JPH01136240A - Register allocation processing system in compiler - Google Patents

Abstract

PURPOSE:To perform the optimization of an object by varying the number of global registers and that of local registers corresponding to a program. CONSTITUTION:The numbers of the global and the local registers are decided tentatively in advance, and they are registered in a register managing table 8. Next, the register managing table 8 is operated based on the result of prediction in a local prediction part 4. Afterwards, the compilation allocation processing of the local register to perform an actual arithmetic processing is performed. And a global count part 5 recognizes the number of the global registers used actually, and the register managing table 8 is operated based on the above result. Hereafter, the compilation allocation processing to perform the actual arithmetic processing is performed by a local allocation part 7, and its result is registered in the register managing table 8.

Description

[Detailed description of the invention] 〔table of contents〕 overview Industrial applications Conventional technology The problem that the invention aims to solve Means to solve problems action Example Effect of the invention 〔overview〕 Register allocation in the compiler is related to the processing method.

The purpose is to allocate general-purpose registers for local or global use depending on the program content during compilation processing.

A register group consisting of multiple registers, a global allocation section that processes the allocation of the registers for use as global registers, and a local allocation section that processes the allocation of the registers for use as local registers. In a compiler having a register management table and a register management table.

a local prediction unit that predicts the number of local registers required for a program input to the compiler for compilation processing;

The allocation includes a global count unit that counts the number of processed registers to be used as the global registers in the compilation process, and the registers to be used as the global and local registers according to the program during the compilation process. The configuration is configured so that the number of is variable.

[Industrial application field]

The present invention relates to a compiler, and more particularly, register allocation in a compiler relates to a processing method.

In a data processing device such as a general-purpose computer, a large number of general-purpose registers are provided and used to perform arithmetic processing.

Therefore, when compiling (translating) a source program to obtain an object module.

It is necessary to obtain an object module (allocated to specify the specific use etc. of each general-purpose register).

[Conventional technology]

General-purpose registers for calculations are assigned register numbers.1 For example, numbers 0 to 5 are assigned as local registers, numbers 6 to 10 are assigned as global registers, and so on. (temporary allocation), and its use was determined in advance. In other words, the number of local registers and the number of global registers were fixed.

Local registers are blocks of the program.

In other words, once an instruction starts executing, it is used to process a continuous unit of processing that cannot be interrupted by anything else.On the other hand, global registers are used to process, for example, a loop consisting of multiple blocks. It is used for this purpose.

In this way, for general-purpose registers that have been assigned their usage in advance, they are assigned to perform actual arithmetic processing within the scope of the assignment for this usage (register assignment in compilation processing; hereinafter simply referred to as compilation assignment).
will be performed again.

In other words, when a source program is compiled to obtain an object module, the register numbers are specified (assigned) to specify (allocate) which general-purpose registers are to be used in which instruction processing, and the module is made into an object. .

[Problem that the invention seeks to solve]

FIG. 3 is an example of a program for explaining the problems of the prior art.

The program 41 shown in FIG. 3(A) includes integer type multiplication,
This example includes division, remainder, and character-related operations, and requires many local registers, but not many global registers.

In particular, rcHl(1:A(1)+B(J)) −
cH2(J:C(J)-8(1)) J is the process that requires the most local registers. That is, since character type data is included in the array, no matter what order the processing is performed, six local registers, the most among nine different instructions, are required.

In such a program 41, there will be a surplus of global registers (if there is no other description that requires global registers). but.

General-purpose register allocation during compilation processing.

Since it is within the range of fixed usage (temporary allocation), surplus global registers cannot be used as local registers. Therefore, it is not possible to actually allocate a temporary name, which is possible with 1 allocation. Therefore, a 5TORE instruction is generated to save this -time name to the generation name, making it impossible to perform optimized processing (object generation).

The program 42 shown in FIG. 3(B) includes control variables that are preferably allocated to global registers, loop counts,
It requires many global registers, including the base and induction variables of the array within the loop.

