- moved all code related to function calls into the helper class so that all future work on the calling convention is in one place only.

src/scripting/backend/codegen.cpp

@@ -5494,7 +5494,7 @@ ExpEmit FxRandom::Emit(VMFunctionBuilder *build)
 	assert(min && max);
 	callfunc = ((PSymbolVMFunction *)sym)->Function;
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 
 	emitters.AddParameterPointerConst(rng);
 	emitters.AddParameter(build, min);
@@ -5601,7 +5601,7 @@ ExpEmit FxRandomPick::Emit(VMFunctionBuilder *build)
 	assert(((PSymbolVMFunction *)sym)->Function != nullptr);
 	callfunc = ((PSymbolVMFunction *)sym)->Function;
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 	emitters.AddParameterPointerConst(rng);
 	emitters.AddParameterIntConst(0);
 	emitters.AddParameterIntConst(choices.Size() - 1);
@@ -5722,7 +5722,7 @@ ExpEmit FxFRandom::Emit(VMFunctionBuilder *build)
 	assert(min && max);
 	callfunc = ((PSymbolVMFunction *)sym)->Function;
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 	emitters.AddParameterPointerConst(rng);
 	emitters.AddParameter(build, min);
 	emitters.AddParameter(build, max);
@@ -5800,7 +5800,7 @@ ExpEmit FxRandom2::Emit(VMFunctionBuilder *build)
 	assert(((PSymbolVMFunction *)sym)->Function != nullptr);
 	callfunc = ((PSymbolVMFunction *)sym)->Function;
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 
 	emitters.AddParameterPointerConst(rng);
 	emitters.AddParameter(build, mask);
@@ -5872,7 +5872,7 @@ ExpEmit FxRandomSeed::Emit(VMFunctionBuilder *build)
 	assert(((PSymbolVMFunction *)sym)->Function != nullptr);
 	callfunc = ((PSymbolVMFunction *)sym)->Function;
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 
 	emitters.AddParameterPointerConst(rng);
 	emitters.AddParameter(build, seed);
@@ -8539,7 +8539,7 @@ ExpEmit FxActionSpecialCall::Emit(VMFunctionBuilder *build)
 {
 	unsigned i = 0;
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 
 	emitters.AddParameterIntConst(abs(Special));			// pass special number
 	emitters.AddParameter(build, Self);
@@ -8983,7 +8983,7 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
 	bool staticcall = ((vmfunc->VarFlags & VARF_Final) || vmfunc->VirtualIndex == ~0u || NoVirtual);
 
 	count = 0;
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 	// Emit code to pass implied parameters
 	ExpEmit selfemit;
 	if (Function->Variants[0].Flags & VARF_Method)
@@ -9054,63 +9054,18 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
 			break;
 		}
 	}
-	count = emitters.EmitParameters(build);
-
 	ArgList.DeleteAndClear();
 	ArgList.ShrinkToFit();
 
-	// Get a constant register for this function
-	if (staticcall)
-	{
-		int funcaddr = build->GetConstantAddress(vmfunc);
-		// Emit the call
-		if (vmfunc->Proto->ReturnTypes.Size() > 0)
-		{ // Call, expecting one result
-			build->Emit(OP_CALL_K, funcaddr, count, MAX(1, AssignCount));
-			goto handlereturns;
-		}
-		else
-		{ // Call, expecting no results
-			build->Emit(OP_CALL_K, funcaddr, count, 0);
-			return ExpEmit();
-		}
-	}
-	else
-	{
-		ExpEmit funcreg(build, REGT_POINTER);
+	emitters.AddTarget(vmfunc, staticcall? -1 : selfemit.RegNum);
+	int resultcount = vmfunc->Proto->ReturnTypes.Size() == 0 ? 0 : MAX(AssignCount, 1);
 
-		build->Emit(OP_VTBL, funcreg.RegNum, selfemit.RegNum, vmfunc->VirtualIndex);
-		if (vmfunc->Proto->ReturnTypes.Size() > 0)
-		{ // Call, expecting one result
-			build->Emit(OP_CALL, funcreg.RegNum, count, MAX(1, AssignCount));
-			goto handlereturns;
-		}
-		else
-		{ // Call, expecting no results
-			build->Emit(OP_CALL, funcreg.RegNum, count, 0);
-			return ExpEmit();
-		}
-	}
-handlereturns:
-	if (AssignCount == 0)
+	assert((unsigned)resultcount <= vmfunc->Proto->ReturnTypes.Size());
+	for (int i = 0; i < resultcount; i++)
 	{
-		// Regular call, will not write to ReturnRegs
-		ExpEmit reg(build, vmfunc->Proto->ReturnTypes[0]->GetRegType(), vmfunc->Proto->ReturnTypes[0]->GetRegCount());
-		build->Emit(OP_RESULT, 0, EncodeRegType(reg), reg.RegNum);
-		return reg;
+		emitters.AddReturn(vmfunc->Proto->ReturnTypes[i]->GetRegType(), vmfunc->Proto->ReturnTypes[i]->GetRegCount());
 	}
-	else
-	{
-		// Multi-Assignment call, this must fill in the ReturnRegs array so that the multi-assignment operator can dispatch the return values.
-		assert((unsigned)AssignCount <= vmfunc->Proto->ReturnTypes.Size());
-		for (int i = 0; i < AssignCount; i++)
-		{
-			ExpEmit reg(build, vmfunc->Proto->ReturnTypes[i]->GetRegType(), vmfunc->Proto->ReturnTypes[i]->GetRegCount());
-			build->Emit(OP_RESULT, 0, EncodeRegType(reg), reg.RegNum);
-			ReturnRegs.Push(reg);
-		}
-	}
-	return ExpEmit();
+	return emitters.EmitCall(build, resultcount > 1? &ReturnRegs : nullptr);
 }
 
