December 2015
Beginner to intermediate
166 pages
3h 8m
English
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Chapter 6. IR to Selection DAG phase
Until the previous chapter, we saw how a frontend language can be converted to LLVM IR. We also saw how IR can be transformed into more optimized code. After a series of analysis and transformation passes, the final IR is the most optimized machine independent code. However, the IR is still an abstract representation of the actual machine code. The compiler has to generate target architecture code for execution.
LLVM uses DAG—a directed acyclic graph representation for code generation. The idea is to convert IR into a SelectionDAG and then go over a series of phases—DAG combine, legalization, instruction selection, instruction scheduling, etc—to finally allocate registers and emit machine code. Note that register ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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