[llvm-commits] [llvm] r157175 - in /llvm/trunk: lib/Target/X86/X86ISelLowering.cpp test/CodeGen/X86/avx-shuffle.ll

Craig Topper craig.topper at gmail.com
Sun May 20 23:40:16 PDT 2012


Author: ctopper
Date: Mon May 21 01:40:16 2012
New Revision: 157175

URL: http://llvm.org/viewvc/llvm-project?rev=157175&view=rev
Log:
Allow 256-bit shuffles to still be split even if only half of the shuffle comes from two 128-bit pieces.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/test/CodeGen/X86/avx-shuffle.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=157175&r1=157174&r2=157175&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon May 21 01:40:16 2012
@@ -4061,13 +4061,14 @@
   SmallVector<int, 8> MaskVec;
 
   for (unsigned i = 0; i != NumElems; ++i) {
-    int idx = SVOp->getMaskElt(i);
-    if (idx < 0)
-      MaskVec.push_back(idx);
-    else if (idx < (int)NumElems)
-      MaskVec.push_back(idx + NumElems);
-    else
-      MaskVec.push_back(idx - NumElems);
+    int Idx = SVOp->getMaskElt(i);
+    if (Idx >= 0) {
+      if (Idx < (int)NumElems)
+        Idx += NumElems;
+      else
+        Idx -= NumElems;
+    }
+    MaskVec.push_back(Idx);
   }
   return DAG.getVectorShuffle(VT, SVOp->getDebugLoc(), SVOp->getOperand(1),
                               SVOp->getOperand(0), &MaskVec[0]);
@@ -5970,14 +5971,15 @@
   DebugLoc dl = SVOp->getDebugLoc();
   MVT EltVT = VT.getVectorElementType().getSimpleVT();
   EVT NVT = MVT::getVectorVT(EltVT, NumLaneElems);
-  SDValue Shufs[2];
+  SDValue Output[2];
 
   SmallVector<int, 16> Mask;
   for (unsigned l = 0; l < 2; ++l) {
     // Build a shuffle mask for the output, discovering on the fly which
     // input vectors to use as shuffle operands (recorded in InputUsed).
     // If building a suitable shuffle vector proves too hard, then bail
-    // out with useBuildVector set.
+    // out with UseBuildVector set.
+    bool UseBuildVector = false;
     int InputUsed[2] = { -1, -1 }; // Not yet discovered.
     unsigned LaneStart = l * NumLaneElems;
     for (unsigned i = 0; i != NumLaneElems; ++i) {
@@ -6009,17 +6011,44 @@
       }
 
       if (OpNo >= array_lengthof(InputUsed)) {
-        // More than two input vectors used! Give up.
-        return SDValue();
+        // More than two input vectors used!  Give up on trying to create a
+        // shuffle vector.  Insert all elements into a BUILD_VECTOR instead.
+        UseBuildVector = true;
+        break;
       }
 
       // Add the mask index for the new shuffle vector.
       Mask.push_back(Idx + OpNo * NumLaneElems);
     }
 
