JPH09288581A - Device and method for generating object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of an object code for the mechanical instruction of multi-branch judgement syntax in a high-grade language. SOLUTION: Prescribed information is collected by a multi-branch judgement syntax information collecting means 1, it is judged by a branch destination table preparation judging means 3 whether or not a branch destination table is to be prepared by the collected information, and it is judged by an index table preparation judging means 5 whether or not an index table is to be prepared by the information collected by the multi-branch judgement syntax information collecting means 1. Concerning the multi-branch judgement syntax for which the preparation of the index table is judged, an optimizing processing means 7 performs optimizing processing so as to stepwisely show the branch destinations with the branch destination table for registering only the mutually different branch destinations among the branch destinations of respective branches of the multi-branch judgement syntax and the index table showing the indexes of branch destinations of the respective branches in this multi-branch judgement syntax.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object generation apparatus and method used in a computer system, and more particularly, to object efficiency when converting a high-level language having a multi-branch judgment syntax into machine instructions (objects). The present invention relates to an object generation apparatus and method that can be improved.

[0002]

2. Description of the Related Art Conventionally, various methods have been attempted by a compiler for object generation of a high-level language multi-branch decision syntax. Mathematically, if all the values of constants that are the targets of multi-branch comparison are collected into one set, the problem of checking whether the value stored in a variable matches one of the sets Results in a search algorithm.
Since various mathematical algorithms exist for retrieval, various methods can be considered for object generation of a multi-branch decision syntax that outputs a machine instruction corresponding to the retrieval.

When the search algorithm is applied to the object generation of the multi-branch judgment syntax, in addition to the information as to whether the value stored in the variable is in the set as a result of the search,
A machine instruction must be output so that information on the branch destination address to be branched can be obtained.

Conventionally, an optimization process for generating an object having a multi-branch decision syntax is performed in order to perform both the search and the determination of the branch destination address at the same time and output a machine instruction that does not impair both the execution speed efficiency and the object efficiency. As a method of outputting all comparison instructions and conditional branch instructions (hereinafter referred to as optimization processing using a comparison instruction sequence) or a method of outputting a branch destination table with a limited range (hereinafter referred to as branch destination table). Is used as an optimization process) is used. When the constant to be compared in each branch is a continuous integer value, the method of outputting the branch destination table by limiting the range can output a more efficient machine instruction.

A block diagram of a general object generation apparatus is shown in FIG. This object generation apparatus includes a macro expansion unit 210 that replaces a lexical phrase described in a high-level language 100, a syntax analysis unit 220 that analyzes a grammar of the high-level language 100, and a high-level language from the analyzed high-level language 100. An intermediate code generation unit 230 that generates an intermediate code that is a type-independent code; an intermediate code optimization unit 240 that performs various optimizations of the generated intermediate code;
An assembler code generation unit 250 that generates an assembler code (machine instruction) from the optimized intermediate code;
An assembler code compiling unit 260 for translating the generated assembler code into an object code (machine language) 300.

Here, the optimization processing in the intermediate code optimization unit 240 includes the above-described optimization processing of the multi-branch judgment syntax. This multi-branch judgment syntax is a syntax that branches to two or more according to a predetermined condition. As a typical example, when the value stored in a certain integer type variable matches a specified constant, An example is a C language switch statement, which is a syntax for branching to the constant label. Hereafter, as a multi-branch judgment syntax, C language switchc
A method of generating an object from the C language will be described taking the h sentence as an example.

First, the optimization process using the comparison instruction sequence will be described. This optimization process is the simplest method,
The value stored in the integer type variable is compared with all the specified constants one after another, and if they match, the machine instruction that branches to the machine instruction sequence corresponding to the execution statement of the constant label is executed. This is the method of output. If none of the specified constants match, a machine instruction for branching to the machine instruction sequence corresponding to the execution statement of the default label is output. The optimization process using the comparison instruction sequence may be performed in the process of generating the intermediate code performed by the intermediate code generation unit 230 (that is, it is handled as the intermediate code generation process instead of the optimization process). However, for convenience of explanation below, it will be treated as an optimization process.

