Andrea Di Biagio 042bee88f3 [X86] Teach method 'isVectorClearMaskLegal' how to check for legal blend masks.
This patch improves the folding of vector AND nodes into blend operations for
targets that feature SSE4.1. A vector AND node where one of the operands is
a constant build_vector with elements that are either zero or all-ones can be
converted into a blend.

This allows for example to simplify the following code:

define <4 x i32> @test(<4 x i32> %A, <4 x i32> %B) {
  %1 = and <4 x i32> %A, <i32 0, i32 0, i32 0, i32 -1>
  %2 = and <4 x i32> %B, <i32 -1, i32 -1, i32 -1, i32 0>
  %3 = or <4 x i32> %1, %2
  ret <4 x i32> %3
}

Before this patch llc (-mcpu=corei7) generated:
        andps  LCPI1_0(%rip), %xmm0, %xmm0
        andps  LCPI1_1(%rip), %xmm1, %xmm1
        orps   %xmm1, %xmm0, %xmm0
        retq

With this patch we generate a single 'vpblendw'.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221343 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-05 13:04:14 +00:00
2014-11-02 12:14:22 +00:00
2014-11-04 01:29:59 +00:00
2014-04-07 03:57:04 +00:00
2014-03-02 13:08:46 +00:00
2014-10-16 22:48:02 +00:00
2014-03-12 22:40:22 +00:00
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
Virtual Machine, a toolkit for the construction of highly optimized compilers,
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LLVM backend for 6502
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