JP3349911B2 - Microprocessor and development support device thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microprocessor and a development support device thereof, and more particularly, to a microprocessor having a pipeline configuration and an instruction cache and a development support device thereof.

[0002]

2. Description of the Related Art As is well known, a microprocessor is
An arithmetic unit that decodes instructions and executes arithmetic and control operations, and is implemented on a silicon chip. With the recent development of LSI technology and widespread and sophisticated market needs, the performance has been steadily improved, and today, models having a word length of 64 bits have been commercialized. In addition, there are not a few that incorporate a cache memory in addition to essential components such as a register, an arithmetic circuit, and a control circuit. The cache memory is a high-speed and small-capacity memory provided inside a central processing unit (CPU) in order to satisfy the trade-off between high speed and large capacity for the internal memory of the computer as is well known.

In order to increase the speed of operation, a microprocessor employing a well-known pipeline configuration has been widely used.

[0004] The pipeline configuration is an extension of a look-ahead method in which an instruction fetching stage and an execution stage in a CPU are performed in parallel. The processing of each instruction is divided into a plurality of stages, and instructions are picked up one after another. In this way, a queue is created at each stage, and one arithmetic and logic unit performs the processing of these stages in parallel.

[0005] In response to the complexity of the microprocessor as described above, debugging has become a problem. There are trace, trap, single step, and the like as this kind of debug technique, but trace is suitable for general debug. As is well known, a trace is provided by providing a trace analyzer and a trace memory outside a CPU or a microprocessor that executes a program to be debugged. The trace analyzer stores addresses of instructions executed by the microprocessor in the trace memory one by one, and analyzes the stored contents later to enable debugging.

Conventionally, in a microprocessor having an instruction cache memory with a pipeline configuration, a memory access stays inside the microprocessor in a real-time trace when the cache function is used, and a trace analyzer directly detects data necessary for the trace. Can not.
Therefore, conventionally, it has been general to invalidate the cache memory and perform tracing.

However, when the cache memory is invalidated, the operation of the microprocessor is significantly different from that when the cache memory is invalidated, so that accurate debugging cannot be performed. In order to solve this problem, in order to enable tracing while keeping the cache memory in a valid state, a conventional microprocessor with a built-in cache memory has been required to start instruction execution, generate a branch instruction, and determine whether a branch destination address can be statically designated. Terminals for displaying each of them externally are provided. The conventional trace analyzer holds an execution flow obtained by statically analyzing a program in advance, and assembles a dynamic instruction processing order based on the execution flow based on a supply signal from each terminal. I have.

However, in the real-time trace when the cache function is used, as described above, the memory access stays inside the microprocessor, and the trace analyzer cannot directly detect the data required for the trace. This is very difficult because it cannot be determined that the branch destination address is not immediately before execution of the instruction.

Generally, this kind of microprocessor is
It has additional information, that is, tag information, for use in detecting a cache hit or in generating an interrupt request for an external break in synchronization with instruction execution. However, this tag information has not been used to trace the execution of instructions in the cache memory.

Referring to FIG. 9 which shows a block diagram of a conventional first microprocessor disclosed in Japanese Patent Application Laid-Open No. 6-161818, the conventional first microprocessor comprises a tag access comparing section 41 and an instruction storing section 42. , A comparison circuit 105, and an instruction address generation circuit 106.

[0011] The first conventional microprocessor includes:
The tag information held by the cache memory 104 is used for comparison by the comparison circuit 105 between the instruction address generated by the instruction address generation circuit 106 every time the instruction is read and the address stored in the cache memory 104 in advance. This is for detecting a so-called cache hit.

However, it is not used for judging the presence or absence of branch execution based on the presence / absence of a branch after execution of a conditional branch instruction or the like at the time of pipeline execution, that is, a preceding fetch cycle.

Referring to FIG. 10 which shows a block diagram of a conventional second microprocessor disclosed in Japanese Patent Application Laid-Open No. Hei 5-334082, this second conventional microprocessor is
It includes a cache memory 104, an instruction code tag embedding circuit 108, and an instruction code tag detection circuit 110.

This second conventional microprocessor is:
The tag information is used to generate an external break interrupt request in synchronization with instruction execution.

