#include <inttypes.h>
#include "nir_search.h"
#include "nir_builder.h"
+#include "nir_worklist.h"
#include "util/half_float.h"
/* This should be the same as nir_search_max_comm_ops in nir_algebraic.py. */
match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
unsigned num_components, const uint8_t *swizzle,
struct match_state *state);
-static void
+static bool
nir_algebraic_automaton(nir_instr *instr, struct util_dynarray *states,
const struct per_op_table *pass_op_table);
-static const uint8_t identity_swizzle[NIR_MAX_VEC_COMPONENTS] = { 0, 1, 2, 3 };
+static const uint8_t identity_swizzle[NIR_MAX_VEC_COMPONENTS] =
+{
+ 0, 1, 2, 3,
+ 4, 5, 6, 7,
+ 8, 9, 10, 11,
+ 12, 13, 14, 15,
+};
/**
* Check if a source produces a value of the given type.
fprintf(stderr, "@%d", val->bit_size);
}
+static void
+add_uses_to_worklist(nir_instr *instr, nir_instr_worklist *worklist)
+{
+ nir_ssa_def *def = nir_instr_ssa_def(instr);
+
+ nir_foreach_use_safe(use_src, def) {
+ nir_instr_worklist_push_tail(worklist, use_src->parent_instr);
+ }
+}
+
+static void
+nir_algebraic_update_automaton(nir_instr *new_instr,
+ nir_instr_worklist *algebraic_worklist,
+ struct util_dynarray *states,
+ const struct per_op_table *pass_op_table)
+{
+
+ nir_instr_worklist *automaton_worklist = nir_instr_worklist_create();
+
+ /* Walk through the tree of uses of our new instruction's SSA value,
+ * recursively updating the automaton state until it stabilizes.
+ */
+ add_uses_to_worklist(new_instr, automaton_worklist);
+
+ nir_instr *instr;
+ while ((instr = nir_instr_worklist_pop_head(automaton_worklist))) {
+ if (nir_algebraic_automaton(instr, states, pass_op_table)) {
+ nir_instr_worklist_push_tail(algebraic_worklist, instr);
+
+ add_uses_to_worklist(instr, automaton_worklist);
+ }
+ }
+
+ nir_instr_worklist_destroy(automaton_worklist);
+}
+
nir_ssa_def *
nir_replace_instr(nir_builder *build, nir_alu_instr *instr,
struct hash_table *range_ht,
struct util_dynarray *states,
const struct per_op_table *pass_op_table,
const nir_search_expression *search,
- const nir_search_value *replace)
+ const nir_search_value *replace,
+ nir_instr_worklist *algebraic_worklist)
{
uint8_t swizzle[NIR_MAX_VEC_COMPONENTS] = { 0 };
fprintf(stderr, " ssa_%d\n", instr->dest.dest.ssa.index);
#endif
- build->cursor = nir_before_instr(&instr->instr);
+ /* If the instruction at the root of the expression tree being replaced is
+ * a unary operation, insert the replacement instructions at the location
+ * of the source of the unary operation. Otherwise, insert the replacement
+ * instructions at the location of the expression tree root.
+ *
+ * For the unary operation case, this is done to prevent some spurious code
+ * motion that can dramatically extend live ranges. Imagine an expression
+ * like -(A+B) where the addtion and the negation are separated by flow
+ * control and thousands of instructions. If this expression is replaced
+ * with -A+-B, inserting the new instructions at the site of the negation
+ * could extend the live range of A and B dramtically. This could increase
+ * register pressure and cause spilling.
+ *
+ * It may well be that moving instructions around is a good thing, but
+ * keeping algebraic optimizations and code motion optimizations separate
+ * seems safest.
+ */
+ nir_alu_instr *const src_instr = nir_src_as_alu_instr(instr->src[0].src);
+ if (src_instr != NULL &&
+ (instr->op == nir_op_fneg || instr->op == nir_op_fabs ||
+ instr->op == nir_op_ineg || instr->op == nir_op_iabs ||
+ instr->op == nir_op_inot)) {
+ /* Insert new instructions *after*. Otherwise a hypothetical
+ * replacement fneg(X) -> fabs(X) would insert the fabs() instruction
+ * before X! This can also occur for things like fneg(X.wzyx) -> X.wzyx
+ * in vector mode. A move instruction to handle the swizzle will get
+ * inserted before X.
+ *
+ * This manifested in a single OpenGL ES 2.0 CTS vertex shader test on
+ * older Intel GPU that use vector-mode vertex processing.
+ */
+ build->cursor = nir_after_instr(&src_instr->instr);
+ } else {
+ build->cursor = nir_before_instr(&instr->instr);
+ }
state.states = states;
nir_algebraic_automaton(ssa_val->parent_instr, states, pass_op_table);
}
+ /* Rewrite the uses of the old SSA value to the new one, and recurse
+ * through the uses updating the automaton's state.
+ */
nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(ssa_val));
+ nir_algebraic_update_automaton(ssa_val->parent_instr, algebraic_worklist,
+ states, pass_op_table);
- /* We know this one has no more uses because we just rewrote them all,
- * so we can remove it. The rest of the matched expression, however, we
- * don't know so much about. We'll just let dead code clean them up.
+ /* Nothing uses the instr any more, so drop it out of the program. Note
+ * that the instr may be in the worklist still, so we can't free it
+ * directly.
*/
nir_instr_remove(&instr->instr);
return ssa_val;
}
-static void
+static bool
nir_algebraic_automaton(nir_instr *instr, struct util_dynarray *states,
const struct per_op_table *pass_op_table)
{
uint16_t search_op = nir_search_op_for_nir_op(op);
const struct per_op_table *tbl = &pass_op_table[search_op];
if (tbl->num_filtered_states == 0)
- return;
+ return false;
/* Calculate the index into the transition table. Note the index
* calculated must match the iteration order of Python's
* itertools.product(), which was used to emit the transition
* table.
