Treat TZCNT/POPCNT/LZCNT as never negative

src/coreclr/jit/assertionprop.cpp

@@ -164,6 +164,35 @@ bool IntegralRange::Contains(int64_t value) const
         case GT_CAST:
             return ForCastOutput(node->AsCast());
 
+#if defined(FEATURE_HW_INTRINSICS)
+        case GT_HWINTRINSIC:
+            switch (node->AsHWIntrinsic()->GetHWIntrinsicId())
+            {
+#if defined(TARGET_XARCH)
+                case NI_BMI1_TrailingZeroCount:
+                case NI_BMI1_X64_TrailingZeroCount:
+                case NI_LZCNT_LeadingZeroCount:
+                case NI_LZCNT_X64_LeadingZeroCount:
+                case NI_POPCNT_PopCount:
+                case NI_POPCNT_X64_PopCount:
+#elif defined(TARGET_ARM64)
+                case NI_AdvSimd_PopCount:
+                case NI_AdvSimd_LeadingZeroCount:
+                case NI_AdvSimd_LeadingSignCount:
+                case NI_ArmBase_LeadingZeroCount:
+                case NI_ArmBase_Arm64_LeadingZeroCount:
+                case NI_ArmBase_Arm64_LeadingSignCount:
+#else
+#error Unsupported platform
+#endif
+                    // TODO-Casts: specify more precise ranges once "IntegralRange" supports them.
+                    return {SymbolicIntegerValue::Zero, SymbolicIntegerValue::ByteMax};
+                default:
+                    break;
+            }
+            break;
+#endif // defined(FEATURE_HW_INTRINSICS)
+
         default:
             break;
     }