C2000 compilation issue with F28035 MCU

Simon Tinguely

We have an issue while compiling a code for a piccolo MCU (F28035) with
the last version of the compiler (v6.1.3).

We have a function starting this way (messagetype is a 69 words structure):

void RS_HeartBeat(Uint16* data, Uint16 ndata)
{
    struct messagetype message;
    Uint32* codechecksumpt;
    int i;
    message.id = 250;

...

}

When looking at the assembly, we have the following instructions:
        MOVB      AL,#0                 ; [CPU_] |1185|
        SUBB      FP,#4                 ; [CPU_U]
        MOVL      XAR5,XAR4             ; [CPU_] |1179|
        MOVB      *+FP[5],#250,UNC      ; [CPU_] |1183|
        ADDB      SP,#70                ; [CPU_U]

We notice that the assignment "message.id = 250;" is done before the
change of the stack pointer.
It happens that an interrupt occurs between
    MOVB      *+FP[5],#250,UNC      ; [CPU_] |1183|
and
    ADDB      SP,#70                ; [CPU_U]

In this case, the value of 250 is lost.

We have this issue with those compilation options:
-v28 -ml -mt -O2 --symdebug:none
--include_path="C:/ti/ccsv5/tools/compiler/c2000_6.1.3/include" --gcc
--diag_warning=225 --display_error_number --diag_suppress=9
--issue_remarks --optimizer_interlist --single_inline
--remove_hooks_when_inlining --opt_for_speed=5 -k --c_src_interlist

Is this behaviour normal? What should we do to prevent that kind of issues?

over 12 years ago

0 Archaeologist over 12 years ago

TI__Guru* 84225 points

I'm not a C2000 expert, but that does look like a bug. I'm not able to reproduce the problem from the test case given; I would need to see the complete body of RS_HeartBeat, as well as the type definitions that it uses.

0 Simon Tinguely over 12 years ago in reply to Archaeologist

Prodigy 230 points

Thank you for your reply:

I did a simplified RS_HeartBeat function which also presents the issue.

Definition of the structure:

#define MAX_DLENGTH 64 /**< max number of data words in a message*/
/// The message type structure.
struct messagetype {
   int16 id; ///< message identifier
   int16 sid; ///< serialization identifier
   int16 dlength; ///< number of data bytes
   Uint16 time_lastsent; ///<time message sent in ms
   Uint16 sentcounter; ///<number of times message has been sent
   Uint16 data[MAX_DLENGTH]; ///<actual message data if any
};

Simplified function in C

void RS_HeartBeat2(Uint16* data, Uint16 ndata)
{
   struct messagetype message;
   int i;
   message.id = 250;
   if (RS_Lock) {
       message.sid = 1;
   } else {
       message.sid = 0;
   }
   message.dlength = 2+ndata;
   //OK it's not nice but since the programmed checksum is not known at compile time
   //the optimizer replaces the value of codechecksum (a constant) and we end up with a bad value
   //this is why this is needed
   for (i=0;(i<ndata)&&(i<MAX_DLENGTH-2);i++){
       message.data[i+2]=data[i];
   }
}

Corresponding ASM

    .sect   ".text"
   .global   _RS_HeartBeat2
;----------------------------------------------------------------------
; 1204 | void RS_HeartBeat2(Uint16* data, Uint16 ndata)
;----------------------------------------------------------------------

;***************************************************************
;* FNAME: _RS_HeartBeat2                FR SIZE: 72           *
;*                                                             *
;* FUNCTION ENVIRONMENT                                        *
;*                                                             *
;* FUNCTION PROPERTIES                                         *
;*                            0 Parameter, 69 Auto, 2 SOE     *
;***************************************************************

