/* * Copyright © 2015 Intel Corporation * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * */ /** @file brw_vec4_cmod_propagation.cpp * * Really similar to brw_fs_cmod_propagation but adapted to vec4 needs. Check * brw_fs_cmod_propagation for further details on the rationale behind this * optimization. */ #include "brw_vec4.h" #include "brw_cfg.h" #include "brw_eu.h" namespace brw { static bool writemasks_incompatible(const vec4_instruction *earlier, const vec4_instruction *later) { return (earlier->dst.writemask != WRITEMASK_X && earlier->dst.writemask != WRITEMASK_XYZW) || (earlier->dst.writemask == WRITEMASK_XYZW && later->src[0].swizzle != BRW_SWIZZLE_XYZW) || (later->dst.writemask & ~earlier->dst.writemask) != 0; } static bool opt_cmod_propagation_local(bblock_t *block, vec4_visitor *v) { bool progress = false; int ip = block->end_ip + 1; foreach_inst_in_block_reverse_safe(vec4_instruction, inst, block) { ip--; if ((inst->opcode != BRW_OPCODE_AND && inst->opcode != BRW_OPCODE_CMP && inst->opcode != BRW_OPCODE_MOV) || inst->predicate != BRW_PREDICATE_NONE || !inst->dst.is_null() || (inst->src[0].file != VGRF && inst->src[0].file != ATTR && inst->src[0].file != UNIFORM)) continue; /* An ABS source modifier can only be handled when processing a compare * with a value other than zero. */ if (inst->src[0].abs && (inst->opcode != BRW_OPCODE_CMP || inst->src[1].is_zero())) continue; if (inst->opcode == BRW_OPCODE_AND && !(inst->src[1].is_one() && inst->conditional_mod == BRW_CONDITIONAL_NZ && !inst->src[0].negate)) continue; if (inst->opcode == BRW_OPCODE_MOV && inst->conditional_mod != BRW_CONDITIONAL_NZ) continue; bool read_flag = false; foreach_inst_in_block_reverse_starting_from(vec4_instruction, scan_inst, inst) { /* A CMP with a second source of zero can match with anything. A CMP * with a second source that is not zero can only match with an ADD * instruction. */ if (inst->opcode == BRW_OPCODE_CMP && !inst->src[1].is_zero()) { bool negate; if (scan_inst->opcode != BRW_OPCODE_ADD) goto not_match; if (writemasks_incompatible(scan_inst, inst)) goto not_match; /* A CMP is basically a subtraction. The result of the * subtraction must be the same as the result of the addition. * This means that one of the operands must be negated. So (a + * b) vs (a == -b) or (a + -b) vs (a == b). */ if ((inst->src[0].equals(scan_inst->src[0]) && inst->src[1].negative_equals(scan_inst->src[1])) || (inst->src[0].equals(scan_inst->src[1]) && inst->src[1].negative_equals(scan_inst->src[0]))) { negate = false; } else if ((inst->src[0].negative_equals(scan_inst->src[0]) && inst->src[1].equals(scan_inst->src[1])) || (inst->src[0].negative_equals(scan_inst->src[1]) && inst->src[1].equals(scan_inst->src[0]))) { negate = true; } else { goto not_match; } if (scan_inst->exec_size != inst->exec_size || scan_inst->group != inst->group) goto not_match; /* From the Sky Lake PRM Vol. 7 "Assigning Conditional Mods": * * * Note that the [post condition signal] bits generated at * the output of a compute are before the .sat. * * So we don't have to bail if scan_inst has saturate. */ /* Otherwise, try propagating the conditional. */ const enum brw_conditional_mod cond = negate ? brw_swap_cmod(inst->conditional_mod) : inst->conditional_mod; if (scan_inst->can_do_cmod() && ((!read_flag && scan_inst->conditional_mod == BRW_CONDITIONAL_NONE) || scan_inst->conditional_mod == cond)) { scan_inst->conditional_mod = cond; inst->remove(block); progress = true; } break; } if (regions_overlap(inst->src[0], inst->size_read(0), scan_inst->dst, scan_inst->size_written)) { if ((scan_inst->predicate && scan_inst->opcode != BRW_OPCODE_SEL) || scan_inst->dst.offset != inst->src[0].offset || scan_inst->exec_size != inst->exec_size || scan_inst->group != inst->group) { break; } /* If scan_inst is a CMP that produces a single value and inst is * a CMP.NZ that consumes only that value, remove inst. */ if (inst->conditional_mod == BRW_CONDITIONAL_NZ && (inst->src[0].type == BRW_REGISTER_TYPE_D || inst->src[0].type == BRW_REGISTER_TYPE_UD) && (inst->opcode == BRW_OPCODE_CMP || inst->opcode == BRW_OPCODE_MOV) && scan_inst->opcode == BRW_OPCODE_CMP && ((inst->src[0].swizzle == BRW_SWIZZLE_XXXX && scan_inst->dst.writemask == WRITEMASK_X) || (inst->src[0].swizzle == BRW_SWIZZLE_YYYY && scan_inst->dst.writemask == WRITEMASK_Y) || (inst->src[0].swizzle == BRW_SWIZZLE_ZZZZ && scan_inst->dst.writemask == WRITEMASK_Z) || (inst->src[0].swizzle == BRW_SWIZZLE_WWWW && scan_inst->dst.writemask == WRITEMASK_W))) { if (inst->dst.writemask != scan_inst->dst.writemask) { src_reg temp(v, glsl_type::vec4_type, 1); /* Given a sequence like: * * cmp.ge.f0(8) g21<1>.zF g20<4>.xF g18<4>.xF * ... * cmp.nz.f0(8) null<1>D g21<4>.zD 0D * * Replace it with something like: * * cmp.ge.f0(8) g22<1>.zF g20<4>.xF g18<4>.xF * mov(8) g21<1>.xF g22<1>.zzzzF * * The added MOV will most likely be removed later. In the * worst case, it should be cheaper to schedule. */ temp.swizzle = brw_swizzle_for_mask(inst->dst.writemask); temp.type = scan_inst->src[0].type; vec4_instruction *mov = v->MOV(scan_inst->dst, temp); /* Modify the source swizzles on scan_inst. If scan_inst * was * * cmp.ge.f0(8) g21<1>.zF g20<4>.wzyxF g18<4>.yxwzF * * replace it with * * cmp.ge.f0(8) g21<1>.zF g20<4>.yyyyF g18<4>.wwwwF */ unsigned src0_chan; unsigned src1_chan; switch (scan_inst->dst.writemask) { case WRITEMASK_X: src0_chan = BRW_GET_SWZ(scan_inst->src[0].swizzle, 0); src1_chan = BRW_GET_SWZ(scan_inst->src[1].swizzle, 0); break; case WRITEMASK_Y: src0_chan = BRW_GET_SWZ(scan_inst->src[0].swizzle, 1); src1_chan = BRW_GET_SWZ(scan_inst->src[1].swizzle, 1); break; case WRITEMASK_Z: src0_chan = BRW_GET_SWZ(scan_inst->src[0].swizzle, 2); src1_chan = BRW_GET_SWZ(scan_inst->src[1].swizzle, 2); break; case WRITEMASK_W: src0_chan = BRW_GET_SWZ(scan_inst->src[0].swizzle, 3); src1_chan = BRW_GET_SWZ(scan_inst->src[1].swizzle, 3); break; default: unreachable("Impossible writemask"); } scan_inst->src[0].swizzle = BRW_SWIZZLE4(src0_chan, src0_chan, src0_chan, src0_chan); /* There's no swizzle on immediate value sources. */ if (scan_inst->src[1].file != IMM) { scan_inst->src[1].swizzle = BRW_SWIZZLE4(src1_chan, src1_chan, src1_chan, src1_chan); } scan_inst->dst = dst_reg(temp); scan_inst->dst.writemask = inst->dst.writemask; scan_inst->insert_after(block, mov); } inst->remove(block); progress = true; break; } if (writemasks_incompatible(scan_inst, inst)) break; /* CMP's result is the same regardless of dest type. */ if (inst->conditional_mod == BRW_CONDITIONAL_NZ && scan_inst->opcode == BRW_OPCODE_CMP && (inst->dst.type == BRW_REGISTER_TYPE_D || inst->dst.type == BRW_REGISTER_TYPE_UD)) { inst->remove(block); progress = true; break; } /* If the AND wasn't handled by the previous case, it isn't safe * to remove it. */ if (inst->opcode == BRW_OPCODE_AND) break; /* Comparisons operate differently for ints and floats */ if (scan_inst->dst.type != inst->dst.type && (scan_inst->dst.type == BRW_REGISTER_TYPE_F || inst->dst.type == BRW_REGISTER_TYPE_F)) break; /* If the instruction generating inst's source also wrote the * flag, and inst is doing a simple .nz comparison, then inst * is redundant - the appropriate value is already in the flag * register. Delete inst. */ if (inst->conditional_mod == BRW_CONDITIONAL_NZ && !inst->src[0].negate && scan_inst->writes_flag()) { inst->remove(block); progress = true; break; } /* The conditional mod of the CMP/CMPN instructions behaves * specially because the flag output is not calculated from the * result of the instruction, but the other way around, which * means that even if the condmod to propagate and the condmod * from the CMP instruction are the same they will in general give * different results because they are evaluated based on different * inputs. */ if (scan_inst->opcode == BRW_OPCODE_CMP || scan_inst->opcode == BRW_OPCODE_CMPN) break; /* From the Sky Lake PRM Vol. 7 "Assigning Conditional Mods": * * * Note that the [post condition signal] bits generated at * the output of a compute are before the .sat. */ if (scan_inst->saturate) break; /* From the Sky Lake PRM, Vol 2a, "Multiply": * * "When multiplying integer data types, if one of the sources * is a DW, the resulting full precision data is stored in * the accumulator. However, if the destination data type is * either W or DW, the low bits of the result are written to * the destination register and the remaining high bits are * discarded. This results in undefined Overflow and Sign * flags. Therefore, conditional modifiers and saturation * (.sat) cannot be used in this case. * * We just disallow cmod propagation on all integer multiplies. */ if (!brw_reg_type_is_floating_point(scan_inst->dst.type) && scan_inst->opcode == BRW_OPCODE_MUL) break; /* Otherwise, try propagating the conditional. */ enum brw_conditional_mod cond = inst->src[0].negate ? brw_swap_cmod(inst->conditional_mod) : inst->conditional_mod; if (scan_inst->can_do_cmod() && ((!read_flag && scan_inst->conditional_mod == BRW_CONDITIONAL_NONE) || scan_inst->conditional_mod == cond)) { scan_inst->conditional_mod = cond; inst->remove(block); progress = true; } break; } not_match: if (scan_inst->writes_flag()) break; read_flag = read_flag || scan_inst->reads_flag(); } } return progress; } bool vec4_visitor::opt_cmod_propagation() { bool progress = false; foreach_block_reverse(block, cfg) { progress = opt_cmod_propagation_local(block, this) || progress; } if (progress) invalidate_analysis(DEPENDENCY_INSTRUCTIONS); return progress; } } /* namespace brw */