glsl: Remove lower_vec_index_to_swizzle.

GLSL's lower_vector_derefs already does this, and even if it didn't
nir_vector_extract() would when glsl-to-nir happens.

No effect on freedreno shader-db.

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/glsl_parser_extras.cpp

@@ -2412,7 +2412,6 @@ do_common_optimization(exec_list *ir, bool linked,
    OPT(do_algebraic, ir, native_integers, options);
    OPT(do_lower_jumps, ir, true, true, options->EmitNoMainReturn,
        options->EmitNoCont);
-   OPT(do_vec_index_to_swizzle, ir);
    OPT(lower_vector_insert, ir, false);
 
    /* If an optimization pass fails to preserve the invariant flag, calling

src/compiler/glsl/ir_optimization.h

@@ -105,7 +105,6 @@ bool do_mat_op_to_vec(exec_list *instructions);
 bool do_minmax_prune(exec_list *instructions);
 bool do_tree_grafting(exec_list *instructions);
 bool do_vec_index_to_cond_assign(exec_list *instructions);
-bool do_vec_index_to_swizzle(exec_list *instructions);
 bool lower_discard(exec_list *instructions);
 void lower_discard_flow(exec_list *instructions);
 bool lower_instructions(exec_list *instructions, unsigned what_to_lower);

src/compiler/glsl/linker.cpp

@@ -3546,7 +3546,6 @@ link_varyings(const struct gl_constants *consts, struct gl_shader_program *prog,
          continue;
 
       lower_vector_derefs(prog->_LinkedShaders[i]);
-      do_vec_index_to_swizzle(prog->_LinkedShaders[i]->ir);
    }
 
    return true;

src/compiler/glsl/lower_vec_index_to_swizzle.cpp

@@ -1,102 +0,0 @@
-/*
- * Copyright © 2010 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.
- */
-
-/**
- * \file lower_vec_index_to_swizzle.cpp
- *
- * Turns constant indexing into vector types to swizzles.  This will
- * let other swizzle-aware optimization passes catch these constructs,
- * and codegen backends not have to worry about this case.
- */
-
-#include "ir.h"
-#include "ir_rvalue_visitor.h"
-#include "ir_optimization.h"
-#include "compiler/glsl_types.h"
-#include "main/macros.h"
-
-namespace {
-
-class ir_vec_index_to_swizzle_visitor : public ir_rvalue_visitor {
-public:
-   ir_vec_index_to_swizzle_visitor()
-   {
-      progress = false;
-   }
-
-   ir_rvalue *convert_vector_extract_to_swizzle(ir_rvalue *val);
-
-   virtual void handle_rvalue(ir_rvalue **);
-
-   bool progress;
-};
-
-} /* anonymous namespace */
-
-void
-ir_vec_index_to_swizzle_visitor::handle_rvalue(ir_rvalue **rv)
-{
-   if (*rv == NULL)
-      return;
-
-   ir_expression *const expr = (*rv)->as_expression();
-   if (expr == NULL || expr->operation != ir_binop_vector_extract)
-      return;
-
-   void *mem_ctx = ralloc_parent(expr);
-   ir_constant *const idx =
-      expr->operands[1]->constant_expression_value(mem_ctx);
-   if (idx == NULL)
-      return;
-
-   this->progress = true;
-
-   /* Page 40 of the GLSL 1.20 spec says:
-    *
-    *     "When indexing with non-constant expressions, behavior is undefined
-    *     if the index is negative, or greater than or equal to the size of
-    *     the vector."
-    *
-    * The quoted spec text mentions non-constant expressions, but this code
-    * operates on constants.  These constants are the result of non-constant
-    * expressions that have been optimized to constants.  The common case here
-    * is a loop counter from an unrolled loop that is used to index a vector.
-    *
-    * The ir_swizzle constructor gets angry if the index is negative or too
-    * large.  For simplicity sake, just clamp the index to [0, size-1].
-    */
-   const int i = CLAMP(idx->value.i[0], 0,
-                       (int) expr->operands[0]->type->vector_elements - 1);
-
-   *rv = new(mem_ctx) ir_swizzle(expr->operands[0], i, 0, 0, 0, 1);
-}
-
-bool
-do_vec_index_to_swizzle(exec_list *instructions)
-{
-   ir_vec_index_to_swizzle_visitor v;
-
-   v.run(instructions);
-
-   return v.progress;
-}

src/compiler/glsl/meson.build

@@ -168,7 +168,6 @@ files_libglsl = files(
   'lower_subroutine.cpp',
   'lower_tess_level.cpp',
   'lower_vec_index_to_cond_assign.cpp',
-  'lower_vec_index_to_swizzle.cpp',
   'lower_vector_derefs.cpp',
   'lower_vector_insert.cpp',
   'opt_algebraic.cpp',

src/compiler/glsl/test_optpass.cpp

@@ -99,8 +99,6 @@ do_optimization(struct exec_list *ir, const char *optimization,
       return do_tree_grafting(ir);
    } else if (strcmp(optimization, "do_vec_index_to_cond_assign") == 0) {
       return do_vec_index_to_cond_assign(ir);
-   } else if (strcmp(optimization, "do_vec_index_to_swizzle") == 0) {
-      return do_vec_index_to_swizzle(ir);
    } else if (strcmp(optimization, "lower_discard") == 0) {
       return lower_discard(ir);
    } else if (sscanf(optimization, "lower_instructions ( %d ) ",