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Remove leftover runtextbeg/end references from RegexCompiler / source…
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… generator (dotnet#66129)

Now that we're operating over a span that represents the full input from beginning to end, we no longer need to access runtextbeg/runtextend, we can use inputSpan.Slice(pos) instead of inputSpan.Slice(pos, end - pos), etc.
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@stephentoub
stephentoub authored Mar 3, 2022
1 parent 28a7265 commit 35c518b
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Showing 2 changed files with 89 additions and 95 deletions.
63 changes: 29 additions & 34 deletions src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.Emitter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -378,7 +378,7 @@ private static RequiredHelperFunctions EmitTryFindNextPossibleStartingPosition(I
var additionalDeclarations = new HashSet<string>();

// Emit locals initialization
writer.WriteLine("int pos = base.runtextpos, end = base.runtextend;");
writer.WriteLine("int pos = base.runtextpos;");
writer.Flush();
int additionalDeclarationsPosition = ((StringWriter)writer.InnerWriter).GetStringBuilder().Length;
int additionalDeclarationsIndent = writer.Indent;
Expand All @@ -391,9 +391,9 @@ private static RequiredHelperFunctions EmitTryFindNextPossibleStartingPosition(I
Debug.Assert(minRequiredLength >= 0);
string clause = minRequiredLength switch
{
0 => "if (pos <= end)",
1 => "if (pos < end)",
_ => $"if (pos < end - {minRequiredLength - 1})"
0 => "if (pos <= inputSpan.Length)",
1 => "if (pos < inputSpan.Length)",
_ => $"if (pos < inputSpan.Length - {minRequiredLength - 1})"
};
using (EmitBlock(writer, clause))
{
Expand Down Expand Up @@ -443,7 +443,7 @@ private static RequiredHelperFunctions EmitTryFindNextPossibleStartingPosition(I
const string NoStartingPositionFound = "NoStartingPositionFound";
writer.WriteLine("// No starting position found");
writer.WriteLine($"{NoStartingPositionFound}:");
writer.WriteLine("base.runtextpos = end;");
writer.WriteLine("base.runtextpos = inputSpan.Length;");
writer.WriteLine("return false;");

// We're done. Patch up any additional declarations.
Expand All @@ -462,8 +462,7 @@ bool EmitAnchors()
{
case FindNextStartingPositionMode.LeadingAnchor_LeftToRight_Beginning:
writer.WriteLine("// Beginning \\A anchor");
additionalDeclarations.Add("int beginning = base.runtextbeg;");
using (EmitBlock(writer, "if (pos > beginning)"))
using (EmitBlock(writer, "if (pos > 0)"))
{
Goto(NoStartingPositionFound);
}
Expand All @@ -481,38 +480,38 @@ bool EmitAnchors()

case FindNextStartingPositionMode.LeadingAnchor_LeftToRight_EndZ:
writer.WriteLine("// Leading end \\Z anchor");
using (EmitBlock(writer, "if (pos < end - 1)"))
using (EmitBlock(writer, "if (pos < inputSpan.Length - 1)"))
{
writer.WriteLine("base.runtextpos = end - 1;");
writer.WriteLine("base.runtextpos = inputSpan.Length - 1;");
}
writer.WriteLine("return true;");
return true;

case FindNextStartingPositionMode.LeadingAnchor_LeftToRight_End:
writer.WriteLine("// Leading end \\z anchor");
using (EmitBlock(writer, "if (pos < end)"))
using (EmitBlock(writer, "if (pos < inputSpan.Length)"))
{
writer.WriteLine("base.runtextpos = end;");
writer.WriteLine("base.runtextpos = inputSpan.Length;");
}
writer.WriteLine("return true;");
return true;