In a microprocessor with a built-in cache memory, once an instruction is read, an instruction read cycle from an external bus, ie, a fetch cycle, does not occur as long as the instruction keeps hitting. For this reason, since a break interrupt request from the outside can be input only during the first fetch cycle, tag information of the break interrupt request is added to the cache memory for instructions and stored in the cache memory.

Although the above tag information has been useful as a countermeasure against the above-mentioned problem of the presence or absence of a conditional branch at the time of execution of a pipeline, a break interrupt request is held until the execution of an instruction, and the break is synchronized with the execution of the instruction. Used to generate an interrupt.

That is, it cannot be used to trace the execution of instructions in the cache memory.

In these conventional first and second microprocessors, it is particularly difficult to predict a branch destination during execution of a conditional branch instruction and a register indirect branch instruction. , The real-time property is lost at the time of execution, a means for observing register write data is required, and a high-speed read method is required.

The reason is that in order to trace a register indirect branch instruction, it is necessary to observe information written to a register inside the processor from outside the processor. When estimating the write information of a register in parallel with the execution of an instruction, a recent microprocessor in which the internal operation operates in a pipeline executes the instruction in one clock, so a means for observing the register value in one clock is required. I need. Assuming that a dedicated terminal for register observation is provided in the processor, the number of register bits + several control signal terminals is required. Enlarging the package by increasing the number of terminals is disadvantageous in terms of cost.

Next, referring to FIG. 11 which shows a block diagram of a third conventional microprocessor and its trace analyzer described in Japanese Patent Application Laid-Open No. H5-222489, this third conventional microprocessor 201 has a built-in cache memory. The trace analyzer 203 changes the tracing method of the microprocessor in response to the supply of the mode display signal MD on the terminal 207.

An important point of the third conventional microprocessor is that a prediction of a branch destination at the time of execution of a register indirect branch instruction is indistinguishable from contents analyzed in advance of a program, and a break interrupt is generated at the time of branch. It is. During this break interrupt processing, a dedicated output cycle is generated to output the contents of the register, that is, the value of the program counter indicating the branch destination, so that the real-time property is lost unlike the operation of the original processor.

As described above, when using the bus terminal of the microprocessor user to suspend the occurrence of an external bus cycle and read and observe the contents of the register from outside the processor, the contents of the register are not limited to a bus cycle such as a normal fe cycle. Since a cycle for outputting the state to the outside is generated, the real-time property is lost.

There is also a method in which a register value is released during an idle state generated between each bus cycle of the microprocessor and the bus. However, a bus cycle of the processor is suspended in a cycle in which the register value is released from the user bus terminal. Therefore, the performance of the program itself is deteriorated.

[0024]

The above-mentioned first and second conventional microprocessors and their development support devices are described in the following.
In a trace method having a real-time trace function for storing the state of an external bus cycle, when a cache memory is enabled and this cache memory is hit, no fetch cycle is generated as an external bus cycle.
On the other hand, since the instruction execution address cannot be known outside the microprocessor, the instruction currently being executed cannot be determined. Therefore, it is not possible to infer all executed instructions from the information stored in the trace memory. was there.

In particular, it is difficult to predict a branch destination at the time of execution of a conditional branch instruction and a register indirect branch instruction. If these configurations can be guessed, the microprocessor loses real-time performance at the time of execution, There is a drawback that a means for observing register write data is required, and a high-speed reading method is required.

Furthermore, the third conventional microprocessor and its development support device use the bus terminal of the user to suspend the occurrence of an external bus cycle and read and observe the contents of the register from outside the processor. In addition to a bus cycle such as a cycle, a cycle dedicated to external output in a register state occurs, so that there is a disadvantage that real-time performance is lost.

An object of the present invention is to provide a microprocessor having a pipeline configuration and a real-time trace function for debugging a microprocessor with a built-in cache memory and a development support apparatus therefor.

