nir: add an instruction set API
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). Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com> Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
This commit is contained in:
Connor Abbott
parent
005c2efb7b
commit
523a28d3fe
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@ -22,6 +22,181 @@
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*/
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#include "nir_instr_set.h"
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#include "nir_vla.h"
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#define HASH(hash, data) _mesa_fnv32_1a_accumulate((hash), (data))
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static uint32_t
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hash_src(uint32_t hash, const nir_src *src)
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{
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assert(src->is_ssa);
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hash = HASH(hash, src->ssa);
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return hash;
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}
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static uint32_t
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hash_alu_src(uint32_t hash, const nir_alu_src *src, unsigned num_components)
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{
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hash = HASH(hash, src->abs);
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hash = HASH(hash, src->negate);
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for (unsigned i = 0; i < num_components; i++)
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hash = HASH(hash, src->swizzle[i]);
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hash = hash_src(hash, &src->src);
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return hash;
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}
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static uint32_t
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hash_alu(uint32_t hash, const nir_alu_instr *instr)
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{
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hash = HASH(hash, instr->op);
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hash = HASH(hash, instr->dest.dest.ssa.num_components);
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if (nir_op_infos[instr->op].algebraic_properties & NIR_OP_IS_COMMUTATIVE) {
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assert(nir_op_infos[instr->op].num_inputs == 2);
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uint32_t hash0 = hash_alu_src(hash, &instr->src[0],
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nir_ssa_alu_instr_src_components(instr, 0));
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uint32_t hash1 = hash_alu_src(hash, &instr->src[1],
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nir_ssa_alu_instr_src_components(instr, 1));
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/* For commutative operations, we need some commutative way of
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* combining the hashes. One option would be to XOR them but that
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* means that anything with two identical sources will hash to 0 and
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* that's common enough we probably don't want the guaranteed
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* collision. Either addition or multiplication will also work.
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*/
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hash = hash0 * hash1;
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} else {
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for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
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hash = hash_alu_src(hash, &instr->src[i],
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nir_ssa_alu_instr_src_components(instr, i));
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}
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}
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return hash;
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}
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static uint32_t
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hash_load_const(uint32_t hash, const nir_load_const_instr *instr)
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{
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hash = HASH(hash, instr->def.num_components);
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hash = _mesa_fnv32_1a_accumulate_block(hash, instr->value.f,
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instr->def.num_components
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* sizeof(instr->value.f[0]));
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return hash;
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}
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static int
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cmp_phi_src(const void *data1, const void *data2)
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{
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nir_phi_src *src1 = *(nir_phi_src **)data1;
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nir_phi_src *src2 = *(nir_phi_src **)data2;
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return src1->pred - src2->pred;
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}
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static uint32_t
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hash_phi(uint32_t hash, const nir_phi_instr *instr)
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{
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hash = HASH(hash, instr->instr.block);
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/* sort sources by predecessor, since the order shouldn't matter */
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unsigned num_preds = instr->instr.block->predecessors->entries;
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NIR_VLA(nir_phi_src *, srcs, num_preds);
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unsigned i = 0;
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nir_foreach_phi_src(instr, src) {
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srcs[i++] = src;
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}
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qsort(srcs, num_preds, sizeof(nir_phi_src *), cmp_phi_src);
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for (i = 0; i < num_preds; i++) {
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hash = hash_src(hash, &srcs[i]->src);
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hash = HASH(hash, srcs[i]->pred);
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}
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return hash;
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}
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static uint32_t
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hash_intrinsic(uint32_t hash, const nir_intrinsic_instr *instr)
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{
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const nir_intrinsic_info *info = &nir_intrinsic_infos[instr->intrinsic];
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hash = HASH(hash, instr->intrinsic);
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if (info->has_dest)
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hash = HASH(hash, instr->dest.ssa.num_components);
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assert(info->num_variables == 0);
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hash = _mesa_fnv32_1a_accumulate_block(hash, instr->const_index,
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info->num_indices
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* sizeof(instr->const_index[0]));
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return hash;
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}
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static uint32_t
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hash_tex(uint32_t hash, const nir_tex_instr *instr)
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{
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hash = HASH(hash, instr->op);
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hash = HASH(hash, instr->num_srcs);
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for (unsigned i = 0; i < instr->num_srcs; i++) {
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hash = HASH(hash, instr->src[i].src_type);
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hash = hash_src(hash, &instr->src[i].src);
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}
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hash = HASH(hash, instr->coord_components);
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hash = HASH(hash, instr->sampler_dim);
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hash = HASH(hash, instr->is_array);
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hash = HASH(hash, instr->is_shadow);
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hash = HASH(hash, instr->is_new_style_shadow);
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hash = HASH(hash, instr->const_offset);
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unsigned component = instr->component;
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hash = HASH(hash, component);
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hash = HASH(hash, instr->sampler_index);
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hash = HASH(hash, instr->sampler_array_size);
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assert(!instr->sampler);
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return hash;
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}
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/* Computes a hash of an instruction for use in a hash table. Note that this
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* will only work for instructions where instr_can_rewrite() returns true, and
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* it should return identical hashes for two instructions that are the same
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* according nir_instrs_equal().