 //==========================================================================
@@ -10621,7 +10576,7 @@ ExpEmit FxReturnStatement::Emit(VMFunctionBuilder *build)
 		assert(pstr->mDestructor != nullptr);
 		ExpEmit reg(build, REGT_POINTER);
 		build->Emit(OP_ADDA_RK, reg.RegNum, build->FramePointer.RegNum, build->GetConstantInt(build->ConstructedStructs[i]->StackOffset));
-		EmitterArray emitters;
+		FunctionCallEmitter emitters;
 		emitters.AddParameter(reg, false);
 		emitters.AddTarget(pstr->mDestructor);
 		emitters.EmitCall(build);
@@ -10816,7 +10771,7 @@ ExpEmit FxClassTypeCast::Emit(VMFunctionBuilder *build)
 	{
 		return ExpEmit(build->GetConstantAddress(nullptr), REGT_POINTER, true);
 	}
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 	emitters.AddParameter(build, basex);
 	emitters.AddParameterPointerConst(const_cast<PClass *>(desttype));
 
@@ -10925,7 +10880,7 @@ ExpEmit FxClassPtrCast::Emit(VMFunctionBuilder *build)
 {
 	ExpEmit clsname = basex->Emit(build);
 
-	EmitterArray emitters;
+	FunctionCallEmitter emitters;
 
 	emitters.AddParameter(clsname, false);
 	emitters.AddParameterPointerConst(desttype);
@@ -11311,7 +11266,7 @@ ExpEmit FxLocalVariableDeclaration::Emit(VMFunctionBuilder *build)
 			{
 				ExpEmit reg(build, REGT_POINTER);
 				build->Emit(OP_ADDA_RK, reg.RegNum, build->FramePointer.RegNum, build->GetConstantInt(StackOffset));
-				EmitterArray emitters;
+				FunctionCallEmitter emitters;
 				emitters.AddParameter(reg, false);
 				emitters.AddTarget(pstr->mConstructor);
 				emitters.EmitCall(build);
@@ -11338,7 +11293,7 @@ void FxLocalVariableDeclaration::Release(VMFunctionBuilder *build)
 			{
 				ExpEmit reg(build, REGT_POINTER);
 				build->Emit(OP_ADDA_RK, reg.RegNum, build->FramePointer.RegNum, build->GetConstantInt(StackOffset));
-				EmitterArray emitters;
+				FunctionCallEmitter emitters;
 				emitters.AddParameter(reg, false);
 				emitters.AddTarget(pstr->mDestructor);
 				emitters.EmitCall(build);

src/scripting/backend/vmbuilder.cpp

@@ -931,7 +931,7 @@ void FFunctionBuildList::DumpJit()
 }
 
 
-void EmitterArray::AddParameter(VMFunctionBuilder *build, FxExpression *operand)
+void FunctionCallEmitter::AddParameter(VMFunctionBuilder *build, FxExpression *operand)
 {
 	ExpEmit where = operand->Emit(build);
 
@@ -958,7 +958,7 @@ void EmitterArray::AddParameter(VMFunctionBuilder *build, FxExpression *operand)
 	});
 }
 
-void EmitterArray::AddParameter(ExpEmit &emit, bool reference)
+void FunctionCallEmitter::AddParameter(ExpEmit &emit, bool reference)
 {
 	numparams += emit.RegCount;
 	emitters.push_back([=](VMFunctionBuilder *build) ->int
@@ -970,7 +970,7 @@ void EmitterArray::AddParameter(ExpEmit &emit, bool reference)
 	});
 }
 
-void EmitterArray::AddParameterPointerConst(void *konst)
+void FunctionCallEmitter::AddParameterPointerConst(void *konst)
 {
 	numparams++;
 	emitters.push_back([=](VMFunctionBuilder *build) ->int
@@ -980,7 +980,7 @@ void EmitterArray::AddParameterPointerConst(void *konst)
 	});
 }
 
