+++ /dev/null
-/*
- * Copyright (C) 2019 Collabora, Ltd.
- *
- * 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 "compiler.h"
-#include "midgard_ops.h"
-
-/* Lowers the invert field on instructions to a dedicated inot (inor)
- * instruction instead, as invert is not always supported natively by the
- * hardware */
-
-void
-midgard_lower_invert(compiler_context *ctx, midgard_block *block)
-{
- mir_foreach_instr_in_block_safe(block, ins) {
- if (ins->type != TAG_ALU_4) continue;
- if (!ins->invert) continue;
-
- unsigned temp = make_compiler_temp(ctx);
-
- midgard_instruction not = {
- .type = TAG_ALU_4,
- .mask = ins->mask,
- .src = { temp, ~0, ~0, ~0 },
- .swizzle = SWIZZLE_IDENTITY,
- .dest = ins->dest,
- .has_inline_constant = true,
- .alu = {
- .op = midgard_alu_op_inor,
- /* TODO: i16 */
- .reg_mode = midgard_reg_mode_32,
- .dest_override = midgard_dest_override_none,
- .outmod = midgard_outmod_int_wrap
- },
- };
-
- ins->dest = temp;
- ins->invert = false;
- mir_insert_instruction_before(ctx, mir_next_op(ins), not);
- }
-}
-
-/* Propagate the .not up to the source */
-
-bool
-midgard_opt_not_propagate(compiler_context *ctx, midgard_block *block)
-{
- bool progress = false;
-
- mir_foreach_instr_in_block_safe(block, ins) {
- if (ins->type != TAG_ALU_4) continue;
- if (ins->alu.op != midgard_alu_op_imov) continue;
- if (!ins->invert) continue;
- if (mir_nontrivial_source2_mod_simple(ins)) continue;
- if (ins->src[1] & PAN_IS_REG) continue;
-
- /* Is it beneficial to propagate? */
- if (!mir_single_use(ctx, ins->src[1])) continue;
-
- /* We found an imov.not, propagate the invert back */
-
- mir_foreach_instr_in_block_from_rev(block, v, mir_prev_op(ins)) {
- if (v->dest != ins->src[1]) continue;
- if (v->type != TAG_ALU_4) break;
-
- v->invert = !v->invert;
- ins->invert = false;
- progress |= true;
- break;
- }
- }
-
- return progress;
-}
-
-/* With that lowering out of the way, we can focus on more interesting
- * optimizations. One easy one is fusing inverts into bitwise operations:
- *
- * ~iand = inand
- * ~ior = inor
- * ~ixor = inxor
- */
-
-static bool
-mir_is_bitwise(midgard_instruction *ins)
-{
- switch (ins->alu.op) {
- case midgard_alu_op_iand:
- case midgard_alu_op_ior:
- case midgard_alu_op_ixor:
- return true;
- default:
- return false;
- }
-}
-
-static bool
-mir_is_inverted_bitwise(midgard_instruction *ins)
-{
- switch (ins->alu.op) {
- case midgard_alu_op_inand:
- case midgard_alu_op_inor:
- case midgard_alu_op_inxor:
- return true;
- default:
- return false;
- }
-}
-
-static midgard_alu_op
-mir_invert_op(midgard_alu_op op)
-{
- switch (op) {
- case midgard_alu_op_iand:
- return midgard_alu_op_inand;
- case midgard_alu_op_inand:
- return midgard_alu_op_iand;
- case midgard_alu_op_ior:
- return midgard_alu_op_inor;
- case midgard_alu_op_inor:
- return midgard_alu_op_ior;
- case midgard_alu_op_ixor:
- return midgard_alu_op_inxor;
- case midgard_alu_op_inxor:
- return midgard_alu_op_ixor;
- default:
- unreachable("Op not invertible");
- }
-}
-
-static midgard_alu_op
-mir_demorgan_op(midgard_alu_op op)
-{
- switch (op) {
- case midgard_alu_op_iand:
- return midgard_alu_op_inor;
- case midgard_alu_op_ior:
- return midgard_alu_op_inand;
- default:
- unreachable("Op not De Morgan-able");
- }
-}
-
-static midgard_alu_op
