For example, something like this:
uint8_t *p8;
uint32_t *p32 = (uint32_t *) p8;
generates a warning like this:
spice-channel.c:1350:10: error: cast from 'uint8_t *' (aka 'unsigned char *') to
'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 to
4 [-Werror,-Wcast-align]
Adding an intermediate cast to (void *) silences the warning.
Signed-off-by: Christophe de Dinechin <dinechin@xxxxxxxxxx>
---
common/canvas_base.c | 14 +++++++++-----
common/mem.c | 24 ++++++++++++++++++++++++
common/mem.h | 33 +++++++++++++++++++++++++++++++--
common/sw_canvas.c | 10 ++++++----
4 files changed, 70 insertions(+), 11 deletions(-)
diff --git a/common/canvas_base.c b/common/canvas_base.c
index 8f653e0..5eb951e 100644
--- a/common/canvas_base.c
+++ b/common/canvas_base.c
@@ -389,7 +389,7 @@ static pixman_image_t *canvas_get_quic(CanvasBase *canvas, SpiceImage *image,
quic_data->current_chunk = 0;
if (quic_decode_begin(quic_data->quic,
- (uint32_t *)image->u.quic.data->chunk[0].data,
+ SPICE_ALIGNED_CAST(uint32_t *,image->u.quic.data->chunk[0].data),
image->u.quic.data->chunk[0].len >> 2,
&type, &width, &height) == QUIC_ERROR) {
spice_warning("quic decode begin failed");
@@ -523,8 +523,8 @@ static void canvas_fix_alignment(uint8_t *bits,
uint8_t *dest = bits;
for (row = height - 1; row > 0; --row) {
uint32_t *dest_aligned, *dest_misaligned;
- dest_aligned = (uint32_t *)(dest + stride_pixman*row);
- dest_misaligned = (uint32_t*)(dest + stride_encoded*row);
+ dest_aligned = SPICE_ALIGNED_CAST(uint32_t *,dest + stride_pixman*row);
+ dest_misaligned = SPICE_UNALIGNED_CAST(uint32_t*,dest + stride_encoded*row);
memmove(dest_aligned, dest_misaligned, stride_encoded);
}
}
@@ -1889,7 +1889,8 @@ static int quic_usr_more_space(QuicUsrContext *usr, uint32_t **io_ptr, int rows_
}
quic_data->current_chunk++;
- *io_ptr = (uint32_t *)quic_data->chunks->chunk[quic_data->current_chunk].data;
+ *io_ptr = SPICE_ALIGNED_CAST(uint32_t *,
+ quic_data->chunks->chunk[quic_data->current_chunk].data);
return quic_data->chunks->chunk[quic_data->current_chunk].len >> 2;
}
@@ -1945,6 +1946,7 @@ static void canvas_mask_pixman(CanvasBase *canvas,
int needs_invert;
pixman_region32_t mask_region;
uint32_t *mask_data;
+ uint8_t *mask_data_src;
int mask_x, mask_y;
int mask_width, mask_height, mask_stride;
pixman_box32_t extents;
@@ -2006,7 +2008,9 @@ static void canvas_mask_pixman(CanvasBase *canvas,
/* round down X to even 32 pixels (i.e. uint32_t) */
extents.x1 = extents.x1 & ~(0x1f);
- mask_data = (uint32_t *)((uint8_t *)mask_data + mask_stride * extents.y1 + extents.x1 / 32);
+ mask_data_src = (uint8_t *)mask_data + mask_stride * extents.y1 + extents.x1 / 32;
+ mask_data = SPICE_UNALIGNED_CAST(uint32_t *, mask_data_src);
+
mask_x -= extents.x1;
mask_y -= extents.y1;
mask_width = extents.x2 - extents.x1;
diff --git a/common/mem.c b/common/mem.c
index e430b5d..5b15bb6 100644
--- a/common/mem.c
+++ b/common/mem.c
@@ -294,3 +294,27 @@ size_t spice_buffer_remove(SpiceBuffer *buffer, size_t len)
buffer->offset -= len;
return len;
}
+
+void spice_alignment_warning(const char *loc, void *p, unsigned sz)
+{
+ static const char *last_loc = NULL;
+ if (loc != last_loc) {
+ last_loc = loc;
+ spice_log(SPICE_LOG_DOMAIN, SPICE_LOG_LEVEL_WARNING, loc, __FUNCTION__,
+ "Misaligned access at %p, alignment %u", p, sz);
+ }
+}
+
+void spice_alignment_debug(const char *loc, void *p, unsigned sz)
+{
+ static const char *last_loc = NULL;
+ static int debug_alignment = -1;
+ if (debug_alignment < 0) {
