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/defer.go

@@ -406,7 +406,7 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 
 	var values llvmValueList
 	lowerArgument := func(value ssa.Value) llvm.Value {
-		return b.getValue(value, getPos(instr))
+		return b.getCallArgument(value, false)
 	}
 	if instr.Call.IsInvoke() {
 		// Method call on an interface.
@@ -438,7 +438,10 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		// Collect all values to be put in the struct (starting with
 		// runtime._defer fields).
 		values = newLLVMValueList(callback, next)
-		values.appendSSAValues(instr.Call.Args, lowerArgument)
+		exported := b.getFunctionInfo(callee).exported
+		values.appendSSAValues(instr.Call.Args, func(value ssa.Value) llvm.Value {
+			return b.getCallArgument(value, exported)
+		})
 
 	} else if makeClosure, ok := instr.Call.Value.(*ssa.MakeClosure); ok {
 		// Immediately applied function literal with free variables.
@@ -612,9 +615,7 @@ func (b *builder) createRunDefers() {
 				valueTypes = append(valueTypes, b.dataPtrType, b.dataPtrType)
 			}
 
-			for _, arg := range callback.Args {
-				valueTypes = append(valueTypes, b.getLLVMType(arg.Type()))
-			}
+			valueTypes = b.appendStoredValueTypes(valueTypes, callback.Args, false)
 
 			// Extract the params from the struct (including receiver).
 			deferredCallType := b.ctx.StructType(valueTypes, false)
@@ -647,6 +648,7 @@ func (b *builder) createRunDefers() {
 				// with a strict calling convention.
 				forwardParams = append(forwardParams, llvm.Undef(b.dataPtrType))
 			}
+			forwardParams = b.prependIndirectResult(callback.Signature(), false, forwardParams, "defer.result")
 
 			b.createCall(fnType, fnPtr, forwardParams, "")
 
@@ -655,9 +657,8 @@ func (b *builder) createRunDefers() {
 
 			// Get the real defer struct type and cast to it.
 			valueTypes := []llvm.Type{b.uintptrType, b.dataPtrType}
-			for _, param := range getParams(callback.Signature) {
-				valueTypes = append(valueTypes, b.getLLVMType(param.Type()))
-			}
+			exported := b.getFunctionInfo(callback).exported
+			valueTypes = b.appendStoredParamTypes(valueTypes, getParams(callback.Signature), exported)
 			deferredCallType := b.ctx.StructType(valueTypes, false)
 
 			// Extract the params from the struct.
@@ -665,11 +666,12 @@ func (b *builder) createRunDefers() {
 
 			// Plain TinyGo functions add some extra parameters to implement async functionality and function receivers.
 			// These parameters should not be supplied when calling into an external C/ASM function.
-			if !b.getFunctionInfo(callback).exported {
+			if !exported {
 				// Add the context parameter. We know it is ignored by the receiving
 				// function, but we have to pass one anyway.
 				forwardParams = append(forwardParams, llvm.Undef(b.dataPtrType))
 			}
+			forwardParams = b.prependIndirectResult(callback.Signature, exported, forwardParams, "defer.result")
 
 			// Call real function.
 			fnType, fn := b.getFunction(callback)
@@ -679,10 +681,7 @@ func (b *builder) createRunDefers() {
 			// Get the real defer struct type and cast to it.
 			fn := callback.Fn.(*ssa.Function)
 			valueTypes := []llvm.Type{b.uintptrType, b.dataPtrType}
-			params := fn.Signature.Params()
-			for v := range params.Variables() {
-				valueTypes = append(valueTypes, b.getLLVMType(v.Type()))
-			}
+			valueTypes = b.appendStoredParamTypes(valueTypes, getParams(fn.Signature), false)
 			valueTypes = append(valueTypes, b.dataPtrType) // closure
 			deferredCallType := b.ctx.StructType(valueTypes, false)
 
@@ -691,6 +690,7 @@ func (b *builder) createRunDefers() {
 
 			// Call deferred function.
 			fnType, llvmFn := b.getFunction(fn)
+			forwardParams = b.prependIndirectResult(fn.Signature, false, forwardParams, "defer.result")
 			b.createCall(fnType, llvmFn, forwardParams, "")
 		case *ssa.Builtin:
 			db := b.deferBuiltinFuncs[callback]