Check all of a vector lane when converting to mask

Author: a74nh

src/coreclr/jit/simd.h

@@ -1598,35 +1598,33 @@ void EvaluateSimdCvtVectorToMask(simdmask_t* result, TSimd arg0)
     uint32_t count = sizeof(TSimd) / sizeof(TBase);
     uint64_t mask  = 0;
 
-    TBase significantBit = 1;
 #if defined(TARGET_XARCH)
-    significantBit = static_cast<TBase>(1) << ((sizeof(TBase) * 8) - 1);
+    TBase significantBit = static_cast<TBase>(1) << ((sizeof(TBase) * 8) - 1);
 #endif
 
     for (uint32_t i = 0; i < count; i++)
     {
         TBase input0;
         memcpy(&input0, &arg0.u8[i * sizeof(TBase)], sizeof(TBase));
 
+#if defined(TARGET_XARCH)
+        // For xarch we have count sequential bits to write depending on if the
+        // corresponding the input element has its most significant bit set
         if ((input0 & significantBit) != 0)
         {
-#if defined(TARGET_XARCH)
-            // For xarch we have count sequential bits to write
-            // depending on if the corresponding the input element
-            // has its most significant bit set
-
             mask |= static_cast<uint64_t>(1) << i;
+        }
 #elif defined(TARGET_ARM64)
-            // For Arm64 we have count total bits to write, but
-            // they are sizeof(TBase) bits apart. We set
-            // depending on if the corresponding input element
-            // has its least significant bit set
-
+        // For Arm64 we have count total bits to write, but they are sizeof(TBase)
+        // bits apart. We set depending on if the corresponding input element has
+        // any bit set (this matches the use of cmpne in outputted assembly).
+        if (input0 != 0)
+        {
             mask |= static_cast<uint64_t>(1) << (i * sizeof(TBase));
+        }
 #else
-            unreached();
+        unreached();
 #endif
-        }
     }
 
     memcpy(&result->u8[0], &mask, sizeof(uint64_t));
@@ -2000,21 +1998,20 @@ SveMaskPattern EvaluateSimdVectorToPattern(TSimd arg0)
     uint32_t count    = sizeof(TSimd) / sizeof(TBase);
     uint32_t finalOne = count;
 
-    TBase significantBit = 1;
-
     // A mask pattern starts with zero or more 1s and then the rest of the mask is filled with 0s.
     // This pattern is extracted using the least significant bits of the vector elements.
 
     // For Arm64 we have count total bits to read, but they are sizeof(TBase) bits apart. We set
-    // depending on if the corresponding input element has its least significant bit set
+    // depending on if the corresponding input element has any bit set (this matches the use
+    // of cmpne in outputted assembly)
 
     // Find an unbroken sequence of 1s.
     for (uint32_t i = 0; i < count; i++)
     {
         TBase input0;
         memcpy(&input0, &arg0.u8[i * sizeof(TBase)], sizeof(TBase));
 
-        bool isSet = (input0 & significantBit) != 0;
+        bool isSet = input0 != 0;
         if (!isSet)
         {
             finalOne = i;
@@ -2028,7 +2025,7 @@ SveMaskPattern EvaluateSimdVectorToPattern(TSimd arg0)
         TBase input0;
         memcpy(&input0, &arg0.u8[i * sizeof(TBase)], sizeof(TBase));
 
-        bool isSet = (input0 & significantBit) != 0;
+        bool isSet = input0 != 0;
         if (isSet)
         {
             // Invalid sequence