12/3/2008. Schedule. Target Code Generation. Target Code Generation. Gap: machine code. Tasks of Code Generator. These tasks interact

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1 Shul Trgt Co Gnrtion Dvi Notkin Autumn 2008 Projt D: intrmit o gnrtion Du: Dmr 3 Du Dmr 10, 5PM (vill Mony 11/17) Projt E: trgt o gnrtion [MiniJv++] Writtn ssignmnt [MiniJv--] Finl on Dmr 11 (on hour, kn ous) CSE401 Au08 2 Trgt Co Gnrtion Input: intrmit lngug (IL) Output: trgt lngug progrm Trgt lngugs inlu solut inry (mhin) o rlotl inry o ssmly o C Using th gnrt intrmit o, onvrt to instrutions n mmory hrtristis o th trgt mhin Trgt o gnrtion must rig th gp Gp: mhin o glol vrils IL unoun numr o intrhngl lol vrils uilt-in prmtr pssing & rsult rturning sttmnts sttmnts n hv ritrry suxprssion trs onitionl rnhs s on intgrs rprsnting Booln vlus glol stti mmory Mhin Co ix numr o rgistrs, o vrious inomptil kins, plus unoun numr o stk lotions lling onvntions ining whr rgumnts & rsults r stor n whih rgistrs my ovrwrittn y ll mhin instrutions instrutions hv rstrit oprn rssing onitionl rnhs s on onition os (my) Tsks o Co Gnrtor Rgistr llotion or h IL vril, slt rgistr/stk lotion/glol mmory lotion(s) to hol it s on it s typ n litim Stk rm lyout Instrution sltion or h IL instrution (squn), slt trgt lngug instrution (squn); must onsir oprn rssing mo sltion Ths tsks intrt Instrution sltion pns on whr oprns r llot Som IL vrils my not n rgistr, pning on th instrutions & rssing mos tht r slt Stk rm lyout my pn on instrution st CSE401 Au08 6 1

2 Rgistr Allotion Intrmit lngug uss unlimit tmporry vrils this intntionlly mks ICG sy Trgt mhin hs ix rsours or rprsnting lols plus othr intrnl things suh s stk pointr MIPS, SPARC: 31 rgistrs + 1 lwys-zro rgistr 68k: 16 rgistrs, ivi into t n rss x86: 8 wor-siz intgr rgistrs (with instrution-spii rstritions on us) plus stk o loting-point t Rgistrs r muh str thn mmory Must us rgistrs in lo/stor RISC mhins Consquns Shoul try to kp vlus in rgistrs i possil Must rus rgistrs, implis r rgistrs tr us Must hnl mor vrils thn rgistrs, implis spill Intrts with instrution sltion on CISC, implis it s rl pin CSE401 Au08 8 Clsss o Rgistrs Clsss o Vrils Fix/it rgistrs Stk pointr, rm pointr, rturn rss,... Clim y mhin rhittur, lling onvntion, or intrnl onvntion or spil purpos Som rgistrs my ovrwrittn y ll prours so llr must sv thm ross lls, i llot llr-sv rgistrs vs. ll-sv rgistrs Srth rgistrs rgistrs kpt roun or tmps (.g., loing spill vlu rom mmory to oprt on it) Fr rgistrs rmining rgistrs r or rgistr llotor to us Wht vrils n th llotor put in rgistrs? Tmporry vrils: sy to llot Din n us xtly on, uring xprssion vlution, implis llotor n r up rgistr whn on Usully not too mny in us t on tim implis lss likly to run out o rgistrs Lol vrils: hr, ut ol n to trmin lst us o vril to r rgistr n sily run out o rgistrs so must mk ision out whih vrils gt rgistr llotion wht out ssignmnts to lol through pointr? wht out uggr? Glol vrils: rlly hr, ut ol s rsrh projt Rgistr Allotion in MiniJv Allot ll lol vrils to stk lotions No n or nlysis to in lst us o lol vrils Eh r o th lol vril trnslt into lo rom stk Eh ssignmnt to lol trnslt to stor into its stk lotion Rgistr Allotion in MiniJv Eh IL xprssion hs xtly on us so n llot rsult vlu o IL xprssion to rgistr Mintin st o llot rgistrs Allot n unllot rgistr or h xprssion rsult Fr rgistr whn on with xprssion rsult Not too mny IL xprssions "tiv" t tim implis unlikly to run out o rgistrs, vn on x86 MiniJv ompilr is i it runs out o rgistrs or IL xprssions CSE401 Au

