JPH0736706A - Optimized compiler - Google Patents

Abstract

PURPOSE:To shorten calculation time for judging the branching conditions of a condition branching sentence provided with plural branches. CONSTITUTION:When it is judged that rebel branching conditions continue in a branching condition judging means 13, the length of the calculation time required for judging the authenticity of the branching conditions is evaluated in a branching condition evaluating means 14 and a block condition branching sentence for which the orders of the branching conditions and basic blocks executed when the branching conditions are judged as true are replaced in an order from the one for which the calculation time is shortest is outputted from a block condition branching sentence replacing means 15. By bringing the branching condition for which the calculation time required for judging the authenticity is short to front when the rebel branching conditions continue in the condition branching sentence provided with the plural branches, the calculation time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compiler for electronic computers.

[0002]

2. Description of the Related Art In order to execute a program written in a high level programming language such as C or FORTRAN on an electronic computer, a compiler that translates the original program into a machine language is generally used. Particularly, in recent years, an optimizing compiler (eg, an optimizing compiler) that performs various optimizations to maximize the performance of the electronic computer and improve the execution performance.
A. V. Aho, R.A. Sethi, J .; D. Ullma
n Co-authored “Compilers-Principles,
Techniques, and Tools, "J.
L. Hennessy, D.M. A. Patterson co-authored "Computer Architecture: A
"Quantitative Approach") is drawing attention.

A procedure for a conventional optimizing compiler to translate an original program into a machine language will be described below with reference to FIGS. 6, 2 and 7.

FIG. 6 is a block diagram of a conventional optimizing compiler. In FIG. 6, 101 is a compiling target code input means, 102 is a lexical analysis means, 103 is a syntax analysis means, 104 is an intermediate language generation means, 105 is an optimization means,
Reference numeral 106 denotes a purpose code generating means.

FIG. 2 shows a FORTRAN program including a block IF statement which is one of block conditional branch statements.
It is a program figure.

In FIG. 2, 21 is a block IF statement including a plurality of conditional branches, 22 is a branch condition requiring comparison operation with a floating point number, and 23 is a basic condition executed when the branch condition 22 is true. A block, 24 is a branch condition that requires only a comparison operation with an integer, and 25 is a basic block executed when the branch condition 24 is true.

FIG. 7 shows a microprocessor of the SPARC architecture (for example, SPAR) obtained as a result of compiling the program of FIG. 2 with a conventional optimizing compiler.
C International, Inc. Written "The
SPARC Architecture Manual
It is a program figure which shows the machine language program of the object code which targets Version 8 ").

In FIG. 7, 201 is a block IF statement 2
1 is a machine language program, 202 is a branch condition 22
The comparison operation with the floating-point number for determining
3 is a basic block corresponding to 3, 204 is a comparison operation with an integer for determining the branch condition 24, and 205 is a basic block corresponding to 25.

With respect to the conventional optimizing compiler configured as described above, the procedure of compiling and the machine language program of the compiling result will be described below.

When the FORTRAN program of FIG. 2 is compiled by the conventional optimizing compiler of FIG. 6, first,
It is input to the compile target code input means 101, subjected to preprocessing such as processing of comment lines and continuation lines, and then passed to the lexical analysis means 102. The lexical analysis means 102 converts the pre-processed code into a token string, and the syntax analysis means 103 which received the code analyzes the syntax of the program from the input token string, and the intermediate language generation means which receives the result. 1
04 outputs the code converted into the intermediate language. When the intermediate language is input, the optimizing means 105 outputs the intermediate language that has been subjected to code optimization such as the removal of common subexpressions, and the object code generating means 106 that receives it outputs the machine language program of the object code. Output. As a result, the branch condition 22 of the block IF statement 21 of FIG. 2 is the machine language program unit 202 of FIG. 7, and the branch condition 24 is the machine language program unit 204.
Further, the basic block 23 executed when the branch condition 22 is determined to be true is instructed to the machine language program unit 203 by the basic block 25 executed when the branch condition 24 is determined to be true.
Is compiled into the machine language program unit 205.

