Similar code fragment A code fragment that has similar part to it in - - PowerPoint PPT Presentation
Similar code fragment A code fragment that has similar part to it in source code introduced in source code because of various reasons. e.g. copy-and-paste makes software maintenance difficult. It is necessary to It is
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 1
introduced in source code because of various reasons.
e.g. “copy-and-paste”
makes software maintenance difficult.
Similar code fragment CF1 If CF1 is defective… It is necessary to check a2. It is necessary to check CF2 and CF3 CF2 CF3 Source file Source file
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 2
for(iter=0; iter<num_regs; iter++) { prom_prom_taken[iter].start_adr = prom_reg_memlist[iter].phys_addr; prom_prom_taken[iter].num_bytes = prom_reg_memlist[iter].reg_size; prom_prom_taken[iter].theres_more = &prom_phys_total[iter+1]; // should be:&prom_prom_taken[iter+1];
}
for(iter=0; iter<num_regs; iter++) { prom_prom_taken[iter].start_adr = (char *) prom_reg_memlist[iter].phys_addr; prom_prom_taken[iter].num_bytes = (unsigned long) prom_reg_memlist[iter].reg_size; prom_prom_taken[iter].theres_more = &prom_phys_total[iter+1]; // should be:&prom_prom_taken[iter+1]; }
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 3
for(iter=0; iter<num_regs; iter++) { prom_prom_taken[iter].start_adr = prom_reg_memlist[iter].phys_addr; prom_prom_taken[iter].num_bytes = prom_reg_memlist[iter].reg_size; prom_prom_taken[iter].theres_more = &prom_phys_total[iter+1]; // should be:&prom_prom_taken[iter+1];
}
for(iter=0; iter<num_regs; iter++) { prom_prom_taken[iter].start_adr = (char *) prom_reg_memlist[iter].phys_addr; prom_prom_taken[iter].num_bytes = (unsigned long) prom_reg_memlist[iter].reg_size; prom_prom_taken[iter].theres_more = &prom_phys_total[iter+1]; // should be:&prom_prom_taken[iter+1]; }
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 4
Input code fragment (Query) Target source files Lexical Analysis
Ii[0] Ii[ni]
Input identifier list Lexical Analysis
It1[0] It1[nt1] It2[0] It2[nt2] Itn[0] Itn[ntn]
Target identifier lists Comparison Similar sublists
Is1[0] Is1[ns1] Is2[0] Is2[ns2]
Ranking
Isn[0] Isn[nsn] Rank Start line # End line # Similarity 1 Lines1 Linee1 Sim1 2 Lines2 Linee2 Sim2
Similarity Ranking
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 5
We compare identifiers in the sliding window with the
It[3] It[0] It[1] It[2] It[n] It[n-1]
Ii[0] Ii[1] Ii[2]
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 6
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 7
arch/ directory in Linux 2.6.6
Architecture-specific implementations in OS 2 incorrect pointer accesses
server/ directory in Canna 3.6
Japanese input system 19 buffer overflow errors
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 8
We used 2 code fragments as queries.
Each code fragment involves an incorrect pointer access.
In both of those queries, the 2 code fragments are
We used 19 code fragments as queries.
Each code fragment involves a buffer overflow error.
In all of those queries, 18 or 19 code fragments are
Department of Computer Science, Graduate School of Information Science & Technology, Osaka University 9