llvm-6502

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Ekaterina Romanova 46f7257ed1 SHLD/SHRD are VectorPath (microcode) instructions known to have poor latency on certain architectures. While generating SHLD/SHRD instructions is acceptable when optimizing for size, optimizing for speed on these platforms should be implemented using alternative sequences of instructions composed of add, adc, shr, shl, or and lea which are directPath instructions. These alternative instructions not only have a lower latency but they also increase the decode bandwidth by allowing simultaneous decoding of a third directPath instruction.

AMD's processors family K7, K8, K10, K12, K15 and K16 are known to have SHLD/SHRD instructions with very poor latency. Optimization guides for these processors recommend using an alternative sequence of instructions. For these AMD's processors, I disabled folding (or (x << c) | (y >> (64 - c))) when we are not optimizing for size.

It might be beneficial to disable this folding for some of the Intel's processors. However, since I couldn't find specific recommendations regarding using SHLD/SHRD instructions on Intel's processors, I haven't disabled this peephole for Intel.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195383 91177308-0d34-0410-b5e6-96231b3b80d8

2013-11-21 23:21:26 +00:00

autoconf

Update to reflect the next release.

2013-11-20 10:10:50 +00:00

bindings

[OCaml] Unbreak make install by providing ocamldoc target

2013-11-21 10:10:16 +00:00

cmake

Revert my CMake patches concerning building with /MT (r194589, r194596)

2013-11-13 20:29:10 +00:00

docs

Remove dangling documentation. llvm-prof was deleted a while ago.

2013-11-21 19:32:37 +00:00

examples

[weak vtables] Place class definitions into anonymous namespaces to prevent weak vtables.

2013-11-19 03:08:35 +00:00

include

Whitespace.

2013-11-21 11:08:31 +00:00

lib

SHLD/SHRD are VectorPath (microcode) instructions known to have poor latency on certain architectures. While generating SHLD/SHRD instructions is acceptable when optimizing for size, optimizing for speed on these platforms should be implemented using alternative sequences of instructions composed of add, adc, shr, shl, or and lea which are directPath instructions. These alternative instructions not only have a lower latency but they also increase the decode bandwidth by allowing simultaneous decoding of a third directPath instruction.

2013-11-21 23:21:26 +00:00

projects

Revert "Revert "Windows: Add support for unicode command lines""

2013-10-07 01:00:07 +00:00

test

2013-11-21 23:21:26 +00:00

tools

[weak vtables] Place class definitions into anonymous namespaces to prevent weak vtables.

2013-11-19 03:08:35 +00:00

unittests

[PM] Widen the interface for invalidate on an analysis result now that

2013-11-21 10:53:05 +00:00

utils

FileCheck: fix a bug with multiple --check-prefix options. Similar to r194565

2013-11-20 13:25:05 +00:00

.arcconfig

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.clang-format

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.gitignore

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CMakeLists.txt

CMake: Some changes to package version names:

2013-11-21 22:47:21 +00:00

CODE_OWNERS.TXT

Add loop rerolling code owner

2013-11-20 20:54:33 +00:00

configure

Update to reflect the next release.

2013-11-20 10:10:50 +00:00

CREDITS.TXT

Update CREDITS

2013-11-17 11:44:36 +00:00

LICENSE.TXT

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llvm.spec.in

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LLVMBuild.txt

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Makefile

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Makefile.common

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Makefile.config.in

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Makefile.rules

Teach the Makefile build system how to handle SOURCES which include

2013-11-14 23:51:29 +00:00

README.txt

Revert "Test commit to check e-mail address. Please discard this."

2013-10-04 10:59:13 +00:00

README.txt

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

This directory and its subdirectories contain source code for the Low Level
Virtual Machine, a toolkit for the construction of highly optimized compilers,
optimizers, and runtime environments.

LLVM is open source software. You may freely distribute it under the terms of
the license agreement found in LICENSE.txt.

Please see the documentation provided in docs/ for further
assistance with LLVM, and in particular docs/GettingStarted.rst for getting
started with LLVM and docs/README.txt for an overview of LLVM's
documentation setup.

If you're writing a package for LLVM, see docs/Packaging.rst for our
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