Commit Graph

3 Commits

Author SHA1 Message Date
Sanjay Patel ee34d9b210 [InstCombine] use redirect of input file in regression tests; NFC
This is a repeat of 1880092722 from 2009. We should have less risk
of hitting bugs at this point because we auto-generate positive CHECK
lines only, but this makes things consistent.

Copying the original commit msg:
"Change tests from "opt %s" to "opt < %s" so that opt doesn't see the
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename."
2020-09-29 11:06:25 -04:00
Roman Lebedev ccf1a5f4bb
[InstCombine] dropRedundantMaskingOfLeftShiftInput(): truncation (PR42563)
Summary:
That fold keeps growing and growing :(
I think this may be one of the last pieces for it.

Since D67677/D67725, the fold knowns the general form
of the pattern - where some masking is needed:
https://rise4fun.com/Alive/F5R
https://rise4fun.com/Alive/gslRa

But there is one more huge piece missing - if you are extracting some bits,
it is not impossible that the origin is wider than the extraction,
i.e. there may be a truncation. And we don't deal with that yet.

But we can, and the generalization remains fully identical:
https://rise4fun.com/Alive/Uar
https://rise4fun.com/Alive/5SW

After a preparatory cleanup i think the diff looks rather clean.

One missing piece is that in some patterns (especially pat. b),
`-1` only needs to be `-1` in final type, but that is for later..

https://bugs.llvm.org/show_bug.cgi?id=42563

Reviewers: spatel, nikic

Reviewed By: spatel

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69125
2019-11-05 12:41:26 +03:00
Roman Lebedev 08de59bed5 [NFC][InstCombine] Tests for "fold variable mask before variable shift-of-trunc" (PR42563)
https://bugs.llvm.org/show_bug.cgi?id=42563

llvm-svn: 375135
2019-10-17 17:20:12 +00:00