On Friday, August 08, 2014 02:56:53 PM Eric Anholt wrote: > Roland Scheidegger <srol...@vmware.com> writes: > > > Am 08.08.2014 22:56, schrieb Neil Roberts: > >> The i965 driver uses a float pointer to point to the value of a uniform and > >> also as the destination within the batch buffer. However the same locations > >> can also be used to store values for integer uniforms. Previously the value > >> was being copied into the batch buffer with a regular assignment. This > >> breaks > >> if the compiler does this by loading and saving through an x87 register > >> because the fst instruction tries to fix up invalid float values. That can > >> corrupt some specific integer values. This patch changes it to use a memcpy > >> instead so that it won't use a floating-point register. > >> > >> Bugzilla: > >> https://urldefense.proofpoint.com/v1/url?u=https://bugs.freedesktop.org/show_bug.cgi?id%3D81150&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=F4msKE2WxRzA%2BwN%2B25muztFm5TSPwE8HKJfWfR2NgfY%3D%0A&m=5ZyizVpb8bGGN4qANo378HB6GFoFoBABoDXdPAyIszE%3D%0A&s=107a04b60233e66abfb9e83a62b90d128d60d6c61eb41b1a08ec7ab537283903 > >> --- > >> src/mesa/drivers/dri/i965/gen6_vs_state.c | 8 +++++++- > >> 1 file changed, 7 insertions(+), 1 deletion(-) > >> > >> diff --git a/src/mesa/drivers/dri/i965/gen6_vs_state.c > >> b/src/mesa/drivers/dri/i965/gen6_vs_state.c > >> index 905e123..cdbc083 100644 > >> --- a/src/mesa/drivers/dri/i965/gen6_vs_state.c > >> +++ b/src/mesa/drivers/dri/i965/gen6_vs_state.c > >> @@ -81,7 +81,13 @@ gen6_upload_push_constants(struct brw_context *brw, > >> * wouldn't be set for them. > >> */ > >> for (i = 0; i < prog_data->nr_params; i++) { > >> - param[i] = *prog_data->param[i]; > >> + /* A memcpy is used here instead of a regular assignment because > >> + * otherwise the value may end up being copied through a > >> + * floating-point register. This will break if the x87 registers > >> are > >> + * used and we are storing an integer value here because the fst > >> + * instruction tries to fix up invalid values and that would > >> corrupt > >> + * an integer value */ > >> + memcpy(param + i, prog_data->param[i], sizeof param[i]); > >> } > > Or just change the pointer type to uint32_t, right?
I think I'd prefer that. --Ken
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