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unixod/LLVM-IR-analysis.md

Last active September 23, 2018 19:02
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LLVM IR analysis
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LLVM-IR-analysis.md

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opt -help-hidden

How the set of passes '-O3' modifies IR.

$ opt -S -O3 file.ll

See target machine assembly.

$ opt -S -O3 file.ll | llc -O3
or
$ opt -S -O3 file.ll | llc -O3 --x86-asm-syntax=intel

(Note llc accepts ll-files as well but produces a different output, even with -O3 provided.)

What optimization passes are used for the '-O3' set.

$ opt -S -O3 -debug-pass=Arguments file.ll

See how MemorySSA is laid on an input IR.

$ opt -S -passes='print<memoryssa>' -disable-output file.ll
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