CS 314 Principles of Programming Languages

Transcription

1 CS 314 Principles of Progrmming Lnguges Lecure 10: Synx Direced Trnslion Zheng (Eddy) Zhng Rugers Universiy Februry 19, 2018

2 Clss Informion Homework 2 is sill being grded. Projec 1 nd homework 4 will be relesed omorrow. 2

3 Review: Recursive Descen Prsing Recursive descen prser for LL(1) Ech non-erminl hs n ssocied prsing procedure h cn recognize ny sequence of okens genered by h non-erminl There is min rouine o iniilize ll globls (e.g:he oken vrible in previous code exmple) nd cll he sr symbol. On reurn, check wheher oken == EOF, nd wheher errors occurred. Wihin prsing procedure, boh non-erminls nd erminls re mched: Non-erminl A: cll procedure for A Token : compre wih curren he firs of he remining okens; If mched, consume inpu, oherwise, ERROR Prsing procedure my conin code h performs some useful compuions (synx direced rnslion) 3

4 Review: Synx Direced Trnslion Exmples: - Inerpreer - Code generor - Type checker - Performnce esimor Use hnd-wrien recursive descen LL(1) prser 4

5 Exmple: he Originl Prser 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= oher < expr > Rule 1 Rule 2 < digi > Rule 3 void expr( ): // reurn vlue of he expression in vl1, vl2; // wo vlues cse +: oken := nex_oken( ); expr( ); expr( ); cse 0..9: digi( ); void digi( ): // reurn vlue of consn cse 1: oken := nex_oken( ); cse 2: oken := nex_oken( ); 5

6 Exmple: Inerpreer 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= oher < expr > Rule 1 Rule 2 < digi > Rule 3 in expr( ) { in vl1, vl2; // wo vlues cse +: oken := nex_oken( ); vl1 = expr( ) ; vl2 = expr( ); reurn vl1 + vl2; cse 0..9: reurn digi( ); // End swich cse //End expr() Inerpreer void expr( ) { cse +: oken := nex_oken( ); expr( ) ; expr( ); cse 0..9: digi( ); // End swich cse //End expr() Originl in digi( ): // reurn vlue of consn cse 1: oken := nex_oken( ); reurn 1; cse 2: oken := nex_oken( ); reurn 2; // End swich cse // End digi( ) void digi( ): // reurn vlue of consn cse 1: oken := nex_oken( ); cse 2: oken := nex_oken( ); // End swich cse // End digi( ) 6

7 Exmple: Inerpreer 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= oher < expr > Rule 1 Rule 2 < digi > Rule 3 in expr( ) { in vl1, vl2; // wo vlues cse +: oken := nex_oken( ); vl1 = expr( ) ; vl2 = expr( ); reurn vl1 + vl2; cse 0..9: reurn digi( ); // End swich cse //End expr() Inerpreer Wh hppens when prsing expression The prsing produces 5 in digi( ): // reurn vlue of consn cse 1: oken := nex_oken( ); reurn 1; cse 2: oken := nex_oken( ); reurn 2; // End swich cse // End digi( ) 7

8 Exmple: Simple Code Generor 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= in expr( ) { in rge_reg; // rge regiser in reg1, reg2; // source regisers cse +: oken := nex_oken( ); rge_reg = nex_regiser( ); reg1 = expr( ) ; reg2 = expr( ); prin_ins(add, reg1, reg2, rge_reg); reurn rge_reg; cse 0..9: reurn digi( ); // End swich cse //End expr() + 09 oher < expr > Rule 1 Rule 2 < digi > Rule 3 Code Generor in digi( ): // reurn vlue of consn in rge_reg; // rge regiser cse 1: oken := nex_oken( ); rge_reg = nex_regiser( ); prin_ins(loadi, 1, rge_reg); reurn rge_reg; cse 2:. // End swich cse // End digi( ) 8

9 Exmple: Simple Code Generor 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= in expr( ) { in rge_reg; // rge regiser in reg1, reg2; // source regisers cse +: oken := nex_oken( ); rge_reg = nex_regiser( ); reg1 = expr( ) ; reg2 = expr( ); prin_ins(add, reg1, reg2, rge_reg); reurn rge_reg; cse 0..9: reurn digi( ); // End swich cse //End expr() + 09 oher < expr > Rule 1 Rule 2 < digi > Rule 3 Code Generor in digi( ): // reurn vlue of consn in rge_reg; // rge regiser cse 1: oken := nex_oken( ); rge_reg = nex_regiser( ); prin_ins(loadi, 1, rge_reg); reurn rge_reg; cse 2:. // End swich cse // End digi( ) ADD r<reg1>, r<reg2> => r<rge_reg> 9

