summaryrefslogtreecommitdiffstats
path: root/src/panfrost/midgard/midgard_ra.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/panfrost/midgard/midgard_ra.c')
-rw-r--r--src/panfrost/midgard/midgard_ra.c506
1 files changed, 506 insertions, 0 deletions
diff --git a/src/panfrost/midgard/midgard_ra.c b/src/panfrost/midgard/midgard_ra.c
new file mode 100644
index 00000000000..cfe091326ed
--- /dev/null
+++ b/src/panfrost/midgard/midgard_ra.c
@@ -0,0 +1,506 @@
+/*
+ * Copyright (C) 2018-2019 Alyssa Rosenzweig <[email protected]>
+ * 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"
+#include "util/register_allocate.h"
+#include "util/u_math.h"
+
+/* For work registers, we can subdivide in various ways. So we create
+ * classes for the various sizes and conflict accordingly, keeping in
+ * mind that physical registers are divided along 128-bit boundaries.
+ * The important part is that 128-bit boundaries are not crossed.
+ *
+ * For each 128-bit register, we can subdivide to 32-bits 10 ways
+ *
+ * vec4: xyzw
+ * vec3: xyz, yzw
+ * vec2: xy, yz, zw,
+ * vec1: x, y, z, w
+ *
+ * For each 64-bit register, we can subdivide similarly to 16-bit
+ * (TODO: half-float RA, not that we support fp16 yet)
+ */
+
+#define WORK_STRIDE 10
+
+/* Prepacked masks/swizzles for virtual register types */
+static unsigned reg_type_to_mask[WORK_STRIDE] = {
+ 0xF, /* xyzw */
+ 0x7, 0x7 << 1, /* xyz */
+ 0x3, 0x3 << 1, 0x3 << 2, /* xy */
+ 0x1, 0x1 << 1, 0x1 << 2, 0x1 << 3 /* x */
+};
+
+static unsigned reg_type_to_swizzle[WORK_STRIDE] = {
+ SWIZZLE(COMPONENT_X, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+
+ SWIZZLE(COMPONENT_X, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+ SWIZZLE(COMPONENT_Y, COMPONENT_Z, COMPONENT_W, COMPONENT_W),
+
+ SWIZZLE(COMPONENT_X, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+ SWIZZLE(COMPONENT_Y, COMPONENT_Z, COMPONENT_Z, COMPONENT_W),
+ SWIZZLE(COMPONENT_Z, COMPONENT_W, COMPONENT_Z, COMPONENT_W),
+
+ SWIZZLE(COMPONENT_X, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+ SWIZZLE(COMPONENT_Y, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+ SWIZZLE(COMPONENT_Z, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+ SWIZZLE(COMPONENT_W, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
+};
+
+struct phys_reg {
+ unsigned reg;
+ unsigned mask;
+ unsigned swizzle;
+};
+
+/* Given the mask/swizzle of both the register and the original source,
+ * compose to find the actual mask/swizzle to give the hardware */
+
+static unsigned
+compose_writemask(unsigned mask, struct phys_reg reg)
+{
+ /* Note: the reg mask is guaranteed to be contiguous. So we shift
+ * into the X place, compose via a simple AND, and shift back */
+
+ unsigned shift = __builtin_ctz(reg.mask);
+ return ((reg.mask >> shift) & mask) << shift;
+}
+
+static unsigned
+compose_swizzle(unsigned swizzle, unsigned mask,
+ struct phys_reg reg, struct phys_reg dst)
+{
+ unsigned out = pan_compose_swizzle(swizzle, reg.swizzle);
+
+ /* Based on the register mask, we need to adjust over. E.g if we're
+ * writing to yz, a base swizzle of xy__ becomes _xy_. Save the
+ * original first component (x). But to prevent duplicate shifting
+ * (only applies to ALU -- mask param is set to xyzw out on L/S to
+ * prevent changes), we have to account for the shift inherent to the
+ * original writemask */
+
+ unsigned rep = out & 0x3;
+ unsigned shift = __builtin_ctz(dst.mask) - __builtin_ctz(mask);
