Fix pr11266.
On x86: (shl V, 1) -> add V,V
Hardware support for vector-shift is sparse and in many cases we scalarize the
result. Additionally, on sandybridge padd is faster than shl.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143311 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2ec0814..1af2449 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -13042,7 +13042,8 @@
// fold (shl (and (setcc_c), c1), c2) -> (and setcc_c, (c1 << c2))
// since the result of setcc_c is all zero's or all ones.
- if (N1C && N0.getOpcode() == ISD::AND &&
+ if (VT.isInteger() && !VT.isVector() &&
+ N1C && N0.getOpcode() == ISD::AND &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
SDValue N00 = N0.getOperand(0);
if (N00.getOpcode() == X86ISD::SETCC_CARRY ||
@@ -13058,6 +13059,22 @@
}
}
+
+ // Hardware support for vector shifts is sparse which makes us scalarize the
+ // vector operations in many cases. Also, on sandybridge ADD is faster than
+ // shl.
+ // (shl V, 1) -> add V,V
+ if (isSplatVector(N1.getNode())) {
+ assert(N0.getValueType().isVector() && "Invalid vector shift type");
+ ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1->getOperand(0));
+ // We shift all of the values by one. In many cases we do not have
+ // hardware support for this operation. This is better expressed as an ADD
+ // of two values.
+ if (N1C && (1 == N1C->getZExtValue())) {
+ return DAG.getNode(ISD::ADD, N->getDebugLoc(), VT, N0, N0);
+ }
+ }
+
return SDValue();
}
@@ -13066,9 +13083,10 @@
static SDValue PerformShiftCombine(SDNode* N, SelectionDAG &DAG,
const X86Subtarget *Subtarget) {
EVT VT = N->getValueType(0);
- if (!VT.isVector() && VT.isInteger() &&
- N->getOpcode() == ISD::SHL)
- return PerformSHLCombine(N, DAG);
+ if (N->getOpcode() == ISD::SHL) {
+ SDValue V = PerformSHLCombine(N, DAG);
+ if (V.getNode()) return V;
+ }
// On X86 with SSE2 support, we can transform this to a vector shift if
// all elements are shifted by the same amount. We can't do this in legalize