case FindNextStartingPositionMode.TrailingAnchor_FixedLength_LeftToRight_EndZ:
// Jump to the end, minus the min required length, which in this case is actually the fixed length, minus 1 (for a possible ending \n).
writer.WriteLine("// Trailing end \\Z anchor with fixed-length match");
using (EmitBlock(writer, $"if (pos < end - {regexTree.FindOptimizations.MinRequiredLength + 1})"))
using (EmitBlock(writer, $"if (pos < inputSpan.Length - {regexTree.FindOptimizations.MinRequiredLength + 1})"))
{
writer.WriteLine($"base.runtextpos = end - {regexTree.FindOptimizations.MinRequiredLength + 1};");
writer.WriteLine($"base.runtextpos = inputSpan.Length - {regexTree.FindOptimizations.MinRequiredLength + 1};");
}
writer.WriteLine("return true;");
return true;

case FindNextStartingPositionMode.TrailingAnchor_FixedLength_LeftToRight_End:
// Jump to the end, minus the min required length, which in this case is actually the fixed length.
writer.WriteLine("// Trailing end \\z anchor with fixed-length match");
using (EmitBlock(writer, $"if (pos < end - {regexTree.FindOptimizations.MinRequiredLength})"))
using (EmitBlock(writer, $"if (pos < inputSpan.Length - {regexTree.FindOptimizations.MinRequiredLength})"))
{
writer.WriteLine($"base.runtextpos = end - {regexTree.FindOptimizations.MinRequiredLength};");
writer.WriteLine($"base.runtextpos = inputSpan.Length - {regexTree.FindOptimizations.MinRequiredLength};");
}
writer.WriteLine("return true;");
return true;
Expand All @@ -528,11 +527,10 @@ bool EmitAnchors()
// the other anchors, which all skip all subsequent processing if found, with BOL we just use it
// to boost our position to the next line, and then continue normally with any searches.
writer.WriteLine("// Beginning-of-line anchor");
additionalDeclarations.Add("int beginning = base.runtextbeg;");
using (EmitBlock(writer, "if (pos > beginning && inputSpan[pos - 1] != '\\n')"))
using (EmitBlock(writer, "if (pos > 0 && inputSpan[pos - 1] != '\\n')"))
{
writer.WriteLine("int newlinePos = global::System.MemoryExtensions.IndexOf(inputSpan.Slice(pos), '\\n');");
using (EmitBlock(writer, "if (newlinePos < 0 || newlinePos + pos + 1 > end)"))
using (EmitBlock(writer, "if ((uint)newlinePos > inputSpan.Length - pos - 1)"))
{
Goto(NoStartingPositionFound);
}
Expand All @@ -546,18 +544,18 @@ bool EmitAnchors()
{
case RegexNodeKind.End when regexTree.FindOptimizations.MaxPossibleLength is int maxLength:
writer.WriteLine("// End \\z anchor with maximum-length match");
using (EmitBlock(writer, $"if (pos < end - {maxLength})"))
using (EmitBlock(writer, $"if (pos < inputSpan.Length - {maxLength})"))
{
writer.WriteLine($"pos = end - {maxLength};");
writer.WriteLine($"pos = inputSpan.Length - {maxLength};");
}
writer.WriteLine();
break;

case RegexNodeKind.EndZ when regexTree.FindOptimizations.MaxPossibleLength is int maxLength:
writer.WriteLine("// End \\Z anchor with maximum-length match");
using (EmitBlock(writer, $"if (pos < end - {maxLength + 1})"))
using (EmitBlock(writer, $"if (pos < inputSpan.Length - {maxLength + 1})"))
{
writer.WriteLine($"pos = end - {maxLength + 1};");
writer.WriteLine($"pos = inputSpan.Length - {maxLength + 1};");
}
writer.WriteLine();
break;
Expand All @@ -569,7 +567,7 @@ bool EmitAnchors()
// Emits a case-sensitive prefix search for a string at the beginning of the pattern.
void EmitIndexOf(string prefix)
{
writer.WriteLine($"int i = global::System.MemoryExtensions.IndexOf(inputSpan.Slice(pos, end - pos), {Literal(prefix)});");
writer.WriteLine($"int i = global::System.MemoryExtensions.IndexOf(inputSpan.Slice(pos), {Literal(prefix)});");
writer.WriteLine("if (i >= 0)");
writer.WriteLine("{");
writer.WriteLine(" base.runtextpos = pos + i;");
Expand All @@ -595,7 +593,7 @@ void EmitFixedSet()
FinishEmitScope loopBlock = default;
if (needLoop)
{
writer.WriteLine("global::System.ReadOnlySpan<char> span = inputSpan.Slice(pos, end - pos);");
writer.WriteLine("global::System.ReadOnlySpan<char> span = inputSpan.Slice(pos);");
string upperBound = "span.Length" + (setsToUse > 1 || primarySet.Distance != 0 ? $" - {minRequiredLength - 1}" : "");
loopBlock = EmitBlock(writer, $"for (int i = 0; i < {upperBound}; i++)");
}
Expand All @@ -604,7 +602,7 @@ void EmitFixedSet()
{
string span = needLoop ?
"span" :
"inputSpan.Slice(pos, end - pos)";
"inputSpan.Slice(pos)";

