diff --git a/src/glsl/lower_jumps.cpp b/src/glsl/lower_jumps.cpp index 9378ab93086..177b75164fd 100644 --- a/src/glsl/lower_jumps.cpp +++ b/src/glsl/lower_jumps.cpp @@ -256,6 +256,50 @@ struct ir_lower_jumps_visitor : public ir_control_flow_visitor { ir->replace_with(new(ir) ir_loop_jump(ir_loop_jump::jump_break)); } + /** + * Create the necessary instruction to replace a break instruction. + */ + ir_instruction *create_lowered_break() + { + void *ctx = this->function.signature; + return new(ctx) ir_assignment( + new(ctx) ir_dereference_variable(this->loop.get_break_flag()), + new(ctx) ir_constant(true), + 0); + } + + /** + * If the given instruction is a break, lower it to an instruction + * that sets the break flag, without consulting + * should_lower_jump(). + * + * It is safe to pass NULL to this function. + */ + void lower_break_unconditionally(ir_instruction *ir) + { + if (get_jump_strength(ir) != strength_break) { + return; + } + ir->replace_with(create_lowered_break()); + } + + /** + * If the block ends in a conditional or unconditional break, lower + * it, even though should_lower_jump() says it needn't be lowered. + */ + void lower_final_breaks(exec_list *block) + { + ir_instruction *ir = (ir_instruction *) block->get_tail(); + lower_break_unconditionally(ir); + ir_if *ir_if = ir->as_if(); + if (ir_if) { + lower_break_unconditionally( + (ir_instruction *) ir_if->then_instructions.get_tail()); + lower_break_unconditionally( + (ir_instruction *) ir_if->else_instructions.get_tail()); + } + } + virtual void visit(class ir_loop_jump * ir) { truncate_after_instruction(ir); @@ -441,7 +485,7 @@ retry: /* we get here if we put code after the if inside a branch */ * Smarter options (such as undoing the increment) are possible but it's not worth implementing them, * because if break is lowered, continue is almost surely lowered too. */ - jumps[lower]->insert_before(new(ir) ir_assignment(new (ir) ir_dereference_variable(this->loop.get_break_flag()), new (ir) ir_constant(true), 0)); + jumps[lower]->insert_before(create_lowered_break()); goto lower_continue; } else if(jump_strengths[lower] == strength_continue) { lower_continue: @@ -573,6 +617,23 @@ lower_continue: } if(this->loop.break_flag) { + /* We only get here if we are lowering breaks */ + assert (lower_break); + + /* If a break flag was generated while visiting the body of + * the loop, then at least one break was lowered, so we need + * to generate an if statement at the end of the loop that + * does a "break" if the break flag is set. The break we + * generate won't violate the CONTAINED_JUMPS_LOWERED + * postcondition, because should_lower_jump() always returns + * false for a break that happens at the end of a loop. + * + * However, if the loop already ends in a conditional or + * unconditional break, then we need to lower that break, + * because it won't be at the end of the loop anymore. + */ + lower_final_breaks(&ir->body_instructions); + ir_if* break_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->loop.break_flag)); break_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break)); ir->body_instructions.push_tail(break_if);