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Sanjay Patel 76b12c4bf0 [InstCombine] transform bitcasted bitwise logic ops with constants (PR26702)
Given that we're not actually reducing the instruction count in the included
regression tests, I think we would call this a canonicalization step.

The motivation comes from the example in PR26702:
https://llvm.org/bugs/show_bug.cgi?id=26702

If we hoist the bitwise logic ahead of the bitcast, the previously unoptimizable
example of:

define <4 x i32> @is_negative(<4 x i32> %x) {
  %lobit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
  %not = xor <4 x i32> %lobit, <i32 -1, i32 -1, i32 -1, i32 -1>
  %bc = bitcast <4 x i32> %not to <2 x i64>
  %notnot = xor <2 x i64> %bc, <i64 -1, i64 -1>
  %bc2 = bitcast <2 x i64> %notnot to <4 x i32>
  ret <4 x i32> %bc2
}

Simplifies to the expected:

define <4 x i32> @is_negative(<4 x i32> %x) {
  %lobit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
  ret <4 x i32> %lobit
}

Differential Revision: http://reviews.llvm.org/D17583



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262645 91177308-0d34-0410-b5e6-96231b3b80d8
2016-03-03 19:19:04 +00:00
bindings Kill LLVMAddTargetData 2016-02-16 00:22:02 +00:00
cmake [cmake] Check the compiler version first 2016-03-02 16:42:56 +00:00
docs [libFuzzer] more trophies 2016-03-02 19:45:10 +00:00
examples Refactor duplicated code for linking with pthread. 2016-03-01 15:54:40 +00:00
include [SCEV] Prove no-overflow via constant ranges 2016-03-03 18:31:29 +00:00
lib [InstCombine] transform bitcasted bitwise logic ops with constants (PR26702) 2016-03-03 19:19:04 +00:00
projects Remove autoconf support 2016-01-26 21:29:08 +00:00
resources In MSVC builds embed a VERSIONINFO resource in our exe and DLL files. 2015-06-12 15:58:29 +00:00
test [InstCombine] transform bitcasted bitwise logic ops with constants (PR26702) 2016-03-03 19:19:04 +00:00
tools [llvm-nm] Restore the previous behaviour (pre r262525). 2016-03-02 22:33:49 +00:00
unittests [ConstantRange] Rename test; NFC 2016-03-03 18:31:33 +00:00
utils TableGen: Accept itinerary data when checking for schedmodel completeness 2016-03-03 00:04:59 +00:00
.arcconfig Updated phabricator server. 2014-04-07 03:57:04 +00:00
.clang-format Test commit. 2014-03-02 13:08:46 +00:00
.clang-tidy adding readability-identifier-naming to llvm clang-tidy configuration. 2015-12-08 17:44:51 +00:00
.gitignore Minor updates to gitignore so that symlinks are ignored in the projects dir. 2015-07-07 20:24:58 +00:00
CMakeLists.txt [CMake] Add test-depends target to build dependencies of check-all 2016-03-02 17:56:30 +00:00
CODE_OWNERS.TXT [docs] Remove references to autotools build. 2016-01-30 01:10:15 +00:00
configure Remove autoconf support 2016-01-26 21:29:08 +00:00
CREDITS.TXT [WebAssembly] Initial WebAssembly backend 2015-06-29 23:51:55 +00:00
LICENSE.TXT Update for a new year. 2015-03-12 01:25:29 +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 Remove the very substantial, largely unmaintained legacy PGO 2013-10-02 15:42:23 +00:00
README.txt Revert previous test commit. 2016-01-04 19:13:29 +00:00

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