3 Rgistr Allotion in MiniJv Stk Frm Lyout X86 rgistr llotor x, x, x, x: llotl, llr-sv rgistrs si, i: srth rgistrs sp: stk pointr; p: rm pointr loting-point stk, or oul vlus CSE401 Au08 13 N sp or ormls lol vrils rturn rss (my) ynmi link (ptr to lling stk rm) (my) stti link (ptr to lxilly-nlosing stk rm) othr run-tim t (.g. llr-sv rgistrs) Assign it rgistr(s) to support ss to stk rms FP: ptr to ginning o stk rm (ix) SP: ptr to n o stk (n mov) All t in stk rm is t ix, sttilly omput ost rom FP Comput ll osts solly rom symol tls MiniJv/X86 stk rm lyout Frm pointr Stk pointr..llr s rm.. orml N orml N-1 orml 1 rturn rss llr s rm ptr llr-sv rgistrs lol M lol M-1 lol 1 rg K rg K-1 rg 1 high rsss stk grows own low rsss Clling Convntions N to in rsponsiilitis o llr n ll in stting up, tring own stk rm Only llr n o som things Only ll n o othr things Som things oul on y oth So, n protool just lik in th IL X86 Clling Squn Frm pointr Cllr: vluts tul rgumnts, pushs thm on stk in right-to-lt orr, to support C vrrgs ltrntiv: 1st k rgumnts in rgistrs svs llr-sv rgistrs in llr s stk xuts ll instrution rturn rss push onto th stk y hrwr Cll: pushs llr s rm pointr on stk th ynmi link sts up ll s rm pointr llots sp or lols, llr-sv rgistrs orr osn t mttr to lling onvntion strts running ll s o... Stk pointr..llr s rm.. orml N orml N-1 orml 1 rturn rss llr s rm ptr llr-sv rgistrs lol M lol M-1 lol 1 rg K rg K-1 rg 1 X86 rturn squn Frm pointr Cll: puts rturn vlu in right pl (x or lotingpoint stk) llots sp or lols, llr-sv rgs pops llr s rm pointr rom stk pops rturn rss rom stk n jumps to it Cllr: llots sp or rgs rstors llr-sv rgistrs rom llr s stk ontinus xution in llr tr ll... Stk pointr..llr s rm.. orml N orml N-1 orml 1 rturn rss llr s rm ptr llr-sv rgistrs lol M lol M-1 lol 1 rg K rg K-1 rg 1 3

4 Instrution Sltion Cogn iiulty pns on trgt Givn on or mor IL instrutions, pik st squn o trgt mhin instrutions with sm smntis st = stst, shortst, lowst powr,... Corrtnss ig issu, prtiulrly i ogn is omplx RISC: sy usully only on wy to o somthing losly rsmls IL instrutions CISC: hr to o wll lots o ltrntiv instrutions with similr smntis lots o possil oprn rssing mos lots o tros mong sp, siz simpl RISC-lik trnsltion my not vry iint C: sy, s long s C pproprit or sir smntis n lv optimiztions to C ompilr CSE401 Au08 20 Exmpl IL o: t3 = t1 + t2; Trgt o (MIPS): $3,$1,$2 Trgt o (SPARC): %1,%2,%3 Trgt o (68k): mov.l 1,3.l 2,3 Trgt o (x86): movl %x,%x l %x,%x On IL instrution my xpn to svrl trgt instrutions Anothr Exmpl IL o: t1 = t1 + 1; Trgt o (MIPS): $1,$1,1 Trgt o (SPARC): %1,1,%1 Trgt o (68k):.l #1,1 or in.l 1 Trgt o (x86): l $1,%x or inl %x Cn hv hois: rquirs mking isions Yt nothr xmpl IL o: // push x onto stk sp = sp - 4; *sp = t1; Trgt o (MIPS): su $sp,$sp,4 sw $1,0($sp) Trgt o (SPARC): su %sp,4,%sp st %1,[%sp+0] Trgt o (68k): mov.l 1,-(sp) Trgt o (x86): pushl %x Svrl IL instrutions n omin to on trgt instrution Instrution Sltion in MiniJv Expn h IL sttmnt into som numr o trgt mhin instrutions on t ttmpt to omin IL sttmnts togthr In Trgt suirtory: strt lsss Trgt n Lotion in strt mthos or mitting mhin o or sttmnts n t ss: mitvrassign, mitfilassign, mitbrnhtru, mitvrr, mitfilr, mitintmul, rturn Lotion rprsnting whr rsult is llot IL sttmnt n xprssion lsss invok ths oprtions to gnrt thir mhin o h IL sttmnt n xprssion hs orrsponing mit oprtion on th Trgt lss Dtils o trgt mhins r hin rom IL n th rst o th ompilr hin th Trgt n Lotion intrs 4

