| /* |
| * Copyright © 2018 Valve Corporation |
| * |
| * SPDX-License-Identifier: MIT |
| */ |
| |
| #include "aco_ir.h" |
| #include "aco_util.h" |
| |
| #include <unordered_map> |
| #include <vector> |
| |
| /* |
| * Implements the algorithm for dominator-tree value numbering |
| * from "Value Numbering" by Briggs, Cooper, and Simpson. |
| */ |
| |
| namespace aco { |
| namespace { |
| |
| inline uint32_t |
| murmur_32_scramble(uint32_t h, uint32_t k) |
| { |
| k *= 0xcc9e2d51; |
| k = (k << 15) | (k >> 17); |
| h ^= k * 0x1b873593; |
| h = (h << 13) | (h >> 19); |
| h = h * 5 + 0xe6546b64; |
| return h; |
| } |
| |
| struct InstrHash { |
| /* This hash function uses the Murmur3 algorithm written by Austin Appleby |
| * https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp |
| * |
| * In order to calculate the expression set, only the right-hand-side of an |
| * instruction is used for the hash, i.e. everything except the definitions. |
| */ |
| std::size_t operator()(Instruction* instr) const |
| { |
| uint32_t hash = uint32_t(instr->format) << 16 | uint32_t(instr->opcode); |
| |
| for (const Operand& op : instr->operands) |
| hash = murmur_32_scramble(hash, op.constantValue()); |
| |
| size_t data_size = get_instr_data_size(instr->format); |
| |
| /* skip format, opcode and pass_flags and op/def spans */ |
| for (unsigned i = sizeof(Instruction) >> 2; i < (data_size >> 2); i++) { |
| uint32_t u; |
| /* Accesses it though a byte array, so doesn't violate the strict aliasing rule */ |
| memcpy(&u, reinterpret_cast<uint8_t*>(instr) + i * 4, 4); |
| hash = murmur_32_scramble(hash, u); |
| } |
| |
| /* Finalize. */ |
| uint32_t len = instr->operands.size() + instr->definitions.size(); |
| hash ^= len; |
| hash ^= hash >> 16; |
| hash *= 0x85ebca6b; |
| hash ^= hash >> 13; |
| hash *= 0xc2b2ae35; |
| hash ^= hash >> 16; |
| return hash; |
| } |
| }; |
| |
| struct InstrPred { |
| bool operator()(Instruction* a, Instruction* b) const |
| { |
| if (a->format != b->format) |
| return false; |
| if (a->opcode != b->opcode) |
| return false; |
| if (a->operands.size() != b->operands.size() || |
| a->definitions.size() != b->definitions.size()) |
| return false; /* possible with pseudo-instructions */ |
| for (unsigned i = 0; i < a->operands.size(); i++) { |
| if (a->operands[i].isConstant()) { |
| if (!b->operands[i].isConstant()) |
| return false; |
| if (a->operands[i].constantValue() != b->operands[i].constantValue()) |
| return false; |
| } else if (a->operands[i].isTemp()) { |
| if (!b->operands[i].isTemp()) |
| return false; |
| if (a->operands[i].tempId() != b->operands[i].tempId()) |
| return false; |
| } else if (a->operands[i].isUndefined() ^ b->operands[i].isUndefined()) |
| return false; |
| if (a->operands[i].isFixed()) { |
| if (!b->operands[i].isFixed()) |
| return false; |
| if (a->operands[i].physReg() != b->operands[i].physReg()) |
| return false; |
| if (a->operands[i].physReg() == exec && a->pass_flags != b->pass_flags) |
| return false; |
| } |
| } |
| for (unsigned i = 0; i < a->definitions.size(); i++) { |
| if (a->definitions[i].isTemp()) { |
| if (!b->definitions[i].isTemp()) |
| return false; |
| if (a->definitions[i].regClass() != b->definitions[i].regClass()) |
| return false; |
| } |
| if (a->definitions[i].isFixed()) { |
