[llvm] r272997 - [X86] Pre-size several SmallVectors instead of calling push_back in a loop. NFC

[Craig Topper via llvm-commits]

Author: ctopper
Date: Fri Jun 17 07:20:50 2016
New Revision: 272997

URL: http://llvm.org/viewvc/llvm-project?rev=272997&view=rev
Log:
[X86] Pre-size several SmallVectors instead of calling push_back in a loop. NFC

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=272997&r1=272996&r2=272997&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Fri Jun 17 07:20:50 2016
@@ -4684,10 +4684,10 @@ static SDValue getOnesVector(EVT VT, con
 static SDValue getUnpackl(SelectionDAG &DAG, const SDLoc &dl, MVT VT,
                           SDValue V1, SDValue V2) {
   unsigned NumElems = VT.getVectorNumElements();
-  SmallVector<int, 8> Mask;
+  SmallVector<int, 8> Mask(NumElems);
   for (unsigned i = 0, e = NumElems/2; i != e; ++i) {
-    Mask.push_back(i);
-    Mask.push_back(i + NumElems);
+    Mask[i * 2]     = i;
+    Mask[i * 2 + 1] = i + NumElems;
   }
   return DAG.getVectorShuffle(VT, dl, V1, V2, &Mask[0]);
 }
@@ -4696,10 +4696,10 @@ static SDValue getUnpackl(SelectionDAG &
 static SDValue getUnpackh(SelectionDAG &DAG, const SDLoc &dl, MVT VT,
                           SDValue V1, SDValue V2) {
   unsigned NumElems = VT.getVectorNumElements();
-  SmallVector<int, 8> Mask;
+  SmallVector<int, 8> Mask(NumElems);
   for (unsigned i = 0, Half = NumElems/2; i != Half; ++i) {
-    Mask.push_back(i + Half);
-    Mask.push_back(i + NumElems + Half);
+    Mask[i * 2]     = i + Half;
+    Mask[i * 2 + 1] = i + NumElems + Half;
   }
   return DAG.getVectorShuffle(VT, dl, V1, V2, &Mask[0]);
 }
@@ -4708,18 +4708,18 @@ static SDValue getUnpackh(SelectionDAG &
 /// This produces a shuffle where the low element of V2 is swizzled into the
 /// zero/undef vector, landing at element Idx.
 /// This produces a shuffle mask like 4,1,2,3 (idx=0) or  0,1,2,4 (idx=3).
-static SDValue getShuffleVectorZeroOrUndef(SDValue V2, unsigned Idx,
+static SDValue getShuffleVectorZeroOrUndef(SDValue V2, int Idx,
                                            bool IsZero,
                                            const X86Subtarget &Subtarget,
                                            SelectionDAG &DAG) {
   MVT VT = V2.getSimpleValueType();
   SDValue V1 = IsZero
     ? getZeroVector(VT, Subtarget, DAG, SDLoc(V2)) : DAG.getUNDEF(VT);
-  unsigned NumElems = VT.getVectorNumElements();
-  SmallVector<int, 16> MaskVec;
-  for (unsigned i = 0; i != NumElems; ++i)
+  int NumElems = VT.getVectorNumElements();
+  SmallVector<int, 16> MaskVec(NumElems);
+  for (int i = 0; i != NumElems; ++i)
     // If this is the insertion idx, put the low elt of V2 here.
-    MaskVec.push_back(i == Idx ? NumElems : i);
+    MaskVec[i] = (i == Idx) ? NumElems : i;
   return DAG.getVectorShuffle(VT, SDLoc(V2), V1, V2, &MaskVec[0]);
 }
 
@@ -10955,7 +10955,7 @@ static SDValue lowerShuffleAsRepeatedMas
   }
 
   // Bail if we already have a repeated lane shuffle mask.
-  SmallVector<int, 8> RepeatedShuffleMask((unsigned)NumLaneElts, -1);
+  SmallVector<int, 8> RepeatedShuffleMask;
   if (is128BitLaneRepeatedShuffleMask(VT, Mask, RepeatedShuffleMask))
     return SDValue();