Pierre Gousseau 4594395329 [X86] Take advantage of the lzcnt instruction on btver2 architectures when ORing comparisons to zero. ...

This change adds transformations such as:
  zext(or(setcc(eq, (cmp x, 0)), setcc(eq, (cmp y, 0))))
  To:
  srl(or(ctlz(x), ctlz(y)), log2(bitsize(x))
This optimisation is beneficial on Jaguar architecture only, where lzcnt has a good reciprocal throughput.
Other architectures such as Intel's Haswell/Broadwell or AMD's Bulldozer/PileDriver do not benefit from it.
For this reason the change also adds a "HasFastLZCNT" feature which gets enabled for Jaguar.

Differential Revision: https://reviews.llvm.org/D23446

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284248 91177308-0d34-0410-b5e6-96231b3b80d8

2016-10-14 16:41:38 +00:00

..

Analysis

Create llvm.addressofreturnaddress intrinsic

2016-10-12 22:13:19 +00:00

AsmParser

[X86] Basic additions to support RegCall Calling Convention.

2016-10-13 07:53:43 +00:00

Bitcode

ThinLTO: handles modules with empty summaries

2016-10-08 04:44:18 +00:00

CodeGen

[DAG] add folds for negated shifted sign bit

2016-10-14 14:26:47 +00:00

DebugInfo

Truncate long names in type records

2016-10-13 17:33:22 +00:00

Demangle

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ExecutionEngine

Use StringRef instead of raw pointer in ExecutionEngine

2016-10-01 06:22:04 +00:00

Fuzzer

[libFuzzer] more detailed message for disabled leak detection

2016-10-13 22:24:10 +00:00

IR

[X86] Basic additions to support RegCall Calling Convention.

2016-10-13 07:53:43 +00:00

IRReader

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LibDriver

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LineEditor

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Linker

[ThinLTO] Don't link module level assembly when importing

2016-10-12 18:39:29 +00:00

LTO

LTO: Use the correct mangler function in LTOCodeGenerator::applyScopeRestrictions().

2016-10-12 20:12:19 +00:00

MC

Tidy the calls to getCurrentSection().first -> getCurrentSectionOnly to help

2016-10-14 05:47:37 +00:00

Object

Next set of additional error checks for invalid Mach-O files for the

2016-10-11 21:04:39 +00:00

ObjectYAML

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Option

Generalize ArgList::AddAllArgs more

2016-09-29 19:47:58 +00:00

Passes

Fix test after renaming -name-anon-functions pass to -name-anon-globals

2016-09-16 17:18:16 +00:00

ProfileData

[Coverage] Factor out logic to create FunctionRecords (NFC)

2016-10-12 22:27:45 +00:00

Support

Define "contiki" OS specifier.

2016-10-14 14:41:46 +00:00

TableGen

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Target

[X86] Take advantage of the lzcnt instruction on btver2 architectures when ORing comparisons to zero.

2016-10-14 16:41:38 +00:00

Transforms

[InstCombine] use m_APInt to allow sub with constant folds for splat vectors

2016-10-14 16:31:54 +00:00

CMakeLists.txt

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LLVMBuild.txt

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