[libc] Fix and simplify the implementation of 'fread' on the GPU

libc/include/llvm-libc-types/rpc_opcodes_t.h

@@ -15,17 +15,16 @@ typedef enum : unsigned short {
   RPC_WRITE_TO_STDOUT = 2,
   RPC_WRITE_TO_STDERR = 3,
   RPC_WRITE_TO_STREAM = 4,
-  RPC_READ_FROM_STDIN = 5,
-  RPC_READ_FROM_STREAM = 6,
-  RPC_OPEN_FILE = 7,
-  RPC_CLOSE_FILE = 8,
-  RPC_MALLOC = 9,
-  RPC_FREE = 10,
-  RPC_HOST_CALL = 11,
-  RPC_ABORT = 12,
-  RPC_FEOF = 13,
-  RPC_FERROR = 14,
-  RPC_CLEARERR = 15,
+  RPC_READ_FROM_STREAM = 5,
+  RPC_OPEN_FILE = 6,
+  RPC_CLOSE_FILE = 7,
+  RPC_MALLOC = 8,
+  RPC_FREE = 9,
+  RPC_HOST_CALL = 10,
+  RPC_ABORT = 11,
+  RPC_FEOF = 12,
+  RPC_FERROR = 13,
+  RPC_CLEARERR = 14,
 } rpc_opcode_t;
 
 #endif // __LLVM_LIBC_TYPES_RPC_OPCODE_H__

libc/src/stdio/gpu/file.h

@@ -14,6 +14,39 @@
 namespace __llvm_libc {
 namespace file {
 
+enum Stream {
+  File = 0,
+  Stdin = 1,
+  Stdout = 2,
+  Stderr = 3,
+};
+
+// When copying between the client and server we need to indicate if this is one
+// of the special streams. We do this by enocding the low order bits of the
+// pointer to indicate if we need to use the host's standard stream.
+LIBC_INLINE uintptr_t from_stream(::FILE *f) {
+  if (f == stdin)
+    return reinterpret_cast<uintptr_t>(f) | Stdin;
+  if (f == stdout)
+    return reinterpret_cast<uintptr_t>(f) | Stdout;
+  if (f == stderr)
+    return reinterpret_cast<uintptr_t>(f) | Stderr;
+  return reinterpret_cast<uintptr_t>(f);
+}
+
+// Get the associated stream out of an encoded number.
+LIBC_INLINE ::FILE *to_stream(uintptr_t f) {
+  ::FILE *stream = reinterpret_cast<FILE *>(f & ~0x3ull);
+  Stream type = static_cast<Stream>(f & 0x3ull);
+  if (type == Stdin)
+    return stdin;
+  if (type == Stdout)
+    return stdout;
+  if (type == Stderr)
+    return stderr;
+  return stream;
+}
+
 template <uint16_t opcode>
 LIBC_INLINE uint64_t write_impl(::FILE *file, const void *data, size_t size) {
   uint64_t ret = 0;
@@ -42,15 +75,13 @@ LIBC_INLINE uint64_t write(::FILE *f, const void *data, size_t size) {
     return write_impl<RPC_WRITE_TO_STREAM>(f, data, size);
 }
 
-template <uint16_t opcode>
 LIBC_INLINE uint64_t read_from_stream(::FILE *file, void *buf, size_t size) {
   uint64_t ret = 0;
   uint64_t recv_size;
-  rpc::Client::Port port = rpc::client.open<opcode>();
+  rpc::Client::Port port = rpc::client.open<RPC_READ_FROM_STREAM>();
   port.send([=](rpc::Buffer *buffer) {
     buffer->data[0] = size;
-    if constexpr (opcode == RPC_READ_FROM_STREAM)
-      buffer->data[1] = reinterpret_cast<uintptr_t>(file);
+    buffer->data[1] = from_stream(file);
   });
   port.recv_n(&buf, &recv_size, [&](uint64_t) { return buf; });
   port.recv([&](rpc::Buffer *buffer) { ret = buffer->data[0]; });
@@ -59,43 +90,7 @@ LIBC_INLINE uint64_t read_from_stream(::FILE *file, void *buf, size_t size) {
 }
 
 LIBC_INLINE uint64_t read(::FILE *f, void *data, size_t size) {
-  if (f == stdin)
-    return read_from_stream<RPC_READ_FROM_STDIN>(f, data, size);
-  else
-    return read_from_stream<RPC_READ_FROM_STREAM>(f, data, size);
-}
-
-enum Stream {
-  File = 0,
-  Stdin = 1,
-  Stdout = 2,
-  Stderr = 3,
-};
-
-// When copying between the client and server we need to indicate if this is one
-// of the special streams. We do this by enocding the low order bits of the
-// pointer to indicate if we need to use the host's standard stream.
-LIBC_INLINE uintptr_t from_stream(::FILE *f) {
-  if (f == stdin)
-    return reinterpret_cast<uintptr_t>(f) | Stdin;
-  if (f == stdout)
-    return reinterpret_cast<uintptr_t>(f) | Stdout;
-  if (f == stderr)
-    return reinterpret_cast<uintptr_t>(f) | Stderr;
-  return reinterpret_cast<uintptr_t>(f);
-}
-
-// Get the associated stream out of an encoded number.
-LIBC_INLINE ::FILE *to_stream(uintptr_t f) {
-  ::FILE *stream = reinterpret_cast<FILE *>(f & ~0x3ull);
-  Stream type = static_cast<Stream>(f & 0x3ull);
-  if (type == Stdin)
-    return stdin;
-  if (type == Stdout)
-    return stdout;
-  if (type == Stderr)
-    return stderr;
-  return stream;
+  return read_from_stream(f, data, size);
 }
 
 } // namespace file

libc/utils/gpu/server/rpc_server.cpp

@@ -98,23 +98,18 @@ struct Server {
       });
       break;
     }
-    case RPC_READ_FROM_STREAM:
-    case RPC_READ_FROM_STDIN: {
+    case RPC_READ_FROM_STREAM: {
       uint64_t sizes[lane_size] = {0};
       void *data[lane_size] = {nullptr};
-      uint64_t rets[lane_size] = {0};
       port->recv([&](rpc::Buffer *buffer, uint32_t id) {
-        sizes[id] = buffer->data[0];
-        data[id] = new char[sizes[id]];
-        FILE *file = port->get_opcode() == RPC_READ_FROM_STREAM
-                         ? reinterpret_cast<FILE *>(buffer->data[1])
-                         : stdin;
-        rets[id] = fread(data[id], 1, sizes[id], file);
+        data[id] = new char[buffer->data[0]];
+        sizes[id] = fread(data[id], 1, buffer->data[0],
+                          file::to_stream(buffer->data[1]));
       });
       port->send_n(data, sizes);
       port->send([&](rpc::Buffer *buffer, uint32_t id) {
         delete[] reinterpret_cast<uint8_t *>(data[id]);
-        std::memcpy(buffer->data, &rets[id], sizeof(uint64_t));
+        std::memcpy(buffer->data, &sizes[id], sizeof(uint64_t));
       });
       break;
     }