*/
- uint16_t index = 0;
+ unsigned index = 0;
for (unsigned i = 0; i < nir_op_infos[op].num_inputs; i++) {
index *= tbl->num_filtered_states;
index += tbl->filter[*util_dynarray_element(states, uint16_t,
alu->src[i].src.ssa->index)];
}
- *util_dynarray_element(states, uint16_t, alu->dest.dest.ssa.index) =
- tbl->table[index];
- break;
+
+ uint16_t *state = util_dynarray_element(states, uint16_t,
+ alu->dest.dest.ssa.index);
+ if (*state != tbl->table[index]) {
+ *state = tbl->table[index];
+ return true;
+ }
+ return false;
}
case nir_instr_type_load_const: {
nir_load_const_instr *load_const = nir_instr_as_load_const(instr);
- *util_dynarray_element(states, uint16_t, load_const->def.index) =
- CONST_STATE;
- break;
+ uint16_t *state = util_dynarray_element(states, uint16_t,
+ load_const->def.index);
+ if (*state != CONST_STATE) {
+ *state = CONST_STATE;
+ return true;
+ }
+ return false;
}
default:
- break;
+ return false;
}
}
static bool
-nir_algebraic_block(nir_builder *build, nir_block *block,
+nir_algebraic_instr(nir_builder *build, nir_instr *instr,
struct hash_table *range_ht,
const bool *condition_flags,
const struct transform **transforms,
const uint16_t *transform_counts,
struct util_dynarray *states,
- const struct per_op_table *pass_op_table)
+ const struct per_op_table *pass_op_table,
+ nir_instr_worklist *worklist)
{
- bool progress = false;
- const unsigned execution_mode = build->shader->info.float_controls_execution_mode;
- nir_foreach_instr_reverse_safe(instr, block) {
- if (instr->type != nir_instr_type_alu)
- continue;
+ if (instr->type != nir_instr_type_alu)
+ return false;
- nir_alu_instr *alu = nir_instr_as_alu(instr);
- if (!alu->dest.dest.is_ssa)
- continue;
+ nir_alu_instr *alu = nir_instr_as_alu(instr);
+ if (!alu->dest.dest.is_ssa)
+ return false;
- unsigned bit_size = alu->dest.dest.ssa.bit_size;
- const bool ignore_inexact =
- nir_is_float_control_signed_zero_inf_nan_preserve(execution_mode, bit_size) ||
- nir_is_denorm_flush_to_zero(execution_mode, bit_size);
-
- int xform_idx = *util_dynarray_element(states, uint16_t,
- alu->dest.dest.ssa.index);
- for (uint16_t i = 0; i < transform_counts[xform_idx]; i++) {
- const struct transform *xform = &transforms[xform_idx][i];
- if (condition_flags[xform->condition_offset] &&
- !(xform->search->inexact && ignore_inexact) &&
- nir_replace_instr(build, alu, range_ht, states, pass_op_table,
- xform->search, xform->replace)) {
- _mesa_hash_table_clear(range_ht, NULL);
- progress = true;
- break;
- }
+ unsigned bit_size = alu->dest.dest.ssa.bit_size;
+ const unsigned execution_mode =
+ build->shader->info.float_controls_execution_mode;
+ const bool ignore_inexact =
+ nir_is_float_control_signed_zero_inf_nan_preserve(execution_mode, bit_size) ||
+ nir_is_denorm_flush_to_zero(execution_mode, bit_size);
+
+ int xform_idx = *util_dynarray_element(states, uint16_t,
+ alu->dest.dest.ssa.index);
+ for (uint16_t i = 0; i < transform_counts[xform_idx]; i++) {
+ const struct transform *xform = &transforms[xform_idx][i];
+ if (condition_flags[xform->condition_offset] &&
+ !(xform->search->inexact && ignore_inexact) &&
+ nir_replace_instr(build, alu, range_ht, states, pass_op_table,
+ xform->search, xform->replace, worklist)) {
+ _mesa_hash_table_clear(range_ht, NULL);
+ return true;
}
}
- return progress;
+ return false;
}
bool
struct hash_table *range_ht = _mesa_pointer_hash_table_create(NULL);
+ nir_instr_worklist *worklist = nir_instr_worklist_create();
+
+ /* Walk top-to-bottom setting up the automaton state. */
nir_foreach_block(block, impl) {
nir_foreach_instr(instr, block) {
nir_algebraic_automaton(instr, &states, pass_op_table);
}
}
+ /* Put our instrs in the worklist such that we're popping the last instr
+ * first. This will encourage us to match the biggest source patterns when
+ * possible.
+ */
nir_foreach_block_reverse(block, impl) {
- progress |= nir_algebraic_block(&build, block, range_ht, condition_flags,
- transforms, transform_counts,
- &states, pass_op_table);
+ nir_foreach_instr_reverse(instr, block) {
+ nir_instr_worklist_push_tail(worklist, instr);
+ }
+ }
+
+ nir_instr *instr;
+ while ((instr = nir_instr_worklist_pop_head(worklist))) {
+ /* The worklist can have an instr pushed to it multiple times if it was
+ * the src of multiple instrs that also got optimized, so make sure that
+ * we don't try to re-optimize an instr we already handled.
+ */
+ if (exec_node_is_tail_sentinel(&instr->node))
+ continue;
+
+ progress |= nir_algebraic_instr(&build, instr,
+ range_ht, condition_flags,
+ transforms, transform_counts, &states,
+ pass_op_table, worklist);
}
+ nir_instr_worklist_destroy(worklist);
ralloc_free(range_ht);
util_dynarray_fini(&states);
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