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*/
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static uint32_t
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hash_instr(const void *data)
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{
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const nir_instr *instr = data;
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uint32_t hash = _mesa_fnv32_1a_offset_bias;
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switch (instr->type) {
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case nir_instr_type_alu:
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hash = hash_alu(hash, nir_instr_as_alu(instr));
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break;
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case nir_instr_type_load_const:
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hash = hash_load_const(hash, nir_instr_as_load_const(instr));
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break;
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case nir_instr_type_phi:
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hash = hash_phi(hash, nir_instr_as_phi(instr));
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break;
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case nir_instr_type_intrinsic:
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hash = hash_intrinsic(hash, nir_instr_as_intrinsic(instr));
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break;
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case nir_instr_type_tex:
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hash = hash_tex(hash, nir_instr_as_tex(instr));
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break;
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default:
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unreachable("Invalid instruction type");
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}
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return hash;
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}
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bool
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nir_srcs_equal(nir_src src1, nir_src src2)
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@ -66,6 +241,12 @@ nir_alu_srcs_equal(const nir_alu_instr *alu1, const nir_alu_instr *alu2,
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return nir_srcs_equal(alu1->src[src1].src, alu2->src[src2].src);
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}
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/* Returns "true" if two instructions are equal. Note that this will only
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* work for the subset of instructions defined by instr_can_rewrite(). Also,
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* it should only return "true" for instructions that hash_instr() will return
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* the same hash for (ignoring collisions, of course).
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*/
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bool
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nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
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{
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@ -204,3 +385,136 @@ nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2)
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return false;
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}
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static bool
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src_is_ssa(nir_src *src, void *data)
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{
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(void) data;
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return src->is_ssa;
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}
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static bool
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dest_is_ssa(nir_dest *dest, void *data)
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{
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(void) data;
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return dest->is_ssa;
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}
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/* This function determines if uses of an instruction can safely be rewritten
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* to use another identical instruction instead. Note that this function must
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* be kept in sync with hash_instr() and nir_instrs_equal() -- only
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* instructions that pass this test will be handed on to those functions, and
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* conversely they must handle everything that this function returns true for.
