gallium/ttn: add support for temp arrays

Since the rest of NIR really would rather have these as variables rather
than registers, create a nir_variable per array.  But rather than
completely re-arrange ttn to be variable based rather than register
based, keep the registers.  In the cases where there is a matching var
for the reg, ttn_emit_instruction will append the appropriate intrinsic
to get things back from the shadow reg into the variable.

NOTE: this doesn't quite handle TEMP[ADDR[]] when the DCL doesn't give
an array id.  But those just kinda suck, and should really go away.
AFAICT we don't get those from glsl.  Might be an issue for some other
state tracker.

v2: rework to use load_var/store_var with deref chains
v3: create new "burner" reg for temporarily holding the (potentially
writemask'd) dest after each instruction; add load_var to initialize
temporary dest in case not all components are overwritten
v4: review comments: asserts and use ttn_src_for_indirect() in
ttn_array_deref() so we can drop later patch converting to use vec1 for
addr reg (since ttn_src_for_indirect() handles the imov to vec1 from
tgsi addr component that we want)
v5: rebase: new requirements about parent mem ctx for derefs

Signed-off-by: Rob Clark <robclark@freedesktop.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

diff --git a/src/gallium/auxiliary/nir/tgsi_to_nir.c b/src/gallium/auxiliary/nir/tgsi_to_nir.c
index fcccdad..c897303 100644 (file)
--- a/src/gallium/auxiliary/nir/tgsi_to_nir.c
+++ b/src/gallium/auxiliary/nir/tgsi_to_nir.c
@@ -44,6 +44,7 @@
 struct ttn_reg_info {
    /** nir register containing this TGSI index. */
    nir_register *reg;
+   nir_variable *var;
    /** Offset (in vec4s) from the start of var for this TGSI index. */
    int offset;
 };
@@ -120,21 +121,32 @@ ttn_emit_declaration(struct ttn_compile *c)
    unsigned i;
 
    if (file == TGSI_FILE_TEMPORARY) {
-      nir_register *reg;
-      if (c->scan->indirect_files & (1 << file)) {
-         reg = nir_local_reg_create(b->impl);
-         reg->num_components = 4;
-         reg->num_array_elems = array_size;
+      if (decl->Declaration.Array) {
+         /* for arrays, we create variables instead of registers: */
+         nir_variable *var = rzalloc(b->shader, nir_variable);
+
+         var->type = glsl_array_type(glsl_vec4_type(), array_size);
+         var->data.mode = nir_var_global;
+         var->name = ralloc_asprintf(var, "arr_%d", decl->Array.ArrayID);
+
+         exec_list_push_tail(&b->shader->globals, &var->node);
 
          for (i = 0; i < array_size; i++) {
-            c->temp_regs[decl->Range.First + i].reg = reg;
+            /* point all the matching slots to the same var,
+             * with appropriate offset set, mostly just so
+             * we know what to do when tgsi does a non-indirect
+             * access
+             */
+            c->temp_regs[decl->Range.First + i].reg = NULL;
+            c->temp_regs[decl->Range.First + i].var = var;
             c->temp_regs[decl->Range.First + i].offset = i;
          }
       } else {
          for (i = 0; i < array_size; i++) {
-            reg = nir_local_reg_create(b->impl);
+            nir_register *reg = nir_local_reg_create(b->impl);
             reg->num_components = 4;
             c->temp_regs[decl->Range.First + i].reg = reg;
+            c->temp_regs[decl->Range.First + i].var = NULL;
             c->temp_regs[decl->Range.First + i].offset = 0;
          }
       }
@@ -245,6 +257,32 @@ ttn_emit_immediate(struct ttn_compile *c)
 static nir_src *
 ttn_src_for_indirect(struct ttn_compile *c, struct tgsi_ind_register *indirect);
 