+ unsigned shifted = out << (2*shift);
+
+ /* ..but we fill in the gaps so it appears to replicate */
+
+ for (unsigned s = 0; s < shift; ++s)
+ shifted |= rep << (2*s);
+
+ return shifted;
+}
+
+/* When we're 'squeezing down' the values in the IR, we maintain a hash
+ * as such */
+
+static unsigned
+find_or_allocate_temp(compiler_context *ctx, unsigned hash)
+{
+ if ((hash < 0) || (hash >= SSA_FIXED_MINIMUM))
+ return hash;
+
+ unsigned temp = (uintptr_t) _mesa_hash_table_u64_search(
+ ctx->hash_to_temp, hash + 1);
+
+ if (temp)
+ return temp - 1;
+
+ /* If no temp is find, allocate one */
+ temp = ctx->temp_count++;
+ ctx->max_hash = MAX2(ctx->max_hash, hash);
+
+ _mesa_hash_table_u64_insert(ctx->hash_to_temp,
+ hash + 1, (void *) ((uintptr_t) temp + 1));
+
+ return temp;
+}
+
+/* Callback for register allocation selection, trivial default for now */
+
+static unsigned int
+midgard_ra_select_callback(struct ra_graph *g, BITSET_WORD *regs, void *data)
+{
+ /* Choose the first available register to minimise register pressure */
+
+ for (int i = 0; i < (16 * WORK_STRIDE); ++i) {
+ if (BITSET_TEST(regs, i)) {
+ return i;
+ }
+ }
+
+ assert(0);
+ return 0;
+}
+
+/* Helper to return the default phys_reg for a given register */
+
+static struct phys_reg
+default_phys_reg(int reg)
+{
+ struct phys_reg r = {
+ .reg = reg,
+ .mask = 0xF, /* xyzw */
+ .swizzle = 0xE4 /* xyzw */
+ };
+
+ return r;
+}
+
+/* Determine which physical register, swizzle, and mask a virtual
+ * register corresponds to */
+
+static struct phys_reg
+index_to_reg(compiler_context *ctx, struct ra_graph *g, int reg)
+{
+ /* Check for special cases */
+ if (reg >= SSA_FIXED_MINIMUM)
+ return default_phys_reg(SSA_REG_FROM_FIXED(reg));
+ else if ((reg < 0) || !g)
+ return default_phys_reg(REGISTER_UNUSED);
+
+ /* Special cases aside, we pick the underlying register */
+ int virt = ra_get_node_reg(g, reg);
+
+ /* Divide out the register and classification */
+ int phys = virt / WORK_STRIDE;
+ int type = virt % WORK_STRIDE;
+
+ struct phys_reg r = {
+ .reg = phys,
+ .mask = reg_type_to_mask[type],
+ .swizzle = reg_type_to_swizzle[type]
+ };
+
+ /* Report that we actually use this register, and return it */
+ ctx->work_registers = MAX2(ctx->work_registers, phys);
+ return r;
+}
+
+/* This routine performs the actual register allocation. It should be succeeded
+ * by install_registers */
+
+struct ra_graph *
+allocate_registers(compiler_context *ctx)
+{
+ /* The number of vec4 work registers available depends on when the
+ * uniforms start, so compute that first */
+
+ int work_count = 16 - MAX2((ctx->uniform_cutoff - 8), 0);
+
+ int virtual_count = work_count * WORK_STRIDE;
+
+ /* First, initialize the RA */
+ struct ra_regs *regs = ra_alloc_reg_set(NULL, virtual_count, true);
+
+ int work_vec4 = ra_alloc_reg_class(regs);
+ int work_vec3 = ra_alloc_reg_class(regs);
+ int work_vec2 = ra_alloc_reg_class(regs);
+ int work_vec1 = ra_alloc_reg_class(regs);
+
+ unsigned classes[4] = {
+ work_vec1,
+ work_vec2,
+ work_vec3,
+ work_vec4
+ };
+
+ /* Add the full set of work registers */
+ for (unsigned i = 0; i < work_count; ++i) {
+ int base = WORK_STRIDE * i;
+
+ /* Build a full set of subdivisions */
+ ra_class_add_reg(regs, work_vec4, base);
+ ra_class_add_reg(regs, work_vec3, base + 1);
+ ra_class_add_reg(regs, work_vec3, base + 2);
+ ra_class_add_reg(regs, work_vec2, base + 3);