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*/
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static bool
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instr_can_rewrite(nir_instr *instr)
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{
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/* We only handle SSA. */
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if (!nir_foreach_dest(instr, dest_is_ssa, NULL) ||
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!nir_foreach_src(instr, src_is_ssa, NULL))
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return false;
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switch (instr->type) {
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case nir_instr_type_alu:
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case nir_instr_type_load_const:
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case nir_instr_type_phi:
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return true;
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case nir_instr_type_tex: {
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nir_tex_instr *tex = nir_instr_as_tex(instr);
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/* Don't support un-lowered sampler derefs currently. */
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if (tex->sampler)
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return false;
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return true;
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}
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case nir_instr_type_intrinsic: {
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const nir_intrinsic_info *info =
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&nir_intrinsic_infos[nir_instr_as_intrinsic(instr)->intrinsic];
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return (info->flags & NIR_INTRINSIC_CAN_ELIMINATE) &&
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(info->flags & NIR_INTRINSIC_CAN_REORDER) &&
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info->num_variables == 0; /* not implemented yet */
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}
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case nir_instr_type_call:
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case nir_instr_type_jump:
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case nir_instr_type_ssa_undef:
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return false;
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case nir_instr_type_parallel_copy:
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default:
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unreachable("Invalid instruction type");
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}
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return false;
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}
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static nir_ssa_def *
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nir_instr_get_dest_ssa_def(nir_instr *instr)
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{
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switch (instr->type) {
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case nir_instr_type_alu:
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assert(nir_instr_as_alu(instr)->dest.dest.is_ssa);
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return &nir_instr_as_alu(instr)->dest.dest.ssa;
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case nir_instr_type_load_const:
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return &nir_instr_as_load_const(instr)->def;
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case nir_instr_type_phi:
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assert(nir_instr_as_phi(instr)->dest.is_ssa);
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return &nir_instr_as_phi(instr)->dest.ssa;
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case nir_instr_type_intrinsic:
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assert(nir_instr_as_intrinsic(instr)->dest.is_ssa);
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return &nir_instr_as_intrinsic(instr)->dest.ssa;
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case nir_instr_type_tex:
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assert(nir_instr_as_tex(instr)->dest.is_ssa);
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return &nir_instr_as_tex(instr)->dest.ssa;
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default:
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unreachable("We never ask for any of these");
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}
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}
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static bool
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cmp_func(const void *data1, const void *data2)
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{
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return nir_instrs_equal(data1, data2);
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}
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struct set *
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nir_instr_set_create(void *mem_ctx)
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{
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return _mesa_set_create(mem_ctx, hash_instr, cmp_func);
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}
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void
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nir_instr_set_destroy(struct set *instr_set)
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{
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_mesa_set_destroy(instr_set, NULL);
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}
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bool
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nir_instr_set_add_or_rewrite(struct set *instr_set, nir_instr *instr)
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{
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if (!instr_can_rewrite(instr))
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return false;
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struct set_entry *entry = _mesa_set_search(instr_set, instr);
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if (entry) {
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nir_ssa_def *def = nir_instr_get_dest_ssa_def(instr);
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nir_ssa_def *new_def =
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nir_instr_get_dest_ssa_def((nir_instr *) entry->key);
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nir_ssa_def_rewrite_uses(def, nir_src_for_ssa(new_def));
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return true;
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}
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_mesa_set_add(instr_set, instr);
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return false;
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}
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void
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nir_instr_set_remove(struct set *instr_set, nir_instr *instr)
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{
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if (!instr_can_rewrite(instr))
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return;
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struct set_entry *entry = _mesa_set_search(instr_set, instr);
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if (entry)
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_mesa_set_remove(instr_set, entry);
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}
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@ -27,3 +27,38 @@
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bool nir_instrs_equal(const nir_instr *instr1, const nir_instr *instr2);
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/**
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* This file defines functions for creating, destroying, and manipulating an
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* "instruction set," which is an abstraction for finding duplicate
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* instructions using a hash set. Note that the question of whether an
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* instruction is actually a duplicate (e.g. whether it has any side effects)
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* is handled transparently. The user can pass any instruction to
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* nir_instr_set_add_or_rewrite() and nir_instr_set_remove(), and if the
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* instruction isn't safe to rewrite or isn't supported, it's silently
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* removed.
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*/
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/*@{*/
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/** Creates an instruction set, using a given ralloc mem_ctx */
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struct set *nir_instr_set_create(void *mem_ctx);
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/** Destroys an instruction set. */
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void nir_instr_set_destroy(struct set *instr_set);
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/**
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* Adds an instruction to an instruction set if it doesn't exist, or if it
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* does already exist, rewrites all uses of it to point to the other
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* already-inserted instruction. Returns 'true' if the uses of the instruction
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* were rewritten.
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*/
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bool nir_instr_set_add_or_rewrite(struct set *instr_set, nir_instr *instr);
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/**
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* Removes an instruction from an instruction set, so that other instructions
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* won't be merged with it.
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*/
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void nir_instr_set_remove(struct set *instr_set, nir_instr *instr);
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/*@}*/
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