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LLVM backend for 6502
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Hal Finkel 4e703f82f2 [PowerPC] Add a DAGToDAG peephole to remove unnecessary zero-exts 
On PPC64, we end up with lots of i32 -> i64 zero extensions, not only from all
of the usual places, but also from the ABI, which specifies that values passed
are zero extended. Almost all 32-bit PPC instructions in PPC64 mode are defined
to do *something* to the higher-order bits, and for some instructions, that
action clears those bits (thus providing a zero-extended result). This is
especially common after rotate-and-mask instructions. Adding an additional
instruction to zero-extend the results of these instructions is unnecessary.

This PPCISelDAGToDAG peephole optimization examines these zero-extensions, and
looks back through their operands to see if all instructions will implicitly
zero extend their results. If so, we convert these instructions to their 64-bit
variants (which is an internal change only, the actual encoding of these
instructions is the same as the original 32-bit ones) and remove the
unnecessary zero-extension (changing where the INSERT_SUBREG instructions are
to make everything internally consistent).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224169 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-12 23:59:36 +00:00
autoconf Require python 2.7. 2014-12-12 15:29:31 +00:00
bindings IR: Split Metadata from Value 2014-12-09 18:38:53 +00:00
cmake Disable --icf=safe to avoid a bug. 2014-12-12 14:28:19 +00:00
docs Require python 2.7. 2014-12-12 15:29:31 +00:00
examples Once more on the cmake build. nativecodegen->native on the dependencies. 2014-12-08 18:24:06 +00:00
include Clean up static analyzer warnings. 2014-12-12 21:48:03 +00:00
lib [PowerPC] Add a DAGToDAG peephole to remove unnecessary zero-exts 2014-12-12 23:59:36 +00:00
projects
test [PowerPC] Add a DAGToDAG peephole to remove unnecessary zero-exts 2014-12-12 23:59:36 +00:00
tools Initial dsymutil tool commit. 2014-12-12 17:31:24 +00:00
unittests IR: Don't track nullptr on metadata RAUW 2014-12-12 19:24:33 +00:00
utils utils: update vim syntax highlighting for LLVM IR 2014-12-12 21:52:44 +00:00
.arcconfig
.clang-format
.clang-tidy Enable display of compiler diagnostics in clang-tidy by default. 2014-10-29 17:29:38 +00:00
.gitignore
CMakeLists.txt Adding a new option to CMake to disable C++ atexit on llvm-shlib. 2014-12-09 18:49:55 +00:00
CODE_OWNERS.TXT Tom Stellard is now the code owner for libclc. 2014-12-12 01:11:48 +00:00
configure Require python 2.7. 2014-12-12 15:29:31 +00:00
CREDITS.TXT
LICENSE.TXT
llvm.spec.in
LLVMBuild.txt
Makefile
Makefile.common
Makefile.config.in Add a check for misbehaving -Wcomment from gcc-4.7 and add 2014-11-05 00:35:15 +00:00
Makefile.rules Add a check for misbehaving -Wcomment from gcc-4.7 and add 2014-11-05 00:35:15 +00:00
README.txt [TEST-COMMIT] As per Developer Policy, Added a blank line. 2014-12-06 00:38:39 +00:00

README.txt 

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

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