A typical example of the assembler code for the intermediate code optimized by the optimization process using this comparison instruction sequence is shown below.

Tst rw10 jz, L0 cp rw10,1 jz, L1 cp rw10,2 jz, L2 jL3 L0: machine instruction sequence 0 L1: machine instruction sequence 1 L2: machine instruction sequence 2 L3: machine instruction sequence 3 This output machine The instruction performance is as follows. Assuming that the values stored in the integer type variables can take the specified constants stochastically evenly, the average execution time required to branch to the matching constant label after entering the switch statement is (Tbcc * n) / 2. However, Tbcc is 2 of comparison instruction and conditional branch instruction.
The execution time required for an instruction, n is the total number of designated constant labels.

The static object size of the machine instruction of the part corresponding to the process of branching to the matched constant label is (Sbcc * n) + Sbra. However, Sbcc is 2 of comparison instruction and conditional branch instruction.
The instruction length of the instruction, Sbra, is the instruction length of the unconditional branch.
Therefore, both the average execution time and the static object size increase as n increases.

FIG. 6 shows the result of object generation for the C language switch statement shown in FIG. 5 by the optimization processing method using the comparison instruction sequence.

Next, the optimization process using the branch destination table will be described. When the specified constants are continuous, this optimization process of creating a branch destination table and outputting a machine instruction that refers to the table can be used.

First, an instruction string for checking whether the value stored in the integer type variable is included between the minimum value and the maximum value of the designated constants is output. If it is not included between them, the instruction sequence that branches to the machine instruction sequence corresponding to the execution statement of the default label is output. If it is included between them, the minimum value in the specified constant is subtracted from the value stored in the integer type variable, and the corresponding branch destination is fetched from the branch destination table using the resulting value as an index. Output a sequence of instructions.

The index is a value indicating which number of data is stored in the table. The branch destination table is a column of data in which the branch destination address to the constant label corresponding to the value obtained by adding the minimum value of the designated constants and the respective indexes is stored.

A typical example of the assembler code for the intermediate code optimized by the optimization process using this branch destination table is shown below.

S50000: dw L0-L50000 dw L1-L50000 dw L2-L50000 cp rw10,2 j ugt, L3 ld rw10, (rw10 * 2 + S50000) L50000: tjp rw10 L0: machine instruction sequence 1 L2: : Machine instruction sequence 2 L3: Machine instruction sequence 3 The S0 label indicates the start address of the branch destination table. In the branch destination table, branch destination addresses to constant labels corresponding to constants 0, 1, 2 are stored in order.

The performance of this output machine instruction is as follows. Assuming that the values stored in the integer type variables can take the specified constants stochastically, sw
The average execution time required from the entry of the hit statement to the branch to the matched constant label is Tbcc + Tld + Tjmp. However, Tbcc is 2 of comparison instruction and conditional branch instruction.
The execution time required for the instruction, Tld is the time required to load the address data from the branch destination table, and Tjmp is the time required for the PC relative branch.

The static object size of the machine instruction corresponding to the process of branching to the matched constant label is Sbcc + Sld + Sjmp + (Saddr * n). However, Sbcc is 2 of comparison instruction and conditional branch instruction.
The instruction length of the instruction, Sld is the instruction length of the instruction that loads the address data from the branch destination table, Sjmp is the instruction length of the PC relative branch instruction, Saddr is the number of bytes required for the branch destination address, and (Saddr * n) is the branch Indicates the data size of the destination table.

FIG. 7 shows the result of object generation for the C language switch statement shown in FIG. 6 by the optimization processing method using the branch destination table.

[0020]

However, in the conventional object generation method of the multi-branch decision syntax, the emphasis is placed on the improvement of the dynamic execution speed efficiency of the output machine instruction. Therefore, the improvement of the object efficiency of the output machine instruction is achieved. Is insufficient. Particularly when outputting the branch destination table, outputting the table of the branch destination addresses for all the branches may increase the object size.

