Update src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexCompiler.cs

danmoseley · stephentoub · web-flow · commit ad175332ca8f · 2026-03-25T10:53:47.000-06:00
Co-authored-by: Stephen Toub &lt;stoub@microsoft.com&gt;
diff --git a/src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexCompiler.cs b/src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexCompiler.cs
@@ -4590,7 +4590,7 @@ void EmitSingleCharRepeater(RegexNode node, bool emitLengthChecksIfRequired = tr
                 // we unroll up to this threshold and use a loop with vectorization beyond it.
                 const int MaxUnrollSize = 8;
 
-                if (iterations <= MaxUnrollSize)
+                if (iterations < MaxUnrollSize)
                 {
                     // if (slice[sliceStaticPos] != c1 ||
                     //     slice[sliceStaticPos + 1] != c2 ||

Original file line number	Diff line number	Diff line change
`@@ -4590,7 +4590,7 @@ void EmitSingleCharRepeater(RegexNode node, bool emitLengthChecksIfRequired = tr`
`4590`	`4590`	`// we unroll up to this threshold and use a loop with vectorization beyond it.`
`4591`	`4591`	`const int MaxUnrollSize = 8;`
`4592`	`4592`
`4593`		`- if (iterations <= MaxUnrollSize)`
	`4593`	`+ if (iterations < MaxUnrollSize)`
`4594`	`4594`	`{`
`4595`	`4595`	`// if (slice[sliceStaticPos] != c1 \|\|`
`4596`	`4596`	`// slice[sliceStaticPos + 1] != c2 \|\|`