5 Implmnting Trgt n Lotion A prtiulr trgt mhin provis onrt sulss o Trgt, plus onrt sulsss o Lotion s n For xmpl, in Trgt/X86 suirtory: lss X86Trgt xtns Trgt lss X86Rgistr xtns Lotion or xprssions whos rsults r in (intgr) rgistrs lss X86FlotingPointStk xtns Lotion or xprssions whos rsults r push on th lotingpoint stk lss X86ComprisonRsult xtns Lotion or ooln xprssions whos rsults r in onition os Coul in Trgt/MIPS,Trgt/C, t. An Exmpl X86 mit mtho Lotion mitintconstnt(int vlu) { Lotion rsult_lotion = llotrg(iltyp.intiltyp()); mitop("movl", intoprn(vlu), rgoprn(rsult_lotion)); rturn rsult_lotion; Lotion llotrg(iltyp): llot nw rgistr to hol vlu o th givn typ voi mitop(string opnm, String rg1,...): mit ssmly o String intoprn(int): rturn th sm syntx or n int onstnt oprn String rgoprn(lotion): rturn th sm syntx or rrn to rgistr An Exmpl X86 Trgt mit mtho Wht x86 o to gnrt or rg1 +.int rg2? x86 int instrution: l %rg, %st smntis: %st = %st + %rg; mit rg1 into rgistr%rg1 mit rg2 into rgistr%rg2 thn? An Exmpl X86 Trgt mit mtho Lotion mit IntA(ILExprrg1,ILExprrg2) { Lotion rg1_lotion=rg1.ogn(this); Lotion rg2_lotion=rg2.ogn(this); mitop("l", rgoprn(rg2_lotion), rgoprn(rg1_lotion)); llotrg(rg2_lotion); rturn rg1_lotion; voi llotrg(lotion): llot rgistr, mk vill or us y ltr instrutions An Exmpl X86 Trgt mit mtho Wht x86 o to gnrt or vr r or ssignmnt? N to ss vr s hom stk lotion x86 stk rrn oprn: %p(ost) smntis: *(%p + ost); %p = rm pointr An Exmpl X86 Trgt mit mtho Lotion mitvrr(ilvrdl vr) { int vr_ost = vr.gtbytost(this); ILTyp vr_typ = vr.gttyp(); Lotion rsult_lotion = llotrg(vr_typ); mitop("movl", ptrostoprn(fp, vr_ost), rgoprn(rsult_lotion)); rturn rsult_lotion; 5

