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If a pop operation on the stack causes the stack pointer to move past the origin of the stack, a stack underflow occurs. If a push operation causes the stack pointer to increment or decrement beyond the maximum extent of the stack, a stack overflow occurs. Some environments that rely heavily on stacks may provide additional operations, for example:
Newer processors contain a dedicated stack engine to optimize stack operations. Pentium M was the first x86 processor to introduce a stack engine. In its implementation, the stack pointer is split among two registers: ESP O , which is a 32-bit register, and ESP d , an 8-bit delta value that is updated directly by stack operations.
A typical stack, storing local data and call information for nested procedure calls (not necessarily nested procedures). This stack grows downward from its origin. The stack pointer points to the current topmost datum on the stack. A push operation decrements the pointer and copies the data to the stack; a pop operation copies data from the ...
This uses operations to copy stack entries. The stack must be depth shallow enough for the CPU's available copy instructions. Hand-written stack code often uses this approach, and achieves speeds like general-purpose register machines. [30] [9] Unfortunately, algorithms for optimal "stack scheduling" are not in wide use by programming languages.
Using pointers significantly improves performance for repetitive operations, like traversing iterable data structures (e.g. strings, lookup tables, control tables, linked lists, and tree structures). In particular, it is often much cheaper in time and space to copy and dereference pointers than it is to copy and access the data to which the ...
SP (Stack pointer): Points to the top of stack in memory. It is automatically updated during PUSH and POP operations. BP (Base Pointer): Points to the top of the call stack. It is primarily used to access function parameters and local variables within the call stack. SI (Source Index): Used as a pointer to the source in string and memory array ...
When stack frame sizes can differ, such as between different functions or between invocations of a particular function, popping a frame off the stack does not constitute a fixed decrement of the stack pointer. At function return, the stack pointer is instead restored to the frame pointer, the value of the stack pointer just before the function ...
stack: 4 F(3) exch stack: F(3) 4 2 sub stack: F(3) 2 fib (recursive call here) stack: F(3) F(2) add stack: F(3)+F(2) which is the expected result. This procedure does not use named variables, purely the stack. Named variables can be created by using the /a exch def construct.