purego: support structs on ppc64le

README.md

@@ -42,7 +42,7 @@ Tier 2 platforms are supported by PureGo on a best-effort basis. Critical bugs o
 
 - **Android**: 386<sup>1,3</sup>, arm<sup>1,3</sup>
 - **FreeBSD**: amd64<sup>3,4</sup>, arm64<sup>3,4</sup>
-- **Linux**: 386<sup>3</sup>, arm<sup>3</sup>, loong64<sup>2</sup>, ppc64le<sup>3</sup>, riscv64<sup>3</sup>, s390x<sup>3, 5</sup>
+- **Linux**: 386<sup>3</sup>, arm<sup>3</sup>, loong64<sup>2</sup>, ppc64le<sup>2</sup>, riscv64<sup>3</sup>, s390x<sup>3, 5</sup>
 - **NetBSD**: amd64<sup>3,4</sup>, arm64<sup>3,4</sup>
 - **Windows**: 386<sup>3,6</sup>, arm<sup>3,6,7</sup>
 

export_test.go

@@ -5,10 +5,12 @@
 
 package purego
 
+import "reflect"
+
 // MaxArgs re-exports maxArgs for external tests.
 const MaxArgs = maxArgs
 
 // StructReturnInMemory re-exports structReturnInMemory for external tests.
-func StructReturnInMemory(size uintptr) bool {
-	return structReturnInMemory(size)
+func StructReturnInMemory(outType reflect.Type) bool {
+	return structReturnInMemory(outType)
 }

func.go

@@ -199,7 +199,7 @@ func RegisterFunc(fptr any, cfn uintptr) {
 			ensureStructSupported()
 			outType := ty.Out(0)
 			checkStructFieldsSupported(outType)
-			if structReturnInMemory(outType.Size()) {
+			if structReturnInMemory(outType) {
 				// A struct returned in memory is allocated by the caller and its
 				// pointer is passed as a hidden first integer argument. When the
 				// integer registers are already full, prepending it spills a
@@ -292,7 +292,7 @@ func RegisterFunc(fptr any, cfn uintptr) {
 		var arm64_r8 uintptr
 		if ty.NumOut() == 1 && ty.Out(0).Kind() == reflect.Struct {
 			outType := ty.Out(0)
-			if structReturnInMemory(outType.Size()) {
+			if structReturnInMemory(outType) {
 				// The caller allocates the return value and passes its pointer
 				// as a hidden first integer argument.
 				val := reflect.New(outType)
@@ -431,10 +431,14 @@ func addValue(v reflect.Value, keepAlive []any, addInt func(x uintptr), addFloat
 			addInt(0)
 		}
 	case reflect.Float32:
-		// On S390X big-endian, float32 goes in upper 32 bits of 64-bit FP register
-		if runtime.GOARCH == "s390x" {
+		switch runtime.GOARCH {
+		case "ppc64le":
+			// A single-precision argument occupies a floating-point register in double format on Power.
+			addFloat(uintptr(math.Float64bits(v.Float())))
+		case "s390x":
+			// S390X big-endian: float32 goes in the upper 32 bits of the 64-bit FP register.
 			addFloat(uintptr(math.Float32bits(float32(v.Float()))) << 32)
-		} else {
+		default:
 			addFloat(uintptr(math.Float32bits(float32(v.Float()))))
 		}
 	case reflect.Float64:
@@ -510,9 +514,9 @@ func checkStructFieldsSupported(ty reflect.Type) {
 // a C function is unsupported on the current platform.
 func ensureStructSupported() {
 	switch runtime.GOARCH {
-	case "amd64", "arm64", "loong64":
+	case "amd64", "arm64", "loong64", "ppc64le":
 	default:
-		panic("purego: struct arguments/returns are only supported on amd64, arm64, and loong64")
+		panic("purego: struct arguments/returns are only supported on amd64, arm64, loong64, and ppc64le")
 	}
 	switch runtime.GOOS {
 	case "android", "darwin", "ios", "linux", "windows":

func_test.go

@@ -604,7 +604,7 @@ func TestABI_StructReturnHiddenPointer(t *testing.T) {
 	// than sysargs holds and RegisterFunc must reject the registration.
 	type bigStruct struct{ A, B, C uint64 } // larger than two eightbytes
 
