I don't think the optimizer is not removing code or variables when -O0. When stepping through with gdb if you try to display a variable that is optimized out, it notifies you by displaying <optimized out>. This is not happening.
I've tried declaring a global variable it works as expected. The problem I'm observing is when a variable is on the stack. The code I'm posting is for example only in trying to illustrate a problem in my code where the stack variables are being used but do not have the expected values. When stepping through with gdb, the stack variables are is flash. I have assert statements in my code that catch this even when not using gdb. I can post a bigger example if that will help. Carl On Sat, 20 Feb 2010 23:49:57 +0100 "N. Coesel" <[email protected]> wrote: >Try this first: > >volatile int i; > >int main() >{ > while(1) > { > i++; > } >} > > >IMHO you are chasing a dead horse because the optimizer is removing code >that doesn't do anything. Inside main, the scope of the variable is limited >to main so volatile probably doesn't mean anything. > > >At 14:16 20-2-2010 -0700, Carl wrote: >>If I declare it as a global it is where I expect at the beginning of RAM >>(0x1100). But if it is on the stack in the main function, even if I >>declare it volatile, use asm(""); // __asm__ __volatile__ (""); or pass >>it to a function, the variable address is in flash at 0x3102. It doesn't >>make sense. >> >>Now if I use the program: >> >>#include <io.h> >> >>int f1() >>{ >> volatile int i = 5; >> i += 2; >> return i; >>} >> >>int main() >>{ >> while(1) >> { >> f1(); >> } >>} >> >>The variable i address is on the stack in RAM at 0x30f8 which makes >>sense. But if I change the compile option to use -02. Then the function >>stack variable, i, goes back to being located in flash at 0x3102. And >>it's value is not initialed to 5 nor is 2 added to it. The value of i is >>constant = 12544 (0x3100.) >> >>I noticed at new version of mspgcc4 is out as of Feb 18, 2010. I've >>tried to install it on both a Fedora 9 and a Ubuntu machine but get the >>same error: >> >>Failed to execute sh do-gcc.sh "/opt/msp430-gcc-4.4.3" "4.4.3" >>"http://ftp.uni-kl.de"; "build" "gcc-4.x" "4.3.1" "2.4.1" >>at ./buildgcc.pl line 237, <STDIN> line 9. >> >> >>Carl >> >> >> >>On Sat, 2010-02-20 at 09:08 +0100, N. Coesel wrote: >>> Carl, >>> >>> Try to declare it outside the function (as a global). >>> >>> At 19:43 19-2-2010 -0800, you wrote: >>> >I tried declaring as volatile and it is at the exact same address. >>> > >>> >Carl >>> > >>> >On Sat, 20 Feb 2010 01:35:03 +0000 >>> > "Wayne Uroda" <[email protected]> wrote: >>> >>try declaring i as volatile, or the compiler will probably get rid of it >>> since it has no effect or side-effect. >>> >>Sent via BlackBerry from Vodafone >>> >> >>> >>-----Original Message----- >>> >>From: Carl <[email protected]> >>> >>Date: Fri, 19 Feb 2010 18:29:03 >>> >>To: <[email protected]> >>> >>Subject: [Mspgcc-users] stack variable in flash? >>> >> >>> >>I'm sure that I'm missing some basic here but I'm not sure what. The >>> >>first variable on the stack is in an unexpected location. I would expect >>> >>it to be located somewhere on the stack in RAM (0x30ff-0x1100) but it is >>> >>located in flash memory and it does not get set or incremented. >>> >> >>> >> >>> >>#include <io.h> >>> >> >>> >>int main() >>> >>{ >>> >> int i=0; >>> >> while(1) >>> >> i++; >>> >>} >>> >> >>> > >> >> >> >>--------------------------------------------------------------------------- >--- >>Download Intel® Parallel Studio Eval >>Try the new software tools for yourself. Speed compiling, find bugs >>proactively, and fine-tune applications for parallel performance. >>See why Intel Parallel Studio got high marks during beta. >>http://p.sf.net/sfu/intel-sw-dev >>_______________________________________________ >>Mspgcc-users mailing list >>[email protected] >>https://lists.sourceforge.net/lists/listinfo/mspgcc-users >> >> > >------------------------------------------------------------------------------ >Download Intel® Parallel Studio Eval >Try the new software tools for yourself. Speed compiling, find bugs >proactively, and fine-tune applications for parallel performance. >See why Intel Parallel Studio got high marks during beta. >http://p.sf.net/sfu/intel-sw-dev >_______________________________________________ >Mspgcc-users mailing list >[email protected] >https://lists.sourceforge.net/lists/listinfo/mspgcc-users
