llvm-project/llvm
Adam Nemet 053c4e825c [AVX512] Fix miscompile for unpack
r189189 implemented AVX512 unpack by essentially performing a 256-bit unpack
between the low and the high 256 bits of src1 into the low part of the
destination and another unpack of the low and high 256 bits of src2 into the
high part of the destination.

I don't think that's how unpack works.  AVX512 unpack simply has more 128-bit
lanes but other than it works the same way as AVX.  So in each 128-bit lane,
we're always interleaving certain parts of both operands rather different
parts of one of the operands.

E.g. for this:
__v16sf a = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
__v16sf b = { 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 };
__v16sf c = __builtin_shufflevector(a, b, 0, 8, 1, 9, 4, 12, 5, 13, 16,
	    			       	     24, 17, 25, 20, 28, 21, 29);

we generated punpcklps (notice how the elements of a and b are not interleaved
in the shuffle).  In turn, c was set to this:

  0 16 1 17 4 20 5 21 8 24 9 25 12 28 13 29

Obviously this should have just returned the mask vector of the shuffle
vector.

I mostly reverted this change and made sure the original AVX code worked
for 512-bit vectors as well.

Also updated the tests because they matched the logic from the code.

llvm-svn: 217602
2014-09-11 16:51:10 +00:00
..
autoconf Delete support for AuroraUX. 2014-08-14 15:15:09 +00:00
bindings Reinstate "Nuke the old JIT." 2014-09-02 22:28:02 +00:00
cmake Don't attempt to run llvm-config in cmake/modules/Makefile when doing 2014-09-10 11:09:23 +00:00
docs [docs] Mention character array constants in docs/LangRef.rst 2014-09-11 12:02:59 +00:00
examples Add doInitialization/doFinalization to DataLayoutPass. 2014-09-10 21:27:43 +00:00
include Use CostPool::PoolRef typedef some more 2014-09-11 00:08:54 +00:00
lib [AVX512] Fix miscompile for unpack 2014-09-11 16:51:10 +00:00
projects [cmake] Use the external project machinery for libcxxabi so that it can 2014-07-25 10:27:40 +00:00
test [AVX512] Fix miscompile for unpack 2014-09-11 16:51:10 +00:00
tools Add doInitialization/doFinalization to DataLayoutPass. 2014-09-10 21:27:43 +00:00
unittests Add doInitialization/doFinalization to DataLayoutPass. 2014-09-10 21:27:43 +00:00
utils utils: Teach lldbDataFormatters how to format ArrayRefs 2014-09-11 01:47:38 +00:00
.arcconfig
.clang-format
.clang-tidy Add .clang-tidy configuration file to provide LLVM-optimized defaults for 2014-09-08 13:30:00 +00:00
.gitignore Add Polly to the ignored trees. 2014-06-25 13:13:36 +00:00
CMakeLists.txt Enabling LLVM & Clang to be cross-compiled using CMake from a single configuration command line 2014-09-03 23:21:18 +00:00
CODE_OWNERS.TXT Add a sentence that all entries should include an email address. 2014-08-04 19:33:25 +00:00
CREDITS.TXT Rise from the dead and update personal info 2014-08-25 17:51:04 +00:00
LICENSE.TXT
LLVMBuild.txt
Makefile
Makefile.common
Makefile.config.in Track clang r213171 2014-07-16 16:50:34 +00:00
Makefile.rules Reinstate "Nuke the old JIT." 2014-09-02 22:28:02 +00:00
README.txt
configure Delete support for AuroraUX. 2014-08-14 15:15:09 +00:00
llvm.spec.in

README.txt

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