nir: Add a pass to inline functions

This commit adds a new NIR pass that lowers all function calls away by
inlining the functions.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

4 files changed, 274 insertions, 0 deletions

diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index 74636b1..1f85172 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -177,6 +177,7 @@ NIR_FILES = \
 	nir/nir_dominance.c \
 	nir/nir_from_ssa.c \
 	nir/nir_gs_count_vertices.c \
+	nir/nir_inline_functions.c \
 	nir/nir_intrinsics.c \
 	nir/nir_intrinsics.h \
 	nir/nir_instr_set.c \
diff --git a/src/compiler/nir/Makefile.sources b/src/compiler/nir/Makefile.sources
index b9506e8..00576f0 100644
--- a/src/compiler/nir/Makefile.sources
+++ b/src/compiler/nir/Makefile.sources
@@ -20,6 +20,7 @@ NIR_FILES = \
 	nir_dominance.c \
 	nir_from_ssa.c \
 	nir_gs_count_vertices.c \
+	nir_inline_functions.c \
 	nir_intrinsics.c \
 	nir_intrinsics.h \
 	nir_instr_set.c \
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 78bbdc0..37d2907 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2149,6 +2149,8 @@ bool nir_split_var_copies(nir_shader *shader);
 bool nir_lower_returns_impl(nir_function_impl *impl);
 bool nir_lower_returns(nir_shader *shader);
 
+bool nir_inline_functions(nir_shader *shader);
+
 void nir_lower_var_copy_instr(nir_intrinsic_instr *copy, void *mem_ctx);
 void nir_lower_var_copies(nir_shader *shader);
 