This is an example of not requiring too many local registers.

For example, data x, y, z, and Q are floating point type data, so floating (floating point) registers are used for processing them, and general purpose registers are not used (not subject to allocation).

Bases of arrays X, Y, and Z in loop, loop count 1
．． By allocating variables such as Q to global registers, the execution speed of the program can be improved.

In such a program 42, local registers are left over (unless there is any other description that requires local registers), but during compilation processing, the leftover local registers are not allowed to be used as global registers. Although it is possible to improve the execution speed of , it has not been possible to perform the compilation process for this purpose.

As described above, in the conventional technology, the purpose of general-purpose registers, that is, the number of local registers and global registers, is fixed in advance, and the temporary allocation of general-purpose registers cannot be changed depending on the contents of the program. . As a result, register usage efficiency was poor, object modules could not be optimized, and execution speed could not be improved.

An object of the present invention is to provide a register allocation processing method in a compiler that can allocate general-purpose registers as local or global registers depending on the contents of a program during compilation processing.

[Means for Solving the Problems] FIG. 1 is a diagram showing the basic structure of the present invention, and shows a data processing device according to the present invention.

In Figure 1, 1 is the compiler, 2 is the processing section, and
3 is a control unit, 4 is a local prediction unit that predicts the number of local registers, 5 is a global count unit that counts the number of global registers actually used, 6 is a global allocation unit that allocates global registers, and 7 is a local register. 8 is a register management table, 9 is a register group consisting of (n + 1) general-purpose registers numbered from 0 to n, and 10 is an intermediate text etc. program.

11 is an object module.

The compiler 1 generates the intermediate text IO by parsing the input source program, and further creates the object module 11 corresponding to the intermediate text 10, so the necessary allocation of the general-purpose register group 9 is not processed. To do this, the processing unit 2 performs 1 allocation.
Intermediate text number 0 (that is, the intermediate text constituting the intermediate text 10) is scanned, and in the compiling process, global register allocation is first processed, and then local register allocation is processed.

The global allocation unit 6 and the local allocation unit 7 respectively perform global register allocation processing and local register allocation processing in the compiling process under the control of the control unit 3.

The local prediction unit 4 utilizes the fact that the intermediate statements are scanned, and in particular, the global register allocation is performed by scanning up to the intermediate statements within the loop for processing.

Predict the number of local registers needed within that loop. The local prediction unit 4 (control unit 3) operates the register management table 8 based on the prediction result, and calculates the number of temporarily determined global registers (registers whose use has been temporarily assigned to be used as). Increase.

The global count unit 5 refers to the register management table 8 to know how many global registers are actually used as a result of the global register compile allocation process, and learns the number of global registers that can be used as local registers. Global count section 5 (
The control unit 3).

Based on the reference result, the register management table 8 is operated to increase the number of local registers (registers whose purpose is assigned for use as a lock).

The register management table 8 includes predetermined assignments (temporary assignments) of each register in the register group 9 to its use (global or local), and
Allocations for performing actual arithmetic processing (allocations in compilation processing) are registered.

[For production]

For register allocation in the compilation process, prior to processing, the number of global and local registers is provisionally determined (the usage is provisionally allocated) in consideration of the number of registers in the register group 9, and the register management table 8 is will be registered.

As a result of prediction in local prediction unit 4, intermediate text 1
If the number of local registers that would be required according to the contents of 0 is less than the number of allocated local registers, the number of local registers will be reduced and the number of global registers will be increased.

Register management table 8 is manipulated.

Thereafter, within the range changed by the above operation, the global allocation unit 6 performs compile allocation of global registers for performing actual arithmetic processing, and the results are registered in the register management table 8.

Even if the number of required global registers is greater than the number of allocated global registers, the necessary processing can be performed because the number of global registers has been increased in advance.

The global count unit 5 refers to the register management table 8 and learns the number of global registers actually used according to the contents of the intermediate text 10.