[0011]

However, in the above-mentioned conventional configuration, a block conditional branch statement having a branch condition having a long calculation time required for true / false judgment at the front of a plurality of branch conditions is compiled and executed. However, even if the value of the branch condition judgment result is false, the number of times the branch condition judgment calculation is performed is increased, and as a result, the execution performance is deteriorated. .

Specifically, referring to FIG. 7, branch condition 2
The calculation of the branch condition 202, which requires a longer calculation time than 04, is always executed regardless of the truth.

The present invention solves the above-described problems, and when a plurality of branch conditions are consecutive incompatible branch conditions, a branch condition determination calculation requiring a long calculation time for true / false determination is performed. It is an object of the present invention to provide an optimizing compiler that reduces the number of executions to shorten the calculation time and improves the program execution performance.

[0014]

In order to solve the above problems, a first optimizing compiler of the present invention comprises a block conditional branch statement detecting means for detecting a block conditional branch statement, and a branch from the detected block conditional branch statement. A branch condition detecting means for detecting a condition, a basic block detecting means for detecting a basic block executed when each branch condition is satisfied from the detected block condition branch statement, and the detected branch condition is an exhaustion event. Branch condition determining means, a branch condition evaluating means for evaluating a calculation time required for determining whether the detected branch condition is true or false, an output of the basic block detecting means, an output of the branch condition determining means, and a branch condition evaluating means. A branch condition and a block condition branch statement order exchanging means for changing the order of the set of basic blocks executed when the branch condition is satisfied A.

Further, the second optimizing compiler of the present invention is the first optimizing compiler, wherein when the executable object code is executed, it is determined that the total number of executions of the block conditional branch statement and each branch condition are true. Measured the number of times
It has branch condition true ratio measuring means for outputting the ratio of the number of times each branch condition is judged to be true to the total number of executions, and the block condition branch statement order exchange means outputs the basic block detecting means and the branch condition judging means. The order of the branch condition and the set of basic blocks executed when the branch condition is satisfied is exchanged from the output of the branch condition evaluating means and the output of the branch condition true ratio measuring means.

[0016]

According to the first configuration of the present invention, when the program includes a block conditional branch statement, the block conditional branch statement detecting means detects this and the branch condition detecting means detects the branch condition from its output. And the basic block detecting means detects a basic block executed when each branch condition is satisfied. Furthermore, from the output of the branch condition detection means,
The branch condition judging means judges whether or not a plurality of continuous branch conditions are rejected, and the branch condition evaluating means evaluates the calculation time required for judging the truth of the branch condition. When the branch condition determining means detects that there are a plurality of consecutive branching branch conditions, the block condition branch statement order exchanging means receiving it detects that
The branching condition evaluation means compares the calculation times of those branching conditions, and outputs the code in which those branching conditions and basic blocks are rearranged in order from the smallest.

Thus, if the branching conditions that are repulsive are continuous and the ratio of those branching conditions is determined to be true in advance, a branch that requires a long calculation time to determine the trueness or falseness is determined. The condition and the basic block that is executed when the branch condition are satisfied are changed in order by changing the order of the branch condition that requires a short calculation time for true / false judgment and the basic block that is executed when the branch condition is satisfied. The expected value of the number of times the branch condition is calculated is reduced by shortening the expected value of the calculation time, assuming that the ratios of those branch conditions that are judged to be true are all equal. be able to.

According to the second configuration of the present invention, when the program includes a block conditional branch statement, the block conditional branch statement detecting means detects this and the branch condition detecting means detects the branch condition from its output. And the basic block detecting means detects a basic block executed when each branch condition is satisfied. Further, from the output of the branch condition detecting means, the branch condition judging means judges whether or not a plurality of continuous branch conditions are rejected, and the branch condition evaluating means evaluates the calculation time required for judging whether the branch condition is true or false. . When the branch condition judging means detects that there are a plurality of consecutive branching branch conditions, the block condition branch statement order exchange means that receives it detects the calculation time of those branch conditions evaluated by the branch condition evaluating means. Branch condition A code that compares the product value of the branch condition true ratio measuring means and the reciprocal of the ratio of the number of times that the branch condition is determined to be true, and rearranges those branch conditions and basic blocks in ascending order. Is output.

