Conditional stack frame allocation
A method for allocating memory includes an operation that determines whether a prototype of a callee function is within a scope of a caller. The caller is a module containing a function call to the callee function. In addition, the method includes determining whether the function call includes one or more unnamed parameters when a prototype of the callee function is within the scope of the caller. Further, the method may include inserting instructions in the caller to allocate a register save area in a memory when it is determined that the function call includes one or more unnamed parameters.
1. A system for allocating memory, comprising:
a processor; and
a memory to store a compiler and one or more modules, the compiler being comprised of instructions that when executed by the processor, cause the processor to perform the following operations:
determining whether a prototype of a callee function is within a scope of a caller, the caller being a module containing a function call to the callee function;
when the prototype of the callee function is not within the scope of the module, inserting instructions in the caller to allocate a register save area in a memory;
when the prototype of the callee function is within the scope of the caller, determining whether the function call includes one or more unnamed parameters;
inserting instructions in the caller to allocate a register save area in a memory when it is determined that the function call includes one or more unnamed parameters;
determining whether all parameters of the function can be passed in registers; and
inserting instructions in the caller to allocate a parameter overflow area in the memory when all parameters of the function call cannot be passed in registers.
2. The system of claim 1 , wherein the inserting of instructions in the caller to allocate a register save area in a memory when it is determined that the function call includes one or more unnamed parameters further comprises:
determining whether all parameters of the function can be passed in registers; and
inserting instructions in the caller to allocate a parameter overflow area in the memory when all parameters of the function call cannot be passed in registers.
3. The system of claim 1 , further comprising:
determining whether all parameters of the function can be passed in registers when it is determined that the function call only includes named parameters; and
omitting instructions in the caller to allocate a register save area in a memory when all parameters of the function call can be passed in registers.
4. The system of claim 1 , further comprising:
determining whether all parameters of the function can be passed in registers when it is determined that the function call only includes named parameters; and
inserting instructions in the caller to allocate a register save area and a parameter overflow area in a memory when all parameters of the function call cannot be passed in registers.
5. The system of claim 2 , wherein the memory is a stack frame of the caller.
6. A computer program product for allocating memory, comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable by a processor circuit to cause the processor to:
determine whether a prototype of a callee function is within a scope of a caller, the caller being a module containing a function call to the callee function;
when the prototype of the callee function is not within the scope of the module, insert instructions in the caller to allocate a register save area in a memory;
when the prototype of the callee function is within the scope of the caller, determine whether the function call includes one or more unnamed parameters; and
in response to determining that the function call includes one or more unnamed parameters, insert instructions in the caller to allocate a register save area in a memory;
determine whether all parameters of the function can be passed in registers; and
insert instructions in the caller to allocate a parameter overflow area in the memory when all parameters of the function call cannot be passed in registers.
7. The computer program product of claim 6 , wherein the inserting of instructions in the caller to allocate a register save area in a memory when it is determined that the function call includes one or more unnamed parameters further comprises:
determining whether all parameters of the function can be passed in registers; and
inserting instructions in the caller to allocate a parameter overflow area in the memory when all parameters of the function call cannot be passed in registers.
8. The computer program product of claim 6 , further comprising:
determining whether all parameters of the function can be passed in registers when it is determined that the function call only includes named parameters; and
omitting instructions in the caller to allocate a register save area in a memory when all parameters of the function call can be passed in registers.
9. The computer program product of claim 6 , further comprising:
determining whether all parameters of the function can be passed in registers when it is determined that the function call only includes named parameters; and
inserting instructions in the caller to allocate a register save area and a parameter overflow area in a memory when all parameters of the function call cannot be passed in registers.