compiler: pass large aggregates by pointer

LLVM ComputeValueVTs recursively expands arrays and structs into one
value type per scalar leaf. SelectionDAG call lowering allocates data
structures proportional to this count, which makes very large values
exhaust memory or crash LLVM.

Count scalar leaves and use pointers for internal parameters and results
when the count exceeds 1024. A result pointer is the first parameter,
and aggregate parameters point to read-only memory. Exported function
types are unchanged.

Keep these SSA values in memory and copy them with memcpy when needed.
Handle calls, interfaces, maps, channels, selects, defers, goroutines,
phis, and multiple results. Update the expected compiler IR and re-enable
the native compress/flate tests.

compiler/goroutine.go

@@ -53,6 +53,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 	var funcType llvm.Type
 	var context llvm.Value
 	hasContext := false
+	exported := false
 	if callee := instr.Call.StaticCallee(); callee != nil {
 		// Static callee is known. This makes it easier to start a new
 		// goroutine.
@@ -71,6 +72,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 			hasContext = true
 		}
 		funcType, funcPtr = b.getFunction(callee)
+		exported = b.getFunctionInfo(callee).exported
 	} else if instr.Call.IsInvoke() {
 		// This is a method call on an interface value.
 		itf := b.getValue(instr.Call.Value, getPos(instr))
@@ -93,7 +95,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 	}
 
 	for _, param := range instr.Call.Args {
-		params = append(params, b.getGoroutineCallArgument(param)...)
+		params = append(params, b.getGoroutineCallArgument(param, exported)...)
 	}
 	if !context.IsNil() {
 		params = append(params, context)
@@ -101,6 +103,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 	if hasContext && instr.Call.StaticCallee() == nil {
 		params = append(params, funcPtr)
 	}
+	params = b.prependIndirectResult(instr.Call.Signature(), exported, params, "go.result")
 
 	paramBundle := b.emitPointerPack(params, instr.Pos())
 	var stackSize llvm.Value
@@ -124,8 +127,13 @@ func (b *builder) createGo(instr *ssa.Go) {
 	b.createCall(fnType, start, []llvm.Value{callee, paramBundle, stackSize, llvm.Undef(b.dataPtrType)}, "")
 }
 
-func (b *builder) getGoroutineCallArgument(value ssa.Value) []llvm.Value {
-	return b.expandFormalParam(b.getValue(value, getPos(value)))
+func (b *builder) getGoroutineCallArgument(value ssa.Value, exported bool) []llvm.Value {
+	typ := b.getLLVMType(value.Type())
+	arg := b.getCallArgument(value, exported)
+	if b.isIndirectParam(typ, exported) {
+		return []llvm.Value{b.copyToIndirectStorage(arg, typ, "go.param")}
+	}
+	return b.expandFormalParam(arg)
 }
 
 // Create an exported wrapper function for functions with the //go:wasmexport