As a result, when the repulsive branch conditions are continuous, the calculation time required for determining the true or false of each branch condition when executing the object code of the compilation result and the branch condition are determined to be true. The branching condition that has a large product of the reciprocal of the number of times and the basic block that is executed when the branching condition is satisfied, and the reciprocal of the number of times that the branching condition is determined to be true The branch condition with a small product of and the basic block executed when the branch condition is satisfied can be exchanged with the order and passed to the rear part of the code, and the time required for the decision calculation of the branch condition can be reduced and the block conditional branch Statement execution time can be minimized.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of an optimizing compiler according to a first embodiment of the present invention.

In FIG. 1, 1 is a code input means for compiling, 10 is a block conditional branch statement detecting means for detecting a block conditional branch statement, 11 is a branch condition detecting means, 12
Is a basic block detecting means, 13 is a branching condition judging means for judging whether the branching condition is an exhaustion event, 14 is a branching condition evaluating means for evaluating the calculation time required for judging whether the branching condition is true or false, and 15 is a branching condition. And block condition branch statement order exchange means for outputting a code that rearranges basic blocks executed when the branch condition is satisfied, 2 lexical analysis means, 3 syntactic analysis means, 4 intermediate language generation means, 5 Is an optimization means, and 6 is an object code generation means.

FIG. 2 shows a FORTRAN program including a block IF statement which is one of block conditional branch statements.
It is a program figure. In FIG. 2, 21 is a block IF statement including a plurality of conditional branches, 22 is a branch condition that requires a comparison operation with a floating point number, 23 is a basic block executed when the branch condition 22 is true, 24 Indicates a branch condition that requires only a comparison operation with an integer, and 25 indicates a basic block executed when the branch condition 24 is true.

FIG. 3 is a program diagram showing a block IF statement whose order has been changed by the block conditional branch statement order changing means 15 of the optimizing compiler of this embodiment.

In FIG. 3, 31 is a block IF statement obtained from 21, 32 is a branch condition in which the order has been changed and the branch condition is first, and 33 is a basic block executed when the branch condition 32 is true. , 34 is a branch condition that requires a comparison operation with a floating-point number 22 that has been rearranged in order, and 35 is a basic block that is executed when the branch condition 34 is true.

FIG. 4 is a program diagram showing a machine language program of the object code obtained as a result of compiling the program of FIG.

In FIG. 4, 41 is a block IF statement 31.
A machine language program corresponding to, 42 is a comparison operation with an integer for judging the branch condition 32, 43 is a basic block corresponding to 33, 44 is a comparison operation with a floating point number for judging the branch condition 34, and 45 is a 35 shows a basic block corresponding to 35.

The operation of the optimizing compiler of the present embodiment constructed as above will be described below with reference to FIGS.

When the FORTRAN program shown in FIG. 2 is compiled by the optimizing compiler of this embodiment, first, it is input to the compiling target code input means 1 and subjected to preprocessing such as processing of comment lines and continuation lines, and then the block. It is passed to the conditional branch statement detecting means 10. Block IF detected
The branch condition detecting means 11 detects each branch condition from the statement, and the basic block detecting means 12 detects the basic block executed when each branch condition is judged to be true. The detected branching condition is judged by the branching condition judging means 13 to determine whether or not continuous branching conditions are continuous.

When the disjoint branch conditions are continuous,
From the output of the branch condition evaluation means 14 in order of decreasing calculation time required for determining the true or false of the branch condition,
The block condition branch statement order exchange unit 15 outputs the block IF statement 31 in which the order of the branch condition and the basic block executed when it is determined to be true is exchanged.

The output of the block conditional branch statement order exchange means 15 is passed to the lexical analysis means 2. The lexical analysis means 2
The preprocessed code is converted into a sequence of tokens, and the parsing unit 3 that receives it analyzes the syntax of the program from the inputted token sequence, and the intermediate language generation unit 4 that receives the result analyzes the intermediate language. Output the code converted to. When the intermediate language is input, the optimizing means 5 outputs the intermediate language which has been subjected to code optimization such as the removal of common subexpressions, and the object code generating means 6 receiving it outputs the machine language program of the object code. Output.

