diff options
| -rw-r--r-- | src/mesa/shader/slang/slang_codegen.c | 128 |
1 files changed, 105 insertions, 23 deletions
diff --git a/src/mesa/shader/slang/slang_codegen.c b/src/mesa/shader/slang/slang_codegen.c index d19d5a0abb6..821ed119014 100644 --- a/src/mesa/shader/slang/slang_codegen.c +++ b/src/mesa/shader/slang/slang_codegen.c @@ -707,6 +707,64 @@ _slang_find_node_type(slang_operation *oper, slang_operation_type type) } +/** + * Count the number of operations of the given time rooted at 'oper'. + */ +static GLuint +_slang_count_node_type(slang_operation *oper, slang_operation_type type) +{ + GLuint i, count = 0; + if (oper->type == type) { + return 1; + } + for (i = 0; i < oper->num_children; i++) { + count += _slang_count_node_type(&oper->children[i], type); + } + return count; +} + + +/** + * Check if the 'return' statement found under 'oper' is a "tail return" + * that can be no-op'd. For example: + * + * void func(void) + * { + * .. do something .. + * return; // this is a no-op + * } + * + * This is used when determining if a function can be inlined. If the + * 'return' is not the last statement, we can't inline the function since + * we still need the semantic behaviour of the 'return' but we don't want + * to accidentally return from the _calling_ function. We'd need to use an + * unconditional branch, but we don't have such a GPU instruction (not + * always, at least). + */ +static GLboolean +_slang_is_tail_return(const slang_operation *oper) +{ + GLuint k = oper->num_children; + + while (k > 0) { + const slang_operation *last = &oper->children[k - 1]; + if (last->type == SLANG_OPER_RETURN) + return GL_TRUE; + else if (last->type == SLANG_OPER_IDENTIFIER || + last->type == SLANG_OPER_LABEL) + k--; /* try prev child */ + else if (last->type == SLANG_OPER_BLOCK_NO_NEW_SCOPE || + last->type == SLANG_OPER_BLOCK_NEW_SCOPE) + /* try sub-children */ + return _slang_is_tail_return(last); + else + break; + } + + return GL_FALSE; +} + + static void slang_resolve_variable(slang_operation *oper) { @@ -1207,38 +1265,62 @@ _slang_gen_function_call(slang_assemble_ctx *A, slang_function *fun, } else { /* non-assembly function */ + /* We always generate an "inline-able" block of code here. + * We may either: + * 1. insert the inline code + * 2. Generate a call to the "inline" code as a subroutine + */ + + + slang_operation *ret = NULL; + inlined = slang_inline_function_call(A, fun, oper, dest); - if (inlined && _slang_find_node_type(inlined, SLANG_OPER_RETURN)) { - slang_operation *callOper; - /* The function we're calling has one or more 'return' statements. - * So, we can't truly inline this function because we need to - * implement 'return' with RET (and CAL). - * Nevertheless, we performed "inlining" to make a new instance - * of the function body to deal with static register allocation. - * - * XXX check if there's one 'return' and if it's the very last - * statement in the function - we can optimize that case. - */ - assert(inlined->type == SLANG_OPER_BLOCK_NEW_SCOPE || - inlined->type == SLANG_OPER_SEQUENCE); - if (_slang_function_has_return_value(fun) && !dest) { - assert(inlined->children[0].type == SLANG_OPER_VARIABLE_DECL); - assert(inlined->children[2].type == SLANG_OPER_IDENTIFIER); - callOper = &inlined->children[1]; + if (!inlined) + return NULL; + + ret = _slang_find_node_type(inlined, SLANG_OPER_RETURN); + if (ret) { + /* check if this is a "tail" return */ + if (_slang_count_node_type(inlined, SLANG_OPER_RETURN) == 1 && + _slang_is_tail_return(inlined)) { + /* The only RETURN is the last stmt in the function, no-op it + * and inline the function body. + */ + ret->type = SLANG_OPER_NONE; } else { - callOper = inlined; + slang_operation *callOper; + /* The function we're calling has one or more 'return' statements. + * So, we can't truly inline this function because we need to + * implement 'return' with RET (and CAL). + * Nevertheless, we performed "inlining" to make a new instance + * of the function body to deal with static register allocation. + * + * XXX check if there's one 'return' and if it's the very last + * statement in the function - we can optimize that case. + */ + assert(inlined->type == SLANG_OPER_BLOCK_NEW_SCOPE || + inlined->type == SLANG_OPER_SEQUENCE); + + if (_slang_function_has_return_value(fun) && !dest) { + assert(inlined->children[0].type == SLANG_OPER_VARIABLE_DECL); + assert(inlined->children[2].type == SLANG_OPER_IDENTIFIER); + callOper = &inlined->children[1]; + } + else { + callOper = inlined; + } + callOper->type = SLANG_OPER_NON_INLINED_CALL; + callOper->fun = fun; + callOper->label = _slang_label_new_unique((char*) fun->header.a_name); } - callOper->type = SLANG_OPER_NON_INLINED_CALL; - callOper->fun = fun; - callOper->label = _slang_label_new_unique((char*) fun->header.a_name); } } if (!inlined) return NULL; - /* Replace the function call with the inlined block */ + /* Replace the function call with the inlined block (or new CALL stmt) */ slang_operation_destruct(oper); *oper = *inlined; _slang_free(inlined); @@ -3024,7 +3106,7 @@ _slang_codegen_function(slang_assemble_ctx * A, slang_function * fun) if (_mesa_strcmp((char *) fun->header.a_name, "main") != 0) { /* we only really generate code for main, all other functions get - * inlined. + * inlined or codegen'd upon an actual call. */ #if 0 /* do some basic error checking though */ |