| if (!b->definitions[i].isFixed()) |
| return false; |
| if (a->definitions[i].physReg() != b->definitions[i].physReg()) |
| return false; |
| if (a->definitions[i].physReg() == exec) |
| return false; |
| } |
| } |
| |
| if (a->isVALU()) { |
| VALU_instruction& aV = a->valu(); |
| VALU_instruction& bV = b->valu(); |
| if (aV.abs != bV.abs || aV.neg != bV.neg || aV.clamp != bV.clamp || aV.omod != bV.omod || |
| aV.opsel != bV.opsel || aV.opsel_lo != bV.opsel_lo || aV.opsel_hi != bV.opsel_hi) |
| return false; |
| |
| if (a->opcode == aco_opcode::v_permlane16_b32 || |
| a->opcode == aco_opcode::v_permlanex16_b32 || |
| a->opcode == aco_opcode::v_permlane64_b32 || |
| a->opcode == aco_opcode::v_readfirstlane_b32) |
| return aV.pass_flags == bV.pass_flags; |
| } |
| if (a->isDPP16()) { |
| DPP16_instruction& aDPP = a->dpp16(); |
| DPP16_instruction& bDPP = b->dpp16(); |
| return aDPP.pass_flags == bDPP.pass_flags && aDPP.dpp_ctrl == bDPP.dpp_ctrl && |
| aDPP.bank_mask == bDPP.bank_mask && aDPP.row_mask == bDPP.row_mask && |
| aDPP.bound_ctrl == bDPP.bound_ctrl && aDPP.fetch_inactive == bDPP.fetch_inactive; |
| } |
| if (a->isDPP8()) { |
| DPP8_instruction& aDPP = a->dpp8(); |
| DPP8_instruction& bDPP = b->dpp8(); |
| return aDPP.pass_flags == bDPP.pass_flags && aDPP.lane_sel == bDPP.lane_sel && |
| aDPP.fetch_inactive == bDPP.fetch_inactive; |
| } |
| if (a->isSDWA()) { |
| SDWA_instruction& aSDWA = a->sdwa(); |
| SDWA_instruction& bSDWA = b->sdwa(); |
| return aSDWA.sel[0] == bSDWA.sel[0] && aSDWA.sel[1] == bSDWA.sel[1] && |
| aSDWA.dst_sel == bSDWA.dst_sel; |
| } |
| |
| switch (a->format) { |
| case Format::SOP1: { |
| if (a->opcode == aco_opcode::s_sendmsg_rtn_b32 || |
| a->opcode == aco_opcode::s_sendmsg_rtn_b64) |
| return false; |
| return true; |
| } |
| case Format::SOPK: { |
| if (a->opcode == aco_opcode::s_getreg_b32) |
| return false; |
| SALU_instruction& aK = a->salu(); |
| SALU_instruction& bK = b->salu(); |
| return aK.imm == bK.imm; |
| } |
| case Format::SMEM: { |
| SMEM_instruction& aS = a->smem(); |
| SMEM_instruction& bS = b->smem(); |
| return aS.sync == bS.sync && aS.cache.value == bS.cache.value; |
| } |
| case Format::VINTRP: { |
| VINTRP_instruction& aI = a->vintrp(); |
| VINTRP_instruction& bI = b->vintrp(); |
| return aI.attribute == bI.attribute && aI.component == bI.component && |
| aI.high_16bits == bI.high_16bits; |
| } |
| case Format::VINTERP_INREG: { |
| VINTERP_inreg_instruction& aI = a->vinterp_inreg(); |
| VINTERP_inreg_instruction& bI = b->vinterp_inreg(); |
| return aI.wait_exp == bI.wait_exp; |
| } |
| case Format::PSEUDO_REDUCTION: { |
| Pseudo_reduction_instruction& aR = a->reduction(); |
| Pseudo_reduction_instruction& bR = b->reduction(); |
| return aR.pass_flags == bR.pass_flags && aR.reduce_op == bR.reduce_op && |
| aR.cluster_size == bR.cluster_size; |
| } |
| case Format::DS: { |
| assert(a->opcode == aco_opcode::ds_bpermute_b32 || |
| a->opcode == aco_opcode::ds_permute_b32 || a->opcode == aco_opcode::ds_swizzle_b32); |
| DS_instruction& aD = a->ds(); |
| DS_instruction& bD = b->ds(); |
| return aD.sync == bD.sync && aD.pass_flags == bD.pass_flags && aD.gds == bD.gds && |
| aD.offset0 == bD.offset0 && aD.offset1 == bD.offset1; |
| } |
| case Format::LDSDIR: { |
| LDSDIR_instruction& aD = a->ldsdir(); |
