--- /dev/null
+/*
+ * Copyright © 2020 Google, Inc.
+ *
+ * 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.
+ */
+
+#include "util/ralloc.h"
+#include "util/u_dynarray.h"
+
+#include "ir3.h"
+
+/**
+ * A bit more extra cleanup after sched pass. In particular, prior to
+ * instruction scheduling, we can't easily eliminate unneeded mov's
+ * from "arrays", because we don't yet know if there is an intervening
+ * array-write scheduled before the use of the array-read.
+ *
+ * NOTE array is equivalent to nir "registers".. ie. it can be length of
+ * one. It is basically anything that is not SSA.
+ */
+
+
+/**
+ * Check if any instruction before `use` and after `src` writes to the
+ * specified array. If `offset` is negative, it is a relative (a0.x)
+ * access and we care about all writes to the array (as we don't know
+ * which array element is read). Otherwise in the case of non-relative
+ * access, we only have to care about the write to the specified (>= 0)
+ * offset.
+ */
+static bool
+has_conflicting_write(struct ir3_instruction *src,
+ struct ir3_instruction *use,
+ unsigned id, int offset)
+{
+ assert(src->block == use->block);
+
+ /* NOTE that since src and use are in the same block, src by
+ * definition appears in the block's instr_list before use:
+ */
+ foreach_instr_rev (instr, &use->node) {
+ if (instr == src)
+ break;
+
+ /* if we are looking at a RELATIV read, we can't move
+ * it past an a0.x write:
+ */
+ if ((offset < 0) && (dest_regs(instr) > 0) &&
+ (instr->regs[0]->num == regid(REG_A0, 0)))
+ return true;
+
+ if (!writes_gpr(instr))
+ continue;
+
+ struct ir3_register *dst = instr->regs[0];
+ if (!(dst->flags & IR3_REG_ARRAY))
+ continue;
+
+ if (dst->array.id != id)
+ continue;
+
+ /*
+ * At this point, we have narrowed down an instruction
+ * that writes to the same array.. check if it the write
+ * is to an array element that we care about:
+ */
+
+ /* is write to an unknown array element? */
+ if (dst->flags & IR3_REG_RELATIV)
+ return true;
+
+ /* is read from an unknown array element? */
+ if (offset < 0)
+ return true;
+
+ /* is write to same array element? */
+ if (dst->array.offset == offset)
+ return true;
+ }
+
+ return false;
+}
+
+/* Can we fold the mov src into use without invalid flags? */
+static bool
+valid_flags(struct ir3_instruction *use, struct ir3_instruction *mov)
+{
+ struct ir3_register *src = mov->regs[1];
+
+ foreach_src_n (reg, n, use) {
+ if (ssa(reg) != mov)
+ continue;
+
+ if (!ir3_valid_flags(use, n, reg->flags | src->flags))
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+instr_cp_postsched(struct ir3_instruction *mov)
+{
+ struct ir3_register *src = mov->regs[1];
+
+ /* only consider mov's from "arrays", other cases we have
+ * already considered already:
+ */
+ if (!(src->flags & IR3_REG_ARRAY))
+ return false;
+
+ int offset = (src->flags & IR3_REG_RELATIV) ? -1 : src->array.offset;
+
+ /* Once we move the array read directly into the consuming
+ * instruction(s), we will also need to update instructions
+ * that had a false-dep on the original mov to have deps
+ * on the consuming instructions:
+ */
+ struct util_dynarray newdeps;
+ util_dynarray_init(&newdeps, mov->uses);
+
+ foreach_ssa_use (use, mov) {
+ if (use->block != mov->block)
+ continue;
+
+ if (is_meta(use))
+ continue;
+
+ if (has_conflicting_write(mov, use, src->array.id, offset))
+ continue;
+
+ if (conflicts(mov->address, use->address))
+ continue;
+
+ if (!valid_flags(use, mov))
+ continue;
+
+ /* Ok, we've established that it is safe to remove this copy: */
+
+ bool removed = false;
+ foreach_src_n (reg, n, use) {
+ if (ssa(reg) != mov)
+ continue;
+
+ use->regs[n + 1] = ir3_reg_clone(mov->block->shader, src);
+
+ /* preserve (abs)/etc modifiers: */
+ use->regs[n + 1]-> flags |= reg->flags;
+
+ removed = true;
+ }
+
+ /* the use could have been only a false-dep, only add to
+ * the newdeps array if we've actually updated a real
+ * src reg for the use:
+ */
+ if (removed) {
+ util_dynarray_append(&newdeps, struct ir3_instruction *, use);
+
+ /* Remove the use from the src instruction: */
+ _mesa_set_remove_key(mov->uses, use);
+ }
+ }
+
+ /* Once we have the complete set of instruction(s) that are are now
+ * directly reading from the array, update any false-dep uses to
+ * now depend on these instructions. The only remaining uses at
+ * this point should be false-deps:
+ */
+ foreach_ssa_use (use, mov) {
+ util_dynarray_foreach(&newdeps, struct ir3_instruction *, instrp) {
+ struct ir3_instruction *newdep = *instrp;
+ ir3_instr_add_dep(use, newdep);
+ }
+ }
+
+ return util_dynarray_num_elements(&newdeps, struct ir3_instruction **) > 0;
+}
+
+bool
+ir3_cp_postsched(struct ir3 *ir)
+{
+ void *mem_ctx = ralloc_context(NULL);
+ bool progress = false;
+
+ ir3_find_ssa_uses(ir, mem_ctx, false);
+
+ foreach_block (block, &ir->block_list) {
+ foreach_instr_safe (instr, &block->instr_list) {
+ if (is_same_type_mov(instr))
+ progress |= instr_cp_postsched(instr);
+ }
+ }
+
+ ralloc_free(mem_ctx);
+
+ return progress;
+}
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