[llvm-commits] [llvm] r166125 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/X86/extract-concat.ll

[Michael Liao]

Author: hliao
Date: Wed Oct 17 15:48:33 2012
New Revision: 166125

URL: http://llvm.org/viewvc/llvm-project?rev=166125&view=rev
Log:
Teach DAG combine to fold (extract_subvec (concat v1, ..) i) to v_i

- If the extracted vector has the same type of all vectored being concatenated
  together, it should be simplified directly into v_i, where i is the index of
  the element being extracted.


Added:
    llvm/trunk/test/CodeGen/X86/extract-concat.ll
Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=166125&r1=166124&r2=166125&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Oct 17 15:48:33 2012
@@ -8610,8 +8610,8 @@
       return SDValue();
 
     // Only handle cases where both indexes are constants with the same type.
-    ConstantSDNode *InsIdx = dyn_cast<ConstantSDNode>(N->getOperand(1));
-    ConstantSDNode *ExtIdx = dyn_cast<ConstantSDNode>(V->getOperand(2));
+    ConstantSDNode *ExtIdx = dyn_cast<ConstantSDNode>(N->getOperand(1));
+    ConstantSDNode *InsIdx = dyn_cast<ConstantSDNode>(V->getOperand(2));
 
     if (InsIdx && ExtIdx &&
         InsIdx->getValueType(0).getSizeInBits() <= 64 &&
@@ -8628,6 +8628,21 @@
     }
   }
 
+  if (V->getOpcode() == ISD::CONCAT_VECTORS) {
+    // Combine:
+    //    (extract_subvec (concat V1, V2, ...), i)
+    // Into:
+    //    Vi if possible
+    for (unsigned i = 0, e = V->getNumOperands(); i != e; ++i)
+      if (V->getOperand(i).getValueType() != NVT)
+        return SDValue();
+    unsigned Idx = dyn_cast<ConstantSDNode>(N->getOperand(1))->getZExtValue();
+    unsigned NumElems = NVT.getVectorNumElements();
+    assert((Idx % NumElems) == 0 &&
+           "IDX in concat is not a multiple of the result vector length.");
+    return V->getOperand(Idx / NumElems);
+  }
+
   return SDValue();
 }
 

Added: llvm/trunk/test/CodeGen/X86/extract-concat.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/extract-concat.ll?rev=166125&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/extract-concat.ll (added)
+++ llvm/trunk/test/CodeGen/X86/extract-concat.ll Wed Oct 17 15:48:33 2012
@@ -0,0 +1,17 @@
+; RUN: llc < %s -mcpu=corei7 -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+define void @foo(<4 x float> %in, <4 x i8>* %out) {
+  %t0 = fptoui <4 x float> %in to <4 x i32>
+  %t1 = trunc <4 x i32> %t0 to <4 x i16>
+  %t2 = shufflevector <4 x i16> %t1, <4 x i16> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+  %t3 = trunc <8 x i16> %t2 to <8 x i8>
+  %t4 = shufflevector <8 x i8> %t3, <8 x i8> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+  %t5 = insertelement <4 x i8> %t4, i8 -1, i32 3
+  store <4 x i8> %t5, <4 x i8>* %out
+  ret void
+; CHECK: foo
+; CHECK: cvttps2dq
+; CHECK-NOT: pextrd
+; CHECK: pshufb
+; CHECK: ret
+}