Reduce stack usage of ParseExpectKet when no array indices are used

Duet3D · Apr 16, 2024 · e7cc658 · e7cc658
1 parent 66f8afa
commit e7cc658
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Showing 2 changed files with 34 additions and 26 deletions.
diff --git a/src/GCodes/GCodeBuffer/ExpressionParser.cpp b/src/GCodes/GCodeBuffer/ExpressionParser.cpp
@@ -24,11 +24,12 @@ namespace StackUsage
 {
 	// The following values are the number of bytes of stack space needed by the corresponding functions and functions they call,
 	// not counting other called functions that call CheckStack. They are obtained from file ExpressionParser.su generated by the compiler.
-	constexpr uint32_t ParseInternal = 80;
-	constexpr uint32_t ParseIdentifierExpression = 288;
+	constexpr uint32_t ParseInternal = 72;
+	constexpr uint32_t ParseIdentifierExpression = 296;
 	constexpr uint32_t GetObjectValueUsingTableNumber = 48;
 	constexpr uint32_t ReadArrayFromFile = 384;
 	constexpr uint32_t ParseGeneralArray = 360;
+	constexpr uint32_t ApplyObjectModelArrayIndex = 112;
 }
 
 // Read a character from the text file.
@@ -107,30 +108,8 @@ void ExpressionParser::ParseExpectKet(ExpressionValue& rslt, bool evaluate, char
 		switch (rslt.GetType())
 		{
 		case TypeCode::ObjectModelArray:
-			{
-				const ObjectModelArrayTableEntry *const entry = rslt.omVal->FindObjectModelArrayEntry(rslt.param & 0xFF);
-				if (entry == nullptr)
-				{
-					THROW_INTERNAL_ERROR;
-				}
-				ObjectExplorationContext context;
-				context.AddIndex(rslt.param >> 16);
-				ReadLocker lock(entry->lockPointer);
-				const size_t numElements = entry->GetNumElements(rslt.omVal, context);
-				if (indexValue < numElements)
-				{
-					context.AddIndex(indexValue);
-					rslt = entry->GetElement(rslt.omVal, context);
-				}
-				else if (evaluate)
-				{
-					throw GCodeException(&gb, indexCol, "array index out of range");
-				}
-				else
-				{
-					rslt.SetNull(nullptr);
-				}
-			}
+			CheckStack(StackUsage::ApplyObjectModelArrayIndex);
+			ApplyObjectModelArrayIndex(rslt, indexCol, indexValue, evaluate);			// call out to separate function to reduce stack usage of this one from 128 to 32 bytes
 			break;
 
 		case TypeCode::HeapArray:
@@ -161,6 +140,33 @@ void ExpressionParser::ParseExpectKet(ExpressionValue& rslt, bool evaluate, char
 	}
 }
 
+// Handle an index after an object model array expression.
+void ExpressionParser::ApplyObjectModelArrayIndex(ExpressionValue& rslt, int indexCol, uint32_t indexValue, bool evaluate) THROWS(GCodeException)
+{
+	const ObjectModelArrayTableEntry *const entry = rslt.omVal->FindObjectModelArrayEntry(rslt.param & 0xFF);
+	if (entry == nullptr)
+	{
+		THROW_INTERNAL_ERROR;
+	}
+	ObjectExplorationContext context;
+	context.AddIndex(rslt.param >> 16);
+	ReadLocker lock(entry->lockPointer);
+	const size_t numElements = entry->GetNumElements(rslt.omVal, context);
+	if (indexValue < numElements)
+	{
+		context.AddIndex(indexValue);
+		rslt = entry->GetElement(rslt.omVal, context);
+	}
+	else if (evaluate)
+	{
+		throw GCodeException(&gb, indexCol, "array index out of range");
+	}
+	else
+	{
+		rslt.SetNull(nullptr);
+	}
+}
+
 // Evaluate an expression. Do not call this one recursively!
 ExpressionValue ExpressionParser::Parse(bool evaluate) THROWS(GCodeException)
 {

diff --git a/src/GCodes/GCodeBuffer/ExpressionParser.h b/src/GCodes/GCodeBuffer/ExpressionParser.h
@@ -106,6 +106,8 @@ class ExpressionParser
 	void __attribute__((noinline)) ReadArrayFromFile(ExpressionValue& rslt, unsigned int offset, unsigned int length, char delimiter) const THROWS(GCodeException);
 	void ReadArrayElementFromFile(ExpressionValue& rslt, LineReader& reader, char delimiter) const THROWS(GCodeException);
 	void GetNextOperand(ExpressionValue& operand, bool evaluate) THROWS(GCodeException);
+	void __attribute__((noinline)) ApplyObjectModelArrayIndex(ExpressionValue& rslt, int indexCol, uint32_t indexValue, bool evaluate) THROWS(GCodeException);
+
 	static bool TypeHasNoLiterals(TypeCode t) noexcept;
 
 	int GetColumn() const noexcept;