Commit Graph

7 Commits

Author SHA1 Message Date
Arnaud A. de Grandmaison 162435e7b5 [AArch64] Swap comparison operands if that enables some folding.
Summary:
AArch64 can fold some shift+extend operations on the RHS operand of
comparisons, so swap the operands if that makes sense.

This provides a fix for https://bugs.llvm.org/show_bug.cgi?id=38751

Reviewers: efriedma, t.p.northover, javed.absar

Subscribers: mcrosier, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D53067

llvm-svn: 344439
2018-10-13 07:43:56 +00:00
Roman Lebedev d7a6244475 [DAGCombine] optimizeSetCCOfSignedTruncationCheck(): handle inverted pattern
Summary:
A follow-up for D49266 / rL337166 + D49497 / rL338044.

This is still the same pattern to check for the [lack of]
signed truncation, but in this case the constants and the predicate
are negated.

https://rise4fun.com/Alive/BDV
https://rise4fun.com/Alive/n7Z

Reviewers: spatel, craig.topper, RKSimon, javed.absar, efriedma, dmgreen

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D51532

llvm-svn: 341287
2018-09-02 13:56:22 +00:00
Roman Lebedev 75c2961b76 [NFC][X86][AArch64] A few more patterns for [lack of] signed truncation check pattern.[NFC][X86][AArch64] A few more patterns for [lack of] signed truncation check pattern.
llvm-svn: 341188
2018-08-31 08:52:03 +00:00
Roman Lebedev 5317e88300 [NFC][X86][AArch64][DAGCombine] More tests for optimizeSetCCOfSignedTruncationCheck()
At least one of these cases is more canonical,
so we really do have to handle it.
https://godbolt.org/g/pkzP3X
https://rise4fun.com/Alive/pQyh

llvm-svn: 337400
2018-07-18 16:19:06 +00:00
Roman Lebedev de506632aa [X86][AArch64][DAGCombine] Unfold 'check for [no] signed truncation' pattern
Summary:

[[ https://bugs.llvm.org/show_bug.cgi?id=38149 | PR38149 ]]

As discussed in https://reviews.llvm.org/D49179#1158957 and later,
the IR for 'check for [no] signed truncation' pattern can be improved:
https://rise4fun.com/Alive/gBf
^ that pattern will be produced by Implicit Integer Truncation sanitizer,
https://reviews.llvm.org/D48958 https://bugs.llvm.org/show_bug.cgi?id=21530
in signed case, therefore it is probably a good idea to improve it.

But the IR-optimal patter does not lower efficiently, so we want to undo it..

This handles the simple pattern.
There is a second pattern with predicate and constants inverted.

NOTE: we do not check uses here. we always do the transform.

Reviewers: spatel, craig.topper, RKSimon, javed.absar

Reviewed By: spatel

Subscribers: kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D49266

llvm-svn: 337166
2018-07-16 12:44:10 +00:00
Roman Lebedev b64e74feed [NFC][X86][AArch64] Negative tests for 'check for [no] signed truncation' pattern
See D49247, D49266

I'm only adding the sane negative tests, and not
adding the one-use tests yet. Also, not adding
negative tests for the second pattern with inverted operands yet,
since it's handling will be added in later differential.

llvm-svn: 337014
2018-07-13 16:14:37 +00:00
Roman Lebedev 1574e49792 [NFC][X86][AArch64] Add tests for the 'check for [no] signed truncation' pattern
Summary:
[[ https://bugs.llvm.org/show_bug.cgi?id=38149 | PR38149 ]]

As discussed in https://reviews.llvm.org/D49179#1158957 and later,
the IR can be improved:
https://rise4fun.com/Alive/gBf
^ that pattern will be produced by Implicit Integer Truncation sanitizer,
https://reviews.llvm.org/D48958
https://bugs.llvm.org/show_bug.cgi?id=21530
in signed case, therefore it is probably a good idea to improve it.

But as it looks from these tests,
i think we want to revert at least some cases in DAGCombine.

Reviewers: spatel, craig.topper, RKSimon, javed.absar

Reviewed By: spatel

Subscribers: kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D49247

llvm-svn: 336917
2018-07-12 17:00:11 +00:00