| Message ID | 4E972AEF.1020802@gjlay.de |
|---|---|
| State | New |
| Headers | show |
On 10/13/2011 11:16 AM, Georg-Johann Lay wrote: > This patch saves some ticks and bytes on stack by JUMPing to no-return > functions instead of CALLing them. > > Passes without regression. > > Ok for trunk? > > Johann > > * config/avr/avr-protos.h (avr_out_call): New prototype. > * config/avr/avr.md (adjust_len): Add alternative "call". > (call_insn, call_calue_insn): Use it. Use avr_out_call to print > assembler. > * config/avr/avr.c (avr_out_call): New function. > (adjust_insn_length): Handle ADJUST_LEN_CALL. You should have a way to turn this off. Otherwise this makes debugging the call to abort impossible. r~
Richard Henderson schrieb: > On 10/13/2011 11:16 AM, Georg-Johann Lay wrote: >> This patch saves some ticks and bytes on stack by JUMPing to no-return >> functions instead of CALLing them. >> >> Passes without regression. >> >> Ok for trunk? >> >> Johann >> >> * config/avr/avr-protos.h (avr_out_call): New prototype. >> * config/avr/avr.md (adjust_len): Add alternative "call". >> (call_insn, call_calue_insn): Use it. Use avr_out_call to print >> assembler. >> * config/avr/avr.c (avr_out_call): New function. >> (adjust_insn_length): Handle ADJUST_LEN_CALL. > > You should have a way to turn this off. Otherwise this makes debugging > the call to abort impossible. > > r~ What do you propose? o A command line option that is on per default like -mnoreturn-tail-calls or -mjmp-noreturn o Hard-coded factor out some function names like "abort", "exit", "_exit" Johann
On 10/13/2011 12:00 PM, Georg-Johann Lay wrote: > What do you propose? > > o A command line option that is on per default like > -mnoreturn-tail-calls or -mjmp-noreturn The command-line-option. I think I prefer -mjump-noreturn, as the inverse -mno-noreturn-tail-calls is too awkward. r~
>> You should have a way to turn this off. Otherwise this makes >> debugging the call to abort impossible. > >What do you propose? > >o A command line option that is on per default like > -mnoreturn-tail-calls or -mjmp-noreturn > >o Hard-coded factor out some function names like "abort", > "exit", "_exit" I'd suggest the first option. That way you can do this for other similar functions like panic(). paul
Richard Henderson schrieb: > On 10/13/2011 12:00 PM, Georg-Johann Lay wrote: > >>What do you propose? >> >>o A command line option that is on per default like >> -mnoreturn-tail-calls or -mjmp-noreturn > > The command-line-option. I think I prefer -mjump-noreturn, > as the inverse -mno-noreturn-tail-calls is too awkward. What about flag_optimize_sibling_calls? What wa are seeing here is actually a tail call. Johann > > r~ >
On 10/13/2011 11:31 PM, Georg-Johann Lay wrote: > Richard Henderson schrieb: >> On 10/13/2011 12:00 PM, Georg-Johann Lay wrote: >> >>> What do you propose? >>> >>> o A command line option that is on per default like >>> -mnoreturn-tail-calls or -mjmp-noreturn >> >> The command-line-option. I think I prefer -mjump-noreturn, >> as the inverse -mno-noreturn-tail-calls is too awkward. > > What about flag_optimize_sibling_calls? > What wa are seeing here is actually a tail call. Because we explicitly don't tail call noreturn for the reason previously explainted. r~
Index: config/avr/avr.md =================================================================== --- config/avr/avr.md (revision 179843) +++ config/avr/avr.md (working copy) @@ -133,11 +133,10 @@ (define_attr "length" "" ;; Following insn attribute tells if and how the adjustment has to be ;; done: ;; no No adjustment needed; attribute "length" is fine. -;; yes Analyse pattern in adjust_insn_length by hand. ;; Otherwise do special processing depending on the attribute. (define_attr "adjust_len" - "out_bitop, out_plus, addto_sp, tsthi, tstsi, compare, + "out_bitop, out_plus, addto_sp, tsthi, tstsi, compare, call, mov8, mov16, mov32, reload_in16, reload_in32, ashlqi, ashrqi, lshrqi, ashlhi, ashrhi, lshrhi, @@ -3634,21 +3633,12 @@ (define_insn "call_insn" ;; Operand 1 not used on the AVR. ;; Operand 2 is 1 for tail-call, 0 otherwise. "" - "@ - %!icall - %~call %x0 - %!ijmp - %~jmp %x0" + { + return avr_out_call (insn, operands[0], 0 != INTVAL (operands[2])); + } [(set_attr "cc" "clobber") - (set_attr_alternative "length" - [(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))])]) + (set_attr "length" "1,*,1,*") + (set_attr "adjust_len" "*,call,*,call")]) (define_insn "call_value_insn" [(parallel[(set (match_operand 0 "register_operand" "=r,r,r,r") @@ -3658,21 +3648,12 @@ (define_insn "call_value_insn" ;; Operand 2 not used on the AVR. ;; Operand 3 is 1 for tail-call, 0 otherwise. "" - "@ - %!icall - %~call %x1 - %!ijmp - %~jmp %x1" + { + return avr_out_call (insn, operands[1], 0 != INTVAL (operands[3])); + } [(set_attr "cc" "clobber") - (set_attr_alternative "length" - [(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))])]) + (set_attr "length" "1,*,1,*") + (set_attr "adjust_len" "*,call,*,call")]) (define_insn "nop" [(const_int 0)] Index: config/avr/avr-protos.h =================================================================== --- config/avr/avr-protos.h (revision 179842) +++ config/avr/avr-protos.h (working copy) @@ -84,6 +84,7 @@ extern const char *avr_out_sbxx_branch ( extern const char* avr_out_bitop (rtx, rtx*, int*); extern const char* avr_out_plus (rtx*, int*, int*); extern const char* avr_out_addto_sp (rtx*, int*); +extern const char* avr_out_call (rtx, rtx, bool); extern bool avr_popcount_each_byte (rtx, int, int); extern int extra_constraint_Q (rtx x); Index: config/avr/avr.c =================================================================== --- config/avr/avr.c (revision 179843) +++ config/avr/avr.c (working copy) @@ -4905,6 +4905,27 @@ avr_out_plus (rtx *xop, int *plen, int * } +/* Print call insn INSN to the assembler file and return "". + ADDRESS is the target address. + If SIBCALL_P then INSN is a tail-call. */ + +const char* +avr_out_call (rtx insn, rtx address, bool sibcall_p) +{ + /* No need to waste stack or time for no-return calls. */ + + if (optimize && find_reg_note (insn, REG_NORETURN, NULL)) + sibcall_p = true; + + if (REG_P (address)) + output_asm_insn (sibcall_p ? "%!ijmp" : "%!icall", &address); + else + output_asm_insn (sibcall_p ? "%~jmp %x0" : "%~call %x0", &address); + + return ""; +} + + /* Output bit operation (IOR, AND, XOR) with register XOP[0] and compile time constant XOP[2]: @@ -5311,6 +5332,8 @@ adjust_insn_length (rtx insn, int len) case ADJUST_LEN_ASHLQI: ashlqi3_out (insn, op, &len); break; case ADJUST_LEN_ASHLHI: ashlhi3_out (insn, op, &len); break; case ADJUST_LEN_ASHLSI: ashlsi3_out (insn, op, &len); break; + + case ADJUST_LEN_CALL: len = AVR_HAVE_JMP_CALL ? 2 : 1; break; default: gcc_unreachable();