Why does the compiler generate a corrupt object file for C6678?

Peter Robertson

I am using TMS320C6x C/C++ Compiler v7.4.4.

I have the following program (test.c), the minimal example I can make to demonstrate the fault:

--------------------
asm("    .sect MODULE");
asm("id: .word 0");
asm("    .sect OVERLAY");
asm("    .word id");
asm("    .text");

extern far void Fn1(void *, unsigned int, unsigned int);
extern far int V;
extern far void *Fn0(void *x);

#pragma CODE_SECTION(A, "OVERLAY");
far void A(void *p) {
   void *P = Fn0(&V);
   if (!P) Fn1(&V, 0,0);
}

#pragma CODE_SECTION(B, "OVERLAY");
far int B(void *p) {return 0;}

--------------------

I run the following makefile to build and display test.obj:

--------------------
default: test.obj
   ofd6x --obj_display=rawdata test.obj > z.lis

test.obj: test.c
   cl6x -O3 -c -mv=6600 test.c
--------------------

In the resulting output file, z.lis, I see the following:

Raw Data for Section "OVERLAY"

00000000: 00 00 00 00 62 83 8c 00 58 a3 00 02 2b 00 00 02 ....b...X...+...
00000010: 01 00 00 00 01 00 00 00 00 00 00 00 6a 00 00 02 ............j...
00000020: 62 03 10 00 f4 54 bc 05 f4 22 3c 05 28 00 00 05 b....T..."<.(...
00000030: 68 00 00 05 d9 0f 28 02 a1 16 8c 05 62 01 88 01 h.....(.....b...
00000040: d9 0f 10 00 2b 00 80 02 a1 06 28 02 5b a3 00 02 ....+.....(.[...
00000050: 40 00 00 03 91 08 00 c0 6b 00 80 02 db 1f ac c1 @.......k.......
00000060: e4 22 3c c5 63 03 14 d0 e4 52 bc c5 62 63 8c c0 ."<.c....R..bc..
00000070: 62 01 85 01 db 1f ac 01 e4 22 3c 05 63 63 8c 00 b........"<.cc..
00000080: e4 52 bc 05 00 20 00 00 00 00 00 00 00 00 00 00 .R... ..........
00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

and in the symbol table:

    25 B               0x00000004 defined   OVERLAY         global function
    26 A               0x0000000c defined   OVERLAY         global function

While B seems correct, the code for C is utter junk, with the first words being:

                  0200002b
                  00000001
                  00000001
                  00000000
                  0200006a
                  00100362
                  05bc54f4

The output from the assembler for the actual start of function C is:

     165 0000000c           A:
     169 0000000c 0200002A!            MVKL    .S2     Fn0,B4
     170 0000001c 0200006A!            MVKH    .S2     Fn0,B4
     175 00000020 00100362             CALL    .S2     B4                ; |13|
     176 00000024 05BC54F4             STW     .D2T1   A11,*SP--(8)      ; |12|
     177 00000028 053C22F4             STW     .D2T1   A10,*+SP(4)       ; |12|
     178 0000002c 05000028!            MVKL    .S1     V,A10
     179 00000030 05000068!            MVKH    .S1     V,A10

This has brought my project to a crashing halt.

Is it a known fault?

How can I make sure this problems is not going to affect a vast amount of similar code?

over 11 years ago

Peter Robertson over 11 years ago

Expert 2770 points

The two references in my description to the function C should have been to function A, but this does not change the problem in any way.

Archaeologist over 11 years ago

TI__Guru* 84285 points

Please tell me what you expected to see. When I run the standalone disassembler (dis6x) on the object file, I get the results I expected, including some padding NOPs that aren't visible in the disassembly you show:

Disassembly of test.obj:

DATA Section MODULE (Little Endian), 0x4 bytes at 0x0 
00000000             MODULE:
00000000             id:
00000000   00000000           .word 0x00000000

TEXT Section OVERLAY (Little Endian), 0xA0 bytes at 0x0 
00000000             OVERLAY:
00000000   00000000           NOP           
00000004             B:
00000004   008c8362           BNOP.S2       B3,4
00000008   0200a358           MVK.L1        0,A4
0000000c             A:
0000000c   0200002b           MVK.S2        0x0000,B4
00000010   00000001 ||        NOP           
00000014   00000001 ||        NOP           
00000018   00000000 ||        NOP           
0000001c   0200006a           MVKH.S2       0x0000,B4
00000020   00100362           B.S2          B4
00000024   05bc54f4           STW.D2T1      A11,*B15--[2]
00000028   053c22f4           STW.D2T1      A10,*+B15[1]
0000002c   05000028           MVK.S1        0x0000,A10
00000030   05000068           MVKH.S1       0x0000,A10

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Why does the compiler generate a corrupt object file for C6678?