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Sanjay Patel 384913118b [ValueTracking] recognize min/max-of-min/max with notted ops (PR35875)
This was originally planned as the fix for:
https://bugs.llvm.org/show_bug.cgi?id=35834
...but simpler transforms handled that case, so I implemented a 
lesser solution. It turns out we need to handle the case with 'not'
ops too because the real code example that we are trying to solve:
https://bugs.llvm.org/show_bug.cgi?id=35875
...has extra uses of the intermediate values, so we can't rely on 
smaller canonicalizations to get us to the goal.

As with rL321672, I've tried to show every possibility in the
codegen tests because that's the simplest way to prove we're doing
the right thing in the wide variety of permutations of this pattern.

We can also show an InstCombine win because we added a fold for
this case in:
rL321998 / D41603

An Alive proof for one variant of the pattern to show that the 
InstCombine and codegen results are correct:
https://rise4fun.com/Alive/vd1

Name: min3_nots
  %nx = xor i8 %x, -1
  %ny = xor i8 %y, -1
  %nz = xor i8 %z, -1
  %cmpxz = icmp slt i8 %nx, %nz
  %minxz = select i1 %cmpxz, i8 %nx, i8 %nz
  %cmpyz = icmp slt i8 %ny, %nz
  %minyz = select i1 %cmpyz, i8 %ny, i8 %nz
  %cmpyx = icmp slt i8 %y, %x
  %r = select i1 %cmpyx, i8 %minxz, i8 %minyz
=>
  %cmpxyz = icmp slt i8 %minxz, %ny
  %r = select i1 %cmpxyz, i8 %minxz, i8 %ny

Name: min3_nots_alt
  %nx = xor i8 %x, -1
  %ny = xor i8 %y, -1
  %nz = xor i8 %z, -1
  %cmpxz = icmp slt i8 %nx, %nz
  %minxz = select i1 %cmpxz, i8 %nx, i8 %nz
  %cmpyz = icmp slt i8 %ny, %nz
  %minyz = select i1 %cmpyz, i8 %ny, i8 %nz
  %cmpyx = icmp slt i8 %y, %x
  %r = select i1 %cmpyx, i8 %minxz, i8 %minyz
=>
  %xz = icmp sgt i8 %x, %z
  %maxxz = select i1 %xz, i8 %x, i8 %z
  %xyz = icmp sgt i8 %maxxz, %y
  %maxxyz = select i1 %xyz, i8 %maxxz, i8 %y
  %r = xor i8 %maxxyz, -1

llvm-svn: 322283
2018-01-11 15:13:47 +00:00
bindings [bindings/go] fix vet errors 2017-12-28 04:10:09 +00:00
cmake [cmake] Use symlinks for Windows-hosted toolchains built on Unix 2018-01-09 07:50:18 +00:00
docs [MIR] Update MIRLangRef with documentation on bundled instructions 2018-01-10 17:53:16 +00:00
examples PR35705: Fix Chapter 9 example code for API changes to DIBuilder 2017-12-20 19:36:54 +00:00
include [FuzzMutate] Avoid using swifterror as a source operand 2018-01-11 14:43:05 +00:00
lib [ValueTracking] recognize min/max-of-min/max with notted ops (PR35875) 2018-01-11 15:13:47 +00:00
projects [cmake] Support moving debuginfo-tests to llvm/projects 2017-12-12 17:06:08 +00:00
resources In MSVC builds embed a VERSIONINFO resource in our exe and DLL files. 2015-06-12 15:58:29 +00:00
runtimes [CMake] Support for cross-compilation when build runtimes 2018-01-08 23:50:59 +00:00
test [ValueTracking] recognize min/max-of-min/max with notted ops (PR35875) 2018-01-11 15:13:47 +00:00
tools [llvm-readobj] Consistent use of ScopedPrinter 2018-01-10 00:14:19 +00:00
unittests [FuzzMutate] Avoid using swifterror as a source operand 2018-01-11 14:43:05 +00:00
utils [TableGen][AsmMatcherEmitter] Generate assembler checks for tied operands 2018-01-10 10:10:56 +00:00
.arcconfig project_id is from another era in phabricator land and does not provide any value. 2016-09-27 15:47:29 +00:00
.clang-format
.clang-tidy .clang-tidy: correct style name is 'camelBack' not 'lowerCase'. 2016-09-13 19:04:26 +00:00
.gitattributes [MC] Fix regression tests on Windows when git “core.autocrlf” is set to true. 2017-11-17 21:59:43 +00:00
.gitignore gitignore: Ignore .vs folder (VS2017 config files) 2017-04-08 00:16:58 +00:00
CMakeLists.txt The trunk version is now 7.0.0svn 2018-01-03 14:52:54 +00:00
CODE_OWNERS.TXT Update my email addresses, NFC. 2017-10-26 10:16:54 +00:00
configure Remove autoconf support 2016-01-26 21:29:08 +00:00
CREDITS.TXT Add myself to CREDITS.txt 2017-09-18 14:33:39 +00:00
LICENSE.TXT Bump year to 2017 in LICENSE.txt 2017-01-12 18:02:42 +00:00
llvm.spec.in [Sparc] Implement i64 load/store support for 32-bit sparc. 2015-08-10 19:11:39 +00:00
LLVMBuild.txt
README.txt Test commit access 2017-08-18 02:39:28 +00:00
RELEASE_TESTERS.TXT Update my email addresses, NFC. 2017-10-26 10:16:54 +00:00

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