[LLVMdev] Switch instruction lowering (original) (raw)

Anton Korobeynikov anton at korobeynikov.info
Wed Oct 29 09:11:38 PDT 2014

Some of the early ideas were actually described in http://llvm.org/pubs/2007-05-31-Switch-Lowering.pdf

On Wed, Oct 29, 2014 at 3:52 AM, Hans Wennborg <hans at chromium.org> wrote:

On Mon, Oct 27, 2014 at 2:54 AM, Paweł Bylica <chfast at gmail.com> wrote:

Hi,

I'm interested in any information about implementations of switch instruction and its runtime cost. If it's very target dependent, I'm mostly care about X86. Pointing some LLVM code is also good. I don't think there's any documentation besides the comments in the code, but switch lowering (to binary tree or jump table, etc.) happens in SelectionDAGBuilder::visitSwitch() For switches which are used to select from a set of constant values, SimplifyCFG will attempt to build a lookup table. - Hans

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-- With best regards, Anton Korobeynikov Faculty of Mathematics and Mechanics, Saint Petersburg State University

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