As an example of the multi-branch judgment syntax, a switch statement in C language as shown in FIG. 8 is taken, and the result of optimization processing using the branch destination table is shown in FIG. Even if the number of types of branch destinations is small, even though the number of branches is large as shown in FIG.
The object was inefficient. For example, when the object efficiency of the output machine instruction is emphasized because the capacity of the device (memory device or the like) for storing the object is limited, the conventional object generation method alone is insufficient.

The present invention has been made in view of the above circumstances, and an object thereof is an object capable of improving the efficiency of an object code of a machine instruction which is a compilation result of a multi-branch judgment syntax of a high-level language. It is to provide a generation device and a method thereof.

[0023]

To achieve the above object, the features of the first invention are an intermediate code optimizing unit for optimizing an intermediate code generated from a high-level language, and And an assembler code compiling unit that compiles an assembler code generated from the intermediate code to generate an object code, wherein the intermediate code optimizing unit includes:
With respect to the intermediate code of the multi-branch judgment syntax, among the branch destinations of the respective branches of the multi-branch judgment syntax, only branch destination tables different from each other are registered, and a branch destination of each branch of the multi-branch judgment syntax. And an index table in which indexes are registered so that the branch destination is indicated step by step. Here, the intermediate code optimizing unit creates a branch destination table based on the multi-branch judgment syntax information collecting means for collecting information on the multi-branch judgment syntax and the information collected by the multi-branch judgment syntax information collecting means. Branch destination table creation determination means for determining whether or not to do,
With respect to the multi-branch determination syntax determined to create the branch destination table by the branch destination table creation determination means, it is determined whether the index table is created based on the information collected by the multi-branch determination syntax information collection means. And a multi-branch determination syntax determined to create an index table by the index table creation determination means for performing the branch table different from the branch destination of each branch of the multi-branch determination syntax. A first optimization in which an optimization process is performed so as to show the branch destination stepwise by a branch destination table in which only the destination is registered and an index table showing the index of the branch destination of each branch of the multi-branch determination syntax. And a processing means.

Further, the branch destination table creation determining means performs an optimization process using a comparison instruction sequence for the multi-branch determination syntax determined not to create the branch destination table.
Optimization processing means, and third optimization processing means for performing optimization processing using the branch destination table for the multi-branch determination syntax determined not to create an index table by the index table creation determination means. It is preferable to further include

To achieve the above object, a feature of the second invention is that optimization is performed on intermediate code generated from a high-level language, and assembler code generated from this optimized intermediate code is compiled. In the object code generation method for generating an object code by performing the optimization, for the intermediate code of the multi-branch judgment syntax,
Among the branch destinations of each branch of the multi-branch determination syntax, only a branch destination table different from each other is registered, and an index table in which the index of the branch destination of each branch of the multi-branch determination syntax is registered. That is, the optimization processing is performed so that the branch destination is shown stepwise.

Here, a multi-branch judgment syntax information collecting step for collecting information on the multi-branch judgment syntax for the intermediate code of the multi-branch judgment syntax at the time of the optimization, and a multi-branch judgment syntax information collecting step. The branch destination table creation determination step that determines whether or not to create the branch destination table based on the information collected by the branch destination table and the multi-branch determination syntax that is determined to create the branch destination table in this branch destination table creation determination step On the other hand, an index table creation determination step of determining whether to create an index table based on the information collected in the multi-branch determination syntax information collection step, and a determination of creating an index table in this index table creation determination step The multi-branch judgment syntax that has been An optimization process for providing a branch destination stepwise by providing a branch destination table in which only different branch destinations are registered and an index table showing an index of the branch destination of each branch of the multi-branch judgment syntax It is preferable to include the optimization processing step of performing

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an object generating apparatus and method according to the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a block diagram of an object generating apparatus according to this embodiment. This object generation device shows the configuration of the multi-branch decision syntax optimization unit 241 in the intermediate code optimization unit 240 described in FIG. The multi-branch decision syntax optimizing unit 241 creates a branch destination table based on the multi-branch decision syntax information collecting means 1 for collecting information on the multi-branch decision syntax information and the information collected by the multi-branch decision syntax information collecting means 1. Multi-branch decision syntax information collection for branch destination table creation determination means 3 for determining whether or not to create, and multi-branch decision syntax information for which the branch destination table creation determination means 3 determines to create a branch destination table An index table creation judging means 5 for judging whether or not to create an index table based on the information collected by the means 1, and a multi-branch judgment syntax judged to create the index table by the index table creation judging means 5. On the other hand, among the branch destinations of each branch of the multi-branch judgment syntax, only the branch destination table different from each other is registered, and And index table indicating an index of a branch destination of the branch of a multi-branch decision syntax,
The optimization processing means 7 for performing the optimization processing so that the branch destination is indicated stepwise.

