[llvm] r229306 - [x86] Tweak the ordering of unpack matching vs. element insertion, and

[Chandler Carruth]

Author: chandlerc
Date: Sun Feb 15 06:01:14 2015
New Revision: 229306

URL: http://llvm.org/viewvc/llvm-project?rev=229306&view=rev
Log:
[x86] Tweak the ordering of unpack matching vs. element insertion, and
don't try to do element insertion for non-zero-index floating point
vectors.

We don't have any useful patterns or lowering for element insertion into
high elements of a floating point vector, and the generic shuffle
lowering will end up being better -- namely it will fall back to unpck.
But we should try to handle other forms of element insertion before
matching unpck patterns.

While this doesn't matter much right now, I'm working on a patch that
makes unpck matching much more powerful, and that patch will break
without this re-ordering.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=229306&r1=229305&r2=229306&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sun Feb 15 06:01:14 2015
@@ -8242,6 +8242,10 @@ static SDValue lowerVectorShuffleAsEleme
                        ExtVT, V1, V2);
   }
 
+  // This lowering only works for the low element with floating point vectors.
+  if (VT.isFloatingPoint() && V2Index != 0)
+    return SDValue();
+
   V2 = DAG.getNode(X86ISD::VZEXT_MOVL, DL, ExtVT, V2);
   if (ExtVT != VT)
     V2 = DAG.getNode(ISD::BITCAST, DL, VT, V2);
@@ -8464,12 +8468,6 @@ static SDValue lowerV2F64VectorShuffle(S
   assert(Mask[0] >= 0 && Mask[0] < 2 && "Non-canonicalized blend!");
   assert(Mask[1] >= 2 && "Non-canonicalized blend!");
 
-  // Use dedicated unpack instructions for masks that match their pattern.
-  if (isShuffleEquivalent(Mask, 0, 2))
-    return DAG.getNode(X86ISD::UNPCKL, DL, MVT::v2f64, V1, V2);
-  if (isShuffleEquivalent(Mask, 1, 3))
-    return DAG.getNode(X86ISD::UNPCKH, DL, MVT::v2f64, V1, V2);
-
   // If we have a single input, insert that into V1 if we can do so cheaply.
   if ((Mask[0] >= 2) + (Mask[1] >= 2) == 1) {
     if (SDValue Insertion = lowerVectorShuffleAsElementInsertion(
@@ -8500,6 +8498,12 @@ static SDValue lowerV2F64VectorShuffle(S
                                                   Subtarget, DAG))
       return Blend;
 
+  // Use dedicated unpack instructions for masks that match their pattern.
+  if (isShuffleEquivalent(Mask, 0, 2))
+    return DAG.getNode(X86ISD::UNPCKL, DL, MVT::v2f64, V1, V2);
+  if (isShuffleEquivalent(Mask, 1, 3))
+    return DAG.getNode(X86ISD::UNPCKH, DL, MVT::v2f64, V1, V2);
+
   unsigned SHUFPDMask = (Mask[0] == 1) | (((Mask[1] - 2) == 1) << 1);
   return DAG.getNode(X86ISD::SHUFP, SDLoc(Op), MVT::v2f64, V1, V2,
                      DAG.getConstant(SHUFPDMask, MVT::i8));
@@ -8561,17 +8565,17 @@ static SDValue lowerV2I64VectorShuffle(S
       return Insertion;
   }
 
+  if (Subtarget->hasSSE41())
+    if (SDValue Blend = lowerVectorShuffleAsBlend(DL, MVT::v2i64, V1, V2, Mask,
+                                                  Subtarget, DAG))
+      return Blend;
+
   // Use dedicated unpack instructions for masks that match their pattern.
   if (isShuffleEquivalent(Mask, 0, 2))
     return DAG.getNode(X86ISD::UNPCKL, DL, MVT::v2i64, V1, V2);
   if (isShuffleEquivalent(Mask, 1, 3))
     return DAG.getNode(X86ISD::UNPCKH, DL, MVT::v2i64, V1, V2);
 
-  if (Subtarget->hasSSE41())
-    if (SDValue Blend = lowerVectorShuffleAsBlend(DL, MVT::v2i64, V1, V2, Mask,
-                                                  Subtarget, DAG))
-      return Blend;
-
   // Try to use byte rotation instructions.
   // Its more profitable for pre-SSSE3 to use shuffles/unpacks.
   if (Subtarget->hasSSSE3())
@@ -8743,12 +8747,6 @@ static SDValue lowerV4F32VectorShuffle(S
                        getV4X86ShuffleImm8ForMask(Mask, DAG));
   }
 
-  // Use dedicated unpack instructions for masks that match their pattern.
-  if (isShuffleEquivalent(Mask, 0, 4, 1, 5))
-    return DAG.getNode(X86ISD::UNPCKL, DL, MVT::v4f32, V1, V2);
-  if (isShuffleEquivalent(Mask, 2, 6, 3, 7))
-    return DAG.getNode(X86ISD::UNPCKH, DL, MVT::v4f32, V1, V2);
-
   // There are special ways we can lower some single-element blends. However, we
   // have custom ways we can lower more complex single-element blends below that
   // we defer to if both this and BLENDPS fail to match, so restrict this to
@@ -8774,6 +8772,12 @@ static SDValue lowerV4F32VectorShuffle(S
         return BlendPerm;
   }
 
+  // Use dedicated unpack instructions for masks that match their pattern.
+  if (isShuffleEquivalent(Mask, 0, 4, 1, 5))
+    return DAG.getNode(X86ISD::UNPCKL, DL, MVT::v4f32, V1, V2);
+  if (isShuffleEquivalent(Mask, 2, 6, 3, 7))
+    return DAG.getNode(X86ISD::UNPCKH, DL, MVT::v4f32, V1, V2);
+
   // Otherwise fall back to a SHUFPS lowering strategy.
   return lowerVectorShuffleWithSHUFPS(DL, MVT::v4f32, Mask, V1, V2, DAG);
 }