Brian/Roland ping?
On 12/07/2016 10:30 AM, Edward O'Callaghan wrote:
> As per the C spec, it is illegal to alias pointers to different
> types. This results in undefined behaviour after optimization
> passes, resulting in very subtle bugs that happen only on a
> full moon..
>
> Use a memcpy() as a well defined coercion between the isomorphic
> bit-field interpretations of memory.
>
> V.2: Use C99 compat STATIC_ASSERT() over C11 static_assert().
>
> Signed-off-by: Edward O'Callaghan <funfunc...@folklore1984.net>
> ---
> src/gallium/drivers/svga/svgadump/svga_shader_dump.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/src/gallium/drivers/svga/svgadump/svga_shader_dump.c
> b/src/gallium/drivers/svga/svgadump/svga_shader_dump.c
> index 4ee1bf2..46126a5 100644
> --- a/src/gallium/drivers/svga/svgadump/svga_shader_dump.c
> +++ b/src/gallium/drivers/svga/svgadump/svga_shader_dump.c
> @@ -30,6 +30,9 @@
> * @author Michal Krol <mic...@vmware.com>
> */
>
> +#include <assert.h>
> +#include <string.h>
> +
> #include "svga_shader.h"
> #include "svga_shader_dump.h"
> #include "svga_shader_op.h"
> @@ -413,6 +416,11 @@ dump_dstreg(struct sh_dstreg dstreg,
>
> static void dump_srcreg( struct sh_srcreg srcreg, struct sh_srcreg *indreg,
> const struct dump_info *di )
> {
> + struct sh_reg srcreg_sh = {0};
> + /* bit-fields carefully aligned, ensure they stay that way. */
> + STATIC_ASSERT(sizeof(struct sh_reg) == sizeof(struct sh_srcreg));
> + memcpy(&srcreg_sh, &srcreg, sizeof(srcreg_sh));
> +
> switch (srcreg.modifier) {
> case SVGA3DSRCMOD_NEG:
> case SVGA3DSRCMOD_BIASNEG:
> @@ -427,7 +435,7 @@ static void dump_srcreg( struct sh_srcreg srcreg, struct
> sh_srcreg *indreg, cons
> case SVGA3DSRCMOD_NOT:
> _debug_printf( "!" );
> }
> - dump_reg( *(struct sh_reg *) &srcreg, indreg, di );
> + dump_reg(srcreg_sh, indreg, di );
> switch (srcreg.modifier) {
> case SVGA3DSRCMOD_NONE:
> case SVGA3DSRCMOD_NEG:
> 
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