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A stack may be implemented as, for example, a singly linked list with a pointer to the top element. A stack may be implemented to have a bounded capacity. If the stack is full and does not contain enough space to accept another element, the stack is in a state of stack overflow. A stack is needed to implement depth-first search.
The scheme allows for larger vector types (float, double, __m128, __m256) to be passed in registers as opposed to on the stack. [ 10 ] For IA-32 and x64 code, __vectorcall is similar to __fastcall and the original x64 calling conventions respectively, but extends them to support passing vector arguments using SIMD registers.
In addition, the stack pointer must always be 4-byte aligned, and must always be 8-byte aligned at a function call with a public interface. [3] This calling convention causes a "typical" ARM subroutine to: In the prologue, push r4 to r11 to the stack, and push the return address in r14 to the stack (this can be done with a single STM instruction);
The fundamental idea behind array programming is that operations apply at once to an entire set of values. This makes it a high-level programming model as it allows the programmer to think and operate on whole aggregates of data, without having to resort to explicit loops of individual scalar operations.
This behavior can be axiomatized in various ways. For example, a common VDM (Vienna Development Method) description of a stack defines top (peek) and remove as atomic, where top returns the top value (without modifying the stack), and remove modifies the stack (without returning a value). [1] In this case pop is defined in terms of top and remove.
The stack easily holds more than two inputs or more than one result, so a rich set of operations can be computed. In stack machine code (sometimes called p-code), instructions will frequently have only an opcode commanding an operation, with no additional fields identifying a constant, register or memory cell, known as a zero address format. [1]
The vector technique was first fully exploited in 1976 by the famous Cray-1. Instead of leaving the data in memory like the STAR-100 and ASC, the Cray design had eight vector registers, which held sixty-four 64-bit words each. The vector instructions were applied between registers, which is much faster than talking to main memory.
The stack is often used to store variables of fixed length local to the currently active functions. Programmers may further choose to explicitly use the stack to store local data of variable length. If a region of memory lies on the thread's stack, that memory is said to have been allocated on the stack, i.e. stack-based memory allocation (SBMA).