[Mesa-dev] [PATCH v3 4/7] nir: add an instruction set API
Connor Abbott
cwabbott0 at gmail.com
Thu Oct 8 21:46:22 PDT 2015
This will replace direct usage of nir_instrs_equal() in the CSE pass,
which reduces an O(n^2) algorithm with an effectively O(n) one. It'll
also be useful for implementing GVN on top of GCM.
v2:
- Add texture support.
- Add more comments.
- Rename instr_can_hash() to instr_can_rewrite() since it's really more
about whether its uses can be rewritten, and it's implicitly used by
nir_instrs_equal() as well.
- Rename nir_instr_set_add() to nir_instr_set_add_or_rewrite() (Jason).
- Make the HASH() macro less magical (Topi).
- Rewrite the commit message.
v3:
- For sorting phi sources, use a VLA, store pointers to the sources, and
compare the predecessor pointer directly (Jason).
Signed-off-by: Connor Abbott <cwabbott0 at gmail.com>
---
Jason, does this look good to you? Still no piglit regressions -- I'm
working on getting perf numbers.
src/glsl/nir/nir_instr_set.c | 314 +++++++++++++++++++++++++++++++++++++++++++
src/glsl/nir/nir_instr_set.h | 35 +++++
2 files changed, 349 insertions(+)
diff --git a/src/glsl/nir/nir_instr_set.c b/src/glsl/nir/nir_instr_set.c
index 72ab048..7460fcc 100644
--- a/src/glsl/nir/nir_instr_set.c
+++ b/src/glsl/nir/nir_instr_set.c
@@ -22,6 +22,181 @@
*/
#include "nir_instr_set.h"
+#include "nir_vla.h"
+
+#define HASH(hash, data) _mesa_fnv32_1a_accumulate((hash), (data))
+
+static uint32_t
+hash_src(uint32_t hash, const nir_src *src)
+{
+ assert(src->is_ssa);
+ hash = HASH(hash, src->ssa);
+ return hash;
+}
+
+static uint32_t
+hash_alu_src(uint32_t hash, const nir_alu_src *src, unsigned num_components)
+{
+ hash = HASH(hash, src->abs);
+ hash = HASH(hash, src->negate);
+
+ for (unsigned i = 0; i < num_components; i++)
+ hash = HASH(hash, src->swizzle[i]);
+
+ hash = hash_src(hash, &src->src);
+ return hash;
+}
+
+static uint32_t
+hash_alu(uint32_t hash, const nir_alu_instr *instr)
+{
+ hash = HASH(hash, instr->op);
+ hash = HASH(hash, instr->dest.dest.ssa.num_components);
+
+ if (nir_op_infos[instr->op].algebraic_properties & NIR_OP_IS_COMMUTATIVE) {
+ assert(nir_op_infos[instr->op].num_inputs == 2);
+ uint32_t hash0 = hash_alu_src(hash, &instr->src[0],
+ nir_ssa_alu_instr_src_components(instr, 0));
+ uint32_t hash1 = hash_alu_src(hash, &instr->src[1],
+ nir_ssa_alu_instr_src_components(instr, 1));
+ /* For commutative operations, we need some commutative way of
+ * combining the hashes. One option would be to XOR them but that
+ * means that anything with two identical sources will hash to 0 and
+ * that's common enough we probably don't want the guaranteed
+ * collision. Either addition or multiplication will also work.
+ */
+ hash = hash0 * hash1;
+ } else {
+ for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
+ hash = hash_alu_src(hash, &instr->src[i],
+ nir_ssa_alu_instr_src_components(instr, i));
+ }
+ }
+
+ return hash;
+}
+
+static uint32_t
+hash_load_const(uint32_t hash, const nir_load_const_instr *instr)
+{
+ hash = HASH(hash, instr->def.num_components);
+
+ hash = _mesa_fnv32_1a_accumulate_block(hash, instr->value.f,
+ instr->def.num_components
+ * sizeof(instr->value.f[0]));
+
+ return hash;
+}
+
+static int
+cmp_phi_src(const void *data1, const void *data2)
+{
+ nir_phi_src *src1 = *(nir_phi_src **)data1;
+ nir_phi_src *src2 = *(nir_phi_src **)data2;
+ return src1->pred - src2->pred;
+}
+
+static uint32_t
+hash_phi(uint32_t hash, const nir_phi_instr *instr)
+{
+ hash = HASH(hash, instr->instr.block);
+
+ /* sort sources by predecessor, since the order shouldn't matter */
+ unsigned num_preds = instr->instr.block->predecessors->entries;
+ NIR_VLA(nir_phi_src *, srcs, num_preds);
