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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2019-06-29 11:51:50 +0000 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2019-06-29 11:51:50 +0000 |
| commit | e3a94ba4a928e7c2c94bb82bce0e525212fe38e1 (patch) | |
| tree | 4021f71cfdc9a6e587492808bec5a5ef85be41ce /llvm/lib/IR/Function.cpp | |
| parent | fe107fcde4d29a5d76ccbe9141a2fc8b5dd990f3 (diff) | |
| download | llvm-e3a94ba4a928e7c2c94bb82bce0e525212fe38e1.zip llvm-e3a94ba4a928e7c2c94bb82bce0e525212fe38e1.tar.gz llvm-e3a94ba4a928e7c2c94bb82bce0e525212fe38e1.tar.bz2 | |
[InstCombine] Shift amount reassociation (PR42391)
Summary:
Given pattern:
`(x shiftopcode Q) shiftopcode K`
we should rewrite it as
`x shiftopcode (Q+K)` iff `(Q+K) u< bitwidth(x)`
This is valid for any shift, but they must be identical.
* https://rise4fun.com/Alive/9E2
* exact on both lshr => exact https://rise4fun.com/Alive/plHk
* exact on both ashr => exact https://rise4fun.com/Alive/QDAA
* nuw on both shl => nuw https://rise4fun.com/Alive/5Uk
* nsw on both shl => nsw https://rise4fun.com/Alive/0plg
Should fix [[ https://bugs.llvm.org/show_bug.cgi?id=42391 | PR42391]].
Reviewers: spatel, nikic, RKSimon
Reviewed By: nikic
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63812
llvm-svn: 364712
Diffstat (limited to 'llvm/lib/IR/Function.cpp')
0 files changed, 0 insertions, 0 deletions