From 94247507e4f728d77268de17530b4b23c65c948a Mon Sep 17 00:00:00 2001 From: Ben Adams Date: Wed, 27 Feb 2019 13:06:52 +0000 Subject: [PATCH] Intrinsicify SpanHelpers.IndexOfAny(char,char) --- .../shared/System/SpanHelpers.Char.cs | 275 +++++++++++++----- 1 file changed, 207 insertions(+), 68 deletions(-) diff --git a/src/System.Private.CoreLib/shared/System/SpanHelpers.Char.cs b/src/System.Private.CoreLib/shared/System/SpanHelpers.Char.cs index 7d4d27aded2c..baeafb0387fb 100644 --- a/src/System.Private.CoreLib/shared/System/SpanHelpers.Char.cs +++ b/src/System.Private.CoreLib/shared/System/SpanHelpers.Char.cs @@ -462,101 +462,240 @@ public static unsafe int IndexOf(ref char searchSpace, char value, int length) } [MethodImpl(MethodImplOptions.AggressiveOptimization)] - public static unsafe int IndexOfAny(ref char searchSpace, char value0, char value1, int length) + public static int IndexOfAny(ref char searchStart, char value0, char value1, int length) { Debug.Assert(length >= 0); + // If vectors are supported, we first align to Vector. + // If the searchSpan has not been fixed or pinned the GC can relocate it during the + // execution of this method, so the alignment only acts as best endeavour. + // The GC cost is likely to dominate over the misalignment that may occur after; + // so we give the GC a free hand to relocate and it is up to the caller + // whether they are operating over fixed data. - fixed (char* pChars = &searchSpace) + nint offset = 0; + nint lengthToExamine = length; + if (Sse2.IsSupported) { - char* pCh = pChars; - char* pEndCh = pCh + length; - - if (Vector.IsHardwareAccelerated && length >= Vector.Count * 2) + // Avx2 branch also operates on Sse2 sizes, so check is combined. + // Needs to be double length to allow us to align the data first. + if (length >= Vector128.Count * 2) { - // Figure out how many characters to read sequentially until we are vector aligned - // This is equivalent to: - // unaligned = ((int)pCh % Unsafe.SizeOf>()) / elementsPerByte - // length = (Vector.Count - unaligned) % Vector.Count - const int elementsPerByte = sizeof(ushort) / sizeof(byte); - int unaligned = ((int)pCh & (Unsafe.SizeOf>() - 1)) / elementsPerByte; - length = (Vector.Count - unaligned) & (Vector.Count - 1); + lengthToExamine = UnalignedCountVector128(ref searchStart); } - - SequentialScan: - while (length >= 4) + } + else if (Vector.IsHardwareAccelerated) + { + // Needs to be double length to allow us to align the data first. + if (length >= Vector.Count * 2) { - length -= 4; + lengthToExamine = UnalignedCountVector(ref searchStart); + } + } - if (pCh[0] == value0 || pCh[0] == value1) - goto Found; - if (pCh[1] == value0 || pCh[1] == value1) - goto Found1; - if (pCh[2] == value0 || pCh[2] == value1) - goto Found2; - if (pCh[3] == value0 || pCh[3] == value1) - goto Found3; + SequentialScan: + // In the non-vector case lengthToExamine is the total length. + // In the vector case lengthToExamine first aligns to Vector, + // then in a second pass after the Vector lengths is the + // remaining data that is shorter than a Vector length. + int lookUp; + while (lengthToExamine >= 4) + { + ref char current = ref Add(ref searchStart, offset); - pCh += 4; - } + lookUp = current; + if (value0 == lookUp || value1 == lookUp) + goto Found; + lookUp = Add(ref current, 1); + if (value0 == lookUp || value1 == lookUp) + goto Found1; + lookUp = Add(ref current, 2); + if (value0 == lookUp || value1 == lookUp) + goto Found2; + lookUp = Add(ref current, 3); + if (value0 == lookUp || value1 == lookUp) + goto Found3; - while (length > 0) - { - length--; + offset += 4; + lengthToExamine -= 4; + } - if (pCh[0] == value0 || pCh[0] == value1) - goto Found; + while (lengthToExamine > 0) + { + lookUp = Add(ref searchStart, offset); + if (value0 == lookUp || value1 == lookUp) + goto Found; - pCh++; - } + offset += 1; + lengthToExamine -= 1; + } - // We get past SequentialScan only if IsHardwareAccelerated is true. However, we still have the redundant check to allow - // the JIT to see that the code is unreachable and eliminate it when the platform does not have hardware accelerated. - if (Vector.IsHardwareAccelerated && pCh < pEndCh) + if (offset < length) + { + if (Sse2.IsSupported || Vector.IsHardwareAccelerated) { - // Get the highest multiple of Vector.Count that is within the search space. - // That will be how many times we iterate in the loop below. - // This is equivalent to: length = Vector.Count * ((int)(pEndCh - pCh) / Vector.Count) - length = (int)((pEndCh - pCh) & ~(Vector.Count - 1)); + goto VectorizedScan; + } + else + { + Debug.Fail("Moving to Vectorized scan when not supported"); + } + } - // Get comparison Vector - Vector values0 = new Vector(value0); - Vector values1 = new Vector(value1); + NotFound: + return -1; + Found3: + return (int)(offset + 3); + Found2: + return (int)(offset + 2); + Found1: + return (int)(offset + 1); + Found: + return (int)offset; - while (length > 0) + VectorizedScan: + // We get past SequentialScan only if IsHardwareAccelerated or intrinsic .IsSupported is true. However, we still have the redundant check to allow + // the JIT to see that the code is unreachable and eliminate it when the platform does not have hardware accelerated. + if (Avx2.IsSupported) + { + lengthToExamine = GetCharVector256SpanLength(offset, length); + if (lengthToExamine > 0) + { + Vector256 values0 = Vector256.Create(value0); + Vector256 values1 = Vector256.Create(value1); + do { - // Using Unsafe.Read instead of ReadUnaligned since the search space is pinned and pCh is always vector aligned - Debug.Assert(((int)pCh & (Unsafe.SizeOf>() - 1)) == 0); - Vector vData = Unsafe.Read>(pCh); - var vMatches = Vector.BitwiseOr( - Vector.Equals(vData, values0), - Vector.Equals(vData, values1)); - if (Vector.Zero.Equals(vMatches)) + Debug.Assert(length - offset >= Vector256.Count); + + Vector256 search = LoadVector256(ref searchStart, offset); + // Bitwise Or to combine the flagged matches for the second value to our match flags + int matches = Avx2.MoveMask( + Avx2.Or( + Avx2.CompareEqual(values0, search), + Avx2.CompareEqual(values1, search)) + .AsByte()); + // Note that MoveMask has converted the equal vector elements into a set of bit flags, + // So the bit position in 'matches' corresponds to the element offset. + if (matches == 0) { - pCh += Vector.Count; - length -= Vector.Count; + // Zero flags set so no matches + offset += Vector256.Count; + lengthToExamine -= Vector256.Count; continue; } - // Find offset of first match - return (int)(pCh - pChars) + LocateFirstFoundChar(vMatches); + + // Find bitflag offset of first match and add to current offset, + // flags are in bytes so divide for chars + return (int)(offset + (BitOperations.TrailingZeroCount(matches) / sizeof(char))); + } while (lengthToExamine > 0); + } + + lengthToExamine = GetCharVector128SpanLength(offset, length); + if (lengthToExamine > 0) + { + Debug.Assert(length - offset >= Vector128.Count); + + Vector128 values0 = Vector128.Create(value0); + Vector128 values1 = Vector128.Create(value1); + Vector128 search = LoadVector128(ref searchStart, offset); + + // Same method as above + int matches = Sse2.MoveMask( + Sse2.Or( + Sse2.CompareEqual(values0, search), + Sse2.CompareEqual(values1, search)) + .AsByte()); + if (matches == 0) + { + // Zero flags set so no matches + offset += Vector128.Count; + // Don't need to change lengthToExamine here as we don't use its current value again. } + else + { + // Find bitflag offset of first match and add to current offset, + // flags are in bytes so divide for chars + return (int)(offset + (BitOperations.TrailingZeroCount(matches) / sizeof(char))); + } + } - if (pCh < pEndCh) + lengthToExamine = length - offset; + if (lengthToExamine > 0) + { + goto SequentialScan; + } + } + else if (Sse2.IsSupported) + { + lengthToExamine = GetCharVector128SpanLength(offset, length); + Debug.Assert(lengthToExamine > 0); + + Vector128 values0 = Vector128.Create(value0); + Vector128 values1 = Vector128.Create(value1); + do + { + Debug.Assert(length - offset >= Vector128.Count); + + Vector128 search = LoadVector128(ref searchStart, offset); + + // Same method as above + int matches = Sse2.MoveMask( + Sse2.Or( + Sse2.CompareEqual(values0, search), + Sse2.CompareEqual(values1, search)) + .AsByte()); + if (matches == 0) { - length = (int)(pEndCh - pCh); - goto SequentialScan; + // Zero flags set so no matches + offset += Vector128.Count; + lengthToExamine -= Vector128.Count; + continue; } + + // Find bitflag offset of first match and add to current offset, + // flags are in bytes so divide for chars + return (int)(offset + (BitOperations.TrailingZeroCount(matches) / sizeof(char))); + } while (lengthToExamine > 0); + + lengthToExamine = length - offset; + if (lengthToExamine > 0) + { + goto SequentialScan; } + } + else if (Vector.IsHardwareAccelerated) + { + lengthToExamine = GetCharVectorSpanLength(offset, length); + Debug.Assert(lengthToExamine > 0); - return -1; - Found3: - pCh++; - Found2: - pCh++; - Found1: - pCh++; - Found: - return (int)(pCh - pChars); + Vector values0 = new Vector(value0); + Vector values1 = new Vector(value1); + do + { + Debug.Assert(length - offset >= Vector.Count); + + Vector search = LoadVector(ref searchStart, offset); + var matches = Vector.BitwiseOr( + Vector.Equals(search, values0), + Vector.Equals(search, values1)); + if (Vector.Zero.Equals(matches)) + { + offset += Vector.Count; + lengthToExamine -= Vector.Count; + continue; + } + + // Find offset of first match + return (int)(offset + LocateFirstFoundChar(matches)); + } while (lengthToExamine > 0); + + lengthToExamine = length - offset; + if (lengthToExamine > 0) + { + goto SequentialScan; + } } + + goto NotFound; } [MethodImpl(MethodImplOptions.AggressiveOptimization)]