+ unsigned i = 0;
+ nir_foreach_phi_src(instr, src) {
+ srcs[i++] = src;
+ }
+
+ qsort(srcs, num_preds, sizeof(nir_phi_src *), cmp_phi_src);
+
+ for (i = 0; i < num_preds; i++) {
+ hash = hash_src(hash, &srcs[i]->src);
+ hash = HASH(hash, srcs[i]->pred);
+ }
+
+ return hash;
+}
+
+static uint32_t
+hash_intrinsic(uint32_t hash, const nir_intrinsic_instr *instr)
+{
+ const nir_intrinsic_info *info = &nir_intrinsic_infos[instr->intrinsic];
+ hash = HASH(hash, instr->intrinsic);
+
+ if (info->has_dest)
+ hash = HASH(hash, instr->dest.ssa.num_components);
+
+ assert(info->num_variables == 0);
+
+ hash = _mesa_fnv32_1a_accumulate_block(hash, instr->const_index,
+ info->num_indices
+ * sizeof(instr->const_index[0]));
+ return hash;
+}
+
+static uint32_t
+hash_tex(uint32_t hash, const nir_tex_instr *instr)
+{
+ hash = HASH(hash, instr->op);
+ hash = HASH(hash, instr->num_srcs);
+
+ for (unsigned i = 0; i < instr->num_srcs; i++) {
+ hash = HASH(hash, instr->src[i].src_type);
+ hash = hash_src(hash, &instr->src[i].src);
+ }
+
+ hash = HASH(hash, instr->coord_components);
+ hash = HASH(hash, instr->sampler_dim);
+ hash = HASH(hash, instr->is_array);
+ hash = HASH(hash, instr->is_shadow);
+ hash = HASH(hash, instr->is_new_style_shadow);
+ hash = HASH(hash, instr->const_offset);
+ unsigned component = instr->component;
+ hash = HASH(hash, component);
+ hash = HASH(hash, instr->sampler_index);
+ hash = HASH(hash, instr->sampler_array_size);
+
+ assert(!instr->sampler);
+
+ return hash;
+}
+
+/* Computes a hash of an instruction for use in a hash table. Note that this
+ * will only work for instructions where instr_can_rewrite() returns true, and
+ * it should return identical hashes for two instructions that are the same
+ * according nir_instrs_equal().
+ */
+
+static uint32_t
+hash_instr(const void *data)
+{
+ const nir_instr *instr = data;
+ uint32_t hash = _mesa_fnv32_1a_offset_bias;
+
+ switch (instr->type) {
+ case nir_instr_type_alu:
+ hash = hash_alu(hash, nir_instr_as_alu(instr));
+ break;
+ case nir_instr_type_load_const:
+ hash = hash_load_const(hash, nir_instr_as_load_const(instr));
+ break;
+ case nir_instr_type_phi:
+ hash = hash_phi(hash, nir_instr_as_phi(instr));
+ break;
+ case nir_instr_type_intrinsic:
+ hash = hash_intrinsic(hash, nir_instr_as_intrinsic(instr));
+ break;
+ case nir_instr_type_tex:
+ hash = hash_tex(hash, nir_instr_as_tex(instr));
+ break;
+ default:
+ unreachable("Invalid instruction type");
+ }
+
+ return hash;
+}
bool
nir_srcs_equal(nir_src src1, nir_src src2)
@@ -66,6 +241,12 @@ nir_alu_srcs_equal(const nir_alu_instr *alu1, const nir_alu_instr *alu2,
return nir_srcs_equal(alu1->src[src1].src, alu2->src[src2].src);
}
+/* Returns "true" if two instructions are equal. Note that this will only
+ * work for the subset of instructions defined by instr_can_rewrite(). Also,
+ * it should only return "true" for instructions that hash_instr() will return
+ * the same hash for (ignoring collisions, of course).
+ */
+
bool
nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
{
@@ -204,3 +385,136 @@ nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
return false;
}
+static bool
+src_is_ssa(nir_src *src, void *data)
+{
+ (void) data;
+ return src->is_ssa;
+}
+
+static bool
+dest_is_ssa(nir_dest *dest, void *data)
+{
+ (void) data;
+ return dest->is_ssa;
+}
+
+/* This function determines if uses of an instruction can safely be rewritten
+ * to use another identical instruction instead. Note that this function must
+ * be kept in sync with hash_instr() and nir_instrs_equal() -- only
+ * instructions that pass this test will be handed on to those functions, and
+ * conversely they must handle everything that this function returns true for.
