LLVM backend for 6502
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Chandler Carruth a341a8070a [x86] Fix two independent miscompiles in the process of getting the same
test case to actually generate correct code.

The primary miscompile fixed here is that we weren't correctly handling
in-place elements in one half of a single-input v8i16 shuffle when
moving a dword of elements from that half to the other half. Some times,
we would clobber the in-place elements in forming the dword to move
across halves.

The fix to this involves forcibly marking the in-place inputs even when
there is no need to gather them into a dword, and to much more carefully
re-arrange the elements when grouping them into a dword to move across
halves. With these two changes we would generate correct shuffles for
the test case, but found another miscompile. There are also some random
perturbations of the generated shuffle pattern in SSE2. It looks like
a wash; more instructions in some cases fewer in others.

The second miscompile would corrupt the results into nonsense. This is
a buggy pattern in one of the added DAG combines. Mapping elements
through a PSHUFD when pairing redundant half-shuffles is *much* harder
than this code makes it out to be -- it requires reasoning about *all*
of where the input is used in the PSHUFD, not just one part of where it
is used. Plus, we can't combine a half shuffle *into* a PSHUFD but the
code didn't guard against it. I think this was just a bad idea and I've
just removed that aspect of the combine. No tests regress as
a consequence so seems OK.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214954 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 10:16:36 +00:00
autoconf [autoconf] Fixup s/3.5/3.6/. Clang's ident was 3.5.0svn in autoconf build. 2014-07-29 08:35:03 +00:00
bindings [OCaml] Add Llvm.{string_of_const,const_element}. 2014-08-03 23:54:22 +00:00
cmake Emit a warning if llvm_map_components_to_libraries() is used noting that its 2014-07-28 13:36:50 +00:00
docs Fix typos in comments and doc 2014-08-05 23:27:34 +00:00
examples Added LLVM_ENABLE_RTTI and LLVM_ENABLE_EH options that allow RTTI and EH 2014-07-22 15:41:18 +00:00
include Remove a virtual function from TargetMachine. NFC. 2014-08-05 22:10:21 +00:00
lib [x86] Fix two independent miscompiles in the process of getting the same 2014-08-06 10:16:36 +00:00
projects [cmake] Use the external project machinery for libcxxabi so that it can 2014-07-25 10:27:40 +00:00
test [x86] Fix two independent miscompiles in the process of getting the same 2014-08-06 10:16:36 +00:00
tools [MCJIT] Make llvm-rtdyld check RuntimeDyld's error state when running in -verify 2014-08-05 20:51:46 +00:00
unittests Fix SmallDenseMap assignment operator. 2014-08-04 22:18:25 +00:00
utils Remove the TargetMachine forwards for TargetSubtargetInfo based 2014-08-04 21:25:23 +00:00
.arcconfig Updated phabricator server. 2014-04-07 03:57:04 +00:00
.clang-format
.gitignore Add Polly to the ignored trees. 2014-06-25 13:13:36 +00:00
CMakeLists.txt Fix building with in-tree libc++abi on FreeBSD 2014-08-01 19:23:15 +00:00
CODE_OWNERS.TXT Add a sentence that all entries should include an email address. 2014-08-04 19:33:25 +00:00
configure [autoconf] Fixup s/3.5/3.6/. Clang's ident was 3.5.0svn in autoconf build. 2014-07-29 08:35:03 +00:00
CREDITS.TXT Update Credits. 2014-05-29 19:59:58 +00:00
LICENSE.TXT
llvm.spec.in
LLVMBuild.txt
Makefile [configure/make] Propagate names of build host tools when making BuildTools 2014-03-25 21:45:41 +00:00
Makefile.common
Makefile.config.in Track clang r213171 2014-07-16 16:50:34 +00:00
Makefile.rules [Make] Fix dependencies for td.expanded 2014-06-20 19:00:41 +00:00
README.txt Trivial test commit. 2014-04-26 19:05:45 +00:00

Low Level Virtual Machine (LLVM)
================================

This directory and its subdirectories contain source code for the Low Level
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