From patchwork Fri Mar 11 13:43:45 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Georg-Johann Lay X-Patchwork-Id: 86422 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) by ozlabs.org (Postfix) with SMTP id E182EB6F2B for ; Sat, 12 Mar 2011 00:44:19 +1100 (EST) Received: (qmail 15330 invoked by alias); 11 Mar 2011 13:44:18 -0000 Received: (qmail 15306 invoked by uid 22791); 11 Mar 2011 13:44:15 -0000 X-SWARE-Spam-Status: No, hits=-0.2 required=5.0 tests=AWL, BAYES_50, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_NONE, TW_FN X-Spam-Check-By: sourceware.org Received: from mo-p00-ob.rzone.de (HELO mo-p00-ob.rzone.de) (81.169.146.162) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 11 Mar 2011 13:44:06 +0000 X-RZG-AUTH: :LXoWVUeid/7A29J/hMvvT2k715jHQaJercGObUOFkj18odoYNahU4Q== X-RZG-CLASS-ID: mo00 Received: from [192.168.0.22] (business-188-111-022-002.static.arcor-ip.net [188.111.22.2]) by post.strato.de (cohen mo43) (RZmta 25.8) with ESMTPA id Q03669n2BCZ4Ug ; Fri, 11 Mar 2011 14:43:46 +0100 (MET) Message-ID: <4D7A2711.4060801@gjlay.de> Date: Fri, 11 Mar 2011 14:43:45 +0100 From: Georg-Johann Lay User-Agent: Thunderbird 2.0.0.24 (X11/20100302) MIME-Version: 1.0 To: gcc-patches@gcc.gnu.org CC: Denis Chertykov , Anatoly Sokolov , Eric Weddington , Anitha Boyapati Subject: [Patch][AVR]: Support tail calls X-IsSubscribed: yes Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org This is a patch to test/review/comment on. It adds tail call optimization to avr backend. The implementation uses struct machine_function to pass information around, i.e. from avr_function_arg_advance to avr_function_ok_for_sibcall. Tail call support is more general than avr-ld's replacement of call/ret sequences with --relax which are sometimes wrong, see http://sourceware.org/PR12494 gcc can, e.g. tail-call bar1 in void bar0 (void); void bar1 (int); int foo (int x) { bar0(); return bar1 (x); } I did not find a way to make this work together with -mcall-prologues. Please let me know if you have suggestion on how call prologues can be combine with tail calls. Regards, Johann 2011-03-10 Georg-Johann Lay * config/avr/avr-protos.h (expand_epilogue): Change prototype * config/avr/avr.h (struct machine_function): Add field sibcall_fails. * config/avr/avr.c (init_cumulative_args, avr_function_arg_advance): Use it. * config/avr/avr.c (expand_epilogue): Add bool parameter. Handle sibcall epilogues. (TARGET_FUNCTION_OK_FOR_SIBCALL): Define to... (avr_function_ok_for_sibcall): ...this new function. (avr_lookup_function_attribute1): New static Function. (avr_naked_function_p, interrupt_function_p, signal_function_p, avr_OS_task_function_p, avr_OS_main_function_p): Use it. * config/avr/avr.md ("sibcall", "sibcall_value", "sibcall_epilogue"): New expander. ("*call_insn", "*call_value_insn"): New insn. ("call_insn", "call_value_insn"): Remove ("call", "call_value", "epilogue"): Change expander to handle sibling calls. Index: config/avr/avr-protos.h =================================================================== --- config/avr/avr-protos.h (revision 170814) +++ config/avr/avr-protos.h (working copy) @@ -76,7 +76,7 @@ extern const char *lshrsi3_out (rtx insn extern bool avr_rotate_bytes (rtx operands[]); extern void expand_prologue (void); -extern void expand_epilogue (void); +extern void expand_epilogue (bool); extern int avr_epilogue_uses (int regno); extern void avr_output_bld (rtx operands[], int bit_nr); Index: config/avr/avr.md =================================================================== --- config/avr/avr.md (revision 170814) +++ config/avr/avr.md (working copy) @@ -2647,94 +2647,85 @@ ;; call (define_expand "call" - [(call (match_operand:HI 0 "call_insn_operand" "") - (match_operand:HI 1 "general_operand" ""))] + [(parallel[(call (match_operand:HI 0 "call_insn_operand" "") + (match_operand:HI 1 "general_operand" "")) + (use (const_int 0))])] ;; Operand 1 not used on the AVR. "" "") +(define_expand "sibcall" + [(parallel[(call (match_operand:HI 0 "call_insn_operand" "") + (match_operand:HI 1 "general_operand" "")) + (use (const_int 1))])] + "" + "") + ;; call value (define_expand "call_value" - [(set (match_operand 0 "register_operand" "") - (call (match_operand:HI 1 "call_insn_operand" "") - (match_operand:HI 2 "general_operand" "")))] + [(parallel[(set (match_operand 0 "register_operand" "") + (call (match_operand:HI 1 "call_insn_operand" "") + (match_operand:HI 2 "general_operand" ""))) + (use (const_int 0))])] ;; Operand 2 not used on the AVR. "" "") -(define_insn "call_insn" - [(call (mem:HI (match_operand:HI 0 "nonmemory_operand" "!z,*r,s,n")) - (match_operand:HI 1 "general_operand" "X,X,X,X"))] -;; We don't need in saving Z register because r30,r31 is a call used registers +(define_expand "sibcall_value" + [(parallel[(set (match_operand 0 "register_operand" "") + (call (match_operand:HI 1 "call_insn_operand" "") + (match_operand:HI 2 "general_operand" ""))) + (use (const_int 1))])] + "" + "") + +(define_insn "*call_insn" + [(parallel[(call (mem:HI (match_operand:HI 0 "nonmemory_operand" "z,s,z,s")) + (match_operand:HI 1 "general_operand" "X,X,X,X")) + (use (match_operand:HI 2 "const_int_operand" "L,L,P,P"))])] ;; Operand 1 not used on the AVR. + ;; Operand 2 is 1 for tail-call, 0 otherwise. "(register_operand (operands[0], HImode) || CONSTANT_P (operands[0]))" - "*{ - if (which_alternative==0) - return \"%!icall\"; - else if (which_alternative==1) - { - if (AVR_HAVE_MOVW) - return (AS2 (movw, r30, %0) CR_TAB - \"%!icall\"); - else - return (AS2 (mov, r30, %A0) CR_TAB - AS2 (mov, r31, %B0) CR_TAB - \"%!icall\"); - } - else if (which_alternative==2) - return AS1(%~call,%x0); - return (AS2 (ldi,r30,lo8(%0)) CR_TAB - AS2 (ldi,r31,hi8(%0)) CR_TAB - \"%!icall\"); -}" - [(set_attr "cc" "clobber,clobber,clobber,clobber") + "@ + %!icall + %~call %x0 + %!ijmp + %~jmp %x0" + [(set_attr "cc" "clobber") (set_attr_alternative "length" - [(const_int 1) - (if_then_else (eq_attr "mcu_have_movw" "yes") - (const_int 2) - (const_int 3)) - (if_then_else (eq_attr "mcu_mega" "yes") - (const_int 2) - (const_int 1)) - (const_int 3)])]) - -(define_insn "call_value_insn" - [(set (match_operand 0 "register_operand" "=r,r,r,r") - (call (mem:HI (match_operand:HI 1 "nonmemory_operand" "!z,*r,s,n")) -;; We don't need in saving Z register because r30,r31 is a call used registers - (match_operand:HI 2 "general_operand" "X,X,X,X")))] + [(const_int 1) + (if_then_else (eq_attr "mcu_mega" "yes") + (const_int 2) + (const_int 1)) + (const_int 1) + (if_then_else (eq_attr "mcu_mega" "yes") + (const_int 2) + (const_int 1))])]) + +(define_insn "*call_value_insn" + [(parallel[(set (match_operand 0 "register_operand" "=r,r,r,r") + (call (mem:HI (match_operand:HI 1 "nonmemory_operand" "z,s,z,s")) + (match_operand:HI 2 "general_operand" "X,X,X,X"))) + (use (match_operand:HI 3 "const_int_operand" "L,L,P,P"))])] ;; Operand 2 not used on the AVR. - "(register_operand (operands[0], VOIDmode) || CONSTANT_P (operands[0]))" - "*{ - if (which_alternative==0) - return \"%!icall\"; - else if (which_alternative==1) - { - if (AVR_HAVE_MOVW) - return (AS2 (movw, r30, %1) CR_TAB - \"%!icall\"); - else - return (AS2 (mov, r30, %A1) CR_TAB - AS2 (mov, r31, %B1) CR_TAB - \"%!icall\"); - } - else if (which_alternative==2) - return AS1(%~call,%x1); - return (AS2 (ldi, r30, lo8(%1)) CR_TAB - AS2 (ldi, r31, hi8(%1)) CR_TAB - \"%!icall\"); -}" - [(set_attr "cc" "clobber,clobber,clobber,clobber") + ;; Operand 3 is 1 for tail-call, 0 otherwise. + "" + "@ + %!icall + %~call %x1 + %!ijmp + %~jmp %x1" + [(set_attr "cc" "clobber") (set_attr_alternative "length" - [(const_int 1) - (if_then_else (eq_attr "mcu_have_movw" "yes") - (const_int 2) - (const_int 