Vector256.IsHardwareAccelerated to return true only on AVX2 (#64345)

dotnet · Jan 27, 2022 · 19291cc · 19291cc
1 parent 9ae484f
commit 19291cc
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Showing 4 changed files with 25 additions and 6 deletions.
diff --git a/src/coreclr/jit/hwintrinsic.cpp b/src/coreclr/jit/hwintrinsic.cpp
@@ -285,7 +285,26 @@ NamedIntrinsic HWIntrinsicInfo::lookupId(Compiler*         comp,
 
     bool isIsaSupported = comp->compSupportsHWIntrinsic(isa);
 
-    if ((strcmp(methodName, "get_IsSupported") == 0) || (strcmp(methodName, "get_IsHardwareAccelerated") == 0))
+    bool isHardwareAcceleratedProp = (strcmp(methodName, "get_IsHardwareAccelerated") == 0);
+#ifdef TARGET_XARCH
+    if (isHardwareAcceleratedProp)
+    {
+        // Special case: Some of Vector128/256 APIs are hardware accelerated with Sse1 and Avx1,
+        // but we want IsHardwareAccelerated to return true only when all of them are (there are
+        // still can be cases where e.g. Sse41 might give an additional boost for Vector128, but it's
+        // not important enough to bump the minimal Sse version here)
+        if (strcmp(className, "Vector128") == 0)
+        {
+            isa = InstructionSet_SSE2;
+        }
+        else if (strcmp(className, "Vector256") == 0)
+        {
+            isa = InstructionSet_AVX2;
+        }
+    }
+#endif
+
+    if ((strcmp(methodName, "get_IsSupported") == 0) || isHardwareAcceleratedProp)
     {
         return isIsaSupported ? (comp->compExactlyDependsOn(isa) ? NI_IsSupported_True : NI_IsSupported_Dynamic)
                               : NI_IsSupported_False;

diff --git a/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Byte.cs b/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Byte.cs
@@ -64,7 +64,7 @@ ref Unsafe.Add(ref searchSpace, offset + 1),
             // Based on http://0x80.pl/articles/simd-strfind.html#algorithm-1-generic-simd "Algorithm 1: Generic SIMD" by Wojciech Muła
             // Some details about the implementation can also be found in https://github.com/dotnet/runtime/pull/63285
         SEARCH_TWO_BYTES:
-            if (Avx2.IsSupported && searchSpaceMinusValueTailLength - Vector256<byte>.Count >= 0)
+            if (Vector256.IsHardwareAccelerated && searchSpaceMinusValueTailLength - Vector256<byte>.Count >= 0)
             {
                 // Find the last unique (which is not equal to ch1) byte
                 // the algorithm is fine if both are equal, just a little bit less efficient
@@ -212,7 +212,7 @@ ref Unsafe.Add(ref searchSpace, relativeIndex + 1),
         // Based on http://0x80.pl/articles/simd-strfind.html#algorithm-1-generic-simd "Algorithm 1: Generic SIMD" by Wojciech Muła
         // Some details about the implementation can also be found in https://github.com/dotnet/runtime/pull/63285
         SEARCH_TWO_BYTES:
-            if (Avx2.IsSupported && searchSpaceMinusValueTailLength >= Vector256<byte>.Count)
+            if (Vector256.IsHardwareAccelerated && searchSpaceMinusValueTailLength >= Vector256<byte>.Count)
             {
                 offset = searchSpaceMinusValueTailLength - Vector256<byte>.Count;
 

diff --git a/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Char.cs b/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Char.cs
@@ -70,7 +70,7 @@ ref Unsafe.As<char, byte>(ref Unsafe.Add(ref searchSpace, offset + 1)),
             // Based on http://0x80.pl/articles/simd-strfind.html#algorithm-1-generic-simd "Algorithm 1: Generic SIMD" by Wojciech Muła
             // Some details about the implementation can also be found in https://github.com/dotnet/runtime/pull/63285
         SEARCH_TWO_CHARS:
-            if (Avx2.IsSupported && searchSpaceMinusValueTailLength - Vector256<ushort>.Count >= 0)
+            if (Vector256.IsHardwareAccelerated && searchSpaceMinusValueTailLength - Vector256<ushort>.Count >= 0)
             {
                 // Find the last unique (which is not equal to ch1) character
                 // the algorithm is fine if both are equal, just a little bit less efficient
@@ -231,7 +231,7 @@ ref Unsafe.As<char, byte>(ref Unsafe.Add(ref searchSpace, relativeIndex + 1)),
             // Based on http://0x80.pl/articles/simd-strfind.html#algorithm-1-generic-simd "Algorithm 1: Generic SIMD" by Wojciech Muła
             // Some details about the implementation can also be found in https://github.com/dotnet/runtime/pull/63285
         SEARCH_TWO_CHARS:
-            if (Avx2.IsSupported && searchSpaceMinusValueTailLength >= Vector256<ushort>.Count)
+            if (Vector256.IsHardwareAccelerated && searchSpaceMinusValueTailLength >= Vector256<ushort>.Count)
             {
                 offset = searchSpaceMinusValueTailLength - Vector256<ushort>.Count;
 

diff --git a/src/tests/JIT/Regression/JitBlue/Runtime_34587/Runtime_34587.cs b/src/tests/JIT/Regression/JitBlue/Runtime_34587/Runtime_34587.cs
@@ -664,7 +664,7 @@ static bool ValidateVector256()
         {
             bool succeeded = true;
 
-            if (Avx.IsSupported)
+            if (Avx2.IsSupported)
             {
                 succeeded &= Vector256.IsHardwareAccelerated;
                 succeeded &= Vector256<byte>.Count == 32;