-	if !purego.StructReturnInMemory(reflect.TypeFor[bigStruct]().Size()) {
+	if !purego.StructReturnInMemory(reflect.TypeFor[bigStruct]()) {
 		t.Skipf("GOARCH=%s does not return large structs via a hidden integer argument", runtime.GOARCH)
 	}
 

struct_amd64.go

@@ -13,7 +13,8 @@ import (
 // structReturnInMemory reports whether a struct return value of the given size
 // is returned through a caller-allocated hidden pointer passed as the first
 // integer argument (true) rather than in registers (false).
-func structReturnInMemory(size uintptr) bool {
+func structReturnInMemory(outType reflect.Type) bool {
+	size := outType.Size()
 	if size == 0 {
 		return false
 	}
@@ -38,7 +39,7 @@ func getStruct(outType reflect.Type, syscall syscallArgs) (v reflect.Value) {
 		switch {
 		case outSize == 0:
 			return reflect.New(outType).Elem()
-		case structReturnInMemory(outSize):
+		case structReturnInMemory(outType):
 			// Returned through the caller-allocated hidden pointer, which the
 			// callee also returns in RAX.
 			return reflect.NewAt(outType, *(*unsafe.Pointer)(unsafe.Pointer(&syscall.a1))).Elem()

struct_arm.go

@@ -31,7 +31,7 @@ func addStruct(v reflect.Value, numInts, numFloats, numStack *int, addInt, addFl
 // structReturnInMemory always reports false on arm: an indirect struct return
 // is recovered from the pointer the callee leaves in a1 (see getStruct) rather
 // than through a caller-allocated hidden first argument.
-func structReturnInMemory(size uintptr) bool {
+func structReturnInMemory(reflect.Type) bool {
 	return false
 }
 

struct_arm64.go

@@ -17,7 +17,7 @@ import (
 // structReturnInMemory always reports false on arm64: a struct returned in
 // memory is passed through the dedicated indirect result register (R8), not as
 // an ordinary integer argument, so it is handled separately.
-func structReturnInMemory(size uintptr) bool {
+func structReturnInMemory(reflect.Type) bool {
 	return false
 }
 

struct_loong64.go

@@ -72,11 +72,11 @@ func loong64Classify(t reflect.Type) (leaves []loong64Leaf, useFP bool) {
 	}
 }
 
-// structReturnInMemory reports whether a struct return value of the given size
-// is returned through a caller-allocated hidden pointer passed as the first
-// integer argument. Aggregates larger than two eightbytes are returned in memory.
-func structReturnInMemory(size uintptr) bool {
-	return size > maxRegAllocStructSize
+// structReturnInMemory reports whether a struct return value is returned through
+// a caller-allocated hidden pointer passed as the first integer argument.
+// Aggregates larger than two eightbytes are returned in memory.
+func structReturnInMemory(outType reflect.Type) bool {
+	return outType.Size() > maxRegAllocStructSize
 }
 
 func getStruct(outType reflect.Type, syscall syscallArgs) reflect.Value {

struct_other.go

@@ -22,10 +22,10 @@ func getStruct(outType reflect.Type, syscall syscallArgs) reflect.Value {
 	panic("purego: struct returns are not supported on this architecture")
 }
 
-// structReturnInMemory reports whether a struct return value of the given size
-// is returned through a caller-allocated hidden pointer. Structs are unsupported
-// on this architecture, so it always reports false.
-func structReturnInMemory(size uintptr) bool {
+// structReturnInMemory reports whether a struct return value is returned through
+// a caller-allocated hidden pointer. Structs are unsupported on this
+// architecture, so it always reports false.
+func structReturnInMemory(reflect.Type) bool {
 	return false
 }