#include "llvm/Support/MathExtras.h"
+#include <algorithm>
#include <cstdint>
#include <limits>
#include <utility>
return -compareImpl(RDigits, LDigits, LScale - RScale);
}
+/// \brief Match scales of two numbers.
+///
+/// Given two scaled numbers, match up their scales. Change the digits and
+/// scales in place. Shift the digits as necessary to form equivalent numbers,
+/// losing precision only when necessary.
+///
+/// If the output value of \c LDigits (\c RDigits) is \c 0, the output value of
+/// \c LScale (\c RScale) is unspecified. If both \c LDigits and \c RDigits
+/// are \c 0, the output value is one of \c LScale and \c RScale; which is
+/// unspecified.
+template <class DigitsT>
+void matchScales(DigitsT &LDigits, int16_t &LScale, DigitsT &RDigits,
+ int16_t &RScale) {
+ static_assert(!std::numeric_limits<DigitsT>::is_signed, "expected unsigned");
+
+ if (LScale < RScale) {
+ // Swap arguments.
+ matchScales(RDigits, RScale, LDigits, LScale);
+ return;
+ }
+ if (!LDigits || !RDigits || LScale == RScale)
+ return;
+
+ // Now LScale > RScale. Get the difference.
+ int32_t ScaleDiff = int32_t(LScale) - RScale;
+ if (ScaleDiff >= 2 * getWidth<DigitsT>()) {
+ // Don't bother shifting. RDigits will get zero-ed out anyway.
+ RDigits = 0;
+ return;
+ }
+
+ // Shift LDigits left as much as possible, then shift RDigits right.
+ int32_t ShiftL = std::min<int32_t>(countLeadingZeros(LDigits), ScaleDiff);
+ assert(ShiftL < getWidth<DigitsT>() && "can't shift more than width");
+
+ int32_t ShiftR = ScaleDiff - ShiftL;
+ if (ShiftR >= getWidth<DigitsT>()) {
+ // Don't bother shifting. RDigits will get zero-ed out anyway.
+ RDigits = 0;
+ return;
+ }
+
+ LDigits <<= ShiftL;
+ RDigits >>= ShiftR;
+
+ LScale -= ShiftL;
+ RScale += ShiftR;
+ assert(LScale == RScale && "scales should match");
+}
+
} // end namespace ScaledNumbers
} // end namespace llvm
EXPECT_EQ(-1, compare(UINT64_MAX, 0, UINT64_C(1), 64));
}
+TEST(ScaledNumberHelpersTest, matchScales) {
+ typedef std::tuple<uint32_t, int16_t, uint32_t, int16_t> Pair32;
+ typedef std::tuple<uint64_t, int16_t, uint64_t, int16_t> Pair64;
+
+#define MATCH_SCALES(T, LDIn, LSIn, RDIn, RSIn, LDOut, RDOut, SOut) \
+ do { \
+ T LDx = LDIn; \
+ T RDx = RDIn; \
+ T LDy = LDOut; \
+ T RDy = RDOut; \
+ int16_t LSx = LSIn; \
+ int16_t RSx = RSIn; \
+ int16_t Sy = SOut; \
+ \
+ matchScales(LDx, LSx, RDx, RSx); \
+ EXPECT_EQ(LDy, LDx); \
+ EXPECT_EQ(RDy, RDx); \
+ if (LDy) \
+ EXPECT_EQ(Sy, LSx); \
+ if (RDy) \
+ EXPECT_EQ(Sy, RSx); \
+ } while (false)
+
+ MATCH_SCALES(uint32_t, 0, 0, 0, 0, 0, 0, 0);
+ MATCH_SCALES(uint32_t, 0, 50, 7, 1, 0, 7, 1);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 31, 1, 9, 0, UINT32_C(1) << 31, 4, 1);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 31, 2, 9, 0, UINT32_C(1) << 31, 2, 2);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 31, 3, 9, 0, UINT32_C(1) << 31, 1, 3);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 31, 4, 9, 0, UINT32_C(1) << 31, 0, 4);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 30, 4, 9, 0, UINT32_C(1) << 31, 1, 3);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 29, 4, 9, 0, UINT32_C(1) << 31, 2, 2);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 28, 4, 9, 0, UINT32_C(1) << 31, 4, 1);
+ MATCH_SCALES(uint32_t, UINT32_C(1) << 27, 4, 9, 0, UINT32_C(1) << 31, 9, 0);
+ MATCH_SCALES(uint32_t, 7, 1, 0, 50, 7, 0, 1);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 31, 1, 4, UINT32_C(1) << 31, 1);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 31, 2, 2, UINT32_C(1) << 31, 2);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 31, 3, 1, UINT32_C(1) << 31, 3);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 31, 4, 0, UINT32_C(1) << 31, 4);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 30, 4, 1, UINT32_C(1) << 31, 3);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 29, 4, 2, UINT32_C(1) << 31, 2);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 28, 4, 4, UINT32_C(1) << 31, 1);
+ MATCH_SCALES(uint32_t, 9, 0, UINT32_C(1) << 27, 4, 9, UINT32_C(1) << 31, 0);
+
+ MATCH_SCALES(uint64_t, 0, 0, 0, 0, 0, 0, 0);
+ MATCH_SCALES(uint64_t, 0, 100, 7, 1, 0, 7, 1);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 63, 1, 9, 0, UINT64_C(1) << 63, 4, 1);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 63, 2, 9, 0, UINT64_C(1) << 63, 2, 2);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 63, 3, 9, 0, UINT64_C(1) << 63, 1, 3);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 63, 4, 9, 0, UINT64_C(1) << 63, 0, 4);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 62, 4, 9, 0, UINT64_C(1) << 63, 1, 3);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 61, 4, 9, 0, UINT64_C(1) << 63, 2, 2);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 60, 4, 9, 0, UINT64_C(1) << 63, 4, 1);
+ MATCH_SCALES(uint64_t, UINT64_C(1) << 59, 4, 9, 0, UINT64_C(1) << 63, 9, 0);
+ MATCH_SCALES(uint64_t, 7, 1, 0, 100, 7, 0, 1);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 63, 1, 4, UINT64_C(1) << 63, 1);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 63, 2, 2, UINT64_C(1) << 63, 2);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 63, 3, 1, UINT64_C(1) << 63, 3);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 63, 4, 0, UINT64_C(1) << 63, 4);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 62, 4, 1, UINT64_C(1) << 63, 3);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 61, 4, 2, UINT64_C(1) << 63, 2);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 60, 4, 4, UINT64_C(1) << 63, 1);
+ MATCH_SCALES(uint64_t, 9, 0, UINT64_C(1) << 59, 4, 9, UINT64_C(1) << 63, 0);
+}
+
} // end namespace