Assembly re-ordering

Other Parts Discussed in Thread: TMS320F28335

Hello

Using CCS 5.2.1, Compiler 6.1.0, processor TMS320F28335.
We are doing a compiler source to object code analysis and I have the following issue which puzzles me.

Building the very simple program:
    void main(void) {
        int a=0, b=0, c=0;
        int d;
   
        a = 1;
        b = 2;
        c = 3;
   
        d = a+b+c;
   
        for(;;);
    }

Built with
"C:/ti/ccsv5/tools/compiler/c2000_6.1.0/bin/cl2000" -v28 -ml -mt --float_support=fpu32 -Ooff -g --diag_error=225 --display_error_number --preproc_with_compile --preproc_dependency="main.pp"  "../main.c"

The assembly listing is:
            main:
    33804d:   FE04        ADDB         SP, #4
     3          int a=0, b=0, c=0;
    33804e:   2B41        MOV          *-SP[1], #0
    33804f:   2B42        MOV          *-SP[2], #0
    338050:   2B43        MOV          *-SP[3], #0
     6          a = 1;
    338051:   56BF0141    MOVB         *-SP[1], #0x01, UNC
     7          b = 2;
    338053:   56BF0242    MOVB         *-SP[2], #0x02, UNC
     8          c = 3;
    338055:   56BF0343    MOVB         *-SP[3], #0x03, UNC
    10          d = a+b+c;
    338057:   9242        MOV          AL, *-SP[2]
    338058:   9441        ADD          AL, *-SP[1]
    338059:   9443        ADD          AL, *-SP[3]
    33805a:   9644        MOV          *-SP[4], AL
    12          for(;;);
            C$DW$L$_main$2$B, C$L1:
33805b:   6F00        SB           C$L1, UNC

Built with:
"C:/ti/ccsv5/tools/compiler/c2000_6.1.0/bin/cl2000" -v28 -ml -mt --float_support=fpu32 -Ooff --symdebug:none --diag_error=225 --display_error_number --preproc_with_compile --preproc_dependency="main.pp"  "../main.c"

The assembly listing is:
            main:
    33804d:   FE04        ADDB         SP, #4
    33804e:   2B42        MOV          *-SP[2], #0
    33804f:   2B41        MOV          *-SP[1], #0
    338050:   2B43        MOV          *-SP[3], #0
    338051:   56BF0242    MOVB         *-SP[2], #0x02, UNC
    338053:   56BF0141    MOVB         *-SP[1], #0x01, UNC
    338055:   56BF0343    MOVB         *-SP[3], #0x03, UNC
    338057:   9242        MOV          AL, *-SP[2]
    338058:   9441        ADD          AL, *-SP[1]
    338059:   9443        ADD          AL, *-SP[3]
    33805a:   9644        MOV          *-SP[4], AL
    33805b:   6F00        SB           0, UNC

Both are build with optimization=off, but without debug there is a re-ordering of the assembly lines.

(1) Is there anywhere that describes what is going on here?  I’ve not been able to find anything in the various PDFs.

(2) Is there a switch to stop this re-ordering?  I would have expected the same assembler in both cases given that optimization=off.

(3) We are trying to determine if using debug (-g) adds anything to the final code loaded into flash, by comparing outputs from hex2000.  But with this re-ordering, a straight compare shows lots of differences.

Regards,
Giles Robinson