From c941f6b329119f2c0877554dfbe642d12ed833f0 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Mon, 18 Jul 2016 17:32:59 +0000
Subject: [PATCH] [X86][AVX] Add target shuffle decode support for VBROADCAST

Currently we only decode broadcasts from a vector of the same size.

llvm-svn: 275823
---
 llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp         |  6 ++++++
 llvm/lib/Target/X86/Utils/X86ShuffleDecode.h           |  3 +++
 llvm/lib/Target/X86/X86ISelLowering.cpp                | 10 ++++++++++
 llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll |  4 ----
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
index 4fe9a9e949d6..18f71675437b 100644
--- a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
+++ b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
@@ -275,6 +275,12 @@ void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
   }
 }
 
+/// Decodes a broadcast of the first element of a vector.
+void DecodeVectorBroadcast(MVT DstVT, SmallVectorImpl<int> &ShuffleMask) {
+  unsigned NumElts = DstVT.getVectorNumElements();
+  ShuffleMask.append(NumElts, 0);
+}
+
 /// Decodes a broadcast of a subvector to a larger vector type.
 void DecodeSubVectorBroadcast(MVT DstVT, MVT SrcVT,
                               SmallVectorImpl<int> &ShuffleMask) {
diff --git a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.h b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.h
index 30b17052b722..dc21c19752c3 100644
--- a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.h
+++ b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.h
@@ -88,6 +88,9 @@ void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask);
 /// datatypes and vector widths.
 void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask);
 
+/// Decodes a broadcast of the first element of a vector.
+void DecodeVectorBroadcast(MVT DstVT, SmallVectorImpl<int> &ShuffleMask);
+
 /// Decodes a broadcast of a subvector to a larger vector type.
 void DecodeSubVectorBroadcast(MVT DstVT, MVT SrcVT,
                               SmallVectorImpl<int> &ShuffleMask);
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index cac36b82e217..e54711195900 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3804,6 +3804,7 @@ static bool isTargetShuffle(unsigned Opcode) {
   case X86ISD::MOVSD:
   case X86ISD::UNPCKL:
   case X86ISD::UNPCKH:
+  case X86ISD::VBROADCAST:
   case X86ISD::VPERMILPI:
   case X86ISD::VPERMILPV:
   case X86ISD::VPERM2X128:
@@ -4920,6 +4921,15 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT, bool AllowSentinelZero,
     DecodeZeroMoveLowMask(VT, Mask);
     IsUnary = true;
     break;
+  case X86ISD::VBROADCAST: {
+    // We only decode broadcasts of same-sized vectors at the moment.
+    if (N->getOperand(0).getValueType() == VT) {
+      DecodeVectorBroadcast(VT, Mask);
+      IsUnary = true;
+      break;
+    }
+    return false;
+  }
   case X86ISD::VPERMILPV: {
     IsUnary = true;
     SDValue MaskNode = N->getOperand(1);
diff --git a/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll b/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll
index 940906edd692..a10ba6ccc41e 100644
--- a/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll
+++ b/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll
@@ -207,7 +207,6 @@ define <16 x i8> @combine_vpbroadcast_pshufb_as_vpbroadcastb128(<16 x i8> %a) {
 ; CHECK-LABEL: combine_vpbroadcast_pshufb_as_vpbroadcastb128:
 ; CHECK:       # BB#0:
 ; CHECK-NEXT:    vpbroadcastb %xmm0, %xmm0
-; CHECK-NEXT:    vpbroadcastb %xmm0, %xmm0
 ; CHECK-NEXT:    retq
   %1 = shufflevector <16 x i8> %a, <16 x i8> undef, <16 x i32> zeroinitializer
   %2 = call <16 x i8> @llvm.x86.ssse3.pshuf.b.128(<16 x i8> %1, <16 x i8> zeroinitializer)
@@ -218,8 +217,6 @@ define <32 x i8> @combine_vpbroadcast_pshufb_as_vpbroadcastb256(<32 x i8> %a) {
 ; CHECK-LABEL: combine_vpbroadcast_pshufb_as_vpbroadcastb256:
 ; CHECK:       # BB#0:
 ; CHECK-NEXT:    vpbroadcastb %xmm0, %ymm0
-; CHECK-NEXT:    vpxor %ymm1, %ymm1, %ymm1
-; CHECK-NEXT:    vpshufb %ymm1, %ymm0, %ymm0
 ; CHECK-NEXT:    retq
   %1 = shufflevector <32 x i8> %a, <32 x i8> undef, <32 x i32> zeroinitializer
   %2 = call <32 x i8> @llvm.x86.avx2.pshuf.b(<32 x i8> %1, <32 x i8> zeroinitializer)
@@ -230,7 +227,6 @@ define <4 x float> @combine_vpbroadcast_pshufb_as_vpbroadcastss128(<4 x float> %
 ; CHECK-LABEL: combine_vpbroadcast_pshufb_as_vpbroadcastss128:
 ; CHECK:       # BB#0:
 ; CHECK-NEXT:    vbroadcastss %xmm0, %xmm0
-; CHECK-NEXT:    vbroadcastss %xmm0, %xmm0
 ; CHECK-NEXT:    retq
   %1 = shufflevector <4 x float> %a, <4 x float> undef, <4 x i32> zeroinitializer
   %2 = bitcast <4 x float> %1 to <16 x i8>