Port:     STR912 Compiler: IAR, Embedded Workbench 4.0 Kickstart (ARM) Optimize: Speed, maximum I found a small problem in vListInitialise for the ARM9 port.  This appears to be a compiler bug since the source code appears to be logically correct.  This is just a FYI in case someone else is having the same problem as I am. I created a library with the FreeRTOS ARM9 port that runs in Thumb mode.  During debug, I was getting warning messages stating that an unaligned memory access was being performed and that the results were unpredictable.  I traced the problem down to the vListInitialise function.  The original function is shown below with a notation showing the line having the problem: void vListInitialise( xList *pxList ) {     /* The list structure contains a list item which is used to mark the     end of the list.  To initialise the list the list end is inserted     as the only list entry. */     pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd );     /* The list end value is the highest possible value in the list to     ensure it remains at the end of the list. */     pxList->xListEnd.xItemValue = portMAX_DELAY;     /* The list end next and previous pointers point to itself so we know     when the list is empty. */     pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd );  <<< Problem line     pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );     pxList->uxNumberOfItems = 0; } In the problem line above, the address of pxList->xListEnd wasn’t being found properly.  The previous line was setting register R1 to portMAX_DELAY, and the compiler was using that value in the next line as the pxList pointer, and then adding 8 to find pxList->xListEnd.  portMAX_DELAY is 0xFFFFFFFF and adding 8 makes an address of 7, which was the value getting stored in pxList->xListEnd.pxNext. I moved the "pxList->xListEnd.xItemValue = portMAX_DELAY;" line to just after the section that sets pxList->xListEnd.pxNext and pxList->xListEnd.pxPrevious and the compiler generated the correct code. I’ll be notifying IAR of this problem.

Thanks for your valuable feedback. When you have maximum optimisation on I presume the "static clustering" option is selected.  I have found static clustering to cause a problem with several IAR builds.  It would be interesting to see if the problem goes away when this option is deselected, while retaining all the other optimisations. Regards.