Based on this, if the number of global registers actually used is less than the number of previously allocated global registers, the register management table 8 is operated to decrease the number of global registers and increase the number of local registers.

After this, within the range modified by said operation.

The local allocation section 7 performs compilation allocation of local registers for performing actual arithmetic processing, and the results are registered in the register management table 8.

In this way, the number of global and local registers that will be required based on experience can be provisionally allocated, and this can be changed depending on the content of the program (intermediate text 10). Therefore, in the compilation process, optimized register allocation can be performed, and the execution speed of the program can be improved.

Note that, even among general-purpose registers, those whose use is determined, such as a stack pointer, a frame pointer, an entry address when a procedure is called, or a return address, are excluded from the register group 9.

〔Example〕

FIG. 2 shows a processing flow for register allocation in the compiler of the present invention.

In this embodiment, the register allocation process will be explained when the compiler shown in FIG. 1 compiles the program shown in FIG. 3.

The local prediction unit 4 of this embodiment has the following as its prediction means:
Except for loop regression calculations, there is a means for checking whether operations other than floating point operations occur within one loop.

The criterion (prediction means) for determining the number of local registers in the local prediction unit 4 is set as described above (the reason is that all floating point operations use floating registers and are therefore not subject to general-purpose register allocation. This is because in the FORTRAN program shown in the figure, many of the operations within the loop are floating point operations such as matrix operations.

Such a prediction means can be realized by making one local and small modification to the compiler (or the program for processing the layout).

The general-purpose register group 9 of this embodiment is made up of 11 registers numbered 0 to 10 (n = 10).

Empirically, as a temporary allocation of uses, six registers numbered 0 to 5 are set as local registers, and five registers numbered 6 to 10 are set as global registers.

According to the present invention, all registers in the general-purpose register group 9 can be used (allocated) as local registers depending on the contents of the program, and seven registers from No. 4 to No. 10 can be used as global registers. The reason for setting the number of global registers that can be used (assigned) as registers to 7 is because, empirically, it is better to reserve 4 local registers for any program. This is because it is considered desirable.

In other words, if the number of local registers is reduced too much, -
This is because a 5TORE command that saves the time name to the generated name will be issued, and the object may become worse.

Note that global registers are used in order from number 10, and local registers are used in order from number 0.

ta) When local registers are left over, the register compile allocation process for the program shown in FIG. 3(B) is performed as shown in FIG.

■ The source program is input to compiler 1.

When intermediate text 10 corresponding to this is generated.

As for the layout, the processing unit 2 extracts one 00 loop from the intermediate text 10.

■ As for the allocation, the processing unit 2
Determine whether this is the innermost (innermost) loop.

(2) In the case of the innermost loop, the processing unit 2 scans the intermediate statements constituting the intermediate text 10 in the case of 9 allocation.

(2) The local prediction unit 4 uses the result of scanning in process (2) to determine whether or not the calculations executed in the loop are only floating point calculations.

■ In the case of only floating point operations, the local prediction unit 4 (
The control unit 3) determines that the number of local registers that will be required within the loop is small (less than the number that was provisionally allocated). and.

The local prediction unit 4 (control unit 3) operates the register management table 8 to predict the numbers 4 to 7.
reallocate (increase by 2) as global registers.

If it is not only floating point operations, the local prediction unit 4 (
The control unit 3) omits the process (2).

(2) The global allocation unit 6 performs compilation allocation of global registers necessary for arithmetic processing in order to generate the object module 11.

This allocation is performed within the range of the number of global registers by referring to the register management table 8 under the control of the control section 3 (local prediction section 4) which knows the number of global registers.

For example, when processing global register allocation for a program such as that shown in FIG. Then, the arrays X, Y in the loop.

Even for the basis of Z, global registers can be allocated for processing. This makes the objects in the loop nicer and also reduces the object size.

Overall program execution speed can be improved.