+ ra_class_add_reg(regs, work_vec2, base + 4);
+ ra_class_add_reg(regs, work_vec2, base + 5);
+ ra_class_add_reg(regs, work_vec1, base + 6);
+ ra_class_add_reg(regs, work_vec1, base + 7);
+ ra_class_add_reg(regs, work_vec1, base + 8);
+ ra_class_add_reg(regs, work_vec1, base + 9);
+
+ for (unsigned a = 0; a < 10; ++a) {
+ unsigned mask1 = reg_type_to_mask[a];
+
+ for (unsigned b = 0; b < 10; ++b) {
+ unsigned mask2 = reg_type_to_mask[b];
+
+ if (mask1 & mask2)
+ ra_add_reg_conflict(regs,
+ base + a, base + b);
+ }
+ }
+ }
+
+ /* We're done setting up */
+ ra_set_finalize(regs, NULL);
+
+ /* Transform the MIR into squeezed index form */
+ mir_foreach_block(ctx, block) {
+ mir_foreach_instr_in_block(block, ins) {
+ if (ins->compact_branch) continue;
+
+ ins->ssa_args.dest = find_or_allocate_temp(ctx, ins->ssa_args.dest);
+ ins->ssa_args.src0 = find_or_allocate_temp(ctx, ins->ssa_args.src0);
+
+ if (!ins->ssa_args.inline_constant)
+ ins->ssa_args.src1 = find_or_allocate_temp(ctx, ins->ssa_args.src1);
+
+ }
+ }
+
+ /* No register allocation to do with no SSA */
+
+ if (!ctx->temp_count)
+ return NULL;
+
+ /* Let's actually do register allocation */
+ int nodes = ctx->temp_count;
+ struct ra_graph *g = ra_alloc_interference_graph(regs, nodes);
+
+ /* Determine minimum size needed to hold values, to indirectly
+ * determine class */
+
+ unsigned *found_class = calloc(sizeof(unsigned), ctx->temp_count);
+
+ mir_foreach_block(ctx, block) {
+ mir_foreach_instr_in_block(block, ins) {
+ if (ins->compact_branch) continue;
+ if (ins->ssa_args.dest < 0) continue;
+ if (ins->ssa_args.dest >= SSA_FIXED_MINIMUM) continue;
+
+ int class = util_logbase2(ins->mask) + 1;
+
+ /* Use the largest class if there's ambiguity, this
+ * handles partial writes */
+
+ int dest = ins->ssa_args.dest;
+ found_class[dest] = MAX2(found_class[dest], class);
+ }
+ }
+
+ for (unsigned i = 0; i < ctx->temp_count; ++i) {
+ unsigned class = found_class[i];
+ if (!class) continue;
+ ra_set_node_class(g, i, classes[class - 1]);
+ }
+
+ /* Determine liveness */
+
+ int *live_start = malloc(nodes * sizeof(int));
+ int *live_end = malloc(nodes * sizeof(int));
+
+ /* Initialize as non-existent */
+
+ for (int i = 0; i < nodes; ++i) {
+ live_start[i] = live_end[i] = -1;
+ }
+
+ int d = 0;
+
+ mir_foreach_block(ctx, block) {
+ mir_foreach_instr_in_block(block, ins) {
+ if (ins->compact_branch) continue;
+
+ /* Dest is < 0 for st_vary instructions, which break
+ * the usual SSA conventions. Liveness analysis doesn't
+ * make sense on these instructions, so skip them to
+ * avoid memory corruption */
+
+ if (ins->ssa_args.dest < 0) continue;
+
+ if (ins->ssa_args.dest < SSA_FIXED_MINIMUM) {
+ /* If this destination is not yet live, it is
+ * now since we just wrote it */
+
+ int dest = ins->ssa_args.dest;
+
+ if (live_start[dest] == -1)
+ live_start[dest] = d;
+ }
+
+ /* Since we just used a source, the source might be
+ * dead now. Scan the rest of the block for
+ * invocations, and if there are none, the source dies
+ * */
+
+ int sources[2] = {
+ ins->ssa_args.src0, ins->ssa_args.src1
+ };
+
+ for (int src = 0; src < 2; ++src) {
+ int s = sources[src];
+
+ if (s < 0) continue;
+
+ if (s >= SSA_FIXED_MINIMUM) continue;
+
+ if (!mir_is_live_after(ctx, block, ins, s)) {
+ live_end[s] = d;
+ }
+ }
+
+ ++d;
+ }
+ }
+
+ /* If a node still hasn't been killed, kill it now */
+
+ for (int i = 0; i < nodes; ++i) {