[0028]

A microprocessor according to the present invention has an instruction execution unit for executing an instruction of an instruction code in response to the supply of the instruction code, and a first instruction which holds a first instruction read from an external memory. An instruction cache memory for outputting the second instruction, an instruction decode unit for decoding the first or second instruction and outputting the instruction code, and a bus control unit for controlling an associated external bus and internal bus. A bus between the external memory and the external bus.
Rear including trace memory for storing cycle status
Debug with a development support device that has a real-time trace function.
A microprocessor that performs a read cycle of the first instruction in response to a fetch cycle that is a read cycle of the first instruction.
The development support device sequentially generates first tag information which is a serial number corresponding to the first instruction and stores the first tag information in the trace memory.
And the instruction cache memory
The second tag information identical to the first tag information is stored in the first command.
Instruction and hold it, and of the first and second instructions
The second tag information of the instruction executed by the instruction execution unit is sequentially stored and held in the order of execution, and the debug
Storing the previous SL second tag information during reading in grayed time
Tag information holding means for outputting in the same order, and the second information read from the tag information holding means during the debugging.
Corresponding compares the first tag information tag information on the standard of
To open the instruction code and the state of the bus cycle.
Instructions actually executed by restoring by the launch support device
Is reproduced .

A microprocessor development support apparatus according to the present invention controls the microprocessor, an external memory holding instructions, a trace memory that stores addresses of instructions executed by the microprocessor one by one, and controls the whole. In the microprocessor development support apparatus provided with a host computer, the trace memory is configured such that, when an instruction is read from the external memory, the first tag information, which is a serial number corresponding to the instruction, the state of an address bus, and the state of a status bus. The state of the data bus is sequentially held.

[0030]

FIG. 1 is a block diagram showing a first embodiment of the present invention. Referring to FIG. 1, a microprocessor and a development support apparatus according to the present embodiment shown in FIG. The system includes a microprocessor 1, a main memory 2 of the development support device, and a tracer 8 for storing addresses of execution instructions of the microprocessor 1 one by one in a trace memory and then analyzing the stored contents for debugging.

The tracer 8 includes a trace analyzer 3 for analyzing the contents of the trace memory 4, a trace memory 4 for storing the contents of the execution instructions of the microprocessor 1 together with tag information, a personal computer 5 as a host computer,
An oscillator 6 for supplying a clock for the entire system, and buffers 7A to 7G for input / output interface of each signal are provided.

Referring to FIG. 2 showing a block diagram of the configuration of the microprocessor 1, the microprocessor 1 includes:
A bus control unit (BCU) 11 for controlling internal addresses, data buses 18, 19 and external data, addresses, status buses 9, 10, 21; an instruction cache 12 for temporarily storing instruction codes; An instruction decode unit (IDU) 13 that decodes and outputs an instruction code IC and tag information, a cache trace control circuit 14 that stores tag information corresponding to the instruction code stored in the instruction cache 12, and executes an instruction code instruction. An execution unit (EXU) 15, a counter 16 that increments for each instruction fetch, a selector 17, an internal address bus 18, and an internal data bus 19 are provided.

Referring to FIG. 3 showing a block diagram of the configuration of the cache trace control circuit 14, the cache trace control circuit 14 stores the tag information TB in the input order and outputs the storage order in a first-in first-out memory (FIFO) 1
41 is provided.

Next, FIG. 1 and FIG. 2 and FIG. 4 which is a flowchart showing the processing flow of this embodiment and FIG. 5 which shows an example of the processing contents of the trace data when the microprocessor 1 and the tracer 8 are executed. The overall operation of the present embodiment will be described with reference to the following. First, when the microprocessor 1 in the development support apparatus reads an instruction code, whether the instruction code has already been read in the internal instruction cache 12 beforehand. (Step S1)
~ S5). If the instruction code has already been read, the instruction code is read from the instruction cache 12, and if not, from the external main memory 2.
In this case, the development support device sends the bus cycle status (the status of the data bus 9, the status of the address bus 10, and the status of the status bus 21) to the trace memory 4 via the trace analyzer 3, At the same time, the tag information TA which is the serial number output by 1 is written (step S6).

Next, the microprocessor 1 adds tag information TB having the same content as the tag information TA written in the trace memory 4 to the read instruction code, and writes the same in the instruction cache 12 (steps S7 to S10).

Next, if an instruction has been previously read into the instruction cache 12, the instruction code and the added tag information TB as described above are stored in the microprocessor 1 if the instruction has not been read. E
The instructions are sequentially sent to the XU 15, and the EXU 15 executes these instructions sequentially (step S11). At this time, the tag information TB is sent to the internal cache trace control circuit 14 from the combination of the instruction code and the tag information TA that are reliably executed by the EXU 15 and stored in chronological order.