-mir_notright_op(midgard_alu_op op)
-{
- switch (op) {
- case midgard_alu_op_iand:
- return midgard_alu_op_iandnot;
- case midgard_alu_op_ior:
- return midgard_alu_op_iornot;
- default:
- unreachable("Op not right able");
- }
-}
-
-bool
-midgard_opt_fuse_dest_invert(compiler_context *ctx, midgard_block *block)
-{
- bool progress = false;
-
- mir_foreach_instr_in_block_safe(block, ins) {
- /* Search for inverted bitwise */
- if (ins->type != TAG_ALU_4) continue;
- if (!mir_is_bitwise(ins) && !mir_is_inverted_bitwise(ins)) continue;
- if (!ins->invert) continue;
-
- ins->alu.op = mir_invert_op(ins->alu.op);
- ins->invert = false;
- progress |= true;
- }
-
- return progress;
-}
-
-/* Next up, we can fuse inverts into the sources of bitwise ops:
- *
- * ~a & b = b & ~a = iandnot(b, a)
- * a & ~b = iandnot(a, b)
- * ~a & ~b = ~(a | b) = inor(a, b)
- *
- * ~a | b = b | ~a = iornot(b, a)
- * a | ~b = iornot(a, b)
- * ~a | ~b = ~(a & b) = inand(a, b)
- *
- * ~a ^ b = ~(a ^ b) = inxor(a, b)
- * a ^ ~b = ~(a ^ b) + inxor(a, b)
- * ~a ^ ~b = a ^ b
- * ~(a ^ b) = inxor(a, b)
- */
-
-static bool
-mir_strip_inverted(compiler_context *ctx, unsigned node)
-{
- if (node == SSA_FIXED_REGISTER(26))
- return false;
-
- /* Strips and returns the invert off a node */
- mir_foreach_instr_global(ctx, ins) {
- if (ins->compact_branch) continue;
- if (ins->dest != node) continue;
-
- bool status = ins->invert;
- ins->invert = false;
- return status;
- }
-
- unreachable("Invalid node stripped");
-}
-
-static bool
-is_ssa_or_constant(unsigned node)
-{
- return !(node & PAN_IS_REG) || (node == SSA_FIXED_REGISTER(26));
-}
-
-bool
-midgard_opt_fuse_src_invert(compiler_context *ctx, midgard_block *block)
-{
- bool progress = false;
-
- mir_foreach_instr_in_block_safe(block, ins) {
- /* Search for inverted bitwise */
- if (ins->type != TAG_ALU_4) continue;
- if (!mir_is_bitwise(ins)) continue;
-
- if (!is_ssa_or_constant(ins->src[0])) continue;
- if (!is_ssa_or_constant(ins->src[1])) continue;
- if (!mir_single_use(ctx, ins->src[0])) continue;
- if (!ins->has_inline_constant && !mir_single_use(ctx, ins->src[1])) continue;
-
- bool not_a = mir_strip_inverted(ctx, ins->src[0]);
- bool not_b =
- ins->has_inline_constant ? false :
- mir_strip_inverted(ctx, ins->src[1]);
-
- /* Edge case: if src0 == src1, it'll've been stripped */
- if ((ins->src[0] == ins->src[1]) && !ins->has_inline_constant)
- not_b = not_a;
-
- progress |= (not_a || not_b);
-
- /* No point */
- if (!(not_a || not_b)) continue;
-
- bool both = not_a && not_b;
- bool left = not_a && !not_b;
- bool right = !not_a && not_b;
-
- /* No-op, but we got to strip the inverts */
- if (both && ins->alu.op == midgard_alu_op_ixor)
- continue;
-
- if (both) {
- ins->alu.op = mir_demorgan_op(ins->alu.op);
- } else if (right || (left && !ins->has_inline_constant)) {
- /* Commute arguments */
- if (left)
- mir_flip(ins);
-
- ins->alu.op = mir_notright_op(ins->alu.op);
- } else if (left && ins->has_inline_constant) {
- /* Some special transformations:
- *
- * ~A & c = ~(~(~A) | (~c)) = ~(A | ~c) = inor(A, ~c)
- * ~A | c = ~(~(~A) & (~c)) = ~(A & ~c) = inand(A, ~c)
- */
-
- ins->alu.op = mir_demorgan_op(ins->alu.op);
- ins->inline_constant = ~ins->inline_constant;
- }
- }
-
- return progress;
-}
-