As a result, the branch condition 32 of the block IF statement 31 of FIG. 3 is executed by the machine language program unit 42 of FIG. 4, the branch condition 34 is executed by the machine language program unit 44, and when the branch condition 32 is determined to be true. The basic block 33 is executed by the machine language program unit 43, and the basic block 35 executed when the branch condition 34 is determined to be true is executed by the machine language program unit 4.
Compile to 5.

As described above, according to the present embodiment, when the program includes the conditional branch statements in which the contradictory branch conditions are consecutive and the ratio of the branch conditions is not known in advance. , A branch condition that requires a long calculation time to determine whether it is true and a basic block that is executed when that branch condition is satisfied, and a branch condition that requires a short calculation time to determine whether it is true and a branch condition that is satisfied Expect the number of times to perform branch condition decision calculations, assuming that the basic blocks to be executed can be exchanged in the order and passed to the rear part of the code, and if the ratio of those branch conditions to be judged as true is all equal. The expected value of the calculation time can be shortened by reducing the value.

(Second Embodiment) FIG. 5 is a block diagram of an optimizing compiler according to a second embodiment of the present invention.

In FIG. 5, reference numeral 1 is a compile target code input means, 10 is a block conditional branch statement detecting means for detecting a block conditional branch statement, 11 is a branch condition detecting means, 12
Is a basic block detecting means, 13 is a branching condition judging means for judging whether the branching condition is an exhaustion event, 14 is a branching condition evaluating means for evaluating the calculation time required for judging whether the branching condition is true or false, and 15 is a branching condition. And block condition branch statement order exchange means for outputting a code obtained by rearranging basic blocks executed when the branch condition is satisfied, 16 branch condition true ratio measuring means, 2 lexical analysis means, 3 syntactic analysis means Reference numeral 4 is an intermediate language generation means, 5 is an optimization means, and 6 is a target code generation means.

The operation of the optimizing compiler of this embodiment constructed as described above will be described below with reference to FIGS.

When the FORTRAN program of FIG. 2 is compiled by the optimizing compiler of this embodiment, first, the executable object code obtained by the conventional optimizing compiler or the optimizing compiler of the first embodiment is executed. The total number of executions of the block conditional branch statement and the number of times each branch condition is determined to be true are measured by the branch condition true ratio measuring means 16, and each branch condition is determined to be true to the total number of executions of the block conditional branch statement. The ratio of the number of times the output is performed is output.

Next, the original FORTRAN code is input to the compile target code input means 1, subjected to preprocessing such as processing of comment lines and continuation lines, and then passed to the block conditional branch statement detection means 10. From the detected block IF statement, the branch condition detecting means 11 detects each branch condition, and the basic block detecting means 12 detects the basic block executed when each branch condition is judged to be true. The detected branching condition is judged by the branching condition judging means 13 to determine whether or not continuous branching conditions are continuous.

When the disjoint branch conditions are continuous,
The calculation time required for determining the truth of the branch condition, which is obtained as the output of the branch condition evaluation means 14, and each branch condition for the total number of executions of the block condition branch statement, which is obtained from the branch condition true ratio measuring means 16, is true. A block condition branch statement order exchange is performed on the block IF statement 31 in which the branch condition and the order of the basic blocks executed when it is determined to be true are switched in order from the smallest product of the determined reciprocal of the ratio. Output from the means 15.

The output of the block conditional branch statement order exchange means 15 is passed to the lexical analysis means 2. The lexical analysis means 2
The preprocessed code is converted into a token string, and the syntax analysis unit 3 that receives the code analyzes the syntax of the program from the input token string, and the intermediate language generation unit 5 that receives the result analyzes the intermediate language. Output the code converted to. When the intermediate language is input, the optimizing means 5 outputs the intermediate language which has been subjected to code optimization such as the removal of common subexpressions, and the object code generating means 6 receiving it outputs the machine language program of the object code. Output.

