From: Chandler Carruth <chandlerc@gmail.com>
Date: Sat, 20 Sep 2014 02:44:21 +0000 (+0000)
Subject: [x86] Replace some duplicated logic reasoning about whether particular
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=8924ed3db48b59882cf8924395095fa9ecf76ac0;p=oota-llvm.git

[x86] Replace some duplicated logic reasoning about whether particular
vector lanes can be modeled as zero with a call to the new function that
computes a bit-vector representing that information.

No functionality changed here, but will allow doing more clever things
with the zero-test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218174 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2d76a9799e2..94452b1e31a 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -7556,10 +7556,16 @@ static SDValue lowerVectorShuffleAsZeroOrAnyExtend(
 static SDValue lowerIntegerElementInsertionVectorShuffle(
     MVT VT, SDLoc DL, SDValue V1, SDValue V2, ArrayRef<int> Mask,
     const X86Subtarget *Subtarget, SelectionDAG &DAG) {
+  SmallBitVector Zeroable = computeZeroableShuffleElements(Mask, V1, V2);
+
   int V2Index = std::find_if(Mask.begin(), Mask.end(),
                              [&Mask](int M) { return M >= (int)Mask.size(); }) -
                 Mask.begin();
 
+  for (int i = 0, Size = Mask.size(); i < Size; ++i)
+    if (i != V2Index && !Zeroable[i])
+      return SDValue(); // Not inserting into a zero vector.
+
   // Check for a single input from a SCALAR_TO_VECTOR node.
   // FIXME: All of this should be canonicalized into INSERT_VECTOR_ELT and
   // all the smarts here sunk into that routine. However, the current
@@ -7572,19 +7578,6 @@ static SDValue lowerIntegerElementInsertionVectorShuffle(
 
   SDValue V2S = V2.getOperand(Mask[V2Index] - Mask.size());
 
-  if (V1.getOpcode() == ISD::BUILD_VECTOR) {
-    for (int M : Mask) {
-      if (M < 0 || M >= (int)Mask.size())
-        continue;
-      SDValue Input = V1.getOperand(M);
-      if (Input.getOpcode() != ISD::UNDEF && !X86::isZeroNode(Input))
-        // A non-zero input!
-        return SDValue();
-    }
-  } else if (!ISD::isBuildVectorAllZeros(V1.getNode())) {
-    return SDValue();
-  }
-
   // First, we need to zext the scalar if it is smaller than an i32.
   MVT EltVT = VT.getVectorElementType();
   assert(EltVT == V2S.getSimpleValueType() &&