberTest.cpp

@@ -285,4 +285,41 @@ TEST(ScaledNumberHelpersTest, getLgCeiling) {
   EXPECT_EQ(INT32_MIN, getLgCeiling(UINT64_C(0), 1));
 }
 
+TEST(ScaledNumberHelpersTest, Compare) {
+  EXPECT_EQ(0, compare(UINT32_C(0), 0, UINT32_C(0), 1));
+  EXPECT_EQ(0, compare(UINT32_C(0), 0, UINT32_C(0), -10));
+  EXPECT_EQ(0, compare(UINT32_C(0), 0, UINT32_C(0), 20));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(64), -3));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(32), -2));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(16), -1));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(8), 0));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(4), 1));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(2), 2));
+  EXPECT_EQ(0, compare(UINT32_C(8), 0, UINT32_C(1), 3));
+  EXPECT_EQ(-1, compare(UINT32_C(0), 0, UINT32_C(1), 3));
+  EXPECT_EQ(-1, compare(UINT32_C(7), 0, UINT32_C(1), 3));
+  EXPECT_EQ(-1, compare(UINT32_C(7), 0, UINT32_C(64), -3));
+  EXPECT_EQ(1, compare(UINT32_C(9), 0, UINT32_C(1), 3));
+  EXPECT_EQ(1, compare(UINT32_C(9), 0, UINT32_C(64), -3));
+  EXPECT_EQ(1, compare(UINT32_C(9), 0, UINT32_C(0), 0));
+
+  EXPECT_EQ(0, compare(UINT64_C(0), 0, UINT64_C(0), 1));
+  EXPECT_EQ(0, compare(UINT64_C(0), 0, UINT64_C(0), -10));
+  EXPECT_EQ(0, compare(UINT64_C(0), 0, UINT64_C(0), 20));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(64), -3));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(32), -2));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(16), -1));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(8), 0));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(4), 1));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(2), 2));
+  EXPECT_EQ(0, compare(UINT64_C(8), 0, UINT64_C(1), 3));
+  EXPECT_EQ(-1, compare(UINT64_C(0), 0, UINT64_C(1), 3));
+  EXPECT_EQ(-1, compare(UINT64_C(7), 0, UINT64_C(1), 3));
+  EXPECT_EQ(-1, compare(UINT64_C(7), 0, UINT64_C(64), -3));
+  EXPECT_EQ(1, compare(UINT64_C(9), 0, UINT64_C(1), 3));
+  EXPECT_EQ(1, compare(UINT64_C(9), 0, UINT64_C(64), -3));
+  EXPECT_EQ(1, compare(UINT64_C(9), 0, UINT64_C(0), 0));
+  EXPECT_EQ(-1, compare(UINT64_MAX, 0, UINT64_C(1), 64));
+}
+
 } // end namespace