From 447029a70064e886d3b0b5ec24413ffd202420f1 Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Mon, 3 Jun 2019 22:57:59 +0300
Subject: [PATCH] Implement fs::file::write_gather (Vectored I/O)

---
 Utilities/File.cpp               | 40 ++++++++++++++++++++++++++++++++
 Utilities/File.h                 | 15 ++++++++++++
 rpcs3/Emu/Cell/SPURecompiler.cpp | 15 +++++++-----
 3 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/Utilities/File.cpp b/Utilities/File.cpp
index 0a5ef837b6..6ae18395c0 100644
--- a/Utilities/File.cpp
+++ b/Utilities/File.cpp
@@ -125,6 +125,7 @@ static fs::error to_error(DWORD e)
 #include <sys/types.h>
 #include <sys/statvfs.h>
 #include <sys/file.h>
+#include <sys/uio.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <libgen.h>
@@ -203,6 +204,34 @@ namespace fs
 #endif
 	}
 
+	u64 file_base::write_gather(const iovec_clone* buffers, u64 buf_count)
+	{
+		u64 total = 0;
+
+		for (u64 i = 0; i < buf_count; i++)
+		{
+			if (!buffers[i].iov_base || buffers[i].iov_len + total < total)
+			{
+				g_tls_error = error::inval;
+				return -1;
+			}
+
+			total += buffers[i].iov_len;
+		}
+
+		const auto buf = std::make_unique<uchar>(total);
+
+		u64 copied = 0;
+
+		for (u64 i = 0; i < buf_count; i++)
+		{
+			std::memcpy(buf.get() + copied, buffers[i].iov_base, buffers[i].iov_len);
+			copied += buffers[i].iov_len;
+		}
+
+		return this->write(buf.get(), total);
+	}
+
 	dir_base::~dir_base()
 	{
 	}
@@ -1157,6 +1186,17 @@ fs::file::file(const std::string& path, bs_t<open_mode> mode)
 		{
 			return m_fd;
 		}
+
+		u64 write_gather(const iovec_clone* buffers, u64 buf_count) override
+		{
+			static_assert(sizeof(iovec) == sizeof(iovec_clone), "Weird iovec size");
+			static_assert(offsetof(iovec, iov_len) == offsetof(iovec_clone, iov_len), "Weird iovec::iov_len offset");
+
+			const auto result = ::writev(m_fd, (const iovec*)buffers, buf_count);
+			verify("file::write_gather" HERE), result != -1;
+
+			return result;
+		}
 	};
 
 	m_file = std::make_unique<unix_file>(fd);
diff --git a/Utilities/File.h b/Utilities/File.h
index fa434dee6d..9b802cdef7 100644
--- a/Utilities/File.h
+++ b/Utilities/File.h
@@ -65,6 +65,13 @@ namespace fs
 		s64 ctime;
 	};
 
+	// Helper, layout is equal to iovec struct
+	struct iovec_clone
+	{
+		const void* iov_base;
+		std::size_t iov_len;
+	};
+
 	// File handle base
 	struct file_base
 	{
@@ -78,6 +85,7 @@ namespace fs
 		virtual u64 seek(s64 offset, seek_mode whence) = 0;
 		virtual u64 size() = 0;
 		virtual native_handle get_handle();
+		virtual u64 write_gather(const iovec_clone* buffers, u64 buf_count);
 	};
 
 	// Directory entry (TODO)
@@ -362,6 +370,13 @@ namespace fs
 		// Get native handle if available
 		native_handle get_handle() const;
 
+		// Gathered write
+		u64 write_gather(const iovec_clone* buffers, u64 buf_count) const
+		{
+			if (!m_file) xnull();
+			return m_file->write_gather(buffers, buf_count);
+		}
+
 #ifdef _WIN32
 		// Windows-specific function
 		bool set_delete(bool autodelete = true) const;
diff --git a/rpcs3/Emu/Cell/SPURecompiler.cpp b/rpcs3/Emu/Cell/SPURecompiler.cpp
index c168c721ca..ff6dc304e4 100644
--- a/rpcs3/Emu/Cell/SPURecompiler.cpp
+++ b/rpcs3/Emu/Cell/SPURecompiler.cpp
@@ -265,15 +265,18 @@ void spu_cache::add(const std::vector<u32>& func)
 		return;
 	}
 
-	// Allocate buffer
-	const auto buf = std::make_unique<be_t<u32>[]>(func.size() + 1);
+	be_t<u32> size = ::size32(func) - 1;
+	be_t<u32> addr = func[0];
 
-	buf[0] = ::size32(func) - 1;
-	buf[1] = func[0];
-	std::memcpy(buf.get() + 2, func.data() + 1, func.size() * 4 - 4);
+	const fs::iovec_clone gather[3]
+	{
+		{&size, sizeof(size)},
+		{&addr, sizeof(addr)},
+		{func.data() + 1, func.size() * 4 - 4}
+	};
 
 	// Append data
-	m_file.write(buf.get(), func.size() * 4 + 4);
+	m_file.write_gather(gather, 3);
 }
 
 void spu_cache::initialize()