The multi-branch judgment syntax information collecting means 1 collects various kinds of information to be used for judgment in each of the following means. Here, the information is, for example, the total number of constant labels of the branch determination syntax or the constant value of each label. The branch destination table creation determination means 3 determines whether to create a branch destination table. Here, this judgment is
Various methods have been tried in the conventional object generation device, but as a basic criterion, if a machine instruction with object efficiency priority is to be output, {(Sbcc * n) + Sbra}-{Sbcc + Sld
+ Sjmp + (Saddr * n)} = (Sbcc-Sa
ddr) * n- (Sbcc + Sld + Sjmp-Sbr
Whether or not to create the branch destination table can be determined by the sign of a). Further, if it is desired to output a machine instruction of execution speed efficiency priority, {(Tbcc * n) / 2}-{Tbcc + Tld + Tj
Whether or not the branch destination table is created can be determined based on whether the mp} is positive or negative.

The index table creation judging means 5 is
With respect to the multi-branch determination syntax determined to create the branch destination table, it is determined whether to create the index table based on the information collected by the multi-branch determination syntax information collecting means 1.

Here, if a plurality of constant labels have the same branch destination address among the constant labels designated by the multi-branch determination syntax, the same data is stored in the branch destination addresses registered in the branch destination table. Will appear. The following switch statement will be described as an example.

Switch (num) {case0: case2: case4: execution expression statement 0; case1: case3: case5: execution expression statement 1; default: execution expression statement D;} First, a conventional branch destination table is used. The machine command output by the method is as follows.

[0033] S50000: dw L0-L50000 dw L1-L50000 dw L0-L50000 dw L1-L50000 dw L0-L50000 dw L1-L50000 cp rw10,5 j ugt, LD ld rw10, (rw10 * 2 + S50000) L50000: tjp rw10 L0 : Machine instruction sequence 0 L1: Machine instruction sequence 1 LD: Machine instruction sequence D As for the performance of this output machine instruction, the static object size is Sbcc + Sld + Sjmp + (Saddr * n), and the average execution time is Tbcc + Tld + Tjmp. Is. In the above case, the branch destination table has only two types of branch destination addresses.

Next, the branch destination table is converted into 2 by the optimization processing using the branch destination table and the index table.
If only a branch destination table of a type is used and a reference to a table in which an index to the branch destination table is registered is used as a table for each constant label, the output machine instruction will be as follows.

[0035] cp rw10,5 j ugt, LD ld rb10, (rw10 + S50001) extz rw10 ld rw10, (rw10 * 2 + S50000) L50000: tjp rw10 S50001: db0 db1 db0 db1 db0 db1 S50000: dw L0-L50000 dw L1-L50000 L0 : Machine instruction sequence 0 L1: Machine instruction sequence 1 LD: Machine instruction sequence D The performance of this output machine instruction is as follows. Static object size is Sbcc + Sld + Sldb + Sjmp + (Sddr *
kind) + n. However, Sldb is 1 from the index table.
The instruction length of the instruction for loading the byte data, kind, is a number indicating a different branch destination type among the branch destinations of the constant label. If the type of branch destination is 255 or less, the value of the index is 1 byte, so the object size is the number of specified constant labels times 1 byte. The average execution time is Tbcc + Tld + Tldb + Tjmp. However, Tldb is 1 from the index table.
This is the execution time required for an instruction to load byte data.