+ /* live_start == -1 most likely indicates a pinned output */
+
+ if (live_end[i] == -1)
+ live_end[i] = d;
+ }
+
+ /* Setup interference between nodes that are live at the same time */
+
+ for (int i = 0; i < nodes; ++i) {
+ for (int j = i + 1; j < nodes; ++j) {
+ bool j_overlaps_i = live_start[j] < live_end[i];
+ bool i_overlaps_j = live_end[j] < live_start[i];
+
+ if (i_overlaps_j || j_overlaps_i)
+ ra_add_node_interference(g, i, j);
+ }
+ }
+
+ ra_set_select_reg_callback(g, midgard_ra_select_callback, NULL);
+
+ if (!ra_allocate(g)) {
+ unreachable("Error allocating registers\n");
+ }
+
+ /* Cleanup */
+ free(live_start);
+ free(live_end);
+
+ return g;
+}
+
+/* Once registers have been decided via register allocation
+ * (allocate_registers), we need to rewrite the MIR to use registers instead of
+ * indices */
+
+static void
+install_registers_instr(
+ compiler_context *ctx,
+ struct ra_graph *g,
+ midgard_instruction *ins)
+{
+ ssa_args args = ins->ssa_args;
+
+ switch (ins->type) {
+ case TAG_ALU_4: {
+ int adjusted_src = args.inline_constant ? -1 : args.src1;
+ struct phys_reg src1 = index_to_reg(ctx, g, args.src0);
+ struct phys_reg src2 = index_to_reg(ctx, g, adjusted_src);
+ struct phys_reg dest = index_to_reg(ctx, g, args.dest);
+
+ unsigned uncomposed_mask = ins->mask;
+ ins->mask = compose_writemask(uncomposed_mask, dest);
+
+ /* Adjust the dest mask if necessary. Mostly this is a no-op
+ * but it matters for dot products */
+ dest.mask = effective_writemask(&ins->alu, ins->mask);
+
+ midgard_vector_alu_src mod1 =
+ vector_alu_from_unsigned(ins->alu.src1);
+ mod1.swizzle = compose_swizzle(mod1.swizzle, uncomposed_mask, src1, dest);
+ ins->alu.src1 = vector_alu_srco_unsigned(mod1);
+
+ ins->registers.src1_reg = src1.reg;
+
+ ins->registers.src2_imm = args.inline_constant;
+
+ if (args.inline_constant) {
+ /* Encode inline 16-bit constant. See disassembler for
+ * where the algorithm is from */
+
+ ins->registers.src2_reg = ins->inline_constant >> 11;
+
+ int lower_11 = ins->inline_constant & ((1 << 12) - 1);
+ uint16_t imm = ((lower_11 >> 8) & 0x7) |
+ ((lower_11 & 0xFF) << 3);
+
+ ins->alu.src2 = imm << 2;
+ } else {
+ midgard_vector_alu_src mod2 =
+ vector_alu_from_unsigned(ins->alu.src2);
+ mod2.swizzle = compose_swizzle(
+ mod2.swizzle, uncomposed_mask, src2, dest);
+ ins->alu.src2 = vector_alu_srco_unsigned(mod2);
+
+ ins->registers.src2_reg = src2.reg;
+ }
+
+ ins->registers.out_reg = dest.reg;
+ break;
+ }
+
+ case TAG_LOAD_STORE_4: {
+ if (OP_IS_STORE_VARY(ins->load_store.op)) {
+ /* TODO: use ssa_args for st_vary */
+ ins->load_store.reg = 0;
+ } else {
+ /* Which physical register we read off depends on
+ * whether we are loading or storing -- think about the
+ * logical dataflow */
+
+ unsigned r = OP_IS_STORE(ins->load_store.op) ?
+ args.src0 : args.dest;
+ struct phys_reg src = index_to_reg(ctx, g, r);
+
+ ins->load_store.reg = src.reg;
+
+ ins->load_store.swizzle = compose_swizzle(
+ ins->load_store.swizzle, 0xF,
+ default_phys_reg(0), src);
+
+ ins->mask = compose_writemask(
+ ins->mask, src);
+ }
+
+ break;
+ }
+
+ default:
+ break;
+ }
+}
+
+void
+install_registers(compiler_context *ctx, struct ra_graph *g)
+{
+ mir_foreach_block(ctx, block) {
+ mir_foreach_instr_in_block(block, ins) {
+ if (ins->compact_branch) continue;
+ install_registers_instr(ctx, g, ins);
+ }
+ }
+
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-16 22:09:14 +0000