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MESC TOOL NEWS:
MESCT-NC308WA-000501D
PC-Version
NC308WA, NC30WA, NC79WA, NC77WA
Precautions
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Please take note of the following problem in using C compilers (with assembler and integrated development environment) NC308WA, NC30WA, NC79WA, and NC77WA:
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Versions Concerned
The following PC versions of C compilers are concerned in this problem:
| NC308WA V.1.00 Release 1--V.2.00 Release 2 | for M16C/80 series MCUs |
| NC30WA V.1.00 Release 1--V.3.20 Release 2 | for M16C/60 and M16C/20 series MCUs |
| NC79WA V.1.00 Release 1--V.3.20 Release 2 | for 7900 series MCUs |
| NC77WA V.3.00 Release 1--V.5.20 Release 2 | for 77xx series MCUs |
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Problem
If an optimize option is used, Windows' error message "This program has performed an illegal operation . . . ." may appear.
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Conditions
This problem occur if the following three conditions are satisfied:
(1)Any of optimize options -O, -O1 through -O5, -OR, and -OS is chosen.
(2)The branch instruction is described in C language.[Example 1]
(3)An unconditional branch instruction exists in the assembly source file obtained by compiling the C source program and is immediately followed by its branch destination.[Example 2]
[Example 1: C Source Program]
-------------------------------------------------------------
void func(void)
{
unsigned char i;
for (i=0;i<2;i++){
if (i==0) return;
switch(i){
case 1:
return;
case 2:
return;
default:
func2();
return; /* Here the error message may appear */
}
}
}
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In this example, using optimize option -O may cause the problem to occur; if not, the problem will not arise.
[Example 2: Assembly Source]
-------------------------------------------------------------
bra L1
L1:
-------------------------------------------------------------
Even if the above conditions are all satisfied, no error may be detected depending on how the C compiler performs the optimize processing, and no error indicates no problem.
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Workaround
Don't use any of optimize options -O, -O1 through -O5, -OR, and -OS.
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Schedule of Fixing Problem
We plan to fix this problem in our next release.
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