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RENESAS TOOL NEWS on December 16, 2004: RSO-M3T-NC308WA_1-041216D
A Note on Using the M3T-NC308WA and
M3T-NC30WA C-Compiler Packages
--On Evaluation of Elements of an Array
in the Controlling Expression of an If Statement--
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Please take note of the following problem in using the M3T-NC308WA and M3T-NC30WA C-compiler packages:
- On evaluation of Elements of an Array in the controlling expression of an if statement
- Products and Versions Concerned
M3T-NC308WA V.3.10 Release 1 through V.5.10 Release 1
(for the M32C/90, M32C/80 and M16C/80 series)
M3T-NC30WA V.5.00 Release 1 and V.5.10 Release 1
(for the M16C/60, M16C/30, M16C/Tiny, M16C/20, M16C/10, and
R8C/Tiny series)
- Description
If two or more expressions testing equality or inequality between
an element of an array and a constant exist in the controlling expression of an if statement, incorrect code is generated.
- Conditions
This problem occurs if the following conditions are all satisfied:
| (1) | Two or more expressions testing equality or inequality between
an element of an array and a constant exist in the controlling
expression of an if statement. |
| (2) | The array in (1) is of type unsigned char or signed char. |
| (3) | The subscripts to the elements of the array in (1) are
continuous numbers. |
| (4) | All the equality/inequality-testing expressions in (1) are
associated with one another using the logical OR operators. |
| (5) | Compile option -O4 or -O5 is used; or any of those, -O1, -O2,
-O3, -OR, and -OS, is used with -Ocompare_byte_to_word (-OCBTW). |
Example:
-------------------------------------------------------------------------
int i;
char c[10]; /* Conditions (2) and (3) */
void func(void)
{
if( c[0] == 0x1 || c[1] == 0x0 ) /* Conditions (1) and (4) */
i = 1;
else
i = 0;
}
-------------------------------------------------------------------------
- Workaround
This problem can be circumvented either of the following ways:
| (1) |
If compile option -O4 or -O5 used, don't associate the
equality/inequality-testing expressions with one another using the
logical OR operators; that is, separate them individually.
Example:
-----------------------------------------------------------------------
int i;
char c[10];
void func(void)
{
if( c[0] == 0x1 )
i = 1;
else if( c[1] == 0x0 )
i = 1;
else
i = 0;
}
----------------------------------------------------------------------- |
| (2) |
If any of the compile options -O1, -O2, -O3, -OR, and -OS is
selected with -OCBTW, deselect -OCBTW. |
- Schedule of Fixing the Problem
This problem has already been resolved in the V.5.20 Release 1 and later
of both the M3T-NC308WA and M3T-NC30WA. So upgrade yours to these online
from Software download for tools.
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