Tool FAQ What's new

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2009/02

Microcomputer > V850 tools > CA850 > Regarding Optimization/Code-Instruction expansion >

• Is there anything we should take care of while describing an expression to speed up the execution?
• The message "Out of memory" is displayed when object size optimization and the execution speed options are selected.
• What are the demerits of Optimization?
• Is the debugging of the Source possible in spite of Optimization?
• How are register variables allocated?
• "tmp1" is declared as "volatile unsigned char *tmp1;", still it is optimized. What should be done to avoid optimization of "tmp1"?
• Is there any method for avoiding expansion of "Bcond" instruction, and "Jcond" instruction?
• Why is the "callt" instruction is output when version-up is done to V2.50?
• It seems that external reference memory is deleted due to optimization. What should be done to avoid this?
• Multiple label definition error is generated when execution speed optimization is selected.
• Is Volatile declaration necessary for variables, where optimization is not specified, but value is changed externally?
• Is it possible to refer to an auto variable when high speed optimization is turned on?
• Is the optimization option ignored if there is a description of assembler instruction?
• Regarding execution speed optimization & object size optimization.
• What is the setting method of CALLT base pointer (CTBP)?

Microcomputer > V850 tools > CA850 > Description of code size reduction >

• How to declare a function without a return value?
• Please provide an example of initializing the variables.
• Provide a description example, where one operand of the comparison operation is constant 16 or 17.
• Provide a description example, where the result of the condition of the if-else statement will be act as the return value.
• Provide a description example, where a value substituted using assignment statement is referred immediately after the substitution sentence.
• Please provide an example of usage of the variable of (unsigned) short and char type.
• Please provide an example of "Deletion of loop variable".
• Please provide an example of reducing the existence range of the variable.
• Provide a description example for expansion of a loop.
• Provide a description example, where "for/while" loop is transformed into "goto" statement.
• Provide a description example, for replacing complex if-else statements logically with equal effect.
• Provide a description example, where a identical function is called with different arguments at each place after branching.
• Provide a description example, where there are identical statements (assignment statement, function call etc.) at each place before joining.
• Provide a description example, where there are identical statements (assignment statements, function call etc.) at each place after branching.
• Please provide an example of replacing access to external variable with access of temporary variable.
• Please provide a description example, where each block of if-else statement includes only the assignment statement to the same variable.
• Please provide an example where assignment of same external variable exists in each case of switch statement and in if-else statement at each place.
• Please provide an example where if-else statement is used in place of the switch statement.
• Does the code efficiency worsen when a lot of data of the "unsigned char" type is used?
• Does the state of the memory arrangement change if there is a change in arrangement of the variable definition in C source?
• Is there any optimization option in V850E that uses half word of zero extension ("zxh") and sign extension ("sxh") instructions?
• Is there any description for the structure packing instruction to return to default?
• What is the priority order, when both structure packing instruction "# pragma pack" and "-Xpack=num" options are specified at the same time?
• Is the structure packing instruction "# pragma pack" is effective during one source file, from the point where this instruction appears?
• When there is an internal variable, does the compiler reserve the stack by four byte boundary regardless of the type of data?
• Which is the default alignment for structure packing from among 1, 2, 4, and 8?
• Which is the correct specification method of the structure packing according to the Pragma instruction?
• Is it possible to forcibly set the alignment condition for the structure type to the byte boundary or half word boundary by specifying an option in the compiler?
• About the size of the structure type defined as per the alignment condition to the structure type.
• Although the structure size is obtained using the "sizeof" operator, the expected value is not returned.