From 3a94be4a35ad9caf6378ea1ba3e36b059aa0dc65 Mon Sep 17 00:00:00 2001
From: drmortalwombat <90205530+drmortalwombat@users.noreply.github.com>
Date: Sun, 12 Sep 2021 17:28:02 +0200
Subject: [PATCH] Use caller saved registers for temps not overlapping calls

---
 oscar64/InterCode.cpp | 62 ++++++++++++++++++++++++++++++++++---------
 oscar64/InterCode.h   |  2 ++
 2 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/oscar64/InterCode.cpp b/oscar64/InterCode.cpp
index c77aa64..bd7fcdf 100644
--- a/oscar64/InterCode.cpp
+++ b/oscar64/InterCode.cpp
@@ -1143,6 +1143,19 @@ bool InterInstruction::RemoveUnusedResultInstructions(InterInstruction* pre, Num
 	return changed;
 }
 
+void InterInstruction::BuildCallerSaveTempSet(NumberSet& requiredTemps, NumberSet& callerSaveTemps)
+{
+	if (mTTemp >= 0)
+		requiredTemps -= mTTemp;
+
+	if (mCode == IC_CALL || mCode == IC_JSR)
+		callerSaveTemps |= requiredTemps;
+
+	if (mSTemp[0] >= 0) requiredTemps += mSTemp[0];
+	if (mSTemp[1] >= 0) requiredTemps += mSTemp[1];
+	if (mSTemp[2] >= 0) requiredTemps += mSTemp[2];
+}
+
 bool InterInstruction::RemoveUnusedStoreInstructions(const GrowingVariableArray& localVars, InterInstruction* pre, NumberSet& requiredTemps)
 {
 	bool	changed = false;
@@ -2234,6 +2247,25 @@ bool InterCodeBasicBlock::RemoveUnusedResultInstructions(int numStaticTemps)
 	return changed;
 }
 
+void InterCodeBasicBlock::BuildCallerSaveTempSet(NumberSet& callerSaveTemps)
+{
+	if (!mVisited)
+	{
+		mVisited = true;
+
+		NumberSet		requiredTemps(mExitRequiredTemps);
+		int i;
+
+		for (i = mInstructions.Size() - 1; i >= 0; i--)
+			mInstructions[i].BuildCallerSaveTempSet(requiredTemps, callerSaveTemps);
+	
+		if (mTrueJump)
+			mTrueJump->BuildCallerSaveTempSet(callerSaveTemps);
+		if (mFalseJump)
+			mFalseJump->BuildCallerSaveTempSet(callerSaveTemps);
+	}
+}
+
 
 void InterCodeBasicBlock::BuildLocalVariableSets(const GrowingVariableArray& localVars)
 {
@@ -3564,25 +3596,31 @@ void InterCodeProcedure::ReduceTemporaries(void)
 		ResetVisited();
 	} while (mBlocks[0]->BuildGlobalRequiredTempSet(totalRequired3));
 
+
+	NumberSet	callerSaved(numRenamedTemps);
+	ResetVisited();
+	mBlocks[0]->BuildCallerSaveTempSet(callerSaved);
+
+	int		callerSavedTemps = 0, calleeSavedTemps = 16;
+
 	mTempOffset.SetSize(0);
-	int	offset = 0;
-	if (!mLeafProcedure)
-		offset += 16;
 
 	for (int i = 0; i < mTemporaries.Size(); i++)
 	{
-		mTempOffset.Push(offset);
-		switch (mTemporaries[i])
+		int size = mTemporaries[i] == IT_FLOAT ? 4 : 2;
+
+		if (callerSavedTemps + size <= 16 && !callerSaved[i])
 		{
-		case IT_FLOAT:
-			offset += 4;
-			break;
-		default:
-			offset += 2;
-			break;
+			mTempOffset.Push(callerSavedTemps);
+			callerSavedTemps += size;
+		}
+		else
+		{
+			mTempOffset.Push(calleeSavedTemps);
+			calleeSavedTemps += size;
 		}
 	}
-	mTempSize = offset;
+	mTempSize = calleeSavedTemps;
 }
 
 void InterCodeProcedure::Disassemble(const char* name, bool dumpSets)
diff --git a/oscar64/InterCode.h b/oscar64/InterCode.h
index 96f7b64..ef9c21f 100644
--- a/oscar64/InterCode.h
+++ b/oscar64/InterCode.h
@@ -284,6 +284,7 @@ public:
 	bool RemoveUnusedResultInstructions(InterInstruction* pre, NumberSet& requiredTemps, int numStaticTemps);
 	bool RemoveUnusedStoreInstructions(const GrowingVariableArray& localVars, InterInstruction* pre, NumberSet& requiredTemps);
 	void PerformValueForwarding(GrowingInstructionPtrArray& tvalue, FastNumberSet& tvalid);
+	void BuildCallerSaveTempSet(NumberSet& requiredTemps, NumberSet& callerSaveTemps);
 
 	void LocalRenameRegister(GrowingIntArray& renameTable, int& num, int fixed);
 	void GlobalRenameRegister(const GrowingIntArray& renameTable, GrowingTypeArray& temporaries);
@@ -382,6 +383,7 @@ public:
 	void BuildGlobalProvidedTempSet(NumberSet fromProvidedTemps);
 	bool BuildGlobalRequiredTempSet(NumberSet& fromRequiredTemps);
 	bool RemoveUnusedResultInstructions(int numStaticTemps);
+	void BuildCallerSaveTempSet(NumberSet& callerSaveTemps);
 
 	void BuildLocalVariableSets(const GrowingVariableArray& localVars);
 	void BuildGlobalProvidedVariableSet(const GrowingVariableArray& localVars, NumberSet fromProvidedVars);