From ff5254bf089cdf032465eac225954fe046154cc1 Mon Sep 17 00:00:00 2001 From: Ian Romanick Date: Wed, 20 Sep 2017 19:51:39 -0500 Subject: [PATCH] glsl: Move 'foo = foo;' optimization to opt_dead_code_local MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The optimization as done in opt_copy_propagation would have to be removed in the next patch. If we just eliminate that optimization altogether, shader-db results, even on platforms that use NIR, are hurt quite substantially. I have not investigated why NIR isn't picking up the slack here. Signed-off-by: Ian Romanick Reviewed-by: Alejandro Piñeiro Cc: Jason Ekstrand --- src/compiler/glsl/opt_copy_propagation.cpp | 19 +++++++------------ src/compiler/glsl/opt_dead_code_local.cpp | 11 +++++++++++ 2 files changed, 18 insertions(+), 12 deletions(-) diff --git a/src/compiler/glsl/opt_copy_propagation.cpp b/src/compiler/glsl/opt_copy_propagation.cpp index b72ae5a5e11..b8ef0de0a30 100644 --- a/src/compiler/glsl/opt_copy_propagation.cpp +++ b/src/compiler/glsl/opt_copy_propagation.cpp @@ -348,18 +348,13 @@ ir_copy_propagation_visitor::add_copy(ir_assignment *ir) ir_variable *lhs_var = ir->whole_variable_written(); ir_variable *rhs_var = ir->rhs->whole_variable_referenced(); - if ((lhs_var != NULL) && (rhs_var != NULL)) { - if (lhs_var == rhs_var) { - /* This is a dumb assignment, but we've conveniently noticed - * it here. Removing it now would mess up the loop iteration - * calling us. Just flag it to not execute, and someone else - * will clean up the mess. - */ - ir->condition = new(ralloc_parent(ir)) ir_constant(false); - this->progress = true; - } else if (lhs_var->data.mode != ir_var_shader_storage && - lhs_var->data.mode != ir_var_shader_shared && - lhs_var->data.precise == rhs_var->data.precise) { + /* Don't try to remove a dumb assignment of a variable to itself. Removing + * it now would mess up the loop iteration calling us. + */ + if (lhs_var != NULL && rhs_var != NULL && lhs_var != rhs_var) { + if (lhs_var->data.mode != ir_var_shader_storage && + lhs_var->data.mode != ir_var_shader_shared && + lhs_var->data.precise == rhs_var->data.precise) { assert(lhs_var); assert(rhs_var); _mesa_hash_table_insert(acp, lhs_var, rhs_var); diff --git a/src/compiler/glsl/opt_dead_code_local.cpp b/src/compiler/glsl/opt_dead_code_local.cpp index a4038794c6b..3cbc441ac9c 100644 --- a/src/compiler/glsl/opt_dead_code_local.cpp +++ b/src/compiler/glsl/opt_dead_code_local.cpp @@ -173,6 +173,17 @@ process_assignment(void *lin_ctx, ir_assignment *ir, exec_list *assignments) bool progress = false; kill_for_derefs_visitor v(assignments); + if (ir->condition == NULL) { + /* If this is an assignment of the form "foo = foo;", remove the whole + * instruction and be done with it. + */ + const ir_variable *const lhs_var = ir->whole_variable_written(); + if (lhs_var != NULL && lhs_var == ir->rhs->whole_variable_referenced()) { + ir->remove(); + return true; + } + } + /* Kill assignment entries for things used to produce this assignment. */ ir->rhs->accept(&v); if (ir->condition) { -- 2.30.2