Optimize some SIMD comparisons with Max/Min trick (#78027)

1 files changed, 74 insertions, 0 deletions

diff --git a/src/coreclr/jit/gentree.cpp b/src/coreclr/jit/gentree.cpp
index cc166cad4a2..28f5a7c1ce2 100644
--- a/src/coreclr/jit/gentree.cpp
+++ b/src/coreclr/jit/gentree.cpp
@@ -20023,6 +20023,28 @@ GenTree* Compiler::gtNewSimdCmpOpNode(genTreeOps  op,
 
             if (intrinsic == NI_Illegal)
             {
+                // If we don't have an intrinsic set for this, try "Max(op1, op2) == op1"
+                // NOTE: technically, we can special case byte type to only require SSE2, but it
+                // complicates the test matrix for little gains.
+                if (((simdSize == 32) && compOpportunisticallyDependsOn(InstructionSet_AVX2)) ||
+                    ((simdSize == 16) && compOpportunisticallyDependsOn(InstructionSet_SSE41)))
+                {
+                    // TODO-AVX512: We can use this trick for longs only with AVX-512
+                    if (!varTypeIsLong(simdBaseType))
+                    {
+                        assert(!varTypeIsFloating(simdBaseType));
+                        GenTree* op1Dup;
+                        op1 = impCloneExpr(op1, &op1Dup, clsHnd, CHECK_SPILL_ALL,
+                                           nullptr DEBUGARG("Clone op1 for vector GreaterThanOrEqual"));
+
+                        // EQ(Max(op1, op2), op1)
+                        GenTree* maxNode =
+                            gtNewSimdMaxNode(type, op1, op2, simdBaseJitType, simdSize, isSimdAsHWIntrinsic);
+                        return gtNewSimdCmpOpNode(GT_EQ, type, maxNode, op1Dup, simdBaseJitType, simdSize,
+                                                  isSimdAsHWIntrinsic);
+                    }
+                }
+
                 // There is no direct support for doing a combined comparison and equality for integral types.
                 // These have to be implemented by performing both halves and combining their results.
                 //
@@ -20249,6 +20271,28 @@ GenTree* Compiler::gtNewSimdCmpOpNode(genTreeOps  op,
 
             if (intrinsic == NI_Illegal)
             {
+                // If we don't have an intrinsic set for this, try "Min(op1, op2) == op1"
+                // NOTE: technically, we can special case byte type to only require SSE2, but it
+                // complicates the test matrix for little gains.
+                if (((simdSize == 32) && compOpportunisticallyDependsOn(InstructionSet_AVX2)) ||
+                    ((simdSize == 16) && compOpportunisticallyDependsOn(InstructionSet_SSE41)))
+                {
+                    // TODO-AVX512: We can use this trick for longs only with AVX-512
+                    if (!varTypeIsLong(simdBaseType))
+                    {
+                        assert(!varTypeIsFloating(simdBaseType));
+                        GenTree* op1Dup;
+                        op1 = impCloneExpr(op1, &op1Dup, clsHnd, CHECK_SPILL_ALL,
+                                           nullptr DEBUGARG("Clone op1 for vector LessThanOrEqual"));
+
+                        // EQ(Min(op1, op2), op1)
+                        GenTree* minNode =
+                            gtNewSimdMinNode(type, op1, op2, simdBaseJitType, simdSize, isSimdAsHWIntrinsic);
+                        return gtNewSimdCmpOpNode(GT_EQ, type, minNode, op1Dup, simdBaseJitType, simdSize,
+                                                  isSimdAsHWIntrinsic);
+                    }
+                }
+
                 // There is no direct support for doing a combined comparison and equality for integral types.
                 // These have to be implemented by performing both halves and combining their results.
                 //
@@ -21082,6 +21126,12 @@ GenTree* Compiler::gtNewSimdMaxNode(var_types   type,
             case TYP_BYTE:
             case TYP_USHORT:
             {
+                if (compOpportunisticallyDependsOn(InstructionSet_SSE41))
+                {
+                    intrinsic = NI_SSE41_Max;
+                    break;
+                }
+
                 GenTree*    constVal  = nullptr;
                 CorInfoType opJitType = simdBaseJitType;
                 var_types   opType    = simdBaseType;
@@ -21156,6 +21206,15 @@ GenTree* Compiler::gtNewSimdMaxNode(var_types   type,
 
             case TYP_INT:
             case TYP_UINT:
+            {
+                if (compOpportunisticallyDependsOn(InstructionSet_SSE41))
+                {
+                    intrinsic = NI_SSE41_Max;
+                    break;
+                }
+                break;
+            }
+
             case TYP_LONG:
             case TYP_ULONG:
             {
@@ -21266,6 +21325,12 @@ GenTree* Compiler::gtNewSimdMinNode(var_types   type,
             case TYP_BYTE:
             case TYP_USHORT:
             {
+                if (compOpportunisticallyDependsOn(InstructionSet_SSE41))
+                {
+                    intrinsic = NI_SSE41_Min;
+                    break;
+                }
+
                 GenTree*    constVal  = nullptr;
                 CorInfoType opJitType = simdBaseJitType;
                 var_types   opType    = simdBaseType;
@@ -21340,6 +21405,15 @@ GenTree* Compiler::gtNewSimdMinNode(var_types   type,
 
             case TYP_INT:
             case TYP_UINT:
+            {
+                if (compOpportunisticallyDependsOn(InstructionSet_SSE41))
+                {
+                    intrinsic = NI_SSE41_Min;
+                    break;
+                }
+                break;
+            }
+
             case TYP_LONG:
             case TYP_ULONG:
             {