[Mesa-dev] [PATCH 1/2] nir/loop_analyze: used nir_alu_src to track loop limit
Timothy Arceri
tarceri at itsqueeze.com
Wed Jun 19 23:14:56 UTC 2019
On 20/6/19 5:57 am, Jason Ekstrand wrote:
> On Wed, Jun 19, 2019 at 3:09 AM Timothy Arceri <tarceri at itsqueeze.com
> <mailto:tarceri at itsqueeze.com>> wrote:
>
> This helps reduce the amount of abstraction in this pass and allows
> us to retain more information about the src such as any swizzles.
> Retaining the swizzle information is required for a bugfix in the
> following patch.
>
> Fixes: 6772a17acc8e ("nir: Add a loop analysis pass")
> ---
> src/compiler/nir/nir_loop_analyze.c | 37 +++++++++++++++--------------
> 1 file changed, 19 insertions(+), 18 deletions(-)
>
> diff --git a/src/compiler/nir/nir_loop_analyze.c
> b/src/compiler/nir/nir_loop_analyze.c
> index e85a404da1b..57d2d94cad2 100644
> --- a/src/compiler/nir/nir_loop_analyze.c
> +++ b/src/compiler/nir/nir_loop_analyze.c
> @@ -543,25 +543,26 @@ guess_loop_limit(loop_info_state *state,
> nir_const_value *limit_val,
> }
>
> static bool
> -try_find_limit_of_alu(nir_loop_variable *limit, nir_const_value
> *limit_val,
> - nir_loop_terminator *terminator,
> loop_info_state *state)
> +try_find_limit_of_alu(nir_alu_src *limit, nir_const_value *limit_val,
> + nir_loop_terminator *terminator)
> {
> - if(!is_var_alu(limit))
> + if(limit->src.ssa->parent_instr->type != nir_instr_type_alu)
> return false;
>
> - nir_alu_instr *limit_alu =
> nir_instr_as_alu(limit->def->parent_instr);
> + nir_alu_instr *limit_alu =
> nir_instr_as_alu(limit->src.ssa->parent_instr);
>
> if (limit_alu->op == nir_op_imin ||
> limit_alu->op == nir_op_fmin) {
> - limit = get_loop_var(limit_alu->src[0].src.ssa, state);
> + limit = &limit_alu->src[0];
>
> - if (!is_var_constant(limit))
> - limit = get_loop_var(limit_alu->src[1].src.ssa, state);
> + if (limit->src.ssa->parent_instr->type !=
> nir_instr_type_load_const)
> + limit = &limit_alu->src[1];
>
>
> This is still horribly broken w.r.t swizzles because we're not tracking
> the component as we make this or the jump above for [if]min.
I think we should probably just do a check to make sure the limit and
invariant are scalar if we don't already. The rest of the pass cannot
handle vectors anyway swizzles or not, and I don't think we should
bother handling it either.
>
>
> - if (!is_var_constant(limit))
> + if (limit->src.ssa->parent_instr->type !=
> nir_instr_type_load_const)
> return false;
>
> - *limit_val =
> nir_instr_as_load_const(limit->def->parent_instr)->value[0];
> + *limit_val =
> +
> nir_instr_as_load_const(limit->src.ssa->parent_instr)->value[0];
>
> terminator->exact_trip_count_unknown = true;
>
> @@ -777,19 +778,19 @@
> is_supported_terminator_condition(nir_alu_instr *alu)
>
> static bool
> get_induction_and_limit_vars(nir_alu_instr *alu, nir_loop_variable
> **ind,
> - nir_loop_variable **limit,
> + nir_alu_src **limit,
> loop_info_state *state)
> {
> bool limit_rhs = true;
>
> /* We assume that the limit is the "right" operand */
> *ind = get_loop_var(alu->src[0].src.ssa, state);
> - *limit = get_loop_var(alu->src[1].src.ssa, state);
> + *limit = &alu->src[1];
>
> if ((*ind)->type != basic_induction) {
> /* We had it the wrong way, flip things around */
> *ind = get_loop_var(alu->src[1].src.ssa, state);
> - *limit = get_loop_var(alu->src[0].src.ssa, state);
> + *limit = &alu->src[0];
> limit_rhs = false;
> }
>
> @@ -799,7 +800,7 @@ get_induction_and_limit_vars(nir_alu_instr *alu,
> nir_loop_variable **ind,
> static void
> try_find_trip_count_vars_in_iand(nir_alu_instr **alu,
> nir_loop_variable **ind,
> - nir_loop_variable **limit,
> + nir_alu_src **limit,
> bool *limit_rhs,
> loop_info_state *state)
> {
> @@ -848,7 +849,7 @@ try_find_trip_count_vars_in_iand(nir_alu_instr
> **alu,
>
> /* Try the other iand src if needed */
> if (*ind == NULL || (*ind && (*ind)->type != basic_induction) ||
> - !is_var_constant(*limit)) {
> + (*limit)->src.ssa->parent_instr->type !=
> nir_instr_type_load_const) {
> src = iand->src[1].src.ssa;
> if (src->parent_instr->type == nir_instr_type_alu) {
> nir_alu_instr *tmp_alu = nir_instr_as_alu(src->parent_instr);
> @@ -891,7 +892,7 @@ find_trip_count(loop_info_state *state)
>
> bool limit_rhs;
> nir_loop_variable *basic_ind = NULL;
> - nir_loop_variable *limit;
> + nir_alu_src *limit;
> if (alu->op == nir_op_inot || alu->op == nir_op_ieq) {
> nir_alu_instr *new_alu = alu;
> try_find_trip_count_vars_in_iand(&new_alu, &basic_ind,
> &limit,
> @@ -931,13 +932,13 @@ find_trip_count(loop_info_state *state)
>
> /* Attempt to find a constant limit for the loop */
> nir_const_value limit_val;
> - if (is_var_constant(limit)) {
> + if (limit->src.ssa->parent_instr->type ==
> nir_instr_type_load_const) {
> limit_val =
> -
> nir_instr_as_load_const(limit->def->parent_instr)->value[0];
> +
> nir_instr_as_load_const(limit->src.ssa->parent_instr)->value[0];
> } else {
> trip_count_known = false;
>
> - if (!try_find_limit_of_alu(limit, &limit_val, terminator,
> state)) {
> + if (!try_find_limit_of_alu(limit, &limit_val, terminator)) {
> /* Guess loop limit based on array access */
> if (!guess_loop_limit(state, &limit_val, basic_ind)) {
> continue;
> --
> 2.21.0
>
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