+/* generate either a constant or indirect deref chain for accessing an
+ * array variable.
+ */
+static nir_deref_var *
+ttn_array_deref(struct ttn_compile *c, nir_intrinsic_instr *instr,
+                nir_variable *var, unsigned offset,
+                struct tgsi_ind_register *indirect)
+{
+   nir_deref_var *deref = nir_deref_var_create(instr, var);
+   nir_deref_array *arr = nir_deref_array_create(deref);
+
+   arr->base_offset = offset;
+   arr->deref.type = glsl_get_array_element(var->type);
+
+   if (indirect) {
+      arr->deref_array_type = nir_deref_array_type_indirect;
+      arr->indirect = *ttn_src_for_indirect(c, indirect);
+   } else {
+      arr->deref_array_type = nir_deref_array_type_direct;
+   }
+
+   deref->deref.child = &arr->deref;
+
+   return deref;
+}
+
 static nir_src
 ttn_src_for_file_and_index(struct ttn_compile *c, unsigned file, unsigned index,
                            struct tgsi_ind_register *indirect)
@@ -256,10 +294,25 @@ ttn_src_for_file_and_index(struct ttn_compile *c, unsigned file, unsigned index,
 
    switch (file) {
    case TGSI_FILE_TEMPORARY:
-      src.reg.reg = c->temp_regs[index].reg;
-      src.reg.base_offset = c->temp_regs[index].offset;
-      if (indirect)
-         src.reg.indirect = ttn_src_for_indirect(c, indirect);
+      if (c->temp_regs[index].var) {
+         unsigned offset = c->temp_regs[index].offset;
+         nir_variable *var = c->temp_regs[index].var;
+         nir_intrinsic_instr *load;
+
+         load = nir_intrinsic_instr_create(b->shader,
+                                           nir_intrinsic_load_var);
+         load->num_components = 4;
+         load->variables[0] = ttn_array_deref(c, load, var, offset, indirect);
+
+         nir_ssa_dest_init(&load->instr, &load->dest, 4, NULL);
+         nir_instr_insert_after_cf_list(b->cf_node_list, &load->instr);
+
+         src = nir_src_for_ssa(&load->dest.ssa);
+
+      } else {
+         assert(!indirect);
+         src.reg.reg = c->temp_regs[index].reg;
+      }
       break;
 
    case TGSI_FILE_ADDRESS:
@@ -345,8 +398,49 @@ ttn_get_dest(struct ttn_compile *c, struct tgsi_full_dst_register *tgsi_fdst)
    memset(&dest, 0, sizeof(dest));
 
    if (tgsi_dst->File == TGSI_FILE_TEMPORARY) {
-      dest.dest.reg.reg = c->temp_regs[index].reg;
-      dest.dest.reg.base_offset = c->temp_regs[index].offset;
+      if (c->temp_regs[index].var) {
+          nir_builder *b = &c->build;
+          nir_intrinsic_instr *load;
+          struct tgsi_ind_register *indirect =
+                tgsi_dst->Indirect ? &tgsi_fdst->Indirect : NULL;
+          nir_register *reg;
+
+         /* this works, because TGSI will give us a base offset
+          * (in case of indirect index) that points back into
+          * the array.  Access can be direct or indirect, we
+          * don't really care.  Just create a one-shot dst reg
+          * that will get store_var'd back into the array var
+          * at the end of ttn_emit_instruction()
+          */
+         reg = nir_local_reg_create(c->build.impl);
+         reg->num_components = 4;
+         dest.dest.reg.reg = reg;
+         dest.dest.reg.base_offset = 0;
+
+         /* since the alu op might not write to all components
+          * of the temporary, we must first do a load_var to
+          * get the previous array elements into the register.
+          * This is one area that NIR could use a bit of
+          * improvement (or opt pass to clean up the mess
+          * once things are scalarized)
+          */
+
+         load = nir_intrinsic_instr_create(c->build.shader,
+                                           nir_intrinsic_load_var);
+         load->num_components = 4;
+         load->variables[0] =
+               ttn_array_deref(c, load, c->temp_regs[index].var,
+                               c->temp_regs[index].offset,
+                               indirect);
+
+         load->dest = nir_dest_for_reg(reg);
+
+         nir_instr_insert_after_cf_list(b->cf_node_list, &load->instr);
+      } else {
+         assert(!tgsi_dst->Indirect);
+         dest.dest.reg.reg = c->temp_regs[index].reg;
+         dest.dest.reg.base_offset = c->temp_regs[index].offset;
+      }
    } else if (tgsi_dst->File == TGSI_FILE_OUTPUT) {
       dest.dest.reg.reg = c->output_regs[index].reg;
       dest.dest.reg.base_offset = c->output_regs[index].offset;
@@ -358,12 +452,28 @@ ttn_get_dest(struct ttn_compile *c, struct tgsi_full_dst_register *tgsi_fdst)
    dest.write_mask = tgsi_dst->WriteMask;
    dest.saturate = false;
 
