Bill Schmidt a5a5a62fff [PPC64LE] Teach swap optimization about the doubleword splat idiom ... With a previous patch, the VSX swap optimization is able to recognize the doubleword load-splat idiom that can be implemented using lxvdsx. However, that does not cover a doubleword splat where the source is a register. We can implement this using xxspltd (a special form of xxpermdi). This patch teaches the swap optimization pass about this idiom. As a prerequisite, it also permits swap optimization to succeed for all forms of SUBREG_TO_REG. Previously we were conservative and only allowed SUBREG_TO_REG when it copied a full register. However, on reflection any form of SUBREG_TO_REG is safe in and of itself, so long as an unsafe operation is not performed on its result. In particular, a widening SUBREG_TO_REG often occurs as an input to a doubleword splat idiom, particularly in auto-vectorized code. The doubleword splat idiom is an XXPERMDI operation where both source registers are identical, and the selection mask is either 0 (splat the first element) or 3 (splat the second element). To determine whether the registers are identical, we use the existing mechanism for looking through "copy-like" operations. That mechanism has a side effect of marking the XXPERMDI operation as using a physical register, which would invalidate its presence in a swap-optimized region. This is correct for the form of XXPERMDI that performs a swap and hence would be removed, but is not what we want for a doubleword-splat variety of XXPERMDI. Therefore we reset the physical-register flag on the XXPERMDI when it represents a splat. A simple test case is added to verify that we generate the splat and that we also remove the xxswapd instructions that would otherwise be associated with the load and store of another operand. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241285 91177308-0d34-0410-b5e6-96231b3b80d8		2015-07-02 17:03:06 +00:00
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Analysis	Delete whitespace at start of line.	2015-07-02 14:17:12 +00:00
AsmParser
Bitcode	Fix for PR23310: llvm-dis crashes when trying to upgrade an intrinsic.	2015-07-02 16:22:40 +00:00
CodeGen	Reapply r240291: Fix shl folding in DAG combiner.	2015-07-02 11:44:54 +00:00
DebugInfo
ExecutionEngine	Use ErrorOr in getRelocationAdress.	2015-06-30 20:32:26 +00:00
Fuzzer
IR	Fix a fixme and make DICompileUnit a distinct node. Tested via clang.	2015-06-30 18:32:18 +00:00
IRReader
LibDriver
LineEditor
Linker
LTO
MC	Convert a member variable to a local one.	2015-07-02 16:59:57 +00:00
Object	Return ErrorOr from getSection.	2015-07-01 12:56:27 +00:00
Option
Passes
ProfileData
Support	[Support] Lazy load of dbghlp.dll on Windows	2015-07-02 14:34:57 +00:00
TableGen
Target	[PPC64LE] Teach swap optimization about the doubleword splat idiom	2015-07-02 17:03:06 +00:00
Transforms	Remove whitespace from start of line, NFC.	2015-07-02 14:25:09 +00:00
CMakeLists.txt
LLVMBuild.txt
Makefile