[X86] Move turning 256-bit INSERT_SUBVECTORS into BLENDI from legalize to DAG combine.

On one test this seems to have given more chance for DAG combine to do other INSERT_SUBVECTOR/EXTRACT_SUBVECTOR combines before the BLENDI was created. Looks like we can still improve more by teaching DAG combine to optimize INSERT_SUBVECTOR/EXTRACT_SUBVECTOR with BLENDI.

llvm-svn: 293944

1 files changed, 39 insertions, 44 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index bc4c2a842a2..c76164ecd79 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -4917,50 +4917,6 @@ static SDValue insertSubVector(SDValue Result, SDValue Vec, unsigned IdxVal,
 static SDValue insert128BitVector(SDValue Result, SDValue Vec, unsigned IdxVal,
                                   SelectionDAG &DAG, const SDLoc &dl) {
   assert(Vec.getValueType().is128BitVector() && "Unexpected vector size!");
-
-  // For insertion into the zero index (low half) of a 256-bit vector, it is
-  // more efficient to generate a blend with immediate instead of an insert*128.
-  // We are still creating an INSERT_SUBVECTOR below with an undef node to
-  // extend the subvector to the size of the result vector. Make sure that
-  // we are not recursing on that node by checking for undef here.
-  if (IdxVal == 0 && Result.getValueType().is256BitVector() &&
-      !Result.isUndef()) {
-    EVT ResultVT = Result.getValueType();
-    SDValue ZeroIndex = DAG.getIntPtrConstant(0, dl);
-    SDValue Undef = DAG.getUNDEF(ResultVT);
-    SDValue Vec256 = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResultVT, Undef,
-                                 Vec, ZeroIndex);
-
-    // The blend instruction, and therefore its mask, depend on the data type.
-    MVT ScalarType = ResultVT.getVectorElementType().getSimpleVT();
-    if (ScalarType.isFloatingPoint()) {
-      // Choose either vblendps (float) or vblendpd (double).
-      unsigned ScalarSize = ScalarType.getSizeInBits();
-      assert((ScalarSize == 64 || ScalarSize == 32) && "Unknown float type");
-      unsigned MaskVal = (ScalarSize == 64) ? 0x03 : 0x0f;
-      SDValue Mask = DAG.getConstant(MaskVal, dl, MVT::i8);
-      return DAG.getNode(X86ISD::BLENDI, dl, ResultVT, Result, Vec256, Mask);
-    }
-
-    const X86Subtarget &Subtarget =
-    static_cast<const X86Subtarget &>(DAG.getSubtarget());
-
-    // AVX2 is needed for 256-bit integer blend support.
-    // Integers must be cast to 32-bit because there is only vpblendd;
-    // vpblendw can't be used for this because it has a handicapped mask.
-
-    // If we don't have AVX2, then cast to float. Using a wrong domain blend
-    // is still more efficient than using the wrong domain vinsertf128 that
-    // will be created by InsertSubVector().
-    MVT CastVT = Subtarget.hasAVX2() ? MVT::v8i32 : MVT::v8f32;
-
-    SDValue Mask = DAG.getConstant(0x0f, dl, MVT::i8);
-    Result = DAG.getBitcast(CastVT, Result);
-    Vec256 = DAG.getBitcast(CastVT, Vec256);
-    Vec256 = DAG.getNode(X86ISD::BLENDI, dl, CastVT, Result, Vec256, Mask);
-    return DAG.getBitcast(ResultVT, Vec256);
-  }
-
   return insertSubVector(Result, Vec, IdxVal, DAG, dl, 128);
 }
 
@@ -34165,6 +34121,45 @@ static SDValue combineInsertSubvector(SDNode *N, SelectionDAG &DAG,
   MVT OpVT = N->getSimpleValueType(0);
   MVT SubVecVT = SubVec.getSimpleValueType();
 
+  // For insertion into the zero index (low half) of a 256-bit vector, it is
+  // more efficient to generate a blend with immediate instead of an insert*128.
+  // We are still creating an INSERT_SUBVECTOR below with an undef node to
+  // extend the subvector to the size of the result vector. Make sure that
+  // we are not recursing on that node by checking for undef here.
+  if (IdxVal == 0 && OpVT.is256BitVector() && SubVecVT.is128BitVector() &&
+      !Vec.isUndef()) {
+    SDValue ZeroIndex = DAG.getIntPtrConstant(0, dl);
+    SDValue Undef = DAG.getUNDEF(OpVT);
+    SDValue Vec256 = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, OpVT, Undef,
+                                 SubVec, ZeroIndex);
+
+    // The blend instruction, and therefore its mask, depend on the data type.
+    MVT ScalarType = OpVT.getVectorElementType();
+    if (ScalarType.isFloatingPoint()) {
+      // Choose either vblendps (float) or vblendpd (double).
+      unsigned ScalarSize = ScalarType.getSizeInBits();
+      assert((ScalarSize == 64 || ScalarSize == 32) && "Unknown float type");
+      unsigned MaskVal = (ScalarSize == 64) ? 0x03 : 0x0f;
+      SDValue Mask = DAG.getConstant(MaskVal, dl, MVT::i8);
+      return DAG.getNode(X86ISD::BLENDI, dl, OpVT, Vec, Vec256, Mask);
+    }
+
+    // AVX2 is needed for 256-bit integer blend support.
+    // Integers must be cast to 32-bit because there is only vpblendd;
+    // vpblendw can't be used for this because it has a handicapped mask.
+
+    // If we don't have AVX2, then cast to float. Using a wrong domain blend
+    // is still more efficient than using the wrong domain vinsertf128 that
+    // will be created by InsertSubVector().
+    MVT CastVT = Subtarget.hasAVX2() ? MVT::v8i32 : MVT::v8f32;
+
+    SDValue Mask = DAG.getConstant(0x0f, dl, MVT::i8);
+    Vec = DAG.getBitcast(CastVT, Vec);
+    Vec256 = DAG.getBitcast(CastVT, Vec256);
+    Vec256 = DAG.getNode(X86ISD::BLENDI, dl, CastVT, Vec, Vec256, Mask);
+    return DAG.getBitcast(OpVT, Vec256);
+  }
+
   // Fold two 16-byte or 32-byte subvector loads into one 32-byte or 64-byte
   // load:
   // (insert_subvector (insert_subvector undef, (load16 addr), 0),