-/* Optimizes a .not away when used as the source of a conditional select:
- *
- * csel(a, b, c) = { b if a, c if !a }
- * csel(!a, b, c) = { b if !a, c if !(!a) } = { c if a, b if !a } = csel(a, c, b)
- * csel(!a, b, c) = csel(a, c, b)
- */
-
-bool
-midgard_opt_csel_invert(compiler_context *ctx, midgard_block *block)
-{
- bool progress = false;
-
- mir_foreach_instr_in_block_safe(block, ins) {
- if (ins->type != TAG_ALU_4) continue;
- if (!OP_IS_CSEL(ins->alu.op)) continue;
- if (!is_ssa_or_constant(ins->src[2])) continue;
- if (!mir_single_use(ctx, ins->src[2])) continue;
- if (!mir_strip_inverted(ctx, ins->src[2])) continue;
-
- mir_flip(ins);
- progress |= true;
- }
-
- return progress;
-}
-
-
-static bool
-mir_is_inverted(compiler_context *ctx, unsigned node)
-{
- mir_foreach_instr_global(ctx, ins) {
- if (ins->compact_branch) continue;
- if (ins->dest != node) continue;
-
- return ins->invert;
- }
-
- unreachable("Invalid node passed");
-}
-
-
-
-/* Optimizes comparisions which invert both arguments
- *
- *
- * ieq(not(a), not(b)) = ieq(a, b)
- * ine(not(a), not(b)) = ine(a, b)
- *
- * This does apply for ilt and ile if we flip the argument order:
- * Proofs below provided by Alyssa Rosenzweig
- *
- * not(x) = −(x+1)
- *
- * ( not(A) <= not(B) ) <=> ( −(A+1) <= −(B+1) )
- * <=> ( A+1 >= B+1)
- * <=> ( B <= A )
- *
- * On unsigned comparisons (ult / ule) we can perform the same optimization
- * with the additional restriction that the source registers must
- * have the same size.
- *
- * TODO: We may not need them to be of the same size, if we can
- * prove that they are the same after sext/zext
- *
- * not(x) = 2n−x−1
- *
- * ( not(A) <= not(B) ) <=> ( 2n−A−1 <= 2n−B−1 )
- * <=> ( −A <= −B )
- * <=> ( B <= A )
- */
-bool
-midgard_opt_drop_cmp_invert(compiler_context *ctx, midgard_block *block)
-{
-
- bool progress = false;
-
- mir_foreach_instr_in_block_safe(block, ins) {
- if (ins->type != TAG_ALU_4) continue;
- if (!OP_IS_INTEGER_CMP(ins->alu.op)) continue;
-
- if ((ins->src[0] & PAN_IS_REG) || (ins->src[1] & PAN_IS_REG)) continue;
- if (!mir_single_use(ctx, ins->src[0]) || !mir_single_use(ctx, ins->src[1])) continue;
-
- bool a_inverted = mir_is_inverted(ctx, ins->src[0]);
- bool b_inverted = mir_is_inverted(ctx, ins->src[1]);
-
- if (!a_inverted || !b_inverted) continue;
- if (OP_IS_UNSIGNED_CMP(ins->alu.op) && mir_srcsize(ins, 0) != mir_srcsize(ins, 1)) continue;
-
-
- mir_strip_inverted(ctx, ins->src[0]);
- mir_strip_inverted(ctx, ins->src[1]);
-
- if (ins->alu.op != midgard_alu_op_ieq && ins->alu.op != midgard_alu_op_ine)
- mir_flip(ins);
-
- progress |= true;
- }
-
- return progress;
-}
-
-/* Optimizes branches with inverted arguments by inverting the
- * branch condition instead of the argument condition.
- */
-bool
-midgard_opt_invert_branch(compiler_context *ctx, midgard_block *block)
-{
- bool progress = false;
-
- mir_foreach_instr_in_block_safe(block, ins) {
- if (ins->type != TAG_ALU_4) continue;
- if (!midgard_is_branch_unit(ins->unit)) continue;
- if (!ins->branch.conditional) continue;
- if (ins->src[0] & PAN_IS_REG) continue;
-
- if (mir_strip_inverted(ctx, ins->src[0])) {
- ins->branch.invert_conditional = !ins->branch.invert_conditional;
-
- progress |= true;
- }
- }
-
- return progress;
-}
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