From 6be82cc3aeca52d56c4531a2e2d616a99257004f Mon Sep 17 00:00:00 2001
From: "Daniel R. Carvalho" <odanrc@yahoo.com.br>
Date: Tue, 1 Jun 2021 10:08:52 -0300
Subject: [PATCH] dev,sim: Fix compiler not finding specialized byte_swap

The specialized version of byte_swap cannot be found by
the compiler. As a temporary workaround to get the major
patch going, move the specialization to the base header
file.

Change-Id: I7d2bfc1c29b70042860ae06cdc043c0490cd8916
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46322
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
---
 src/dev/virtio/base.hh | 11 ++++++-----
 src/sim/byteswap.hh    | 18 +++++++++++++++---
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/dev/virtio/base.hh b/src/dev/virtio/base.hh
index 350e51024b..6eeb4a4a71 100644
--- a/src/dev/virtio/base.hh
+++ b/src/dev/virtio/base.hh
@@ -68,17 +68,18 @@ class VirtQueue;
  * of byte swapping.
  */
 
-
-static inline vring_used_elem
-swap_byte(vring_used_elem v)
+template <typename T>
+inline std::enable_if_t<std::is_same<T, vring_used_elem>::value, T>
+swap_byte(T v)
 {
     v.id = swap_byte(v.id);
     v.len = swap_byte(v.len);
     return v;
 }
 
-static inline vring_desc
-swap_byte(vring_desc v)
+template <typename T>
+inline std::enable_if_t<std::is_same<T, vring_desc>::value, T>
+swap_byte(T v)
 {
     v.addr = swap_byte(v.addr);
     v.len = swap_byte(v.len);
diff --git a/src/sim/byteswap.hh b/src/sim/byteswap.hh
index 30e63d1a54..82282ec76a 100644
--- a/src/sim/byteswap.hh
+++ b/src/sim/byteswap.hh
@@ -33,9 +33,6 @@
 #ifndef __SIM_BYTE_SWAP_HH__
 #define __SIM_BYTE_SWAP_HH__
 
-#include "base/types.hh"
-#include "enums/ByteOrder.hh"
-
 // This lets us figure out what the byte order of the host system is
 #if defined(__linux__)
 #include <endian.h>
@@ -55,6 +52,12 @@
 
 #include <type_traits>
 
+#include "base/types.hh"
+#include "enums/ByteOrder.hh"
+
+struct vring_used_elem;
+struct vring_desc;
+
 // These functions actually perform the swapping for parameters of various bit
 // lengths.
 inline uint64_t
@@ -135,6 +138,15 @@ swap_byte(T x)
     return x;
 }
 
+// Make the function visible in case we need to declare a version of it for
+// other types
+template <typename T>
+std::enable_if_t<std::is_same<T, vring_used_elem>::value, T>
+swap_byte(T v);
+template <typename T>
+std::enable_if_t<std::is_same<T, vring_desc>::value, T>
+swap_byte(T v);
+
 template <typename T, size_t N>
 inline std::array<T, N>
 swap_byte(std::array<T, N> a)