Comparing the performances when using only the branch destination table and when using the branch destination table and the index table, (execution time when only the branch destination table)-(branch destination table and index table) = (Tbc)
c + Tld + Tldb + Tjmp}-{Tbcc + Tl
d + Tjmp} = Tldb, which slightly deteriorates in execution time, but this value does not depend on the number of constant labels or the types of different branch destinations. In the object size, (object size of optimization process using branch destination table)-(object size of optimization process using branch destination table and index table) = {Sbcc + Sld + Sldb + Sjmp + (Saddr * kind) + n}-{Sbcc + Sld + Sjmp + (Saddr * n)} = Sldb + kind- (Saddr-1) * (n-kind). This can be positive or negative, but if n is much larger than kind, the larger n is, the smaller the object size will be.

The condition of (object size in case of only branch destination table) <(object size in case of using branch destination table and index table) is k
Solving for ind, kind <{(Saddr-1) * n-Sldb} / S
We get the solution of addr. When the kind of branch target kind satisfies the condition of the above expression with respect to the total number n of constant labels, it is more advantageous for the object size to output the machine instruction only for the branch target table.

The optimization processing means 7 performs the optimization processing using the branch destination table and the index table for the multi-branch determination syntax determined by the index table creation determination means 5 to create the index table. The optimization process using the branch destination table and the index table will be described below.

As an example of the multi-branch judgment syntax, the C language switch statement as shown in FIG. 8 is taken and the result of the optimization processing by this means is shown in FIG. As shown in the figure, among branch destinations of each branch of the multi-branch judgment syntax, only branch destinations different from each other are registered, and an index table in which indexes of branch destinations of each branch of the multi-branch judgment syntax are registered. The branch destination is indicated stepwise by. By performing such optimization processing, the size of the object can be reduced in a predetermined case.

According to this embodiment, the object efficiency is improved by automatically implementing the object generating apparatus and the method when the branch destination table and the index table are used.

The object generating apparatus of this embodiment can be used not only in the C language switch statement but also in a language compiler having a multi-branch judgment syntax.

Second Embodiment In the first embodiment described above, the description is given of the process for optimizing only the multi-branch judgment syntax determined to create the index table. It is also possible to change the contents of the optimization process according to the judgments of the creation judgment means 3 and the index table creation judgment means 5. A flowchart of the processing in this case is shown in FIG. The operation of the object generation device according to the present embodiment will be described using this flowchart.

First, information on the total number of constant labels and the constant value of each label is collected (step S101). Then, it is determined whether or not the branch destination table can be created by this information collection (step S102). This judgment can be made by the method described in the branch destination table creation judging means 3 described above. Accordingly, if it is not determined that the branch destination table is created, the optimization process using the comparison instruction sequence is performed (step S103). Since the description of this optimization processing has been given above, it is omitted here.

Subsequently, when it is determined that the branch destination table can be created, the label of the multi-branch determination syntax is associated with the branch destination (step S104). With this association, the number of types of branch destinations is checked to determine whether the index table can be created (step S10).
5). This judgment can be made by the method described in the index table creation judging means 5 described above. Thus, if it is not determined that the branch destination table is created, the optimization processing using the branch destination table is performed (step S106). Since the description of this optimization processing has been given above, it is omitted here.

Subsequently, when it is judged that the index table can be created, an optimization process using the branch destination table and the index table is performed (step S1).
07).

As described above, according to this embodiment, the optimum object can be automatically generated. Also,
In this embodiment, the optimization of the multi-branch decision syntax of the high-level language becomes strong, so that the object efficiency of the output machine instruction is improved.

As a result, when the machine instruction output from the compiler is recorded in the ROM, there is an advantage that the amount of ROM used can be reduced.

[0048]

As described above, according to the object generating apparatus and the method thereof according to the present invention, the efficiency of the object code of the machine instruction which is the compilation result of the multi-branch judgment syntax of the high-level language can be improved. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a multi-branch decision syntax optimization unit of an object generation device according to the present invention.

FIG. 2 is a diagram showing a processing flow of multi-branch judgment syntax optimization of the object generation method according to the present invention.

FIG. 3 is a result of compiling the switch statement of FIG. 8 by the method of the present invention.