| LDSDIR_instruction& bD = b->ldsdir(); |
| return aD.sync == bD.sync && aD.attr == bD.attr && aD.attr_chan == bD.attr_chan && |
| aD.wait_vdst == bD.wait_vdst; |
| } |
| case Format::MTBUF: { |
| MTBUF_instruction& aM = a->mtbuf(); |
| MTBUF_instruction& bM = b->mtbuf(); |
| return aM.sync == bM.sync && aM.dfmt == bM.dfmt && aM.nfmt == bM.nfmt && |
| aM.offset == bM.offset && aM.offen == bM.offen && aM.idxen == bM.idxen && |
| aM.cache.value == bM.cache.value && aM.tfe == bM.tfe && |
| aM.disable_wqm == bM.disable_wqm; |
| } |
| case Format::MUBUF: { |
| MUBUF_instruction& aM = a->mubuf(); |
| MUBUF_instruction& bM = b->mubuf(); |
| return aM.sync == bM.sync && aM.offset == bM.offset && aM.offen == bM.offen && |
| aM.idxen == bM.idxen && aM.cache.value == bM.cache.value && aM.tfe == bM.tfe && |
| aM.lds == bM.lds && aM.disable_wqm == bM.disable_wqm; |
| } |
| case Format::MIMG: { |
| MIMG_instruction& aM = a->mimg(); |
| MIMG_instruction& bM = b->mimg(); |
| return aM.sync == bM.sync && aM.dmask == bM.dmask && aM.unrm == bM.unrm && |
| aM.cache.value == bM.cache.value && aM.tfe == bM.tfe && aM.da == bM.da && |
| aM.lwe == bM.lwe && aM.r128 == bM.r128 && aM.a16 == bM.a16 && aM.d16 == bM.d16 && |
| aM.disable_wqm == bM.disable_wqm; |
| } |
| case Format::FLAT: |
| case Format::GLOBAL: |
| case Format::SCRATCH: |
| case Format::EXP: |
| case Format::SOPP: |
| case Format::PSEUDO_BRANCH: |
| case Format::PSEUDO_BARRIER: unreachable("unsupported instruction format"); |
| default: return true; |
| } |
| } |
| }; |
| |
| using expr_set = aco::unordered_map<Instruction*, uint32_t, InstrHash, InstrPred>; |
| |
| struct vn_ctx { |
| Program* program; |
| monotonic_buffer_resource m; |
| expr_set expr_values; |
| aco::unordered_map<uint32_t, Temp> renames; |
| |
| /* The exec id should be the same on the same level of control flow depth. |
| * Together with the check for dominator relations, it is safe to assume |
| * that the same exec_id also means the same execution mask. |
| * Discards increment the exec_id, so that it won't return to the previous value. |
| */ |
| uint32_t exec_id = 1; |
| |
| vn_ctx(Program* program_) : program(program_), m(), expr_values(m), renames(m) |
| { |
| static_assert(sizeof(Temp) == 4, "Temp must fit in 32bits"); |
| unsigned size = 0; |
| for (Block& block : program->blocks) |
| size += block.instructions.size(); |
| expr_values.reserve(size); |
| } |
| }; |
| |
| /* dominates() returns true if the parent block dominates the child block and |
| * if the parent block is part of the same loop or has a smaller loop nest depth. |
| */ |
| bool |
| dominates(vn_ctx& ctx, uint32_t parent, uint32_t child) |
| { |
| Block& parent_b = ctx.program->blocks[parent]; |
| Block& child_b = ctx.program->blocks[child]; |
| if (!dominates_logical(parent_b, child_b) || parent_b.loop_nest_depth > child_b.loop_nest_depth) |
| return false; |
| if (parent_b.loop_nest_depth == child_b.loop_nest_depth && parent_b.loop_nest_depth == 0) |
| return true; |
| |
| unsigned parent_loop_nest_depth = ctx.program->blocks[parent].loop_nest_depth; |
| while (parent < child && parent_loop_nest_depth <= ctx.program->blocks[child].loop_nest_depth) |
| child = ctx.program->blocks[child].logical_idom; |
| |
| return parent == child; |
| } |
| |
