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[APInt] Add APIntOps::absdiff to compute the absolute difference of 2 unsigned values #82255

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Merged
merged 1 commit into from
Feb 19, 2024
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[APInt] Add APIntOps::absdiff to compute the absolute difference of 2 unsigned values #82255

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5 changes: 5 additions & 0 deletions llvm/include/llvm/ADT/APInt.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2187,6 +2187,11 @@ inline const APInt &umax(const APInt &A, const APInt &B) {
return A.ugt(B) ? A : B;
}

/// Determine the absolute difference of two APInts considered to be unsigned.
inline const APInt absdiff(const APInt &A, const APInt &B) {
return A.uge(B) ? (A - B) : (B - A);
}

/// Compute GCD of two unsigned APInt values.
///
/// This function returns the greatest common divisor of the two APInt values
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34 changes: 34 additions & 0 deletions llvm/unittests/ADT/APIntTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2497,6 +2497,40 @@ TEST(APIntTest, clearLowBits) {
EXPECT_EQ(16u, i32hi16.popcount());
}

TEST(APIntTest, AbsDiff) {
using APIntOps::absdiff;

APInt MaxU1(1, 1, false);
APInt MinU1(1, 0, false);
EXPECT_EQ(1u, absdiff(MaxU1, MinU1).getZExtValue());
EXPECT_EQ(1u, absdiff(MinU1, MaxU1).getZExtValue());

APInt MaxU4(4, 15, false);
APInt MinU4(4, 0, false);
EXPECT_EQ(15u, absdiff(MaxU4, MinU4).getZExtValue());
EXPECT_EQ(15u, absdiff(MinU4, MaxU4).getZExtValue());

APInt MaxS8(8, 127, true);
APInt MinS8(8, -128, true);
EXPECT_EQ(1u, absdiff(MaxS8, MinS8).getZExtValue());
EXPECT_EQ(1u, absdiff(MinS8, MaxS8).getZExtValue());

APInt MaxU16(16, 65535, false);
APInt MinU16(16, 0, false);
EXPECT_EQ(65535u, absdiff(MaxU16, MinU16).getZExtValue());
EXPECT_EQ(65535u, absdiff(MinU16, MaxU16).getZExtValue());

APInt MaxS16(16, 32767, true);
APInt MinS16(16, -32768, true);
APInt ZeroS16(16, 0, true);
EXPECT_EQ(1u, absdiff(MaxS16, MinS16).getZExtValue());
EXPECT_EQ(1u, absdiff(MinS16, MaxS16).getZExtValue());
EXPECT_EQ(32768u, absdiff(ZeroS16, MinS16));
EXPECT_EQ(32768u, absdiff(MinS16, ZeroS16));
EXPECT_EQ(32767u, absdiff(ZeroS16, MaxS16));
EXPECT_EQ(32767u, absdiff(MaxS16, ZeroS16));
}

TEST(APIntTest, GCD) {
using APIntOps::GreatestCommonDivisor;

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