diff --git a/src/compiler/nir/nir_inline_functions.c b/src/compiler/nir/nir_inline_functions.c
new file mode 100644
index 0000000..4a08dcc
--- /dev/null
+++ b/src/compiler/nir/nir_inline_functions.c
@@ -0,0 +1,270 @@
+/*
+ * 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.
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+#include "nir_control_flow.h"
+
+struct inline_functions_state {
+   struct set *inlined;
+   nir_builder builder;
+   bool progress;
+};
+
+static bool inline_function_impl(nir_function_impl *impl, struct set *inlined);
+
+static bool
+rewrite_param_derefs_block(nir_block *block, void *void_state)
+{
+   nir_call_instr *call = void_state;
+
+   nir_foreach_instr_safe(block, instr) {
+      if (instr->type != nir_instr_type_intrinsic)
+         continue;
+
+      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+      for (unsigned i = 0;
+           i < nir_intrinsic_infos[intrin->intrinsic].num_variables; i++) {
+         if (intrin->variables[i]->var->data.mode != nir_var_param)
+            continue;
+
+         int param_idx = intrin->variables[i]->var->data.location;
+
+         nir_deref_var *call_deref;
+         if (param_idx >= 0) {
+            assert(param_idx < call->callee->num_params);
+            call_deref = call->params[param_idx];
+         } else {
+            call_deref = call->return_deref;
+         }
+         assert(call_deref);
+
+         nir_deref_var *new_deref = nir_deref_as_var(nir_copy_deref(intrin, &call_deref->deref));
+         nir_deref *new_tail = nir_deref_tail(&new_deref->deref);
+         new_tail->child = intrin->variables[i]->deref.child;
+         ralloc_steal(new_tail, new_tail->child);
+         intrin->variables[i] = new_deref;
+      }
+   }
+
+   return true;
+}
+
+static void
+lower_param_to_local(nir_variable *param, nir_function_impl *impl, bool write)
+{
+   if (param->data.mode != nir_var_param)
+      return;
+
+   nir_parameter_type param_type;
+   if (param->data.location >= 0) {
+      assert(param->data.location < impl->num_params);
+      param_type = impl->function->params[param->data.location].param_type;
+   } else {
+      /* Return variable */
+      param_type = nir_parameter_out;
+   }
+
+   if ((write && param_type == nir_parameter_in) ||
+       (!write && param_type == nir_parameter_out)) {
+      /* In this case, we need a shadow copy.  Turn it into a local */
+      param->data.mode = nir_var_local;
+      exec_list_push_tail(&impl->locals, &param->node);
+   }
+}
+
+static bool
+lower_params_to_locals_block(nir_block *block, void *void_state)
+{
+   nir_function_impl *impl = void_state;
+
+   nir_foreach_instr_safe(block, instr) {
+      if (instr->type != nir_instr_type_intrinsic)
+         continue;
+
+      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+      switch (intrin->intrinsic) {
+      case nir_intrinsic_store_var:
+         lower_param_to_local(intrin->variables[0]->var, impl, true);
+         break;
+
+      case nir_intrinsic_copy_var:
+         lower_param_to_local(intrin->variables[0]->var, impl, true);
+         lower_param_to_local(intrin->variables[1]->var, impl, false);
+         break;
+
+      case nir_intrinsic_load_var:
+         /* All other intrinsics which access variables (image_load_store)
+          * do so in a read-only fasion.
+          */
+         for (unsigned i = 0;
+              i < nir_intrinsic_infos[intrin->intrinsic].num_variables; i++) {
+            lower_param_to_local(intrin->variables[i]->var, impl, false);
+         }
+         break;
+
+      default:
+         continue;
+      }
+   }
+
+   return true;
+}
+
+static bool
+inline_functions_block(nir_block *block, void *void_state)
+{
+   struct inline_functions_state *state = void_state;
+
+   nir_builder *b = &state->builder;
+
+   /* This is tricky.  We're iterating over instructions in a block but, as
+    * we go, the block and its instruction list are being split into
+    * pieces.  However, this *should* be safe since foreach_safe always
+    * stashes the next thing in the iteration.  That next thing will
+    * properly get moved to the next block when it gets split, and we
+    * continue iterating there.
+    */
+   nir_foreach_instr_safe(block, instr) {
+      if (instr->type != nir_instr_type_call)
+         continue;
+
+      state->progress = true;
+
+      nir_call_instr *call = nir_instr_as_call(instr);
+      assert(call->callee->impl);
+
+      inline_function_impl(call->callee->impl, state->inlined);
+
+      nir_function_impl *callee_copy =
+         nir_function_impl_clone(call->callee->impl);
+      callee_copy->function = call->callee;
+
+      /* Add copies of all in parameters */
+      assert(call->num_params == callee_copy->num_params);
+
+      exec_list_append(&b->impl->locals, &callee_copy->locals);
+      exec_list_append(&b->impl->registers, &callee_copy->registers);
+
+      b->cursor = nir_before_instr(&call->instr);
+
+      /* We now need to tie the two functions together using the
+       * parameters.  There are two ways we do this: One is to turn the
+       * parameter into a local variable and do a shadow-copy.  The other
+       * is to treat the parameter as a "proxy" and rewrite derefs to use
+       * the actual variable that comes from the call instruction.  We
+       * implement both schemes.  The first is needed in the case where we
+       * have an in parameter that we write or similar.  The second case is
+       * needed for handling things such as images and uniforms properly.
+       */
+
+      /* Figure out when we need to lower to a shadow local */
+      nir_foreach_block(callee_copy, lower_params_to_locals_block, callee_copy);
+      for (unsigned i = 0; i < callee_copy->num_params; i++) {
+         nir_variable *param = callee_copy->params[i];
+
+         if (param->data.mode == nir_var_local &&
+             call->callee->params[i].param_type != nir_parameter_out) {
+            nir_copy_deref_var(b, nir_deref_var_create(b->shader, param),
+                                  call->params[i]);
+         }
+      }
+
+      nir_foreach_block(callee_copy, rewrite_param_derefs_block, call);
+
+      /* Pluck the body out of the function and place it here */
+      nir_cf_list body;
+      nir_cf_list_extract(&body, &callee_copy->body);
+      nir_cf_reinsert(&body, b->cursor);
+
+      b->cursor = nir_before_instr(&call->instr);
+
+      /* Add copies of all out parameters and the return */
+      assert(call->num_params == callee_copy->num_params);
+      for (unsigned i = 0; i < callee_copy->num_params; i++) {
+         nir_variable *param = callee_copy->params[i];
+
+         if (param->data.mode == nir_var_local &&
+             call->callee->params[i].param_type != nir_parameter_in) {
+            nir_copy_deref_var(b, call->params[i],
+                                  nir_deref_var_create(b->shader, param));
+         }
+      }
+      if (!glsl_type_is_void(call->callee->return_type) &&
+          callee_copy->return_var->data.mode == nir_var_local) {
+         nir_copy_deref_var(b, call->return_deref,
+                               nir_deref_var_create(b->shader,
+                                                    callee_copy->return_var));
+      }
+
+      nir_instr_remove(&call->instr);
+   }
+
+   return true;
+}
+
+static bool
+inline_function_impl(nir_function_impl *impl, struct set *inlined)
+{
+   if (_mesa_set_search(inlined, impl))
+      return false; /* Already inlined */
+
+   struct inline_functions_state state;
+
+   state.inlined = inlined;
+   state.progress = false;
+   nir_builder_init(&state.builder, impl);
+
+   nir_foreach_block(impl, inline_functions_block, &state);
+
+   if (state.progress) {
+      /* SSA and register indices are completely messed up now */
+      nir_index_ssa_defs(impl);
+      nir_index_local_regs(impl);
+
+      nir_metadata_preserve(impl, nir_metadata_none);
+   }
+
+   _mesa_set_add(inlined, impl);
+
+   return state.progress;
+}
+
+bool
+nir_inline_functions(nir_shader *shader)
+{
+   struct set *inlined = _mesa_set_create(NULL, _mesa_hash_pointer,
+                                          _mesa_key_pointer_equal);
+   bool progress = false;
+
+   nir_foreach_function(shader, function) {
+      if (function->impl)
+         progress = inline_function_impl(function->impl, inlined) || progress;
+   }
+
+   _mesa_set_destroy(inlined, NULL);
+
+   return progress;
+}