In this series of operations, similarly to the case where the microprocessor 1 stores the state of the instruction code reading cycle, that is, the fetch cycle in the trace memory 4, other data access cycles are also stored in chronological order. The tag information TA is incremented each time the state of the external buses 9, 10, 21 becomes a fetch cycle.

For convenience of explanation, in this embodiment,
The instruction length is fixed and the instruction length is equal to the data bus width.

By repeating this series of operations, the cache trace control circuit 14 in the microprocessor 1 stores the tag information TB shown in FIG.
The tag information TA, address A, status S, and data D shown in FIG.

With such contents stored,
The execution of the user program is stopped in the microprocessor 1 during execution of the instruction by using a technique such as a break interrupt (step S12). Thereafter, the tag information TB having the contents shown in FIG. 5A from the cache trace control circuit 14 and the tag information TA having the contents shown in FIG.
The address A, status S, and data D are read onto the memory of the personal computer 5 (step S13). Next, the state of the bus cycle including the tag information TA of FIG. 5B is rearranged based on the tag information TB (step S1).
4). The rearrangement of the instruction code portion is performed by tag information TB, T
Those whose values of A match each other are rearranged in the memory of the personal computer 5 in the order of the tag information TB.

Referring to FIG. 5 again, a specific example will be described in which the instruction once fetched by the instruction cache 12 is repeated by execution of a branch instruction, and then, the instruction once fetched by the instruction cache 12 is used as a branch instruction. Each case will be described.

Referring to FIG. 5A, after the tag information TB becomes 001, 002 to 00A, 00B, 008,
009 and the number recur. This part is a place where the instruction is executed again by the branch instruction taken into the instruction cache 12.

First, 00B, 008, 0 of the tag information TB
The method of searching for the address where the instruction executed in step 09 is located will be described.
The contents of the trace memory 4 in (B) may be referred to. That is, it can be seen that 00B of the tag information TA of the trace memory is the Bnz instruction (branch instruction) of the instruction code 11 of the address FFFF0028H. Similarly, 008 of the tag information TA is an ADD instruction of the instruction code 8 of the address FFFF001CH, and 009 is an address FFFF0
This is a Sub instruction of instruction code 9 of 020H.

Next, the trace of the data access cycle will be described. When the tag information TA shown in FIG.
07,008,008. The first 008 is data access trace information. Here, data 00000000H is stored in the address FFFF1000H. Here, the reason why two 008s are consecutive is that the counter of the tag information TA is incremented only when the microprocessor generates a fetch from the external bus. That is, it does not count up at the time of data access. Further, in searching for which instruction the data access was executed, the store instruction of the tag information TA002 can be found by looking back the contents of the trace memory 4 from 008 to 007,006 of the tag information TA. With this method, tracing in the activated state of the instruction cache 12 is possible without losing the real-time property of the microprocessor 1.

Next, the operation of the microprocessor 1 according to the present embodiment will be described in detail with reference to FIGS. 1, 2 and 3. First, the reset signal RA input to the EXU 15 is set to L level. To initialize the hardware. The other reset signal R is different from a reset signal in a normal microprocessor, and is a signal for initializing a development support device such as a break interrupt request as described later. When the reset signal RA is set to L level, the EXU 15 enters the break interrupt processing state, sets the break interrupt response signal TPK to L level once, and initializes the cache trace control circuit 14.

The EXU 15 sets the select signal SL to L level, and clears the counter 16. At the same time, in response to the L level setting of the select signal SL, the selector 17 outputs the internal data bus IBS as a state for outputting the tag information TA. Thereafter, when the reset signal RA is set to the H level, the microprocessor 1 starts the break interrupt processing.

Next, the microprocessor 1 operates the BCU 11
Are output to an external circuit via the address bus 10 and the status bus 21. Thereby, the data bus 9 is transferred from the external memory.
To start the program fetch for break interrupt processing. The fetched instruction code is sent to the IDU 13 via the internal instruction code data bus IB1, and the IDU 13 analyzes the instruction. Next, the IDU 13 sends the EXU 1 via the internal instruction code data bus IB2.
5, and the EXU 15 executes this instruction.