-void EmitterArray::AddParameterPointer(int index, bool konst)
+void FunctionCallEmitter::AddParameterPointer(int index, bool konst)
 {
 	numparams++;
 	emitters.push_back([=](VMFunctionBuilder *build) ->int
@@ -990,7 +990,7 @@ void EmitterArray::AddParameterPointer(int index, bool konst)
 	});
 }
 
-void EmitterArray::AddParameterFloatConst(double konst)
+void FunctionCallEmitter::AddParameterFloatConst(double konst)
 {
 	numparams++;
 	emitters.push_back([=](VMFunctionBuilder *build) ->int
@@ -1000,7 +1000,7 @@ void EmitterArray::AddParameterFloatConst(double konst)
 	});
 }
 
-void EmitterArray::AddParameterIntConst(int konst)
+void FunctionCallEmitter::AddParameterIntConst(int konst)
 {
 	numparams++;
 	emitters.push_back([=](VMFunctionBuilder *build) ->int
@@ -1018,7 +1018,7 @@ void EmitterArray::AddParameterIntConst(int konst)
 	});
 }
 
-void EmitterArray::AddParameterStringConst(const FString &konst)
+void FunctionCallEmitter::AddParameterStringConst(const FString &konst)
 {
 	numparams++;
 	emitters.push_back([=](VMFunctionBuilder *build) ->int
@@ -1028,7 +1028,7 @@ void EmitterArray::AddParameterStringConst(const FString &konst)
 	});
 }
 
-int EmitterArray::EmitParameters(VMFunctionBuilder *build)
+ExpEmit FunctionCallEmitter::EmitCall(VMFunctionBuilder *build, TArray<ExpEmit> *ReturnRegs)
 {
 	int paramcount = 0;
 	for (auto &func : emitters)
@@ -1036,18 +1036,27 @@ int EmitterArray::EmitParameters(VMFunctionBuilder *build)
 		paramcount += func(build);
 	}
 	assert(paramcount == numparams);
-	return paramcount;
-}
 
+	if (virtualselfreg == -1)
+	{
+		build->Emit(OP_CALL_K, build->GetConstantAddress(target), paramcount, returns.Size());
+	}
+	else
+	{
+		ExpEmit funcreg(build, REGT_POINTER);
 
-ExpEmit EmitterArray::EmitCall(VMFunctionBuilder *build)
-{
-	int count = EmitParameters(build);
-	build->Emit(OP_CALL_K, build->GetConstantAddress(target), count, returns.Size());
-	if (returns.Size() == 0) return ExpEmit();
+		build->Emit(OP_VTBL, funcreg.RegNum, virtualselfreg, target->VirtualIndex);
+		build->Emit(OP_CALL, funcreg.RegNum, paramcount, returns.Size());
+	}
 
-	ExpEmit out(build, returns[0]);
-	build->Emit(OP_RESULT, 0, returns[0], out.RegNum);
-	return out;
+	assert(returns.Size() < 2 || ReturnRegs != nullptr);
+	for (unsigned i = 0; i < returns.Size(); i++)
+	{
+		ExpEmit reg(build, returns[i].first, returns[i].second);
+		build->Emit(OP_RESULT, 0, EncodeRegType(reg), reg.RegNum);
+		if (ReturnRegs) ReturnRegs->Push(reg);
+		else return reg;
+	}
+	return ExpEmit();
 }
 

src/scripting/backend/vmbuilder.h

@@ -163,13 +163,14 @@ extern FFunctionBuildList FunctionBuildList;
 //==========================================================================
 extern int EncodeRegType(ExpEmit reg);
 
-class EmitterArray
+class FunctionCallEmitter
 {
 	// std::function and TArray are not compatible so this has to use std::vector instead.
 	std::vector<std::function<int(VMFunctionBuilder *)>> emitters;
-	TArray<int> returns;
+	TArray<std::pair<int, int>> returns;
 	unsigned numparams = 0;	// This counts the number of pushed elements, which can differ from the number of emitters with vectors.
 	VMFunction *target = nullptr;
+	int virtualselfreg = -1;
 
 public:
 	void AddParameter(VMFunctionBuilder *build, FxExpression *operand);
@@ -179,15 +180,15 @@ public:
 	void AddParameterFloatConst(double konst);
 	void AddParameterIntConst(int konst);
 	void AddParameterStringConst(const FString &konst);
-	int EmitParameters(VMFunctionBuilder *build);
-	ExpEmit EmitCall(VMFunctionBuilder *build);
-	void AddReturn(int regtype)
+	ExpEmit EmitCall(VMFunctionBuilder *build, TArray<ExpEmit> *ReturnRegs = nullptr);
+	void AddReturn(int regtype, int regcount = 1)
 	{
-		returns.Push(regtype);
+		returns.Push({ regtype, regcount });
 	}
-	void AddTarget(VMFunction *func)
+	void AddTarget(VMFunction *func, int virtreg = -1)
 	{
 		target = func;
+		virtualselfreg = virtreg;
 	}
 	unsigned Count() const
 	{