_RS_HeartBeat2:
;** 1208   -----------------------    message.id = 250;
;** 1211   -----------------------    message.sid = RS_Lock != 0u;
;** 1215   -----------------------    message.dlength = ndata+2u;
;** 1219   -----------------------    if ( !ndata ) goto g5;
        MOVL      *SP++,XAR2            ; [CPU_]
        MOVZ      AR2,SP                ; [CPU_]
        MOVW      DP,#_RS_Lock          ; [CPU_U]
        MOVB      XAR5,#0               ; [CPU_]
        SUBB      FP,#4                 ; [CPU_U]
;----------------------------------------------------------------------
; 1206 | struct messagetype message;
; 1207 | int i;
;----------------------------------------------------------------------
        MOVL      XT,XAR4               ; [CPU_] |1205|
;----------------------------------------------------------------------
; 1208 | message.id = 250; //
; 1209 | //      codechecksumpt = (Uint32*) &(codeinfo.code_checksum);
; 1210 | if (RS_Lock) {
;----------------------------------------------------------------------
        MOVB      *+FP[5],#250,UNC      ; [CPU_] |1208|
;----------------------------------------------------------------------
; 1211 | message.sid = 1;
; 1212 | } else {
; 1213 | message.sid = 0;
;----------------------------------------------------------------------
        MOV       AH,@_RS_Lock          ; [CPU_] |1211|
        ADDB      SP,#70                ; [CPU_U]
        MOVB      XAR5,#1,NEQ           ; [CPU_] |1211|
;----------------------------------------------------------------------
; 1215 | message.dlength = 2+ndata;
; 1216 | //OK it's not nice but since the programmed checksum is not known at co
;     | mpile time
; 1217 | //the optimizer replaces the value of codechecksum (a constant) and we
;     | end up with a bad value
; 1218 | //this is why this is needed
;----------------------------------------------------------------------
        MOVB      AH,#2                 ; [CPU_] |1215|
        ADD       AH,AL                 ; [CPU_] |1215|
        MOV       *+FP[6],AR5           ; [CPU_] |1211|
;----------------------------------------------------------------------
; 1219 | for (i=0;(i<ndata)&&(i<MAX_DLENGTH-2);i++){
;----------------------------------------------------------------------
        CMPB      AL,#0                 ; [CPU_] |1219|
        MOV       *+FP[7],AH            ; [CPU_] |1215|
        BF        $C$L266,EQ            ; [CPU_] |1219|
        ; branchcc occurs ; [] |1219|
;***     -----------------------    #pragma MUST_ITERATE(1, 65535, 1)
;***     -----------------------    #pragma LOOP_FLAGS(256u)
;***     -----------------------    L$1 = (int)ndata-1;
;** 1219   -----------------------    i = 0;
        ADDB      AL,#-1                ; [CPU_]
        SETC      SXM                   ; [CPU_]
        MOV       PL,#0                 ; [CPU_] |1219|
        MOVZ      AR6,AL                ; [CPU_]
$C$L265:
;***   -----------------------g3:
;** 1219   -----------------------    if ( i >= 62 ) goto g5;
        MOV       AL,PL                 ; [CPU_]
        CMPB      AL,#62                ; [CPU_] |1219|
        BF        $C$L266,GEQ           ; [CPU_] |1219|
        ; branchcc occurs ; [] |1219|
;** 1220   -----------------------    *((long)(i+2)+5L+&message) = data[i];
;** 1219   -----------------------    ++i;
;** 1219   -----------------------    if ( (L$1 = L$1-1) != (-1) ) goto g3;
;***   -----------------------g5:
;***     -----------------------    return;
;----------------------------------------------------------------------
; 1220 | message.data[i+2]=data[i];
;----------------------------------------------------------------------
        MOVZ      AR4,SP                ; [CPU_U] |1220|
        MOV       ACC,AL                ; [CPU_] |1220|
        MOVL      XAR7,XT               ; [CPU_] |1220|
        SUBB      XAR4,#69              ; [CPU_U] |1220|
        ADDL      XAR7,ACC              ; [CPU_]
        MOVB      AL,#2                 ; [CPU_] |1220|
        ADD       AL,PL                 ; [CPU_] |1220|
        MOV       ACC,AL                ; [CPU_] |1220|
        ADDB      ACC,#5                ; [CPU_] |1220|
        ADDL      XAR4,ACC              ; [CPU_]
        MOV       AL,PL                 ; [CPU_]
        PREAD     *+XAR4[0],*XAR7       ; [CPU_] |1220|
        ADDB      AL,#1                 ; [CPU_] |1219|
        MOV       PL,AL                 ; [CPU_] |1219|
        BANZ      $C$L265,AR6--         ; [CPU_] |1219|
        ; branchcc occurs ; [] |1219|
$C$L266:
        SUBB      SP,#70                ; [CPU_U]
        MOVL      XAR2,*--SP            ; [CPU_]
        LRETR     ; [CPU_]
        ; return occurs ; []

0 Archaeologist over 12 years ago in reply to Simon Tinguely

TI__Guru* 84225 points

Thank you, now I can reproduce the problem. I've submitted SDSCM00046991 to track this issue.

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C2000 compilation issue with F28035 MCU