10 Exmple: Simple Code Generor 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= in expr( ) { in rge_reg; // rge regiser in reg1, reg2; // source regisers cse +: oken := nex_oken( ); rge_reg = nex_regiser( ); reg1 = expr( ) ; reg2 = expr( ); prin_ins(add, reg1, reg2, rge_reg); reurn rge_reg; cse 0..9: reurn digi( ); // End swich cse //End expr() + 09 oher < expr > Rule 1 Rule 2 < digi > Rule 3 Code Generor in digi( ): // reurn vlue of consn in rge_reg; // rge regiser cse 1: oken := nex_oken( ); rge_reg = nex_regiser( ); prin_ins(loadi, 1, rge_reg); reurn rge_reg; cse 2:. // End swich cse // End digi( ) LOADI 1 => r<rge_reg> 10

11 Exmple: Code Generor (con.) Wh hppens when you prse he progrm: ? Firs cll o nex_regiser() will reurn 1 in expr( ) { in rge_reg; // rge regiser in reg1, reg2; // source regisers cse +: oken := nex_oken( ); rge_reg = nex_regiser( ); reg1 = expr( ) ; reg2 = expr( ); prin_ins(add, reg1, reg2, rge_reg); reurn rge_reg; cse 0..9: reurn digi( ); // End swich cse //End expr() The prsing produces: LOADI 2 => r2 LOADI 1 => r4 LOADI 2 => r5 ADD r4, r5 => r3 ADD r2, r3 => r1 in digi( ): // reurn vlue of consn in rge_reg; // rge regiser cse 1: oken := nex_oken( ); rge_reg = nex_regiser( ); prin_ins(loadi, 1, rge_reg); reurn rge_reg; cse 2:. // End swich cse // End digi( ) 11

12 Exmple: Type Checker 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= oher < expr > Rule 1 Rule 2 < digi > Rule 3 sring expr( ) { // reurns ype expression sring ype1, ype2; // oher ype expressions cse +: oken := nex_oken( ); ype1 = expr( ); ype2 = expr( ); if (ype1 == in && ype2 == in ){ reurn in ; else{ reurn error ; cse 0..9: reurn digi ( ); sring digi( ) { // reurns ype expression cse 1: oken := nex_oken( ); reurn in ; cse 2: oken := nex_oken( ); reurn in ; 12

13 Exmple: Type Checker (con.) Wh hppens when you prse subprogrm ? The prsing produces: in 13

14 Exmple: Bsic Performnce Predicor 1: < expr > ::= + < expr > < expr > 2: < digi > 3: < digi > ::= oher < expr > Rule 1 Rule 2 < digi > Rule 3 in expr( ) { // reurns cycles in cyc1, cyc2; // subexpression cycles cse +: oken := nex_oken ( ) cyc1 = expr( ); cyc2 = expr( ); // ADD kes 2 cycles reurn cyc1 + cyc2 + 2; cse 0..9: reurn digi ( ); in digi( ) { // reurns cycles cse 1: oken := nex_oken ( ); reurn 1; // LOADI kes 1 cycle cse 2: oken := nex_oken ( ); reurn 1; // LOADI kes 1 cycle 14

15 Exmple: Bsic Performnce Predicor (con.) Wh hppens when you prse subprogrm ? The prsing produces: 7 ADD kes 2 cycles LOADI kes 1 cycle 15

16 Imperive Progrmming Lnguge Imperive: Sequence of se-chnging cions. Mnipule n bsrc mchine wih: 1. Vribles nming memory locions 2. Arihmeic nd logicl operions 3. Reference, evlue, ssign operions 4. Explici conrol flow semens Key operions: Assignmen nd conrol flow Fis he Von Neumnn rchiecure closely 16

17 Run-ime Sorge Orgnizion Typicl memory lyou S c k H e p C o d e S i c & G l o b l Mos Lnguge runime lyou he ddress spce in similr wy Pieces (sck, hep, code & globls) my move, bu ll will be here Sck nd hep grow owrd ech oher Arrys live on one of he scks, in he globl re, or in he hep 17

18 Sck vs Hep Sck: Procedure civions, siclly lloced locl vribles, prmeer vlues Lifeime sme s subrouine in which vribles re declred Sck frme is pushed wih ech invocion of subrouine, nd popped fer subrouine exi Hep: Dynmiclly lloced d srucure, whose size my no be known in dvnce Lifeime exends beyond subrouine in which hey re creed Mus be explicily freed or grbge colleced 18

19 How Does Address Spce Mpping Work? 19 The big picure Compiler s view S c k H e p C o d e S i c G l o b l S c k H e p G l o b l G l o b l G l o b l S c k S c k C o d e C o d e H e p H e p C o d e S i c S i c S i c & & & & virul ddress spces OS s view TLB 0 high physicl ddress spce TLB is n ddress cche used by he OS o speed virul-o-physicl ddress rnslion. A process my hve >1 level TLB

20 Nex Lecure Things o do: Sr progrmming in C. Red Sco, Chper ; ALSU Nex ime: - Procedure bsrcions; Runime sck; Scoping 20