Add support for 256-bit versions of VPERMIL instruction. This is a new

instruction introduced in AVX, which can operate on 128 and 256-bit vectors.
It considers a 256-bit vector as two independent 128-bit lanes. It can permute
any 32 or 64 elements inside a lane, and restricts the second lane to
have the same permutation of the first one. With the improved splat support
introduced early today, adding codegen for this instruction enable more
efficient 256-bit code:

Instead of:
  vextractf128  $0, %ymm0, %xmm0
  punpcklbw %xmm0, %xmm0
  punpckhbw %xmm0, %xmm0
  vinsertf128 $0, %xmm0, %ymm0, %ymm1
  vinsertf128 $1, %xmm0, %ymm1, %ymm0
  vextractf128  $1, %ymm0, %xmm1
  shufps  $1, %xmm1, %xmm1
  movss %xmm1, 28(%rsp)
  movss %xmm1, 24(%rsp)
  movss %xmm1, 20(%rsp)
  movss %xmm1, 16(%rsp)
  vextractf128  $0, %ymm0, %xmm0
  shufps  $1, %xmm0, %xmm0
  movss %xmm0, 12(%rsp)
  movss %xmm0, 8(%rsp)
  movss %xmm0, 4(%rsp)
  movss %xmm0, (%rsp)
  vmovaps (%rsp), %ymm0
We get:
  vextractf128  $0, %ymm0, %xmm0
  punpcklbw %xmm0, %xmm0
  punpckhbw %xmm0, %xmm0
  vinsertf128 $0, %xmm0, %ymm0, %ymm1
  vinsertf128 $1, %xmm0, %ymm1, %ymm0
  vpermilps $85, %ymm0, %ymm0

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135662 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 41 insertions, 0 deletions

diff --git a/lib/Target/X86/Utils/X86ShuffleDecode.cpp b/lib/Target/X86/Utils/X86ShuffleDecode.cpp
index cd06060748..c1ff0e5011 100644
--- a/lib/Target/X86/Utils/X86ShuffleDecode.cpp
+++ b/lib/Target/X86/Utils/X86ShuffleDecode.cpp
@@ -187,4 +187,31 @@ void DecodeUNPCKLPMask(EVT VT,
   }
 }
 
+void DecodeVPERMILPSMask(unsigned NElts, unsigned Imm,
+                        SmallVectorImpl<unsigned> &ShuffleMask) {
+  DecodeVPERMILMask(MVT::getVectorVT(MVT::i32, NElts), Imm, ShuffleMask);
+}
+
+void DecodeVPERMILPDMask(unsigned NElts, unsigned Imm,
+                        SmallVectorImpl<unsigned> &ShuffleMask) {
+  DecodeVPERMILMask(MVT::getVectorVT(MVT::i64, NElts), Imm, ShuffleMask);
+}
+
+// DecodeVPERMILMask - Decodes VPERMIL permutes for any 128-bit
+// with 32/64-bit elements. For 256-bit vectors, it's considered
+// as two 128 lanes and the mask of the first lane should be
+// identical of the second one.
+void DecodeVPERMILMask(EVT VT, unsigned Imm,
+                       SmallVectorImpl<unsigned> &ShuffleMask) {
+  unsigned NumElts = VT.getVectorNumElements();
+  unsigned NumLanes = VT.getSizeInBits()/128;
+
+  for (unsigned l = 0; l != NumLanes; ++l) {
+    for (unsigned i = 0; i != NumElts/NumLanes; ++i) {
+      unsigned Idx = (Imm >> (i*2)) & 0x3 ;
+      ShuffleMask.push_back(Idx+(l*NumElts/NumLanes));
+    }
+  }
+}
+
 } // llvm namespace
diff --git a/lib/Target/X86/Utils/X86ShuffleDecode.h b/lib/Target/X86/Utils/X86ShuffleDecode.h
index b18f670330..4a5214028f 100644
--- a/lib/Target/X86/Utils/X86ShuffleDecode.h
+++ b/lib/Target/X86/Utils/X86ShuffleDecode.h
@@ -82,6 +82,20 @@ void DecodeUNPCKLPDMask(unsigned NElts,
 void DecodeUNPCKLPMask(EVT VT,
                        SmallVectorImpl<unsigned> &ShuffleMask);
 
+
+void DecodeVPERMILPSMask(unsigned NElts, unsigned Imm,
+                        SmallVectorImpl<unsigned> &ShuffleMask);
+
+void DecodeVPERMILPDMask(unsigned NElts, unsigned Imm,
+                        SmallVectorImpl<unsigned> &ShuffleMask);
+
+// DecodeVPERMILMask - Decodes VPERMIL permutes for any 128-bit
+// with 32/64-bit elements. For 256-bit vectors, it's considered
+// as two 128 lanes and the mask of the first lane should be
+// identical of the second one.
+void DecodeVPERMILMask(EVT VT, unsigned Imm,
+                       SmallVectorImpl<unsigned> &ShuffleMask);
+
 } // llvm namespace
 
 #endif