3)) - (if_then_else (eq_attr "mcu_mega" "yes") - (const_int 2) - (const_int 1)) - (const_int 3)])]) + [(const_int 1) + (if_then_else (eq_attr "mcu_mega" "yes") + (const_int 2) + (const_int 1)) + (const_int 1) + (if_then_else (eq_attr "mcu_mega" "yes") + (const_int 2) + (const_int 1))])]) (define_insn "nop" [(const_int 0)] @@ -3246,8 +3237,15 @@ (define_expand "epilogue" [(const_int 0)] "" - " { - expand_epilogue (); + expand_epilogue (false /* sibcall_p */); DONE; - }") + }) + +(define_expand "sibcall_epilogue" + [(const_int 0)] + "" + { + expand_epilogue (true /* sibcall_p */); + DONE; + }) Index: config/avr/avr.c =================================================================== --- config/avr/avr.c (revision 170814) +++ config/avr/avr.c (working copy) @@ -100,6 +100,7 @@ static rtx avr_function_arg (CUMULATIVE_ static void avr_function_arg_advance (CUMULATIVE_ARGS *, enum machine_mode, const_tree, bool); static void avr_help (void); +static bool avr_function_ok_for_sibcall (tree, tree); /* Allocate registers from r25 to r8 for parameters for function calls. */ #define FIRST_CUM_REG 26 @@ -231,6 +232,9 @@ static const struct default_options avr_ #undef TARGET_HELP #define TARGET_HELP avr_help +#undef TARGET_FUNCTION_OK_FOR_SIBCALL +#define TARGET_FUNCTION_OK_FOR_SIBCALL avr_function_ok_for_sibcall + struct gcc_target targetm = TARGET_INITIALIZER; static void @@ -330,17 +334,34 @@ avr_regno_reg_class (int r) return ALL_REGS; } +/* A helper for the subsequent function attribute used to dig for + attribute 'name' in a FUNCTION_DECL or FUNCTION_TYPE */ + +static inline int +avr_lookup_function_attribute1 (const_tree func, const char *name) +{ + if (FUNCTION_DECL == TREE_CODE (func)) + { + if (NULL_TREE != lookup_attribute (name, DECL_ATTRIBUTES (func))) + { + return true; + } + + func = TREE_TYPE (func); + } + + gcc_assert (TREE_CODE (func) == FUNCTION_TYPE + || TREE_CODE (func) == METHOD_TYPE); + + return NULL_TREE != lookup_attribute (name, TYPE_ATTRIBUTES (func)); +} + /* Return nonzero if FUNC is a naked function. */ static int avr_naked_function_p (tree func) { - tree a; - - gcc_assert (TREE_CODE (func) == FUNCTION_DECL); - - a = lookup_attribute ("naked", TYPE_ATTRIBUTES (TREE_TYPE (func))); - return a != NULL_TREE; + return avr_lookup_function_attribute1 (func, "naked"); } /* Return nonzero if FUNC is an interrupt function as specified @@ -349,13 +370,7 @@ avr_naked_function_p (tree func) static int interrupt_function_p (tree func) { - tree a; - - if (TREE_CODE (func) != FUNCTION_DECL) - return 0; - - a = lookup_attribute ("interrupt", DECL_ATTRIBUTES (func)); - return a != NULL_TREE; + return avr_lookup_function_attribute1 (func, "interrupt"); } /* Return nonzero if FUNC is a signal function as specified @@ -364,13 +379,7 @@ interrupt_function_p (tree func) static int signal_function_p (tree func) { - tree a; - - if (TREE_CODE (func) != FUNCTION_DECL) - return 0; - - a = lookup_attribute ("signal", DECL_ATTRIBUTES (func)); - return a != NULL_TREE; + return avr_lookup_function_attribute1 (func, "signal"); } /* Return nonzero if FUNC is a OS_task function. */ @@ -378,12 +387,7 @@ signal_function_p (tree func) static int avr_OS_task_function_p (tree func) { - tree a; - - gcc_assert (TREE_CODE (func) == FUNCTION_DECL); - - a = lookup_attribute ("OS_task", TYPE_ATTRIBUTES (TREE_TYPE (func))); - return a != NULL_TREE; + return avr_lookup_function_attribute1 (func, "OS_task"); } /* Return nonzero if FUNC is a OS_main function. */ @@ -391,12 +395,7 @@ avr_OS_task_function_p (tree func) static int avr_OS_main_function_p (tree func) { - tree a; - - gcc_assert (TREE_CODE (func) == FUNCTION_DECL); - - a = lookup_attribute ("OS_main", TYPE_ATTRIBUTES (TREE_TYPE (func))); - return a != NULL_TREE; + return avr_lookup_function_attribute1 (func, "OS_main"); } /* Return the number of hard registers