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What a compiler does

The goal of an optimizing compiler is the efficient translation of a higher-level language into the fastest possible machine language that accurately represents the high-level language source. What makes a representation good is: it gives the correct answers, and it executes quickly.

Naturally, it makes no difference how fast a program runs if it doesn’t produce the right answers. However, you can sometimes trade accuracy for speed. But given an expression of a program that executes correctly, an optimizing compiler looks for ways to streamline it. As a first cut, this usually means simplifying the code, throwing out extraneous instructions, and sharing intermediate results between statements. More advanced optimizations seek to restructure the program and may actually make the code grow in size, though the number of instructions executed will (hopefully) shrink.

When it comes to finally generating machine language, the compiler has to know about the registers and rules for issuing instructions. For performance, it needs to understand the costs of those instructions and the latencies of machine resources, such as the pipelines. This is especially true for processors that can execute more than one instruction at a time. It takes a balanced instruction mix — the right proportion of floating-point, fixed point, memory and branch operations, etc. — to keep the machine busy.

Initially compilers were tools that allowed us to write in something more readable than assembly language. Today they border on artificial intelligence as they take our high-level source code and translate it into highly optimized machine language across a wide variety of single- and multiple-processor architectures. In the area of high performance computing, the compiler at times has a greater impact on the performance of our program than either the processor or memory architecture. Throughout the history of high performance computing, if we are not satisfied with the performance of our program written in a high-level language, we will gladly rewrite all or part of the program in assembly language. Thankfully, today’s compilers usually make that step unnecessary.

In this chapter we cover the basic operation of optimizing compilers. In a later chapter we will cover the techniques used to analyze and compile programs for advanced architectures such as parallel or vector processing systems. We start our look at compilers examining how the relationship between programmers and their compilers has changed over time.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, High performance computing. OpenStax CNX. Aug 25, 2010 Download for free at http://cnx.org/content/col11136/1.5
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