+ debug_alignment = getenv("SPICE_DEBUG_ALIGNMENT") != NULL;
+ }
+ if (debug_alignment && loc != last_loc) {
+ last_loc = loc;
+ spice_log(SPICE_LOG_DOMAIN, SPICE_LOG_LEVEL_DEBUG, loc, __FUNCTION__,
+ "Expected misaligned access at %p, alignment %u", p, sz);
+ }
+}
diff --git a/common/mem.h b/common/mem.h
index 857e8b0..56b9b0e 100644
--- a/common/mem.h
+++ b/common/mem.h
@@ -19,6 +19,7 @@
#ifndef _H_MEM
#define _H_MEM
+#include "log.h"
#include <stdlib.h>
#include <spice/macros.h>
@@ -116,7 +117,7 @@ size_t spice_strnlen(const char *str, size_t max_len);
__p; \
}))
# define _SPICE_RENEW(struct_type, mem, n_structs, func) \
- (struct_type *) (__extension__ ({ \
+ (struct_type *) (__extension__ ({ \
size_t __n = (size_t) (n_structs); \
size_t __s = sizeof (struct_type); \
void *__p = (void *) (mem); \
@@ -132,7 +133,6 @@ size_t spice_strnlen(const char *str, size_t max_len);
#else
/* Unoptimized version: always call the _n() function. */
-
#define _SPICE_NEW(struct_type, n_structs, func) \
((struct_type *) spice_##func##_n ((n_structs), sizeof (struct_type)))
#define _SPICE_RENEW(struct_type, mem, n_structs, func) \
@@ -140,6 +140,35 @@ size_t spice_strnlen(const char *str, size_t max_len);
#endif
+/* Cast to a type with stricter alignment constraints (to build with clang) */
+extern void spice_alignment_warning(const char *loc, void *p, unsigned sz);
+extern void spice_alignment_debug(const char *loc, void *p, unsigned sz);
+
+static inline void *spice_alignment_check(const char *loc,
+ void *ptr, unsigned sz)
+{
+ if (((uintptr_t) ptr & (sz-1U)) != 0)
+ spice_alignment_warning(loc, ptr, sz);
+ return ptr;
+
+}
+
+static inline void *spice_alignment_weak_check(const char *loc,
+ void *ptr, unsigned sz)
+{
+ if (((uintptr_t) ptr & (sz-1U)) != 0)
+ spice_alignment_debug(loc, ptr, sz);
+ return ptr;
+
+}
+#define SPICE_ALIGNED_CAST(type, value) \
+ ((type)spice_alignment_check(SPICE_STRLOC, \
+ (void *)(value), __alignof(type)))
+
+#define SPICE_UNALIGNED_CAST(type, value) \
+ ((type)spice_alignment_weak_check(SPICE_STRLOC, \
+ (void *)(value), __alignof(type)))
+
#define spice_new(struct_type, n_structs) _SPICE_NEW(struct_type, n_structs, malloc)
#define spice_new0(struct_type, n_structs) _SPICE_NEW(struct_type, n_structs, malloc0)
#define spice_renew(struct_type, mem, n_structs) _SPICE_RENEW(struct_type, mem, n_structs, realloc)
diff --git a/common/sw_canvas.c b/common/sw_canvas.c
index 531d608..e727090 100644
--- a/common/sw_canvas.c
+++ b/common/sw_canvas.c
@@ -355,8 +355,8 @@ static void clear_dest_alpha(pixman_image_t *dest,
}
stride = pixman_image_get_stride(dest);
- data = (uint32_t *) (
- (uint8_t *)pixman_image_get_data(dest) + y * stride + 4 * x);
+ data = SPICE_ALIGNED_CAST(uint32_t *,
+ (uint8_t *)pixman_image_get_data(dest) + y * stride + 4 * x);
if ((*data & 0xff000000U) == 0xff000000U) {
spice_pixman_fill_rect_rop(dest,
@@ -1010,7 +1010,7 @@ static void canvas_put_image(SpiceCanvas *spice_canvas,
src = pixman_image_create_bits(PIXMAN_x8r8g8b8,
src_width,
src_height,
- (uint32_t*)src_data,
+ SPICE_ALIGNED_CAST(uint32_t*,src_data),
src_stride);
@@ -1265,7 +1265,9 @@ SpiceCanvas *canvas_create_for_data(int width, int height, uint32_t format,
pixman_image_t *image;
image = pixman_image_create_bits(spice_surface_format_to_pixman (format),
- width, height, (uint32 *) data, stride);
+ width, height,
+ SPICE_ALIGNED_CAST(uint32_t *,data),
+ stride);
return canvas_create_common(image, format,
bits_cache,
--
2.11.0 (Apple Git-81)
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