Next, when the EXU 15 executes the dedicated instruction for terminating the break interrupt, the select signal SL becomes H level, and the clear request to the counter 16 is released. At the same time, the selector 17 enters a state where it can output the counter output N as the tag information output TA in response to the H level of the select signal SL. Thereafter, execution of the original user program is started.

The microprocessor 1 outputs an address A to the address bus 10 and a status S to the status bus 21 based on the value of a preset program counter, similarly to the above-described program fetch for break interrupt processing. I do. An instruction of the user program is fetched from an external memory based on the contents of the address A and the status S. During this cycle, BC
U11 sends a one-pulse signal to the counter clock CKN to count up the counter 16, and outputs a value obtained by counting up the counter output N from "0" to "1". This value N is output to the outside via the selector 17 as tag information TA.

Next, inside the microprocessor 1,
The fetched instruction code is transferred to the BC via the data bus 9.
Read into U11. The BCU 11 adds the counter output N to the instruction code as tag information TA.

The instruction code and the added tag information TA
To the instruction cache 12 and the IDU 13 via the internal instruction code data bus IB1 and the internal tag information TAI. The instruction cache 12 stores the instruction code and the additional tag information TA until a read operation from the same address occurs again. However, when the contents of the instruction cache 12 are updated, the instruction code and the additional tag information TA do not exist. Therefore, when the instruction once flashed is read from the external memory again, the tag information TA
Becomes a new value different from the value before the update. The IDU 13 separates the instruction code from the tag information TA, and
15 via the internal instruction code data bus IB2. At the same time as sending the tag information TA to the cache trace control circuit 14 as the tag information TB, a write request is made by the tag information write control signal CT. The cache trace control circuit 14, as shown in FIG.
141 is stored as a storage element, and is stored in the order of writing. By repeating this series of operations, the tag information TB is sequentially stored.

At this time, the BCU 11 sends one pulse of the clock CKN for counting up the counter 16 every time the instruction is read.

Thus, the tag information TB is incremented each time an external fetch cycle occurs. Also,
During this repetitive operation, if the instruction code and the tag information TA are stored in the instruction cache 12 in advance, the instruction code and the tag information TA are sent from the instruction cache 12 to the IDU 13 instead of from an external memory.

Next, the cache trace control circuit 1
4 will be described. First, the trace analyzer 3 outputs a reset signal R corresponding to a break interrupt request signal to the microprocessor 1 to issue a break interrupt request. EX
Upon receiving the break interrupt request, U15 sets the select signal SL to the L level and sets the break interrupt response signal TP, similarly to the operation of receiving the request of the reset signal RA.
K is temporarily set to L level. At the same time, select signal S
In response to the L-level setting of L, the selector 17 outputs the data on the internal data bus IBS as tag information TA. The cache trace control circuit 14 sequentially outputs the tag information TB to the internal data bus IBS in response to the control of the level of the tag information read signal RDEN. The selector 17 outputs the tag information TB to the outside. After this reading, if the processing corresponding to the execution of the user program is performed again, the cache trace control circuit 14 of the tag information TB
The state can be switched to a state in which writing is possible.

Next, referring again to FIGS. 1 and 2, the operation of the entire development support apparatus of the present embodiment will be described in detail.
The development support device of the present embodiment has a form of a general development support device using the personal computer 5 as a host. The personal computer 5 controls the trace analyzer 3 via the system control bus 23 and the system data bus 24. First, when performing real-time tracing, the personal computer 5 is set to the trace analyzer 3 so that real-time tracing is possible.

Trace analyzer 3 supplies reset signal RA to microprocessor 1 to initialize the internal circuit. At the same time, the trace memory address AT
And writing control by controlling the WE, OE, and CS signals of the trace memory.

In the present embodiment, a method is used in which the state of the bus is written into the trace memory 4 for each clock, and the trace memory address AT is incremented for each clock from the time when the real-time trace is started.
Thus, the states of the data bus 9, the address bus 10, the status bus 21, and the tag information TA can be written to the trace memory 4 every clock.

When the reset signal R of the trace analyzer 3 is set to the H level by the debugger which is a dedicated program existing in the memory of the personal computer 5 from the personal computer 5, the microprocessor 1 enters the break interrupt processing state. Start program fetch of area. As a result, the break interrupt processing program is executed. This break interrupt processing program enables communication with the debugger through the trace analyzer 3. When a request for terminating break interrupt processing is issued from the personal computer 5 by this general method, the break interrupt processing program executes a dedicated instruction for terminating break interrupts.