| /** Returns whether this instruction can safely be removed |
| * and replaced by an equal expression. |
| * This is in particular true for ALU instructions and |
| * read-only memory instructions. |
| * |
| * Note that expr_set must not be used with instructions |
| * which cannot be eliminated. |
| */ |
| bool |
| can_eliminate(aco_ptr<Instruction>& instr) |
| { |
| switch (instr->format) { |
| case Format::FLAT: |
| case Format::GLOBAL: |
| case Format::SCRATCH: |
| case Format::EXP: |
| case Format::SOPP: |
| case Format::PSEUDO_BRANCH: |
| case Format::PSEUDO_BARRIER: return false; |
| case Format::DS: |
| return instr->opcode == aco_opcode::ds_bpermute_b32 || |
| instr->opcode == aco_opcode::ds_permute_b32 || |
| instr->opcode == aco_opcode::ds_swizzle_b32; |
| case Format::SMEM: |
| case Format::MUBUF: |
| case Format::MIMG: |
| case Format::MTBUF: |
| if (!get_sync_info(instr.get()).can_reorder()) |
| return false; |
| break; |
| default: break; |
| } |
| |
| if (instr->definitions.empty() || instr->opcode == aco_opcode::p_phi || |
| instr->opcode == aco_opcode::p_linear_phi || |
| instr->opcode == aco_opcode::p_pops_gfx9_add_exiting_wave_id || |
| instr->opcode == aco_opcode::p_shader_cycles_hi_lo_hi || |
| instr->definitions[0].isNoCSE()) |
| return false; |
| |
| return true; |
| } |
| |
| bool |
| is_trivial_phi(Block& block, Instruction* instr) |
| { |
| if (!is_phi(instr)) |
| return false; |
| |
| /* Logical LCSSA phis must be kept in order to prevent the optimizer |
| * from doing invalid transformations. */ |
| if (instr->opcode == aco_opcode::p_phi && (block.kind & block_kind_loop_exit)) |
| return false; |
| |
| return std::all_of(instr->operands.begin(), instr->operands.end(), |
| [&](Operand& op) { return op == instr->operands[0]; }); |
| } |
| |
| void |
| process_block(vn_ctx& ctx, Block& block) |
| { |
| std::vector<aco_ptr<Instruction>> new_instructions; |
| new_instructions.reserve(block.instructions.size()); |
| |
| for (aco_ptr<Instruction>& instr : block.instructions) { |
| /* first, rename operands */ |
| for (Operand& op : instr->operands) { |
| if (!op.isTemp()) |
| continue; |
| auto it = ctx.renames.find(op.tempId()); |
| if (it != ctx.renames.end()) |
| op.setTemp(it->second); |
| } |
| |
| if (instr->opcode == aco_opcode::p_discard_if || |
| instr->opcode == aco_opcode::p_demote_to_helper || instr->opcode == aco_opcode::p_end_wqm) |
| ctx.exec_id++; |
| |
| /* simple copy-propagation through renaming */ |
| bool copy_instr = |
| is_trivial_phi(block, instr.get()) || instr->opcode == aco_opcode::p_parallelcopy || |
| (instr->opcode == aco_opcode::p_create_vector && instr->operands.size() == 1); |
| if (copy_instr && !instr->definitions[0].isFixed() && instr->operands[0].isTemp() && |
| instr->operands[0].regClass() == instr->definitions[0].regClass()) { |
| ctx.renames[instr->definitions[0].tempId()] = instr->operands[0].getTemp(); |
| continue; |
| } |
| |
| if (!can_eliminate(instr)) { |
| new_instructions.emplace_back(std::move(instr)); |
| continue; |
| } |
| |
| instr->pass_flags = ctx.exec_id; |
| std::pair<expr_set::iterator, bool> res = ctx.expr_values.emplace(instr.get(), block.index); |
| |
| /* if there was already an expression with the same value number */ |
| if (!res.second) { |
| Instruction* orig_instr = res.first->first; |
