glsl: Remove lower_output_reads.

No longer used since 214c774ba6 ("mesa/st: Remove st_glsl_to_tgsi.").

Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18466>

src/compiler/glsl/ir_optimization.h

@@ -112,7 +112,6 @@ void lower_discard_flow(exec_list *instructions);
 bool lower_instructions(exec_list *instructions, unsigned what_to_lower);
 bool lower_clip_cull_distance(struct gl_shader_program *prog,
                               gl_linked_shader *shader);
-void lower_output_reads(unsigned stage, exec_list *instructions);
 bool lower_packing_builtins(exec_list *instructions, int op_mask);
 bool lower_vector_insert(exec_list *instructions, bool lower_nonconstant_index);
 bool lower_vector_derefs(gl_linked_shader *shader);

src/compiler/glsl/lower_output_reads.cpp

@@ -1,182 +0,0 @@
-/*
- * Copyright © 2012 Vincent Lejeune
- * Copyright © 2012 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 "ir.h"
-#include "util/hash_table.h"
-
-/**
- * \file lower_output_reads.cpp
- *
- * In GLSL, shader output variables (such as varyings) can be both read and
- * written.  However, on some hardware, reading an output register causes
- * trouble.
- *
- * This pass creates temporary shadow copies of every (used) shader output,
- * and replaces all accesses to use those instead.  It also adds code to the
- * main() function to copy the final values to the actual shader outputs.
- */
-
-namespace {
-
-class output_read_remover : public ir_hierarchical_visitor {
-protected:
-   /**
-    * A hash table mapping from the original ir_variable shader outputs
-    * (ir_var_shader_out mode) to the new temporaries to be used instead.
-    */
-   hash_table *replacements;
-
-   unsigned stage;
-public:
-   output_read_remover(unsigned stage);
-   ~output_read_remover();
-   virtual ir_visitor_status visit(class ir_dereference_variable *);
-   virtual ir_visitor_status visit_leave(class ir_emit_vertex *);
-   virtual ir_visitor_status visit_leave(class ir_return *);
-   virtual ir_visitor_status visit_leave(class ir_function_signature *);
-};
-
-} /* anonymous namespace */
-
-/**
- * Hash function for the output variables - computes the hash of the name.
- * NOTE: We're using the name string to ensure that the hash doesn't depend
- * on any random factors, otherwise the output_read_remover could produce
- * the random order of the assignments.
- *
- * NOTE: If you want to reuse this function please take into account that
- * generally the names of the variables are non-unique.
- */
-static unsigned
-hash_table_var_hash(const void *key)
-{
-   const ir_variable * var = static_cast<const ir_variable *>(key);
-   return _mesa_hash_string(var->name);
-}
-
-output_read_remover::output_read_remover(unsigned stage)
-{
-   this->stage = stage;
-   replacements = _mesa_hash_table_create(NULL, hash_table_var_hash,
-                                          _mesa_key_pointer_equal);
-}
-
-output_read_remover::~output_read_remover()
-{
-   _mesa_hash_table_destroy(replacements, NULL);
-}
-
-ir_visitor_status
-output_read_remover::visit(ir_dereference_variable *ir)
-{
-   if (ir->var->data.mode != ir_var_shader_out || ir->var->data.fb_fetch_output)
-      return visit_continue;
-
-   hash_entry *entry = _mesa_hash_table_search(replacements, ir->var);
-   ir_variable *temp = entry ? (ir_variable *) entry->data : NULL;
-
-   /* If we don't have an existing temporary, create one. */
-   if (temp == NULL) {
-      void *var_ctx = ralloc_parent(ir->var);
-      temp = new(var_ctx) ir_variable(ir->var->type, ir->var->name,
-                                      ir_var_temporary);
-      /* copy flags which affect arithematical precision */
-      temp->data.invariant = ir->var->data.invariant;
-      temp->data.precise = ir->var->data.precise;
-      temp->data.precision = ir->var->data.precision;
-      _mesa_hash_table_insert(replacements, ir->var, temp);
-      ir->var->insert_after(temp);
-   }
-
-   /* Update the dereference to use the temporary */
-   ir->var = temp;
-
-   return visit_continue;
-}
-
-/**
- * Create an assignment to copy a temporary value back to the actual output.
- */
-static ir_assignment *
-copy(void *ctx, ir_variable *output, ir_variable *temp)
-{
-   ir_dereference_variable *lhs = new(ctx) ir_dereference_variable(output);
-   ir_dereference_variable *rhs = new(ctx) ir_dereference_variable(temp);
-   return new(ctx) ir_assignment(lhs, rhs);
-}
-
-/** Insert a copy-back assignment before a "return" statement or a call to
- * EmitVertex().
- */
-static void
-emit_return_copy(const void *key, void *data, void *closure)
-{
-   ir_return *ir = (ir_return *) closure;
-   ir->insert_before(copy(ir, (ir_variable *) key, (ir_variable *) data));
-}
-
-/** Insert a copy-back assignment at the end of the main() function */
-static void
-emit_main_copy(const void *key, void *data, void *closure)
-{
-   ir_function_signature *sig = (ir_function_signature *) closure;
-   sig->body.push_tail(copy(sig, (ir_variable *) key, (ir_variable *) data));
-}
-
-ir_visitor_status
-output_read_remover::visit_leave(ir_return *ir)
-{
-   hash_table_call_foreach(replacements, emit_return_copy, ir);
-   return visit_continue;
-}
-
-ir_visitor_status
-output_read_remover::visit_leave(ir_emit_vertex *ir)
-{
-   hash_table_call_foreach(replacements, emit_return_copy, ir);
-   return visit_continue;
-}
-
-ir_visitor_status
-output_read_remover::visit_leave(ir_function_signature *sig)
-{
-   if (strcmp(sig->function_name(), "main") != 0)
-      return visit_continue;
-
-   hash_table_call_foreach(replacements, emit_main_copy, sig);
-   return visit_continue;
-}
-
-void
-lower_output_reads(unsigned stage, exec_list *instructions)
-{
-   /* Due to the possible interactions between multiple tessellation control
-    * shader invocations, we leave output variables as-is.
-    */
-   if (stage == MESA_SHADER_TESS_CTRL)
-      return;
-
-   output_read_remover v(stage);
-   visit_list_elements(&v, instructions);
-}

src/compiler/glsl/meson.build

@@ -172,7 +172,6 @@ files_libglsl = files(
   'lower_vec_index_to_swizzle.cpp',
   'lower_vector_derefs.cpp',
   'lower_vector_insert.cpp',
-  'lower_output_reads.cpp',
   'opt_algebraic.cpp',
   'opt_array_splitting.cpp',
   'opt_constant_folding.cpp',