-   if (tgsi_dst->Indirect)
+   if (tgsi_dst->Indirect && (tgsi_dst->File != TGSI_FILE_TEMPORARY))
       dest.dest.reg.indirect = ttn_src_for_indirect(c, &tgsi_fdst->Indirect);
 
    return dest;
 }
 
+static nir_variable *
+ttn_get_var(struct ttn_compile *c, struct tgsi_full_dst_register *tgsi_fdst)
+{
+   struct tgsi_dst_register *tgsi_dst = &tgsi_fdst->Register;
+   unsigned index = tgsi_dst->Index;
+
+   if (tgsi_dst->File == TGSI_FILE_TEMPORARY) {
+      /* we should not have an indirect when there is no var! */
+      if (!c->temp_regs[index].var)
+         assert(!tgsi_dst->Indirect);
+      return c->temp_regs[index].var;
+   }
+
+   return NULL;
+}
+
 static nir_ssa_def *
 ttn_get_src(struct ttn_compile *c, struct tgsi_full_src_register *tgsi_fsrc)
 {
@@ -1134,6 +1244,7 @@ ttn_emit_instruction(struct ttn_compile *c)
    struct tgsi_full_instruction *tgsi_inst = &c->token->FullInstruction;
    unsigned i;
    unsigned tgsi_op = tgsi_inst->Instruction.Opcode;
+   struct tgsi_full_dst_register *tgsi_dst = &tgsi_inst->Dst[0];
 
    if (tgsi_op == TGSI_OPCODE_END)
       return;
@@ -1142,7 +1253,7 @@ ttn_emit_instruction(struct ttn_compile *c)
    for (i = 0; i < TGSI_FULL_MAX_SRC_REGISTERS; i++) {
       src[i] = ttn_get_src(c, &tgsi_inst->Src[i]);
    }
-   nir_alu_dest dest = ttn_get_dest(c, &tgsi_inst->Dst[0]);
+   nir_alu_dest dest = ttn_get_dest(c, tgsi_dst);
 
    switch (tgsi_op) {
    case TGSI_OPCODE_RSQ:
@@ -1332,6 +1443,25 @@ ttn_emit_instruction(struct ttn_compile *c)
       assert(!dest.dest.is_ssa);
       ttn_move_dest(b, dest, nir_fsat(b, ttn_src_for_dest(b, &dest)));
    }
+
+   /* if the dst has a matching var, append store_global to move
+    * output from reg to var
+    */
+   nir_variable *var = ttn_get_var(c, tgsi_dst);
+   if (var) {
+      unsigned index = tgsi_dst->Register.Index;
+      unsigned offset = c->temp_regs[index].offset;
+      nir_intrinsic_instr *store =
+         nir_intrinsic_instr_create(b->shader, nir_intrinsic_store_var);
+      struct tgsi_ind_register *indirect = tgsi_dst->Register.Indirect ?
+                                           &tgsi_dst->Indirect : NULL;
+
+      store->num_components = 4;
+      store->variables[0] = ttn_array_deref(c, store, var, offset, indirect);
+      store->src[0] = nir_src_for_reg(dest.dest.reg.reg);
+
+      nir_instr_insert_after_cf_list(b->cf_node_list, &store->instr);
+   }
 }
 
 /**