-    if (InputUsed[0] < 0) {
+    if (UseBuildVector) {
+      SmallVector<SDValue, 16> SVOps;
+      for (unsigned i = 0; i != NumLaneElems; ++i) {
+        // The mask element.  This indexes into the input.
+        int Idx = SVOp->getMaskElt(i+LaneStart);
+        if (Idx < 0) {
+          SVOps.push_back(DAG.getUNDEF(EltVT));
+          continue;
+        }
+
+        // The input vector this mask element indexes into.
+        int Input = Idx / NumElems;
+
+        // Turn the index into an offset from the start of the input vector.
+        Idx -= Input * NumElems;
+
+        // Extract the vector element by hand.
+        SVOps.push_back(DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, EltVT,
+                                    SVOp->getOperand(Input),
+                                    DAG.getIntPtrConstant(Idx)));
+      }
+
+      // Construct the output using a BUILD_VECTOR.
+      Output[l] = DAG.getNode(ISD::BUILD_VECTOR, dl, NVT, &SVOps[0],
+                              SVOps.size());
+    } else if (InputUsed[0] < 0) {
       // No input vectors were used! The result is undefined.
-      Shufs[l] = DAG.getUNDEF(NVT);
+      Output[l] = DAG.getUNDEF(NVT);
     } else {
       SDValue Op0 = Extract128BitVector(SVOp->getOperand(InputUsed[0] / 2),
                                         (InputUsed[0] % 2) * NumLaneElems,
@@ -6029,14 +6058,14 @@
         Extract128BitVector(SVOp->getOperand(InputUsed[1] / 2),
                             (InputUsed[1] % 2) * NumLaneElems, DAG, dl);
       // At least one input vector was used. Create a new shuffle vector.
-      Shufs[l] = DAG.getVectorShuffle(NVT, dl, Op0, Op1, &Mask[0]);
+      Output[l] = DAG.getVectorShuffle(NVT, dl, Op0, Op1, &Mask[0]);
     }
 
     Mask.clear();
   }
 
   // Concatenate the result back
-  return DAG.getNode(ISD::CONCAT_VECTORS, dl, VT, Shufs[0], Shufs[1]);
+  return DAG.getNode(ISD::CONCAT_VECTORS, dl, VT, Output[0], Output[1]);
 }
 
 /// LowerVECTOR_SHUFFLE_128v4 - Handle all 128-bit wide vectors with

Modified: llvm/trunk/test/CodeGen/X86/avx-shuffle.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avx-shuffle.ll?rev=157175&r1=157174&r2=157175&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/avx-shuffle.ll (original)
+++ llvm/trunk/test/CodeGen/X86/avx-shuffle.ll Mon May 21 01:40:16 2012
@@ -149,17 +149,26 @@
 }
 
 ; PR12413
+; CHECK: shuf1
 ; CHECK: vpshufb
 ; CHECK: vpshufb
 ; CHECK: vpshufb
 ; CHECK: vpshufb
-define <32 x i8> @shuf(<32 x i8> %inval1, <32 x i8> %inval2) {
+define <32 x i8> @shuf1(<32 x i8> %inval1, <32 x i8> %inval2) {
 entry:
- %0 = shufflevector <32 x i8> %inval1, <32 x i8> %inval2, <32 x i32> <i32 0,
-i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14, i32 16, i32 18, i32 20, i32
-22, i32 24, i32 26, i32 28, i32 30, i32 32, i32 34, i32 36, i32 38, i32 40, i32
-42, i32 44, i32 46, i32 48, i32 50, i32 52, i32 54, i32 56, i32 58, i32 60, i32
-62>
+ %0 = shufflevector <32 x i8> %inval1, <32 x i8> %inval2, <32 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14, i32 16, i32 18, i32 20, i32 22, i32 24, i32 26, i32 28, i32 30, i32 32, i32 34, i32 36, i32 38, i32 40, i32 42, i32 44, i32 46, i32 48, i32 50, i32 52, i32 54, i32 56, i32 58, i32 60, i32 62>
+ ret <32 x i8> %0
+}
+
+; handle the case where only half of the 256-bits is splittable
+; CHECK: shuf2
+; CHECK: vpshufb
+; CHECK: vpshufb
+; CHECK: vpextrb
+; CHECK: vpextrb
+define <32 x i8> @shuf2(<32 x i8> %inval1, <32 x i8> %inval2) {
+entry:
+ %0 = shufflevector <32 x i8> %inval1, <32 x i8> %inval2, <32 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14, i32 16, i32 18, i32 20, i32 22, i32 24, i32 26, i32 28, i32 30, i32 31, i32 34, i32 36, i32 38, i32 40, i32 42, i32 44, i32 46, i32 48, i32 50, i32 52, i32 54, i32 56, i32 58, i32 60, i32 62>
  ret <32 x i8> %0
 }
 





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