| assert(instr->definitions.size() == orig_instr->definitions.size()); |
| /* check if the original instruction dominates the current one */ |
| if (dominates(ctx, res.first->second, block.index) && |
| ctx.program->blocks[res.first->second].fp_mode.canReplace(block.fp_mode)) { |
| for (unsigned i = 0; i < instr->definitions.size(); i++) { |
| assert(instr->definitions[i].regClass() == orig_instr->definitions[i].regClass()); |
| assert(instr->definitions[i].isTemp()); |
| ctx.renames[instr->definitions[i].tempId()] = orig_instr->definitions[i].getTemp(); |
| if (instr->definitions[i].isPrecise()) |
| orig_instr->definitions[i].setPrecise(true); |
| if (instr->definitions[i].isSZPreserve()) |
| orig_instr->definitions[i].setSZPreserve(true); |
| if (instr->definitions[i].isInfPreserve()) |
| orig_instr->definitions[i].setInfPreserve(true); |
| if (instr->definitions[i].isNaNPreserve()) |
| orig_instr->definitions[i].setNaNPreserve(true); |
| /* SPIR_V spec says that an instruction marked with NUW wrapping |
| * around is undefined behaviour, so we can break additions in |
| * other contexts. |
| */ |
| if (instr->definitions[i].isNUW()) |
| orig_instr->definitions[i].setNUW(true); |
| } |
| } else { |
| ctx.expr_values.erase(res.first); |
| ctx.expr_values.emplace(instr.get(), block.index); |
| new_instructions.emplace_back(std::move(instr)); |
| } |
| } else { |
| new_instructions.emplace_back(std::move(instr)); |
| } |
| } |
| |
| block.instructions = std::move(new_instructions); |
| } |
| |
| void |
| rename_phi_operands(Block& block, aco::unordered_map<uint32_t, Temp>& renames) |
| { |
| for (aco_ptr<Instruction>& phi : block.instructions) { |
| if (!is_phi(phi)) |
| break; |
| |
| for (Operand& op : phi->operands) { |
| if (!op.isTemp()) |
| continue; |
| auto it = renames.find(op.tempId()); |
| if (it != renames.end()) |
| op.setTemp(it->second); |
| } |
| } |
| } |
| } /* end namespace */ |
| |
| void |
| value_numbering(Program* program) |
| { |
| vn_ctx ctx(program); |
| std::vector<unsigned> loop_headers; |
| |
| for (Block& block : program->blocks) { |
| assert(ctx.exec_id > 0); |
| /* decrement exec_id when leaving nested control flow */ |
| if (block.kind & block_kind_loop_header) |
| loop_headers.push_back(block.index); |
| if (block.kind & block_kind_merge) { |
| ctx.exec_id--; |
| } else if (block.kind & block_kind_loop_exit) { |
| ctx.exec_id -= program->blocks[loop_headers.back()].linear_preds.size(); |
| ctx.exec_id -= block.linear_preds.size(); |
| loop_headers.pop_back(); |
| } |
| |
| if (block.logical_idom == (int)block.index) |
| ctx.expr_values.clear(); |
| |
| if (block.logical_idom != -1) |
| process_block(ctx, block); |
| else |
| rename_phi_operands(block, ctx.renames); |
| |
| /* increment exec_id when entering nested control flow */ |
| if (block.kind & block_kind_branch || block.kind & block_kind_loop_preheader || |
| block.kind & block_kind_break || block.kind & block_kind_continue) |
| ctx.exec_id++; |
| else if (block.kind & block_kind_continue_or_break) |
| ctx.exec_id += 2; |
| } |
| |
| /* rename loop header phi operands */ |
| for (Block& block : program->blocks) { |
| if (block.kind & block_kind_loop_header) |
| rename_phi_operands(block, ctx.renames); |
| } |
| } |
| |
| } // namespace aco |
