intermediate code

Question

Consider four programming languages viz. C, C++, C# and JAVA and three machines which have different configuration (such as OS, hardware). If someone needs to write a compiler for the above mentioned languages and machines, then the number of compilers required with and without intermediate code phase are --------- and ------ respectively.

Answer 1

If we generate machine code directly from source code (without intermediate code ) then for 4 languages and 3 machines we need to write 4 front ends , 4*3 code optimizers and 4*3 target code generators.

By converting source code to intermediate code a machine independent code optimizer may be written. So we require only 4 front ends + 1 code optimizer + 3 target code generator.

Please notice  4*3 target code generators are required but with intermediate step (as machine independent code optimizer are there) we require only 4 front end + 3 target code generator.

So with intermediate code we require (4+3) = 7 compiler bt withour intermediate code we need (4*3)=12 compiers

Answer 2

While generating machine code directly from source code is possible, it entails two problems With m languages and n target machines, we need to write m front ends, m × n optimizers, and m × n code generators

The code optimizer which is one of the largest and very-difficult-to-write components of a compiler, cannot be reused

By converting source code to an intermediate code, a machine-independent code optimizer may be written T

This means just m front ends, n code generators and 1 optimizer

 

nptel

Comments

but your answer is not correct, answer is 7 and 12.....please help me if you get the answer

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machine-independent code optimizer - is it language independent too?

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Hi,

Actually You Can think that from Lexical Analysis to Machine Independent Code Optimization is Front End (Same For all Systems) Starting from Machine Dependent Code Opttimization To target Code generation is Back End (differes from setup)