Vext Lowering was missing opportunities
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167318 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 3b8d79b..ebcec11 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1601,8 +1601,8 @@
CallOpc = ARMISD::CALL_NOLINK;
else if (doesNotRet && isDirect && !isARMFunc &&
Subtarget->hasRAS() && !Subtarget->isThumb1Only() &&
- // Emit regular call when code size is the priority
- !HasMinSizeAttr)
+ // Emit regular call when code size is the priority
+ !HasMinSizeAttr)
// "mov lr, pc; b _foo" to avoid confusing the RSP
CallOpc = ARMISD::CALL_NOLINK;
else
@@ -1611,8 +1611,8 @@
if (!isDirect && !Subtarget->hasV5TOps()) {
CallOpc = ARMISD::CALL_NOLINK;
} else if (doesNotRet && isDirect && Subtarget->hasRAS() &&
- // Emit regular call when code size is the priority
- !HasMinSizeAttr)
+ // Emit regular call when code size is the priority
+ !HasMinSizeAttr)
// "mov lr, pc; b _foo" to avoid confusing the RSP
CallOpc = ARMISD::CALL_NOLINK;
else
@@ -3929,6 +3929,36 @@
return SDValue();
}
+// check if an VEXT instruction can handle the shuffle mask when the
+// vector sources of the shuffle are the same.
+static bool isSingletonVEXTMask(ArrayRef<int> M, EVT VT, unsigned &Imm) {
+ unsigned NumElts = VT.getVectorNumElements();
+
+ // Assume that the first shuffle index is not UNDEF. Fail if it is.
+ if (M[0] < 0)
+ return false;
+
+ Imm = M[0];
+
+ // If this is a VEXT shuffle, the immediate value is the index of the first
+ // element. The other shuffle indices must be the successive elements after
+ // the first one.
+ unsigned ExpectedElt = Imm;
+ for (unsigned i = 1; i < NumElts; ++i) {
+ // Increment the expected index. If it wraps around, just follow it
+ // back to index zero and keep going.
+ ++ExpectedElt;
+ if (ExpectedElt == NumElts)
+ ExpectedElt = 0;
+
+ if (M[i] < 0) continue; // ignore UNDEF indices
+ if (ExpectedElt != static_cast<unsigned>(M[i]))
+ return false;
+ }
+
+ return true;
+}
+
static bool isVEXTMask(ArrayRef<int> M, EVT VT,
bool &ReverseVEXT, unsigned &Imm) {
@@ -4688,6 +4718,12 @@
if (isVREVMask(ShuffleMask, VT, 16))
return DAG.getNode(ARMISD::VREV16, dl, VT, V1);
+ if (V2->getOpcode() == ISD::UNDEF &&
+ isSingletonVEXTMask(ShuffleMask, VT, Imm)) {
+ return DAG.getNode(ARMISD::VEXT, dl, VT, V1, V1,
+ DAG.getConstant(Imm, MVT::i32));
+ }
+
// Check for Neon shuffles that modify both input vectors in place.
// If both results are used, i.e., if there are two shuffles with the same
// source operands and with masks corresponding to both results of one of