Smart contract processing method and system, computer device, and readable storage medium
The present disclosure relates to a smart contract processing method and a system, and a readable storage medium. By segmenting a function requiring performance analysis, establishing a symbol calculation model and calculating a GAS consumption formula, and performing further optimization, a GAS value consumed by the execution of a program containing a polynomial cycle can be automatically calculated, or a GAS value consumed by the execution of a program containing a non-linear cycle can be calculated with minimal human assistance, so as to reflect the performance thereof.
1. A smart contract processing method, comprising the following steps:
acquiring a smart contract, segmenting a performance analyzing function of the smart contract, so as to extract a complete program segment;
establishing a symbol calculation model according to the program segment; and
acquiring a GAS consumption formula according to the symbol calculation model, simplifying and outputting same.
2. The smart contract processing method of claim 1 , wherein the segmenting the performance analyzing function of the smart contract, so as to extract the complete program segment comprises the following steps:
performing a syntax analysis of the smart contract and establishing a syntax tree;
creating a Solidity system dependency diagram according to the syntax tree; and
segmenting the Solidity system dependency diagram using a segmenting algorithm to extract the complete program segment.
3. The smart contract processing method of claim 1 , wherein the establishing a symbol calculation model according to the program segment comprises:
converting the program segment into an execution code program for an EVM according to a compilation principle of a Solidity compiler;
converting the execution code program into a symbol calculation expression for GAS accumulation according to the GAS consumed by the execution code program and a GAS size comparison table, and generating a cycle invariant; and
generating the cycle invariant automatically for a case that the execution code program contains a polynomial cycle, and manually assisting in adding a cycle invariant for a case that the execution code program contains a non-linear cycle.
4. The smart contract processing method of claim 3 , wherein the acquiring the GAS consumption formula according to the symbol calculation model, simplifying and outputting same comprises:
for a case that the execution code program contains a cycle, expressing a cycle assignment statement as a system of first order constant coefficient difference equations for a program variable with respect to a number of cycles, obtaining a closed form solution of the system of first order constant coefficient difference equations, substituting the closed form solution into a cycle condition, and obtaining an expression for the calculation of cycle GAS consumption with respect to the number of cycles;
for a case that the execution code program contains logical control, converting a logical control statement into a homogeneous polynomial containing symbols of relevant variables as a GAS consumption expression; and
accumulating in turn all GAS consumption expressions in all program segments according to a symbol calculation method to acquire a final GAS consumption formula, and simplifying and outputting the GAS consumption formula.
5. The smart contract processing method of claim 4 , wherein the symbol calculation method comprises the following steps:
inputting a polynomial cycle program P, a number m of program variables, and an upper bound U on a number of power of polynomial invariants;
initializing LoopInv to be empty;
representing the polynomial cycle program P by a polynomial variation system T, wherein T consists of V, L, Y, l0 and O, V represents a set of variables, L represents a set of finite positions, Y represents a set of state variations, l0 represents an initial position, and O represents an initial condition;
acquiring a set S of sample points according to the polynomial variation system T;
calculating, by means of a BM algorithm, a Grobner basis I(S)=<p1, p2, . . . , ps> of the set S of sample points with elimination ideal under a subdivision dictionary order, and calculating the lowest number of all polynomials p1, p2, . . . , ps in I(S) with pi=0 as a candidate invariant of the polynomial cycle program P, wherein i=1, 2, . . . , s;
verifying the candidate invariant: when pi(V)|pi(V′) is set up, assigning the LoopInv to LoopInv{circumflex over ( )}pi, wherein V′ represents the set of variables after the variation; and
repeating the step of verifying the candidate invariant, iterating over values of i until i>s, and generating a cycle invariant of the polynomial cycle program P according to the LoopInv.
6. A smart contract processing system, comprising:
means for acquiring a smart contract, segmenting a performance analyzing function of the smart contract, so as to extract a complete program segment;
means for establishing a symbol calculation model according to the program segment; and
means for acquiring a GAS consumption formula according to the symbol calculation model, simplifying and outputting same.
7. A computer device, comprising a processor and a memory that stores a computer program, the computer program being executed by the processor to implement the steps of the smart contract processing method of claim 1 .