As a result, the user program is now executed, and instruction fetch is started from the address indicated by the program counter rewritten by the debugger during the break interrupt processing in advance. As a result, the trace result is stored in the trace memory 4 in real time.

Next, when the trace is terminated and the trace result is to be read from the trace memory 4 and the microprocessor 1, the break interrupt request signal from the debugger, that is, the reset signal R is activated.

The microprocessor 1 has a reset signal R
When a break request is accepted, break interrupt processing starts. The details are as described above. Here, the difference between the case where the break interrupt processing by the reset signal RA is started and the case of processing by the break interrupt request of the reset signal R will be described. The processing by the break interrupt request of the reset signal R is a general event break processing, and is used for the purpose of generating a break interrupt in synchronization with the execution of the instruction and facilitating the restart of the user program processing from the break interrupt processing. You. On the other hand, the break interrupt processing by the reset signal RA is the initialization of the hardware of the development support device,
Since the purpose is to determine the initial state, it is not a break interrupt request particularly synchronized with the execution of the instruction.

When the break interrupt processing is started by the above processing, the trace analyzer 3 separates the data bus 9, the address bus 10, and the status bus 21 from the corresponding buses of the microprocessor 1 under the control of the debugger. The gate control signals G1 to G4 are set to the H level via the system data bus 24. Thereby, the buffers 7A to 7D connect the data bus 9A of the trace memory 4 to the system data bus 24. Thus, preparation for reading from the microprocessor 1 is completed.

To read the contents of the trace memory 4,
The personal computer 5 sends the trace memory address AT via the system control bus 23 to the address to be read from the trace memory 4. At the same time, Trace Analyzer 3
Sets the WE, OE, and CS signals of the trace memory to a read state. Thereby, data D is output to data bus 9A.

In this embodiment, since the width of the system data is equal to or larger than the data width of the trace memory, data for one frame can be read at a time.

By repeating this series of operations, the trace memory 4
And the tag information TA from the microprocessor 1
Are read into the memory of the personal computer 5, the tag information, the related addresses, and the data are rearranged according to the above-described processing flow by the dedicated program, and are displayed on the display.

Referring to FIG. 3 and FIG. 6 showing a time chart of the operation of the cache trace control circuit 14 according to the present embodiment, the cache trace control circuit 14 includes the FIFO 141 as a storage element as described above, and Has a configuration that allows an asynchronous access method of FIFO. The clock CK having the same frequency as the clock frequency supplied to the microprocessor 1 is always supplied, and at the time of writing, the tag information writing control signal CT is set to the H level for one clock, thereby making the FIFO of the tag information TB FIFO.
141 is written.

Next, when reading, when the tag information read control signal RDEN is set to the H level for one clock, the FIFO
One piece of tag information TB is read from O141. By repeating this series of operations, all contents can be read / written.

Next, referring to FIG. 7 which shows a block diagram of a cache trace control circuit 14A which characterizes the second embodiment of the present invention, the cache trace control circuit 14A of the present embodiment shown in FIG. The difference from the first embodiment is that S is used as a storage element instead of FIFO.
A counter 142 as a peripheral circuit thereof;
43, logic circuits G1 to G5, and an inverter I1.

Next, the writing of tag information will be described first with reference to FIG. 7. First, the break interrupt response signal TPK is set to the H level. Next, when the reset signal RA is set to the L level, the AND circuit G4 sets the clear signal CLR to the L level and sets the counter 143 to the counter 143.
Clear Next, when the reset signal RA is set to the H level, the AND circuit G4 outputs the clear signal C to the counter 143.
LR is set to H level, and the clear state of the counter 143 is released. At this time, the count value NT of the counter 143 is "
Then, the clock CK is inverted in advance by the inverter I1 to generate an inverted clock CKB. The count value NT is supplied to the address terminal of the SRAM 142. Next, the tag information TB is transmitted to the data terminal of the SRAM 142. To supply.

