Identifier length and limited programmer memory

Identifier length and limited programmer memory

Because early variable mnemonics were limited to as few as six to eight characters, many early programmers abbreviated concepts in their variable names. The past thirty years have seen a steady increase in permitted name length and, slowly, an increase in the actual identifier length. However, in theory names can be too long for programmers to comprehend and manipulate effectively. Most obvious...

Programmer-Centric Conditions for Itanium Memory Consistency

We formulate a programmer-centric description of the memory consistency model provided by the Itanium architecture. This allows reasoning about programs at a non-operational level in the natural way, not obscured by the implementation details of the underlying architecture. However, our definition is not tight. We provide two very similar definitions and show that the specification of the Itani...

What Every Programmer Should Know About Memory

As CPU cores become both faster and more numerous, the limiting factor for most programs is now, and will be for some time, memory access. Hardware designers have come up with ever more sophisticated memory handling and acceleration techniques–such as CPU caches–but these cannot work optimally without some help from the programmer. Unfortunately, neither the structure nor the cost of using the ...

Enabling Programmer-Controlled Combined Memory Consistency for Parallel Code Optimization

Enabling Programmer-controlled Combined Memory Consistency for Compiler Optimization

In this paper, we present a novel compiler technique that provides the capability to guarantee a different memory consistency model for different variables within the same shared memory parallel program. Programmers need only focus on their parallel algorithm and which variables can tolerate the use of old values, while the compiler automatically guarantees sequential consistency for all remain...