Johan Bezem

Code generation error converting 32 to 64 bit

Discussion created by Johan Bezem on May 6, 2010
Latest reply on May 10, 2010 by Johan Bezem

I'm using CW7.1.2 for ColdFire (7.1 build 14, patch 7.1.2 build 11, version 5.9.0) for an MCF5235.

Standard calling convention (StdABI), no optimization at all (also no peephole, etc).

 

I had problems with the MQX function _psp_ticks_to_time using an older version of MQX and could narrow it down to the instruction

      tmp = tick_ptr->TICKS[0] * tpms;

I created a small self-contained sample file like this:

 

typedef unsigned long uint_32;typedef unsigned long long uint_64;void compilerError(uint_64 tick){  static uint_32         tpms;  uint_64                tmp;  tmp = tick * tpms;}

 When I create a disassembly I get the following:

 

;
;    9:   tmp = tick * tpms;
;
0x00000008  0x223900000000           move.l   _tpms$5,d1
0x0000000E  0x203C00000000           move.l   #_tpms$5,d0
0x00000014  0x48EF0003000C           movem.l  d0-d1,12(a7)
0x0000001A  0x4CEE00030008           movem.l  8(a6),d0-d1
0x00000020  0x48EF00030004           movem.l  d0-d1,4(a7)
0x00000026  0x41EEFFF8               lea      -8(a6),a0
0x0000002A  0x2E88                   move.l   a0,(a7)
0x0000002C  0x4EB900000000           jsr      ___rt_mul64

 The red-colored instruction looks wrong to me: Instead of zero-extending 'tpms' into d0, d0 is filled with the immediate value "the address of variable tpms".

In MQX 3.4 (I haven't had time to check any later versions yet) the function _psp_ticks_to_time has been replaced with a much smaller and simpler function (the previous code is commented-out, though), but the fact remains that the compiler seems to make a relevant mistake, as illustrated by my sample code.

 

 

I searched in the forums, but couldn't find any refernce:

Can anyone confirm my findings? Is this error corrected in 7.2? I cannot easily (medical equipment) move to 7.2, but this error in 7.1.2 might be a _good_ reason to start the move-process, _if_ the error is corrected in 7.2...

 

If you need a complete workspace to reproduce this, let me know, I assume I can create one easily.

 

Regards,

 

Johan

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