On Fri, Feb 6, 2015 at 6:42 AM, Francisco Jerez <curroje...@riseup.net> wrote:
> If the source type differs from the original type of the constant we
> need to bit-cast it before propagating, otherwise the original type
> information will be lost. If the constant was a vector float there
> isn't much we can do, because the result of bit-casting the component
> values of a vector float cannot itself be represented as an immediate.
> ---
> src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> index 81567d2..0a961ce 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
> @@ -113,6 +113,16 @@ try_constant_propagate(struct brw_context *brw,
> vec4_instruction *inst,
> if (value.file != IMM)
> return false;
>
> + if (value.type == BRW_REGISTER_TYPE_VF) {
> + /* The result of bit-casting the component values of a vector float
> + * cannot in general be represented as an immediate.
> + */
> + if (inst->src[arg].type != BRW_REGISTER_TYPE_F)
> + return false;
> + } else {
> + value.type = inst->src[arg].type;
> + }
> +
> if (inst->src[arg].abs) {
> if (!brw_abs_immediate(value.type, &value.fixed_hw_reg)) {
> return false;
Wow. Did you hit this in practice?
Actually, I suspect this might be the cause of
https://bugs.freedesktop.org/show_bug.cgi?id=86811 (only reacquired a
BDW recently, so never investigated)
Hm, but running the test with INTEL_DEVID_OVERRIDE and
INTEL_DEBUG=vec4vs doesn't show the VF immediate being propagated into
the shift, so perhaps it's not the problem.
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