Similar to bug #11813, I am seeing this on 68hc11 compiles with version 3.1 of the 68hc11 development chain.


c code with in-line lst file output:

The pointer pos_desc seems to be located at the head of the stack at the time of entry here. The tsx loads x with the stack pointer and ldx 0,x de-references that pointer. Then cmpb 14,x compares g_ack_ref (in b) with recode slice which is offset 14 bytes from what pos_desc is pointing to.

The error is later in the bclr opcode, where the stack pointer had not yet been dereferenced.

    if(pos_desc->recode_slice == g_ack_ref)
10430     eaac:       f6 b3 7c        ldab    b37c <g_ack_ref>
10431     eaaf:       30              tsx
10432     eab0:       ee 00           ldx     0,x
10433     eab2:       e1 0e           cmpb    14,x
10434     eab4:       26 08           bne     eabe <.LM91>
    {
#if 1
        // don't use because of compiler error.
        ipcr_print_str("rcv nack on recode: ");
        ipcr_print_uint8(g_ack_ref);
        ipcr_print_flush();

        pos_desc->pos_state
            &= ~(TERA_FSP_RECODE_SLICE_CREATED | TERA_FSP_RECODE_SLICE_XMITTED);
10438     eab6:       30              tsx
   * we seem to be missing a ldx 0,x here, or we should drop the tsx (above)
10439     eab7:       1d 0d 0c        bclr    13,x #$0c



compiler command line:

m6811-elf-gcc -x c -c -I../inc -Os -Wall -Wcast-align -Winline -Wmissing-prototypes -Wpadded -Wshadow -fomit-frame-pointer -g -m68hc11 -mshort -msoft-reg-count=12 -static filename.cpp -o filename.o