8. A readable storage medium having stored a computer program, wherein the computer program is executed by a processor to implement the steps of the smart contract processing method of claim 1 .
9. A static analysis method for performance of a Solidity smart contract, comprising the following steps:
(1) inputting a Solidity smart contract, and segmenting a performance analyzing function of the Solidity smart contract, so as to extract a complete program segment;
(2) establishing a symbol calculation model according to the complete program segment in step (1); and
(3) calculating a GAS consumption formula according to the symbol calculation model in step (2), and outputting a simplified GAS formula.
10. The static analysis method for performance of the Solidity smart contract of claim 9 , wherein the step (1) further comprises the following sub-steps:
(1.1) performing a syntax analysis of the input Solidity smart contract and establishing a syntax tree;
(1.2) creating a Solidity system dependency diagram according to the syntax tree; and
(1.3) segmenting the Solidity system dependency diagram using a segmenting algorithm to extract the complete program segment.
11. The static analysis method for performance of the Solidity smart contract of claim 9 , wherein the step (2) is specified as follows:
(2.1) converting the complete program segment into an execution code (or an assembly instruction) program for an EVM according to a compilation principle of a Solidity compiler; and
(2.2) converting the execution code program into a symbol calculation expression for GAS accumulation according to a GAS size comparison table consumed by the execution code program, and generating a cycle invariant; generating the cycle invariant automatically for a case that the execution code program contains a polynomial cycle, and manually assisting in adding a cycle invariant for a case that the execution code program contains a non-linear cycle.
12. The static analysis method for performance of the Solidity smart contract of claim 11 , wherein the step (3) is specified as follows:
(3.1) for a case that the execution code program contains a cycle, expressing a cycle assignment statement as a system of first order constant coefficient difference equations for a program variable with respect to a number of cycles, obtaining a closed form solution of the system of first order constant coefficient difference equations, substituting the closed form solution into a cycle condition, and obtaining an expression for the calculation of cycle GAS consumption with respect to the number of cycles; for a case that the execution code program contains logical control, converting a logical control statement into a homogeneous polynomial containing symbols of relevant variables as a GAS consumption expression; and
(3.2) accumulating in turn all GAS consumption expressions in all program segments according to a symbol calculation method to acquire a final GAS consumption formula, and outputting a simplified GAS formula.
13. The static analysis method for performance of the Solidity smart contract of claim 12 , wherein the symbol calculation method is specified as follows:
(4.1) inputting a polynomial cycle program P, a number m of program variables, and an upper bound U on a number of power of polynomial invariants;
(4.2) initializing LoopInv to be empty;
(4.3) representing the polynomial cycle program P by a polynomial variation system T, wherein T consists of V, L, Y, l0 and O, V represents a set of variables, L represents a set of finite positions, Y represents a set of state variations, l0 represents an initial position, and O represents an initial condition;
(4.4) acquiring a set S of sample points according to the polynomial cycle program P in step (4.3);
(4.5) calculating, by means of a BM algorithm, a Grobner basis I(S)=<p1, p2, . . . , ps> of the set S of sample points with elimination ideal under a subdivision dictionary order, and calculating the lowest number of all polynomials p1, p2, . . . , ps in I(S) with pi=0 as a candidate invariant of the polynomial cycle program P, wherein i=1, 2, . . . , s;
(4.6) verifying the candidate invariant: when pi(V)|pi(V′) is set up, assigning the LoopInv to LoopInv{circumflex over ( )}pi, wherein V′ represents the set of variables after the variation; and
(4.7) repeating the step (4.6) until i>s, and generating a cycle invariant of the polynomial cycle program P.
14. The computer device of claim 7 , wherein the segmenting the performance analyzing function of the smart contract, so as to extract the complete program segment comprises the following steps:
performing a syntax analysis of the smart contract and establishing a syntax tree;
creating a Solidity system dependency diagram according to the syntax tree; and
segmenting the Solidity system dependency diagram using a segmenting algorithm to extract the complete program segment.
