Multiplication bug on EDE Crossview for M16C?

Feb 09, 2008 4 Replies
B

Hi to all recently i noticed a strange behavior debugging a a simple code that i wrote in C for the Mitsubishi-Renesas microcontroller M16C:



void Function_multiply(void) { unsigned char term1,term2,result; term1=6; term2=8;



result= term1 * term2; } I expect that result=48 ,with no loss of data,being the 2 terms small numbers



instead i have result=6 ,same with other small numers



To have result=48 i need to declare the local variable as unsigned int.



I dont think that i s a real bug,but i find strange that some option in the compiler could generate this unexpecyed situation



Thanks you for your attention Have a nice weekend



Diego,Milan Italy


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A

If this is the exact code that you were using, how did you verify the result ?

As stated, the function has no side effects, and the result value is ignored, so the compiler is free to optimize (part of) the function body away. If you use a debugger to look at the result, your results may not be reliable.

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D

i =

ll

int.

=

=

dy =

t =

It would be very helpful to see what assembly is produced, if the assemb= ly is correct then the compiler is fine and its probably a debugger fault. = =

Interesting tho.

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B

wrote

the

thanks for helping me No,this is not the exact code,in fact i use the result and it leads me to a bigger error let me know your hints

Diego

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B

It would be very helpful to see what assembly is produced, if the assembly is correct then the compiler is fine and its probably a debugger fault. Interesting tho.

ok,but i have it at work so i have to wait til next week to copy the section relative to the problem many thanks to you

have you all a nice weekend

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