to push/pop in the prologue/epilogue @@ -864,7 +863,7 @@ avr_epilogue_uses (int regno ATTRIBUTE_U /* Output RTL epilogue. */ void -expand_epilogue (void) +expand_epilogue (bool sibcall_p) { int reg; int live_seq; @@ -875,6 +874,8 @@ expand_epilogue (void) /* epilogue: naked */ if (cfun->machine->is_naked) { + gcc_assert (!sibcall_p); + emit_jump_insn (gen_return ()); return; } @@ -1016,7 +1017,8 @@ expand_epilogue (void) emit_insn (gen_popqi (zero_reg_rtx)); } - emit_jump_insn (gen_return ()); + if (!sibcall_p) + emit_jump_insn (gen_return ()); } } @@ -1629,6 +1631,10 @@ init_cumulative_args (CUMULATIVE_ARGS *c cum->regno = FIRST_CUM_REG; if (!libname && stdarg_p (fntype)) cum->nregs = 0; + + /* Assume the calle may be tail called */ + + cfun->machine->sibcall_fails = 0; } /* Returns the number of registers to allocate for a function argument. */ @@ -1676,6 +1682,23 @@ avr_function_arg_advance (CUMULATIVE_ARG cum->nregs -= bytes; cum->regno -= bytes; + /* A parameter is being passed in a call-saved register. As the original + contents of these regs has to be restored before leaving the function, + a function must not pass arguments in call-saved regs in order to get + tail-called. */ + + if (cum->regno >= 0 + && !call_used_regs[cum->regno]) + { + /* FIXME: We ship info on failing tail-call in struct machine_function. + This uses internals of calls.c:expand_call() and the way args_so_far + is used. targetm.function_ok_for_sibcall() needs to be extended to + pass &args_so_far, too. At present, CUMULATIVE_ARGS is target + dependent so that such an extension is not wanted. */ + + cfun->machine->sibcall_fails = 1; + } + if (cum->nregs <= 0) { cum->nregs = 0; @@ -1683,6 +1706,60 @@ avr_function_arg_advance (CUMULATIVE_ARG } } +/* Implement `TARGET_FUNCTION_OK_FOR_SIBCALL' */ +/* Decide whether we can make a sibling call to a function. DECL is the + declaration of the function being targeted by the call and EXP is the + CALL_EXPR representing the call. */ + +static bool +avr_function_ok_for_sibcall (tree decl_callee, tree exp_callee) +{ + tree fntype_callee; + + /* Tail-calling must fail if callee-saved regs are used to pass + function args. We must not tail-call when `epilogue_restores' + is used. Unfortunalelly, we cannot tell at this point if that + actually will happen or not, and we cannot step back from + tail-calling. Thus, we inhibit tail-calling with -mcall-prologues. */ + + if (cfun->machine->sibcall_fails + || TARGET_CALL_PROLOGUES) + { + return false; + } + + fntype_callee = TREE_TYPE (CALL_EXPR_FN (exp_callee)); + + if (decl_callee) + { + decl_callee = TREE_TYPE (decl_callee); + } + else + { + decl_callee = fntype_callee; + + while (FUNCTION_TYPE != TREE_CODE (decl_callee) + && METHOD_TYPE != TREE_CODE (decl_callee)) + { + decl_callee = TREE_TYPE (decl_callee); + } + } + + /* Ensure that caller and callee have compatible epilogues */ + + if (interrupt_function_p (current_function_decl) + || signal_function_p (current_function_decl) + || avr_naked_function_p (decl_callee) + || avr_naked_function_p (current_function_decl) + || (avr_OS_task_function_p (decl_callee) ^ avr_OS_task_function_p (current_function_decl)) + || (avr_OS_main_function_p (decl_callee) ^ avr_OS_main_function_p (current_function_decl))) + { + return false; + } + + return true; +} + /*********************************************************************** Functions for outputting various mov's for a various modes ************************************************************************/ Index: config/avr/avr.h =================================================================== --- config/avr/avr.h (revision 170814) +++ config/avr/avr.h (working copy) @@ -828,4 +828,7 @@ struct GTY(()) machine_function /* Current function stack size. */ int stack_usage; + + /* 'true' if a callee might be tail called */ + int sibcall_fails; };