15. The computer device of claim 7 , wherein the establishing a symbol calculation model according to the program segment comprises:
converting the program segment into an execution code program for an EVM according to a compilation principle of a Solidity compiler;
converting the execution code program into a symbol calculation expression for GAS accumulation according to the GAS consumed by the execution code program and a GAS size comparison table, and generating a cycle invariant; and
generating the cycle invariant automatically for a case that the execution code program contains a polynomial cycle, and manually assisting in adding a cycle invariant for a case that the execution code program contains a non-linear cycle.
16. The computer device of claim 15 , wherein the acquiring the GAS consumption formula according to the symbol calculation model, simplifying and outputting same comprises:
for a case that the execution code program contains a cycle, expressing a cycle assignment statement as a system of first order constant coefficient difference equations for a program variable with respect to a number of cycles, obtaining a closed form solution of the system of first order constant coefficient difference equations, substituting the closed form solution into a cycle condition, and obtaining an expression for the calculation of cycle GAS consumption with respect to the number of cycles;
for a case that the execution code program contains logical control, converting a logical control statement into a homogeneous polynomial containing symbols of relevant variables as a GAS consumption expression; and
accumulating in turn all GAS consumption expressions in all program segments according to a symbol calculation method to acquire a final GAS consumption formula, and simplifying and outputting the GAS consumption formula.
17. The computer device of claim 16 , wherein the symbol calculation method comprises the following steps:
inputting a polynomial cycle program P, a number m of program variables, and an upper bound U on a number of power of polynomial invariants;
initializing LoopInv to be empty;
representing the polynomial cycle program P by a polynomial variation system T, wherein T consists of V, L, Y, l0 and O, V represents a set of variables, L represents a set of finite positions, Y represents a set of state variations, l0 represents an initial position, and O represents an initial condition;
acquiring a set S of sample points according to the polynomial variation system T;
calculating, by means of a BM algorithm, a Grobner basis I(S)=<p1, p2, . . . , ps> of the set S of sample points with elimination ideal under a subdivision dictionary order, and calculating the lowest number of all polynomials p1, p2, . . . , ps in I(S) with pi=0 as a candidate invariant of the polynomial cycle program P, wherein i=1, 2, . . . , s;
verifying the candidate invariant: when pi(V)|pi(V′) is set up, assigning the LoopInv to LoopInv{circumflex over ( )}pi, wherein V′ represents the set of variables after the variation; and
repeating the step of verifying the candidate invariant, iterating over values of i until i>s, and generating a cycle invariant of the polynomial cycle program P according to the LoopInv.
18. The readable storage medium of claim 8 , wherein the segmenting the performance analyzing function of the smart contract, so as to extract the complete program segment comprises the following steps:
performing a syntax analysis of the smart contract and establishing a syntax tree;
creating a Solidity system dependency diagram according to the syntax tree; and
segmenting the Solidity system dependency diagram using a segmenting algorithm to extract the complete program segment.
19. The readable storage medium of claim 8 , wherein the establishing a symbol calculation model according to the program segment comprises:
converting the program segment into an execution code program for an EVM according to a compilation principle of a Solidity compiler;
converting the execution code program into a symbol calculation expression for GAS accumulation according to the GAS consumed by the execution code program and a GAS size comparison table, and generating a cycle invariant; and
generating the cycle invariant automatically for a case that the execution code program contains a polynomial cycle, and manually assisting in adding a cycle invariant for a case that the execution code program contains a non-linear cycle.
20. The readable storage medium of claim 19 , wherein the acquiring the GAS consumption formula according to the symbol calculation model, simplifying and outputting same comprises:
for a case that the execution code program contains a cycle, expressing a cycle assignment statement as a system of first order constant coefficient difference equations for a program variable with respect to a number of cycles, obtaining a closed form solution of the system of first order constant coefficient difference equations, substituting the closed form solution into a cycle condition, and obtaining an expression for the calculation of cycle GAS consumption with respect to the number of cycles;
for a case that the execution code program contains logical control, converting a logical control statement into a homogeneous polynomial containing symbols of relevant variables as a GAS consumption expression; and
accumulating in turn all GAS consumption expressions in all program segments according to a symbol calculation method to acquire a final GAS consumption formula, and simplifying and outputting the GAS consumption formula.