compiler: remove parentHandle from calling convention

This removes the parentHandle argument from the internal calling convention.
It was formerly used to implment coroutines.
Now that coroutines have been removed, it is no longer necessary.

transform/interface-lowering.go

@@ -417,13 +417,11 @@ func (p *lowerInterfacesPass) defineInterfaceImplementsFunc(fn llvm.Value, itf *
 // possible types.  This is later converted to a switch statement by the LLVM
 // simplifycfg pass.
 func (p *lowerInterfacesPass) defineInterfaceMethodFunc(fn llvm.Value, itf *interfaceInfo, signature *signatureInfo) {
-	parentHandle := fn.LastParam()
-	context := llvm.PrevParam(parentHandle)
+	context := fn.LastParam()
 	actualType := llvm.PrevParam(context)
 	returnType := fn.Type().ElementType().ReturnType()
 	context.SetName("context")
 	actualType.SetName("actualType")
-	parentHandle.SetName("parentHandle")
 	fn.SetLinkage(llvm.InternalLinkage)
 	fn.SetUnnamedAddr(true)
 	AddStandardAttributes(fn, p.config)
@@ -431,13 +429,12 @@ func (p *lowerInterfacesPass) defineInterfaceMethodFunc(fn llvm.Value, itf *inte
 	// Collect the params that will be passed to the functions to call.
 	// These params exclude the receiver (which may actually consist of multiple
 	// parts).
-	params := make([]llvm.Value, fn.ParamsCount()-4)
+	params := make([]llvm.Value, fn.ParamsCount()-3)
 	for i := range params {
 		params[i] = fn.Param(i + 1)
 	}
 	params = append(params,
 		llvm.Undef(llvm.PointerType(p.ctx.Int8Type(), 0)),
-		llvm.Undef(llvm.PointerType(p.ctx.Int8Type(), 0)),
 	)
 
 	// Start chain in the entry block.
@@ -519,7 +516,6 @@ func (p *lowerInterfacesPass) defineInterfaceMethodFunc(fn llvm.Value, itf *inte
 	nilPanic := p.mod.NamedFunction("runtime.nilPanic")
 	p.builder.CreateCall(nilPanic, []llvm.Value{
 		llvm.Undef(llvm.PointerType(p.ctx.Int8Type(), 0)),
-		llvm.Undef(llvm.PointerType(p.ctx.Int8Type(), 0)),
 	}, "")
 	p.builder.CreateUnreachable()
 }