Compiler issue c2000

Lee Magnusson

Other Parts Discussed in Thread: TMS320F28069

Hi,

I'm using the latest compiler, 6.4.6 for a tms320f28069. I am using optimization level 4 and have an issue with the compiled code. Consider this c code:

struct {

float inv_bus_voltage;
float cogging_gain;
} foc_command;

foc_command.inv_bus_voltage = 1.0 / foc_command.bus_voltage;
foc_command.cogging_gain = 0.0;

The generated assembly looks like this:

MOVW DP,#_foc_command+14 ; [CPU_U]
MOVB ACC,#0 ; [CPU_] |469|
.dwpsn file "../main.cpp",line 467,column 5,is_stmt,isa 0
MOV32 @_foc_command+14,R1H ; [CPU_] |467|
.dwpsn file "../main.cpp",line 466,column 5,is_stmt,isa 0
MOV32 @_foc_command+12,R0H

which then looks like this:

3f5cb9: 761F0055 MOVW DP, #0x55
3f5cbb: 0200 MOVB ACC, #0
467 foc_command.cogging_gain = 0.0;
3f5cbc: E2030100 MOV32 @0x0, R1H
466 foc_command.inv_bus_voltage = 1.0 / foc_command.bus_voltage;
3f5cbe: E203003E MOV32 @0x3e, R0H

So R0H fails to get written to the correct spot because it's on a different data page. Can this be fixed?

Update:

____________________________

At optimization level 0 and below it switches the value that it messes up.

3f605f: 761F0054 MOVW DP, #0x54
3f6061: E203003E MOV32 @0x3e, R0H
467 foc_command.cogging_gain = 0.0;
3f6063: E590 ZERO R0
3f6064: E2030000 MOV32 @0x0, R0H

over 10 years ago

0 George Mock over 10 years ago

TI__Guru**** 252950 points

In summary, you are saying that a data page boundary falls in the middle of the foc_command structure, and the compiler fails to keep the DP register updated to the correct value while accessing different fields of that structure.

To advance this issue, we need to reproduce it ourselves. Let's pursue the optimization level 0 form of the problem first. Please preprocess the source file with this problem and submit it. We also need to see all of the compiler options used.

Thanks and regards,

-George

0 Lee Magnusson over 10 years ago in reply to George Mock

Intellectual 280 points

Hi George,

Thanks. Your description is accurate. I created some preprocessed files but would prefer not to submit on the forum. Is there another way to submit?

0 George Mock over 10 years ago in reply to Lee Magnusson

TI__Guru**** 252950 points

Lee Magnusson said:
Is there another way to submit?

You can send it just to me. Hover your mouse over my forum avatar. In the resulting pop-up, click on Send a private message. In that message compose interface, use the paper clip icon to attach the .zip file. Don't forget we also need to see all the compiler options.

Thanks and regards,

-George

0 George Mock over 10 years ago in reply to George Mock

TI__Guru**** 252950 points

Thank you for sending in a test case. All the source files you sent have the file extension .pp. So I had to make an educated guess that one of them is a CLA source file (file extension .cla) and the rest are C++ files (file extension .cpp). Further, the CLA file defines the global structure foc_command, while one of the C++ source files refers to it.

If I am correct about all of that, then you are experiencing a known compiler problem. The SDOWP ID is SDSCM00050582. You can look it up with the SDOWP link below in my signature. The workaround is that all data shared between CLA and the C2000 CPU cannot be defined in the CLA source, but in the C or C++ source.

Thanks and regards,

-George

0 Lee Magnusson over 10 years ago in reply to George Mock

Intellectual 280 points

Thanks, that explains it. Is there any recommended procedure for finding issues like this? Would this be a compiler warning if I had an option set to display it?

0 George Mock over 10 years ago in reply to Lee Magnusson

TI__Guru**** 252950 points

Lee Magnusson said:
Would this be a compiler warning if I had an option set to display it?

No, but that is a very good suggestion. I filed SDSCM00052289 as an enhancement request in the SDOWP system. The linker could detect when global variables are defined in CLA code and used in C/C++ code, and then issue an error diagnostic. Feel free to follow this entry with the SDOWP link below in my signature.

Thanks and regards,

-George