6 Continu An Exmpl X86 Trgt mit mtho voi mitvrassign(ilvrdl vr, Lotion rhs_lotion) { int vr_ost = vr.gtbytost(this); mitop("movl", rgoprn(rhs_lotion), ptrostoprn(fp, vr_ost)); String ptrostoprn(lotion, int): rturn th sm syntx or rrn to "ptr + ost" mmory lotion voi mitassign(ilassignlexpr lhs, ILExpr rhs) { Lotion rhs_lotion = rhs.ogn(this); lhs.ognassign(rhs_lotion, this); llotrg(rhs_lotion); Eh ILAssignlExpr implmnts ognassign invoks pproprit mitassign oprtion,.g. mitvrassign CSE401 Au08 31 Gnrtion or Comprisons Wht o to gnrt or rg1 <.int rg2 MIPS: us n slt instrution to omput oolnvlu int rsult into rgistr x86 (n most othr mhins): no irt instrution Hv omprison instrutions, whih st onition os.g. mpl %rg2, %rg1 Ltr onitionl rnh instrutions n tst onition os.g. jl, jl, jg, jg, j, jn ll Wht instrutions to gnrt? Gnrtion or Comprs Lotion mitintlssthnvlu(ilexpr rg1,ilexpr rg2) { Lotion rg1_lotion=rg1.ogn(this); Lotion rg2_lotion=rg2.ogn(this); mitop("mpl",rgoprn(rg2_lotion),); llotrg(rg1_lotion); Lotion rsult_lotion = llotrg(iltyp.intiltyp()); String tru_ll = gtnwll(); mitop("jl", tru_ll); mitop("movl", intoprn(0),rgoprn(rsult_lotion)); String on_ll = gtnwll(); mitop("jmp", on_ll); mitll(tru_ll); mitop("movl", intoprn(1),rgoprn(rsult_lotion)); mitll(on_ll); rturn rsult_lotion; Gnrtion or Brnh Gnrtion or Brnh Wht o to gnrt or itru tst goto ll voi mitconitionlbrnhtru(ilexpr tst,illltrgt){ Lotion tst_lotion=tst.ogn(this); mitop("mpl", intoprn(0), rgoprn(tst_lotion)); mitop("jn", trgt.gtnm()); Wht is gnrt or itru rg1 <.int rg2 goto ll <mit rg1 into %rg1> <mit rg2 into %rg2> mpl %rg2, %rg1 jl tru_ll movl $0, %rs jmp on_ll tru_ll: movl $1, %rs on_ll: mpl $0, %rs jn ll Cn w o ttr? 6

7 Optimiz Brnhs I: ooln-vlu IL xprssions n gnrt two wys, pning on thir onsuming ontxt or thir vlu or or thir onition o Existing o gn oprtion on IL xprssion prous its vlu Nw ogntst oprtion on IL xprssion prous its onition o X86ComprisonRsultLotion rprsnts this rsult Now onitionl rnhs n vlut thir tst xprssion in th "or onition o" styl Optimiz Brnhs voi mitconitionlbrnhtru(ilexpr tst, ILLltrgt){ Lotion tst_lotion=tst.ogn(this); X86ComprisonRsultLo = (X86ComprisonRsultLo) tst_lotion; mitop("j" +.rnhtruop(), trgt.gtnm()); IL ogntst Dult Bhvior lss ILExpr xtns ILExpr {... Lotion ogntst(trgt trgt) { rturn trgt.mittst(this); In X86Trgt lss: Lotion mittst(ilexpr rg) { Lotion rg_lotion = rg.ogn(this); mitop("mpl", intoprn(0), rgoprn(rg_lotion)); llotrg(rg_lotion); rturn nw X86ComprisonRsultLo("n"); IL ogntst Spiliz Bhvior lss ILIntLssThnExpr xtns ILExpr { Lotion ogntst(trgt trgt) { rturn trgt.mitintlssthntst(rg1, rg2); In X86Trgt lss: Lotion mitintlssthntst(ilexpr rg1,ilexpr rg2) { Lotion rg1_lotion=rg1.ogn(this); Lotion rg2_lotion=rg2.ogn(this); mitop("mpl",rgoprn(rg2_lotion), ); llotrg(rg1_lotion); rturn nw X86ComprisonRsultLo("l"); Rgistr Allotion: Cool Algorithm Bgin With Dt Flow Grph How to onvrt th ininit squn o tmporry t rrns, t1, t2, into init ssignmnt rgistr numrs $8, $9,, $25 Gol: Us vill rgistrs with minimum spilling Prolm: Minimizing th numr o rgistrs is NPomplt it is quivlnt to hromti numr-- minimum olors to olor nos o grph so no g onnts sm olor prour-wi rgistr llotion only liv vrils rquir rgistr storg tlow nlysis: vril is liv t no N i th vlu it hols is us on som pth urthr own th ontrol-low grph; othrwis it is two vrils(vlus) intrr whn thir liv rngs ovrlp 7