span = (needLoop, primarySet.Distance) switch
{
Expand Down Expand Up @@ -704,7 +702,7 @@ void EmitLiteralAfterAtomicLoop()

using (EmitBlock(writer, "while (true)"))
{
writer.WriteLine($"global::System.ReadOnlySpan<char> slice = inputSpan.Slice(pos, end - pos);");
writer.WriteLine($"global::System.ReadOnlySpan<char> slice = inputSpan.Slice(pos);");
writer.WriteLine();

// Find the literal. If we can't find it, we're done searching.
Expand Down Expand Up @@ -847,7 +845,7 @@ private static RequiredHelperFunctions EmitTryMatchAtCurrentPosition(IndentedTex

// Declare some locals.
string sliceSpan = "slice";
writer.WriteLine("int pos = base.runtextpos, end = base.runtextend;");
writer.WriteLine("int pos = base.runtextpos;");
writer.WriteLine($"int original_pos = pos;");
bool hasTimeout = EmitLoopTimeoutCounterIfNeeded(writer, rm);
bool hasTextInfo = EmitInitializeCultureForTryMatchAtCurrentPositionIfNecessary(writer, rm, analysis);
Expand Down Expand Up @@ -965,7 +963,7 @@ void SliceInputSpan(IndentedTextWriter writer, bool defineLocal = false)
{
writer.Write("global::System.ReadOnlySpan<char> ");
}
writer.WriteLine($"{sliceSpan} = inputSpan.Slice(pos, end - pos);");
writer.WriteLine($"{sliceSpan} = inputSpan.Slice(pos);");
}

// Emits the sum of a constant and a value from a local.
Expand Down Expand Up @@ -2288,8 +2286,7 @@ void EmitAnchors(RegexNode node)
}
else
{
additionalDeclarations.Add(node.Kind == RegexNodeKind.Beginning ? "int beginning = base.runtextbeg;" : "int start = base.runtextstart;");
using (EmitBlock(writer, node.Kind == RegexNodeKind.Beginning ? "if (pos != beginning)" : "if (pos != start)"))
using (EmitBlock(writer, node.Kind == RegexNodeKind.Beginning ? "if (pos != 0)" : "if (pos != base.runtextstart)"))
{
Goto(doneLabel);
}
Expand All @@ -2307,8 +2304,7 @@ void EmitAnchors(RegexNode node)
else
{
// We can't use our slice in this case, because we'd need to access slice[-1], so we access the inputSpan field directly:
additionalDeclarations.Add("int beginning = base.runtextbeg;");
using (EmitBlock(writer, $"if (pos > beginning && inputSpan[pos - 1] != '\\n')"))
using (EmitBlock(writer, $"if (pos > 0 && inputSpan[pos - 1] != '\\n')"))
{
Goto(doneLabel);
}
Expand Down Expand Up @@ -3032,9 +3028,8 @@ void EmitSingleCharAtomicLoop(RegexNode node, bool emitLengthChecksIfRequired =
// .* was used with RegexOptions.Singleline, which means it'll consume everything. Just jump to the end.
// The unbounded constraint is the same as in the Notone case above, done purely for simplicity.

// int i = end - pos;
TransferSliceStaticPosToPos();
writer.WriteLine($"int {iterationLocal} = end - pos;");
writer.WriteLine($"int {iterationLocal} = inputSpan.Length - pos;");
}
else
{
Expand Down
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