From 23d42b46e306d4104e534842f6dec3500d331cae Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Tue, 24 Feb 2015 01:00:22 -0800 Subject: [PATCH] glsl: Delete dead discard conditions in constant folding. opt_constant_folding() already detects conditional assignments where the condition is constant, and either deletes the assignment or the condition. Make it handle discards in the same fashion. Spotted happening in the wild in Tropico 5 shaders. Signed-off-by: Kenneth Graunke Reviewed-by: Ian Romanick Reviewed-by: Connor Abbott Reviewed-by: Matt Turner Reviewed-by: Eric Anholt --- src/glsl/opt_constant_folding.cpp | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/src/glsl/opt_constant_folding.cpp b/src/glsl/opt_constant_folding.cpp index 74b855e5e94..4aae3f0ddf2 100644 --- a/src/glsl/opt_constant_folding.cpp +++ b/src/glsl/opt_constant_folding.cpp @@ -50,6 +50,7 @@ public: /* empty */ } + virtual ir_visitor_status visit_enter(ir_discard *ir); virtual ir_visitor_status visit_enter(ir_assignment *ir); virtual ir_visitor_status visit_enter(ir_call *ir); @@ -93,6 +94,29 @@ ir_constant_folding_visitor::handle_rvalue(ir_rvalue **rvalue) } } +ir_visitor_status +ir_constant_folding_visitor::visit_enter(ir_discard *ir) +{ + if (ir->condition) { + ir->condition->accept(this); + handle_rvalue(&ir->condition); + + ir_constant *const_val = ir->condition->as_constant(); + /* If the condition is constant, either remove the condition or + * remove the never-executed assignment. + */ + if (const_val) { + if (const_val->value.b[0]) + ir->condition = NULL; + else + ir->remove(); + this->progress = true; + } + } + + return visit_continue_with_parent; +} + ir_visitor_status ir_constant_folding_visitor::visit_enter(ir_assignment *ir) { -- 2.30.2