JPH03233727A - System for optimizing unconditional branching text - Google Patents

Abstract

PURPOSE:To optimize an unconditional branching text just with the signal execution of a branching instruction by outputting an internally generated label to the jumping destination of an unconditional branching instruction not to a position right before an unconditional branching text when this text is outputted right after an internally generated label text. CONSTITUTION:It is decided whether an intermediate text 110 is unconditionally a branching text or not. If so, an unconditional text producing means 107 is called out. If not, an intermediate text output means 108 is called out via an output text deciding means 106. When the output right before an unconditional text to be outputted is not an internally generated label, a new internally generated label name is set as a branching destination by the means 107. If the output right before the unconditional text to be outputted is an internally generated label, the name of this label is set as a branching destination and an internally generated label holding area 109 becomes idle. Thus, an unconditional branching text is optimized just with the single execution of a branching instruction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optimization method for unconditional branch text, and more particularly to an optimization method for unconditional branch text in a compiler related to language processing.

[Conventional technology]

Conventionally, compiler intermediate text outputs unconditional branch text as is, even if it immediately follows an internally generated label.

[Problem to be solved by the invention]

In the conventional unconditional branch text output method described above, an object program with an unconditional branch instruction is generated immediately after an internally generated label, and an unconditional branch must be performed again immediately after the branch instruction to the internally generated label at runtime. There is a drawback.

[Means to solve the problem]

The unconditional branch text optimization method of the present invention unconditionally determines whether or not the intermediate text output by the compiler is a branch text, and if it is an unconditional branch text, an unconditional branch text creation means is executed. If the output is not an unconditional branch text, the output text judgment means calls the intermediate text output means, and if the output immediately before the unconditional text to be output is not an internally generated label, it sets a new internally generated label name as the branch destination and outputs it. If the output immediately before the unconditional text to be output is an internally generated label, the internally generated label name is set as the branch destination, and the internally generated label reservation area is emptied. If is not empty, output the internally generated label text to the intermediate text file and empty the internally generated label reservation area, and if the text to be output is not an internally generated label, output to the intermediate text file, and if the text to be output is internally generated. If it is a label, the intermediate text output means outputs it to the internally generated label storage area.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this embodiment shown in FIG. 1, a source program 101
．． Object program 102, compiler 103.
Analysis processing unit 104. Object program generation processing unit 105. Output text determining means 106. Unconditional branch text creation means 107. Intermediate text output means 108. It consists of an internally generated label reservation area 109 and intermediate text 110.

Referring to FIG. 2, the unconditional branch text creation means 107 in FIG. 1 determines whether the output immediately before the unconditional branch text is an internally generated label (step 201). Step 2: Setting the pending internally generated label name as the branch destination
02. Step 20 of emptying the internally generated label reservation area
3. It consists of step 204 of setting a new internally generated label name to the branch destination.

Referring to FIG. 3, intermediate text output means 1 in FIG.
Step 301.08 determines whether the internally generated label reservation area is empty. Step 302 of outputting internally generated label text to an intermediate text file. Empty the internally generated label reservation area 303. Step 304 of determining whether the output text is a label. Step 305 of outputting the output text to the internally generated label reservation area
, and step 306 of outputting the output text to an intermediate text file.

Next, the operation of this embodiment will be explained.

When the analysis processing unit 104 of the compiler 103 outputs intermediate text, the output text determining means 106 determines whether the text to be output is an unconditional branch text, and if it is not an unconditional branch text, transfers control to the intermediate text output means 108. .

If the text to be output is an unconditional branch text, control is transferred to the unconditional branch text creation means 107, and step 201 of determining whether the immediately preceding unconditional branch text to be output is an internally generated label is performed when the internally generated label area 109 is Step 204 determines whether it is an internally generated label immediately before the unconditional branch text to be output based on whether it is empty or not, and if the result is not an internally generated label, sets a new internally generated label name as the branch destination. The label name is set as the branch destination of the unconditional branch text, the process is terminated, and control is transferred to the intermediate text output means 108. If the immediately preceding unconditional branch text to be output is an internally generated label, step 202 of setting the pending internally generated label name as the branch destination sets the pending internally generated label name in the internally generated label reservation area 109. A step 203 of setting the branch destination of the unconditional branch text and emptying the internally generated label reservation area empties the internally generated label reservation area 109, ends the process, and transfers control to the intermediate text output means 108.

In step 301, the intermediate text output means 108 determines whether the internally generated label reservation area 109 is empty or not, and if it is not empty, the internally generated label text is converted into intermediate text. In step 302 of outputting to a file, the internally generated label text is output to the intermediate text 110, and in step 303, the internally generated label reservation area is emptied.
Empty 9. Determine whether the output text is a label Step 304 determines whether the output intermediate text is an internally generated label, and if it is an internally generated label, output it to the internally generated label reservation area 109 (Step 305)
, if the label is not an internally generated label, the intermediate text is output to the intermediate text file 110 and the process ends in step 306.

〔Effect of the invention〕

As explained above, when an unconditional branch text is output immediately after an internally generated label text, the present invention outputs the internally generated label at the destination of the unconditional branch instruction instead of immediately before the unconditional branch text. This has the effect that the branch instruction only needs to be executed once, instead of having to take another unconditional branch immediately after the branch instruction to the internally generated label at the time of execution.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is an unconditional branch text creation means 1 shown in FIG.
FIG. 3 is a flowchart showing the processing of the intermediate text output means 108 shown in FIG. 101...Source program, 102...Object program, 103...Compiler, 104...
-Analysis processing unit, 105...Object program generation processing unit, 106...Output text program determination means, 107...Unconditional branch text creation means, 108
... Intermediate text output means, 109... Internally generated label reservation area, ■ O... Intermediate text.

Claims (1)

[Claims] The compiler unconditionally determines whether or not the output intermediate text is a branch text, and if it is an unconditional branch text, calls an unconditional branch text creation means, and if the intermediate text is not an unconditional branch text. If the output immediately before the unconditional text to be output is not an internally generated label, the output text judgment means calls the intermediate text output means, and if the output immediately before the unconditional text to be output is not an internally generated label, it sets a new internally generated label name as the branch destination, If the output is an internally generated label, the internally generated label name is set as the branch destination, and the internally generated label reservation area is empty. Output the label text to the intermediate text file and empty the internally generated label reservation area, and if the text to be output is not an internally generated label, output it to the intermediate text file, and if the text to be output is an internally generated label, the internally generated label An optimization method for unconditional branch text, comprising intermediate text output means for outputting to a reservation area.