At the same time as this timing, the tag information read signal RDEN is set to L for writing to the SRAM 142.
The level and tag information write control signal CT is set to the H level for one clock, and the clock CK is supplied. Then NA
The ND circuit G2 sets the read control signal RE to L level,
The ND circuit G3 outputs the write control signal WE to H level during one clock.
The level is set to the L level, the L level is set to the H level, and the CS signal CS is set to the L level for one clock via the NOR circuit G5. As a result, the tag information TB becomes SR
When the data is written into the AM 142 and the NAND circuit G3 sends the output write control signal WE to the counter 143 via the AND circuit G1, the counter 143 counts up to “1”. By repeating this operation, the tag information TB is stored in the order of input.

Next, the cache trace of this embodiment will be described.
FIG. 8 is a time chart showing a read operation of control circuit 14A.
The readout procedure of the tag information will be described with reference to FIG. 1. First, when the reset signal RA is set to the H level and the microprocessor 1 receives the break interrupt request, the break interrupt response signal TPK goes to the L level. As a result, the AND circuit G4 outputs the L-level clear signal CLR to clear the counter 143. Next, when the break interrupt response signal TPK becomes H level, AN
The D circuit G4 sets the clear signal CLR to H level and cancels the clear request of the counter 143. At this time, the counter 14
3 is “0” and supplies the count value NT to the SRAM 142 as an address signal. At this time, the clock CK and the inverted clock CKB are supplied. At the same time as this timing, the tag information read signal RDEN is set to the H level for one clock and the tag information write signal CT is set to the L level for one clock. As a result, the NOR circuit G5 becomes the SRAM 142
To the L level for one clock,
The ND circuit G3 sets the write control signal WE to H level,
The ND circuit G2 sets the read control signal OE from H level to L level and from L level to H level. As a result, one piece of tag information TB is output to the instruction code data bus IBS. The NAND circuit G2 outputs the output read control signal OE to the counter 14 via the AND circuit G1.
3, the counter 143 counts up. "
1 ". By repeating this operation, the SRAM
It is possible to read out all the data 142.

As described above, according to the present invention, it is possible to execute the trace for debugging without losing the real-time property of the microprocessor even when the user program is executed in the valid state of the instruction cache 12.

The reason is that the tag information added to the instruction code read from the external memory or the instruction cache 12 is stored in the internal EXU 15 immediately before execution. This operation is independent of, or parallel to, the internal operation of a conventional processor having a pipeline function, so that the inherent high speed of the microprocessor is not lost. Also, since the tag information is stored in the execution order of the instruction, after the execution of the user program,
Since the data can be read out slowly for analysis, the real-time property is not lost.

When a dedicated terminal for tracing is provided in consideration of the high speed of the microprocessor, the number of dedicated terminals can be minimized in the present invention.

The reason is that, considering the memory space of the processor as a premise, the conventional method requires a number of address terminals that can be expressed in the space because it outputs logical or physical addresses to the outside. On the other hand, in the present invention, tag information is added to each instruction every time an instruction fetch cycle occurs, and the number of required dedicated terminals can be reduced by using the data shortening function of the tag information as described below.

For example, if a memory space of 4 G is provided, in the conventional technology, 32 dedicated terminals are required for expressing by an address.

However, in the present invention, tag information is attached to each instruction every time an instruction fetch cycle occurs. Thus, the number of terminals can be reduced in consideration of the following points.

First, the program area does not exist in the entire area of 4 Gbytes, and there is a work area for handling data and the like.

Secondly, since tag information is added in units of execution instructions, it is effective for a processor having instructions having many instructions having long instruction lengths. Recent RISC
Even a chip usually has a minimum of 2 bytes or 4 bytes. If one 4-byte instruction is used and one tag is used, it is 1/4.
With just a bit. In other words, the expression can be four times as large as the address representing the memory space. So this
Only 1/4 of the conventional one, that is, in this example, the number of terminals is
It can be reduced to eight.

[0080]

[0081]

[0082]

As described above, the microprocessor and the development support device of the present invention include the tag information generating means, the tag information holding means, and the tag information output means.
Since the tag information added to the instruction code is stored immediately before execution in the internal EXU, the instruction cache is enabled,
There is an effect that even if the user program is executed, the microprocessor can be executed without losing the real-time property of the microprocessor.

When a dedicated terminal for tracing is provided in consideration of the high speed of the microprocessor, tag information is added to each instruction every time an instruction fetch cycle occurs, and a data shortening function of the tag information is used. This has the effect of minimizing the number of required dedicated terminals.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a microprocessor and a development support device thereof according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a microprocessor according to an embodiment.

