gallium: fix reference counting functions to be strict-aliasing compliant

Historically, parts of mesa code are not strict-aliasing safe, hence
-fno-strict-aliasing is needed to compile (this got forgotten for scons
builds for gallium, which indeed not only caused compiler warnings but also
unexplicable crashes in non-debug builds). However, we should try to eliminate
code not complying with strict-aliasing code at least for gallium.
Hence change pipe_reference functions to make them strict-aliasing compliant.
This adds a bit more complexity (especially for derived classes) but is the
right thing to do, and it does in fact fix a segfault.

3 files changed, 9 insertions, 2 deletions

diff --git a/src/gallium/auxiliary/pipebuffer/pb_buffer.h b/src/gallium/auxiliary/pipebuffer/pb_buffer.h
index 4ef372233f0..eb7e84be848 100644
--- a/src/gallium/auxiliary/pipebuffer/pb_buffer.h
+++ b/src/gallium/auxiliary/pipebuffer/pb_buffer.h
@@ -237,8 +237,9 @@ pb_reference(struct pb_buffer **dst,
 {
    struct pb_buffer *old = *dst;
 
-   if (pipe_reference((struct pipe_reference**)dst, &src->base.reference))
+   if (pipe_reference(&(*dst)->base.reference, &src->base.reference))
       pb_destroy( old );
+   *dst = src;
 }
 
 
diff --git a/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c b/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
index 2f973684f67..a9375abd218 100644
--- a/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
+++ b/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
@@ -243,6 +243,7 @@ fenced_buffer_list_check_free_locked(struct fenced_buffer_list *fenced_list,
    struct pb_fence_ops *ops = fenced_list->ops;
    struct list_head *curr, *next;
    struct fenced_buffer *fenced_buf;
+   struct pb_buffer *pb_buf;
    struct pipe_fence_handle *prev_fence = NULL;
 
    curr = fenced_list->delayed.next;
@@ -271,7 +272,9 @@ fenced_buffer_list_check_free_locked(struct fenced_buffer_list *fenced_list,
       fenced_buffer_remove_locked(fenced_list, fenced_buf);
       pipe_mutex_unlock(fenced_buf->mutex);
 
-      pb_reference((struct pb_buffer **)&fenced_buf, NULL);
+      pb_buf = &fenced_buf->base;
+      pb_reference(&pb_buf, NULL);
+      
 
       curr = next; 
       next = curr->next;
diff --git a/src/gallium/auxiliary/pipebuffer/pb_bufmgr_cache.c b/src/gallium/auxiliary/pipebuffer/pb_bufmgr_cache.c
index 57d1ede45a4..f0c88a0ccbf 100644
--- a/src/gallium/auxiliary/pipebuffer/pb_bufmgr_cache.c
+++ b/src/gallium/auxiliary/pipebuffer/pb_bufmgr_cache.c
@@ -293,8 +293,11 @@ pb_cache_manager_create_buffer(struct pb_manager *_mgr,
    if(buf) {
       LIST_DEL(&buf->head);
       pipe_mutex_unlock(mgr->mutex);
+#if 0
+      /* XXX this didn't do anything right??? */
       /* Increase refcount */
       pb_reference((struct pb_buffer**)&buf, &buf->base);
+#endif
       return &buf->base;
    }