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[FastISel] Remove kill tracking

Authored by nikic on Mar 9 2021, 12:04 PM.

Description

[FastISel] Remove kill tracking

This is a followup to D98145: As far as I know, tracking of kill
flags in FastISel is just a compile-time optimization. However,
I'm not actually seeing any compile-time regression when removing
the tracking. This probably used to be more important in the past,
before FastRA was switched to allocate instructions in reverse
order, which means that it discovers kills as a matter of course.

As such, the kill tracking doesn't really seem to serve a purpose
anymore, and just adds additional complexity and potential for
errors. This patch removes it entirely. The primary changes are
dropping the hasTrivialKill() method and removing the kill
arguments from the emitFast methods. The rest is mechanical fixup.

Differential Revision: https://reviews.llvm.org/D98294

Details

Committed
nikicApr 3 2021, 6:50 AM
Differential Revision
D98294: [FastISel] Remove kill tracking
Parents
rG3bcb6a389ff4: Silence `-Wunused-private-field` warning on isIsolatedFromAbove.
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