FIG. 4 is a block diagram showing a general object generation device.

FIG. 5 is a C language switch that is an example of a multi-branch determination syntax.
It is a ch sentence.

6 is an example of a result of compiling the switch statement of FIG. 5 with a C compiler.

7 is an example of a result of compiling the switch statement of FIG. 5 with a C compiler.

FIG. 8 is a multi-branch determination syntax used to describe the present embodiment.

9 is an example of a result of compiling the switch statement of FIG. 8 by a conventional method.

[Explanation of symbols]

 1 multi-branch determination syntax information collection means 3 branch destination table creation means 5 index table creation means 7 optimization processing means 11 intermediate code 13 optimized intermediate code 100 high-level language 200 object code generation section 210 macro expansion section 220 syntax analysis section 230 Intermediate code generation unit 240 Intermediate code optimization unit 241 Multi-branch decision syntax optimization unit 250 Assembler code generation unit 260 Assembler code compilation unit 300 Object code

Claims (5)

[Claims] 1. An intermediate code optimizing unit for optimizing intermediate code generated from a high-level language, and an assembler for compiling an assembler code generated from this optimized intermediate code to generate an object code. In the object code generation device including a code compiling unit, the intermediate code optimizing unit, with respect to the intermediate code of the multi-branch judgment syntax, among branch destinations of each branch of the multi-branch judgment syntax, only branch destinations different from each other A branch destination table in which is registered, and an index table in which the index of the branch destination of each branch of the multi-branch determination syntax is registered, and the optimization processing is performed so as to indicate the branch destination stepwise. An object generation device characterized by the above. 2. The intermediate code optimizing unit collects information on the multi-branch judgment syntax, and multi-branch judgment syntax information collecting means, and a branch destination table based on the information collected by the multi-branch judgment syntax information collecting means. Branch destination table creation determination means for determining whether or not to create a branch destination table, and the multi-branch determination syntax information collection for the multi-branch determination syntax determined to create the branch destination table by the branch destination table creation determination means. Index table creation judging means for judging whether or not to create an index table based on the information collected by the means, and the multi-branch judgment syntax judged to create the index table by the index table creation judging means A branch destination table in which only different branch destinations are registered among the branch destinations of each branch of the multi-branch determination syntax,
An index table showing an index of a branch destination of each branch of the multi-branch determination syntax, and a first optimization processing means for performing an optimization process so as to show the branch destination stepwise by the index table. The object generation device according to claim 1. 3. The object generation device performs an optimization process using a comparison instruction sequence for a multi-branch determination syntax determined by the branch destination table creation determination means not to create a branch destination table. Optimization processing means, and third optimization processing means for performing optimization processing using a branch destination table for the multi-branch determination syntax determined not to create an index table by the index table creation determination means. The object generating apparatus according to claim 2, further comprising: 4. An object code generation method for optimizing an intermediate code generated from a high-level language and compiling an assembler code generated from this optimized intermediate code to generate an object code. At the time of optimization, for the intermediate code of the multi-branch decision syntax, among the branch destinations of each branch of the multi-branch decision syntax, a branch destination table in which only different branch destinations are registered, and the multi-branch decision syntax An object generation method, comprising: an index table in which an index of a branch destination of each branch is registered; and performing an optimization process for gradually indicating the branch destination. 5. A multi-branch judgment syntax information collecting step for collecting information on the multi-branch judgment syntax for an intermediate code of the multi-branch judgment syntax at the time of the optimization, and a multi-branch judgment syntax information collecting step. For the branch destination table creation determination step that determines whether to create a branch destination table based on the collected information, and the multi-branch determination syntax that is determined to create a branch destination table in this branch destination table creation determination step An index table creation determination step of determining whether to create an index table based on the information collected in the multi-branch determination syntax information collection step, and an index table creation determination step of determining an index table creation For the multi-branch decision syntax, An optimization process is performed in which a branch destination table in which only different branch destinations are registered and an index table indicating the index of the branch destination of each branch of the multi-branch determination syntax are provided to show the branch destination stepwise. The object generation method according to claim 4, further comprising: an optimization processing step.