FIG. 3 is a block diagram illustrating a configuration of a cache trace control circuit that characterizes the present embodiment;

FIG. 4 is a flowchart illustrating an example of an operation of the microprocessor and the development support device according to the present embodiment;

FIG. 5 is a diagram illustrating an example of trace data when a trace is executed by the microprocessor and the development support device according to the present embodiment;

FIG. 6 is a time chart showing an example of the operation of the present embodiment.

FIG. 7 is a block diagram showing a configuration of a cache trace control circuit which characterizes a second embodiment of the microprocessor and the development support device of the present invention.

FIG. 8 is a time chart showing an example of the operation of the present embodiment.

FIG. 9 is a block diagram illustrating an example of a conventional first microprocessor.

FIG. 10 is a block diagram illustrating an example of a second conventional microprocessor.

FIG. 11 is a block diagram showing an example of a conventional third microprocessor and its development support device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microprocessor 2 Main memory 3 Trace analyzer 4 Trace memory 5 Personal computer 6 Oscillator 7A-7G buffer 8 Tracer 9 Data bus 10 Address bus 11 BCU 12 Instruction cache 13 IDU 14, 14A Cache trace control circuit 15 EXU 16 Counter 17 Selector 18 Internal Address bus 19 Internal data bus 21 Status bus 141 FIFO 142 SRAM 143 Counter G1 to G5 Logic circuit I1 Inverter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06F 11/28-11/34 G06F 9/38

Claims (6)

(57) [Claims] An instruction execution unit for executing an instruction of the instruction code in response to the supply of the instruction code; an instruction cache memory for holding a first instruction read from an external memory and outputting a second instruction; , An instruction decoding unit for decoding the first or second instruction and outputting the instruction code, and a bus control unit for controlling an associated external bus and internal bus, wherein a bus for the external memory and the external bus is provided. A microprocessor for debugging with a development support device having a real-time trace function including a trace memory for storing a state of a cycle, wherein the first instruction is generated sequentially according to a fetch cycle which is a read cycle of the first instruction. The first tag information as the corresponding reference number is held in the trace memory, and the instruction cache is stored. A second memory which adds the same second tag information as the first tag information to the first instruction and holds the same, and which of the first and second instructions is executed by the instruction execution unit. Tag information holding means for sequentially storing and holding the second tag information of the instruction in the order in which the instructions are executed, and outputting the second tag information in the order in which the second tag information is stored at the time of reading during the debugging; The first tag information is compared with the second tag information read from the information holding means, and the instruction code and the bus cycle state corresponding to the first tag information are actually executed by the development support apparatus. A microprocessor which reproduces an instruction execution procedure. 2. The method according to claim 1, wherein the instruction decode unit is configured to:
2. The microprocessor according to claim 1, wherein said instruction code is generated by decoding a second instruction, and said second tag information is separated and supplied to said tag information holding means. 3. The tag information holding means includes a FIFO for holding the second tag information, wherein the tag information holding means is synchronized with a second clock having the same frequency as a first clock supplied to the bus control unit. 2. The microprocessor according to claim 1, wherein writing of the second tag information and reading of the second tag information are performed. 4. The tag information holding means includes: an SRAM holding the second tag information; an address generation means of the SRAM; and a writing / reading means of the SRAM, and is supplied to the bus control unit. the microprocessor of claim 1, wherein in that synchronization with the second clock of the first clock with the same frequency to read the writing and the second tag information of the second tag information. 5. The microprocessor according to claim 1, wherein:
In a microprocessor development support device comprising: an external memory holding instructions; a trace memory for sequentially storing addresses of instructions executed by the microprocessor; and a host computer for controlling the entirety. Microprocessor development support characterized in that, when an instruction is read from an external memory, first tag information, an address bus state, a status bus state, and a data bus state, which are reference numbers corresponding to the instruction, are sequentially held. apparatus. 6. The state of the address bus and the state of the status bus corresponding to the first tag information, the first tag information corresponding to the second tag information output from the microprocessor, and the host computer. 6. The microprocessor development support apparatus according to claim 5 , wherein the microprocessor reads and rearranges the state of the data bus and reproduces an execution procedure of an instruction actually executed by the microprocessor.