Module: Mesa Branch: master Commit: 4a026d6ba50034c326eb6cfd0b555f57d83ab609 URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=4a026d6ba50034c326eb6cfd0b555f57d83ab609
Author: Ian Romanick <[email protected]> Date: Mon Aug 1 13:55:46 2011 -0700 glsl: Slight change to the code generated by if-flattening Now the condition (for the then-clause) and the inverse condition (for the else-clause) get written to separate temporary variables. In the presence of complex conditions, this shouldn't result in more code being generated. If the original if-statement was if (a && b && c && d && e) { ... } else { ... } The lowered code will be if_to_cond_assign_then = a && b && c && d && e; ... if_to_cond_assign_else = !if_to_cond_assign_then; ... Reviewed-by: Eric Anholt <[email protected]> --- src/glsl/lower_if_to_cond_assign.cpp | 60 ++++++++++++++++++++++------------ 1 files changed, 39 insertions(+), 21 deletions(-) diff --git a/src/glsl/lower_if_to_cond_assign.cpp b/src/glsl/lower_if_to_cond_assign.cpp index 5c74bc1..a709755 100644 --- a/src/glsl/lower_if_to_cond_assign.cpp +++ b/src/glsl/lower_if_to_cond_assign.cpp @@ -136,7 +136,6 @@ ir_if_to_cond_assign_visitor::visit_leave(ir_if *ir) return visit_continue; bool found_control_flow = false; - ir_variable *cond_var; ir_assignment *assign; ir_dereference_variable *deref; @@ -154,31 +153,50 @@ ir_if_to_cond_assign_visitor::visit_leave(ir_if *ir) void *mem_ctx = ralloc_parent(ir); - /* Store the condition to a variable so the assignment conditions are - * simpler. + /* Store the condition to a variable. Move all of the instructions from + * the then-clause of the if-statement. Use the condition variable as a + * condition for all assignments. */ - cond_var = new(mem_ctx) ir_variable(glsl_type::bool_type, - "if_to_cond_assign_condition", - ir_var_temporary); - ir->insert_before(cond_var); - - deref = new(mem_ctx) ir_dereference_variable(cond_var); - assign = new(mem_ctx) ir_assignment(deref, - ir->condition, NULL); + ir_variable *const then_var = + new(mem_ctx) ir_variable(glsl_type::bool_type, + "if_to_cond_assign_then", + ir_var_temporary); + ir->insert_before(then_var); + + ir_dereference_variable *then_cond = + new(mem_ctx) ir_dereference_variable(then_var); + + assign = new(mem_ctx) ir_assignment(then_cond, ir->condition); ir->insert_before(assign); - /* Now, move all of the instructions out of the if blocks, putting - * conditions on assignments. - */ - move_block_to_cond_assign(mem_ctx, ir, deref, + move_block_to_cond_assign(mem_ctx, ir, then_cond, &ir->then_instructions); - ir_rvalue *inverse = - new(mem_ctx) ir_expression(ir_unop_logic_not, - glsl_type::bool_type, - deref->clone(mem_ctx, NULL), - NULL); - move_block_to_cond_assign(mem_ctx, ir, inverse, &ir->else_instructions); + /* If there are instructions in the else-clause, store the inverse of the + * condition to a variable. Move all of the instructions from the + * else-clause if the if-statement. Use the (inverse) condition variable + * as a condition for all assignments. + */ + if (!ir->else_instructions.is_empty()) { + ir_variable *const else_var = + new(mem_ctx) ir_variable(glsl_type::bool_type, + "if_to_cond_assign_else", + ir_var_temporary); + ir->insert_before(else_var); + + ir_dereference_variable *else_cond = + new(mem_ctx) ir_dereference_variable(else_var); + + ir_rvalue *inverse = + new(mem_ctx) ir_expression(ir_unop_logic_not, + then_cond->clone(mem_ctx, NULL)); + + assign = new(mem_ctx) ir_assignment(else_cond, inverse); + ir->insert_before(assign); + + move_block_to_cond_assign(mem_ctx, ir, else_cond, + &ir->else_instructions); + } ir->remove(); _______________________________________________ mesa-commit mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/mesa-commit