As a result, the branch condition 32 of the block IF statement 31 of FIG. 3 is executed by the machine language program unit 42 of FIG. 4, the branch condition 34 is executed by the machine language program unit 44, and when the branch condition 32 is determined to be true. The basic block 33 is executed by the machine language program unit 43, and the basic block 35 executed when the branch condition 34 is determined to be true is executed by the machine language program unit 4.
Compile to 5.

As described above, according to the present embodiment, when the program includes conditional branch statements in which contradictory branch conditions are continuous, at what ratio these branch conditions are judged to be true. , The calculation time required for true / false determination and the reciprocal value of its true ratio are large, and the basic block executed when the branch condition is satisfied, the calculation time required for true / false determination and its The branch condition with a small true ratio and the basic block that is executed when the branch condition is satisfied can be swapped in the order and passed to the back of the code, and the branch condition judgment calculation compared to when the original program is executed as it is. The calculation time can be shortened by reducing the time.

[0043]

As described above, according to the first aspect of the present invention, codes that are rearranged in order from the one having the smallest calculation time required for determining the trueness of the branching condition when the repulsive branching conditions are continuous. The expected value of the calculation time can be shortened by reducing the expected value of the number of times the branch condition is output and the branch condition determination calculation is performed assuming that the ratios at which those branch conditions are determined to be true are all equal.

In the second aspect of the present invention, the product of the calculation time required to determine the truth of the branch condition and the reciprocal of the ratio at which the branch condition is determined to be true when the repulsive branch conditions are continuous. It is possible to reduce the time required for branch condition judgment calculation and minimize the execution time of the block conditional branch statement by outputting the code rearranged in order from the smallest value of.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optimizing compiler according to a first embodiment of the present invention.

FIG. 2 is a source program diagram of FORTRAN for explaining the operation of the embodiment.

FIG. 3 is a program diagram of FORTRAN after a block IF sentence replacement process for explaining the operation of the embodiment.

FIG. 4 is an object program diagram of a machine language for explaining the operation of the embodiment.

FIG. 5 is a configuration diagram of an optimizing compiler according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional optimizing compiler.

FIG. 7 is an object program diagram of a machine language for explaining the operation of the conventional example.

[Explanation of symbols]

 10 block condition branch statement detecting means 11 branch condition detecting means 12 basic block detecting means 13 branch condition determining means 14 branch condition evaluating means 15 block condition branch statement order exchanging means 16 branch condition true ratio measuring means

Claims (2)

[Claims] 1. A compile target code input means, a block conditional branch statement detecting means for detecting a block conditional branch statement which is a conditional branch statement having a plurality of branches from an output of the compile target code input means, and the block. A branch condition detecting means for detecting a branch condition from the output of the conditional branch statement detecting means, and a basic set of statements executed when each branch condition is satisfied from the output of the block conditional branch statement detecting means. Detecting blocks, basic block detection means, from the output of the branch condition detection means, to determine whether those branch conditions are discharge events, branch condition determination means, from the output of the branch condition detection means, A branch condition evaluation means for evaluating the calculation time required for determining the truth of those branch conditions, the basic block detection means, the branch condition determination means, and the From the output of the branch condition evaluation means, when there are continuous branching conditions, those branching conditions and the basic block executed when the branching conditions are satisfied are required to determine the trueness or falseness of the branching conditions. An optimizing compiler comprising block conditional branch statement order exchanging means for outputting codes rearranged in order of decreasing calculation time. 2. The total number of executions of a block conditional branch statement and the number of times each branch condition is determined to be true during execution of the executable object code are measured, and each branch condition for all executions is determined to be true. The branch condition true ratio measuring means for outputting the ratio of the number of times of the branching, and the block condition branch statement order exchange means includes the basic block detecting means, the branch condition determining means, the branch condition evaluating means, and the branch condition true ratio. From the output of the measurement means, when the branching conditions are continuous, the branching conditions and the basic blocks executed when the branching conditions are satisfied are calculated as the calculation time required to judge the trueness or falseness of the branching conditions. 3. The optimizing compiler according to claim 1, wherein the code is rearranged in order from a product having a smaller value of a product of the branching condition and the reciprocal of the ratio determined to be true.