8 Liv Vril Anlysis Rgistr Intrrn Grph := +8; print(); := r(); := r(); := r(); := + *; < 10 print(); := 10; := + ; print(); := r(); := r(); := r(); := + *; i ( < 10 ) thn := +8; print(); ls := 10; := + ; print(); i print(); := +8; print(); := r(); := r(); := r(); := + *; < 10 print(); := 10; := + ; print(); Grph Coloring Apply Huristi NP omplt prolm Huristi: olor sy nos lst in no N with lowst gr rmov N rom th grph olor th simplii grph st olor o N to th irst olor tht is not us y ny o N s nighors Bsis u to Chitin (1982) Apply Huristi Apply Huristi 8

9 9 Continu Continu Continu Continu Continu Continu

10 Continu Finl Assignmnt := r(); := r(); := r(); := + *; i ( < 10 ) thn := +8; print(); ls := 10; := + ; print(); i print(); Wht is th O(running tim)? Aptl? Exmpl: or smll groups { int tmp_2 = 2**; int tmp_ = *; int tmp_ = *; x := tmp_ + tmp_2 + tmp_; y := tmp_ - tmp_2 + tmp_; givn tht n r liv on ntry n on xit, n tht x n y r liv on xit: () onstrut th rgistr intrrn grph () olor th grph; how mny rgistrs r n? CSE401 Au Rgistrs N Co Gnrtion Summry tmp_2 tmp_ x tmp_ y Co gnrtion is Mhin spii Error pron Lst lgnt o th ompiltion pross Co gnrtion is Pl whr ky trnsormtion tks pl in th ompilr Most visil impt on prormn 10

11 Gnrtion to Optimiztion: t-low Snsitivity Th t-low nlysis skth or rgistr llotion vi oloring givs l or mny o th thniqus t th sis o optimiztion Dt-low nlysis gthrs inormtion out th possil st o vlus lult t vrious points in progrm, using ontrollow grph (CFG) rprsnttion Dt-low nlysis usully works y stting up tlow qutions or th CFG no, solving ths qutions y rhing ixpoint Du to Killl (1973) UW CSE PhD #7 (1972) Dt-low nlysis is low-snsitiv th orr o sttmnt in th CFG mttrs But lmost lwys pth-insnsitiv osn t onsir th vlus o prits t onitionls Cn ontxt-snsitiv tht is, som nlyss r out whih lling ontxt ours CSE401 Au08 61 CSE401 Au08 62 Forwr t-low Th lssi xmpl o t-low nlysis is rhing initions whih initions my rh givn point in th o Dtlow qutions or h lok in CFG Rh in [S] = p pr(s) Rh out [p] Rh out [S] = Gn[S] (Rh in [S] Kill [S]) N Gn[: y is ssign] = { Kill[: y is ssign] = Ds[y] { Ds[y] is th st o initions tht ssign to y CSE401 Au08 63 Boring Exmpl (wikipi) 1: i ==4 thn 2: = 5; 3: ls 4: = 3; 5: ni 6: 7: i < 4 thn 8:... CSE401 Au08 64 Anothr xmpl: rom Stnor w B0 D0: y = 3 D1: x = 10 D2: y = 11 I D3: x = 1 D4: y = 2 B1 D5: z = x D6: x = 4 B2 For ll s Ssgn, s Sllo, s Sntry, i I : [JOIN] Rs( s) i = Fs pr(s) Rs(s ) i [TRANSF] Rs(s ) i = Fi I ([[s]](ρ, (i, Rs( s) i))) i [ALLOC] Rs(s ) i h, whr [[s]]gn(ρ) = (i, h) [ENTRY] Rs( s) i o i CSE401 Au08 65 CSE401 Au

12 CSE401 Au