+ */
+
+static bool
+instr_can_rewrite(nir_instr *instr)
+{
+ /* We only handle SSA. */
+ if (!nir_foreach_dest(instr, dest_is_ssa, NULL) ||
+ !nir_foreach_src(instr, src_is_ssa, NULL))
+ return false;
+
+ switch (instr->type) {
+ case nir_instr_type_alu:
+ case nir_instr_type_load_const:
+ case nir_instr_type_phi:
+ return true;
+ case nir_instr_type_tex: {
+ nir_tex_instr *tex = nir_instr_as_tex(instr);
+
+ /* Don't support un-lowered sampler derefs currently. */
+ if (tex->sampler)
+ return false;
+
+ return true;
+ }
+ case nir_instr_type_intrinsic: {
+ const nir_intrinsic_info *info =
+ &nir_intrinsic_infos[nir_instr_as_intrinsic(instr)->intrinsic];
+ return (info->flags & NIR_INTRINSIC_CAN_ELIMINATE) &&
+ (info->flags & NIR_INTRINSIC_CAN_REORDER) &&
+ info->num_variables == 0; /* not implemented yet */
+ }
+ case nir_instr_type_call:
+ case nir_instr_type_jump:
+ case nir_instr_type_ssa_undef:
+ return false;
+ case nir_instr_type_parallel_copy:
+ default:
+ unreachable("Invalid instruction type");
+ }
+
+ return false;
+}
+
+static nir_ssa_def *
+nir_instr_get_dest_ssa_def(nir_instr *instr)
+{
+ switch (instr->type) {
+ case nir_instr_type_alu:
+ assert(nir_instr_as_alu(instr)->dest.dest.is_ssa);
+ return &nir_instr_as_alu(instr)->dest.dest.ssa;
+ case nir_instr_type_load_const:
+ return &nir_instr_as_load_const(instr)->def;
+ case nir_instr_type_phi:
+ assert(nir_instr_as_phi(instr)->dest.is_ssa);
+ return &nir_instr_as_phi(instr)->dest.ssa;
+ case nir_instr_type_intrinsic:
+ assert(nir_instr_as_intrinsic(instr)->dest.is_ssa);
+ return &nir_instr_as_intrinsic(instr)->dest.ssa;
+ case nir_instr_type_tex:
+ assert(nir_instr_as_tex(instr)->dest.is_ssa);
+ return &nir_instr_as_tex(instr)->dest.ssa;
+ default:
+ unreachable("We never ask for any of these");
+ }
+}
+
+static bool
+cmp_func(const void *data1, const void *data2)
+{
+ return nir_instrs_equal(data1, data2);
+}
+
+struct set *
+nir_instr_set_create(void *mem_ctx)
+{
+ return _mesa_set_create(mem_ctx, hash_instr, cmp_func);
+}
+
+void
+nir_instr_set_destroy(struct set *instr_set)
+{
+ _mesa_set_destroy(instr_set, NULL);
+}
+
+bool
+nir_instr_set_add_or_rewrite(struct set *instr_set, nir_instr *instr)
+{
+ if (!instr_can_rewrite(instr))
+ return false;
+
+ struct set_entry *entry = _mesa_set_search(instr_set, instr);
+ if (entry) {
+ nir_ssa_def *def = nir_instr_get_dest_ssa_def(instr);
+ nir_ssa_def *new_def =
+ nir_instr_get_dest_ssa_def((nir_instr *) entry->key);
+ nir_ssa_def_rewrite_uses(def, nir_src_for_ssa(new_def));
+ return true;
+ }
+
+ _mesa_set_add(instr_set, instr);
+ return false;
+}
+
+void
+nir_instr_set_remove(struct set *instr_set, nir_instr *instr)
+{
+ if (!instr_can_rewrite(instr))
+ return;
+
+ struct set_entry *entry = _mesa_set_search(instr_set, instr);
+ if (entry)
+ _mesa_set_remove(instr_set, entry);
+}
+
diff --git a/src/glsl/nir/nir_instr_set.h b/src/glsl/nir/nir_instr_set.h
index f5baffa..a7f6c9d 100644
--- a/src/glsl/nir/nir_instr_set.h
+++ b/src/glsl/nir/nir_instr_set.h
@@ -27,3 +27,38 @@
bool nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2);
+/**
+ * This file defines functions for creating, destroying, and manipulating an
+ * "instruction set," which is an abstraction for finding duplicate
+ * instructions using a hash set. Note that the question of whether an
+ * instruction is actually a duplicate (e.g. whether it has any side effects)
+ * is handled transparently. The user can pass any instruction to
+ * nir_instr_set_add_or_rewrite() and nir_instr_set_remove(), and if the
+ * instruction isn't safe to rewrite or isn't supported, it's silently
+ * removed.
+ */
+
+/*@{*/
+
+/** Creates an instruction set, using a given ralloc mem_ctx */
+struct set *nir_instr_set_create(void *mem_ctx);
+
+/** Destroys an instruction set. */
+void nir_instr_set_destroy(struct set *instr_set);
+
+/**
+ * Adds an instruction to an instruction set if it doesn't exist, or if it
+ * does already exist, rewrites all uses of it to point to the other
+ * already-inserted instruction. Returns 'true' if the uses of the instruction
+ * were rewritten.
+ */
+bool nir_instr_set_add_or_rewrite(struct set *instr_set, nir_instr *instr);
+
+/**
+ * Removes an instruction from an instruction set, so that other instructions
+ * won't be merged with it.
+ */
+void nir_instr_set_remove(struct set *instr_set, nir_instr *instr);
+
+/*@}*/
+
--
2.1.0
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