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RENESAS TOOL NEWS on November 16, 2003: RSO-M3T-NC308WA_3-031116D
A Note on Using C compilers
M3T-NC308WA and M3T-NC30WA
--On Function Calls Using the Indirection Operator--
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Please take note of the following problem in using the M3T-NC308WA and M3T-NC30WA C compilers (with an assembler and integrated development environment):
- On function calls using the indirection operator
- Products and Versions Concerned
-
- M3T-NC308WA V.5.00 Release 1 and V.5.10 Release 1
for the M32C/80 and M16C/80 series
- M3T-NC30WA V.5.20 Release 1
for the M16C/60, M16C/30, M16C/Tiny, M16C/20, M16C/10, and R8C/Tiny series
- Description
Function calls using the indirection operator may cause incorrect code to be generated.
- Conditions
This problem occurs if the following five conditions are satisfied:
| (1) | The -OS optimizing option is selected. |
| (2) | At the processing immediately before ending a function, A, another one, B, is called using the indirection operator. |
| (3) | A pointer variable pointing to function B is declared outside of function A. |
| (4) | In the arguments of function A is included an argument passed to the stack. |
| (5) | The code for "enter #00H" is created at the beginning of function A. |
- Example
--------------------------------------------------------
void (*sub)(void); /* Condition (3) */
:
void func(long l) /* Condition (4) */
{
:
(*sub)(); /* Condition (2) */
}
--------------------------------------------------------
- Workaround
Place a dummy asm function immediately after a function call using the indirection operator.
--------------------------------------------------------
void func(long l)
{
:
(*sub)();
asm(); /* A dummy asm function placed */
}
--------------------------------------------------------
- Schedule of Fixing the Problem
We plan to fix this problem in our next release of the products.
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