(2) The global count unit 5 (control unit 3) refers to the register management table 8 and learns the number actually used as a global register in the process (2). 9For example, if only registers from number 5 onwards are used,
The register management table 8 is operated so as to change the temporary allocation of register No. 4 from a global register to a local register.

(2) After processing (2), the processing unit 2 takes out one block in the loop for 9 allocation.

■ Local allocation is part 7, object module 1
1, compile allocation of local registers necessary for arithmetic processing is performed. This allocation is performed under the control of control unit 3 (local allocation unit 7), which knows the number of local registers. This is done with reference to the management table 8.

When processing the allocation of local registers for a program such as that shown in FIG. 3(B), the number of local registers is reduced by two in process (2).

Since the data x, y, z, and Q are of floating point type, they are not subject to general-purpose register allocation, and compile allocation can be performed within the range of four local registers without causing any problems.

[Phase] For each block in the loop, the process of extracting it and compiling and allocating the local register (processes ① and ②) is repeated.

■ For each loop of the program, processing ■ or 0 is repeated.

(bl If there are excess global registers, Figure 3 (A)
When performing register compilation allocation processing for a program such as the following, the processing is performed as follows.

Because the inside of the loop is not only floating point operations.

Processing ■ is omitted.

Therefore, in process (2), the number of global registers is set to five at most, and the compile allocation process is performed within this range.

In a program like the one shown in Figure 3 (A) (unless there is any other description that requires global registers), global registers are not used in process (2), so all registers in register group 9 are localized in process (2). The cash register management table 8 is operated so that it can be used as a register.

tc+ Cases other than the above As in the case (middle) above, process (2) is performed with the number of global registers up to 5, and according to the result, the number of local registers is changed (increased) in process (2). .

Although the present invention has been described above with reference to embodiments, the present invention can be modified in various ways according to its gist.

For example, as a prediction means in the local prediction unit 4, when scanning the intermediate 8 votes in process Alternatively, the number of necessary local registers may be precisely determined by performing allocation).

Also, if there are no 8 votes that use many local registers (character operations, integer multiplication, division, remainder) in the loop, the number of local registers required for one intermediate 8 vote is small (about 1 for each operand). ), so
It is believed that the number of local registers required is small. Therefore, the prediction means may predict the number of local registers based on the above judgment.

(Effects of the Invention) As explained above, according to the present invention, the register allocation in the compiler is made general-purpose by allowing the number of global registers and the number of local registers to be changed according to the program during processing without being fixed. It is possible to improve register usage efficiency, optimize objects, and improve program execution speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of the present invention. FIG. 2 is a processing flow diagram for register allocation. FIG. 3 is a diagram illustrating problems in the prior art. In the figure, 1 is the compiler, 2 is the allocation processing section, 3 is the control section, 4 is the local prediction section, 5 is the global count section, 6
is a global allocation section, 7 is a local allocation section, 8 is a register management table, 9 is a register group, 10 is an intermediate text, and 11 is an object module.

Claims (1)

[Claims] A register group (9) consisting of a plurality of registers to be used as global registers and a plurality of registers to be used as local registers, and allocation of the registers for use as the global registers. a global allocation unit (6) that performs processing; and a local allocation unit (7) that performs allocation processing for using the register as the local register.
and a register management table (8) in which the results of the allocation processing for each of the registers are registered, with respect to the program (10) input to the compiler for compilation processing, the necessary a local prediction unit (4) that predicts the number of local registers; and a global count that counts the number of registers allocated to be used as the global registers in the compilation process with reference to the register management table (8). Part (5). Performing the prediction prior to the global register allocation process, increasing the number of registers to be used as global registers based on the result, and using the registers as local registers based on the count result after the global register allocation process. Register allocation in a compiler, characterized in that the number of registers to be used as the global and local registers is made variable according to the program (10) during compilation processing by increasing the number of registers to be used as the global and local registers. Processing method.