Simplify handling of v16i8 shuffles and fix a missed optimization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157043 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 75e0588..e1f777b 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5770,21 +5770,11 @@
DebugLoc dl = SVOp->getDebugLoc();
ArrayRef<int> MaskVals = SVOp->getMask();
+ bool V2IsUndef = V2.getOpcode() == ISD::UNDEF;
+
// If we have SSSE3, case 1 is generated when all result bytes come from
// one of the inputs. Otherwise, case 2 is generated. If no SSSE3 is
// present, fall back to case 3.
- // FIXME: kill V2Only once shuffles are canonizalized by getNode.
- bool V1Only = true;
- bool V2Only = true;
- for (unsigned i = 0; i < 16; ++i) {
- int EltIdx = MaskVals[i];
- if (EltIdx < 0)
- continue;
- if (EltIdx < 16)
- V2Only = false;
- else
- V1Only = false;
- }
// If SSSE3, use 1 pshufb instruction per vector with elements in the result.
if (TLI.getSubtarget()->hasSSSE3()) {
@@ -5796,23 +5786,16 @@
// Otherwise, we have elements from both input vectors, and must zero out
// elements that come from V2 in the first mask, and V1 in the second mask
// so that we can OR them together.
- bool TwoInputs = !(V1Only || V2Only);
for (unsigned i = 0; i != 16; ++i) {
int EltIdx = MaskVals[i];
- if (EltIdx < 0 || (TwoInputs && EltIdx >= 16)) {
- pshufbMask.push_back(DAG.getConstant(0x80, MVT::i8));
- continue;
- }
+ if (EltIdx < 0 || EltIdx >= 16)
+ EltIdx = 0x80;
pshufbMask.push_back(DAG.getConstant(EltIdx, MVT::i8));
}
- // If all the elements are from V2, assign it to V1 and return after
- // building the first pshufb.
- if (V2Only)
- V1 = V2;
V1 = DAG.getNode(X86ISD::PSHUFB, dl, MVT::v16i8, V1,
DAG.getNode(ISD::BUILD_VECTOR, dl,
MVT::v16i8, &pshufbMask[0], 16));
- if (!TwoInputs)
+ if (V2IsUndef)
return V1;
// Calculate the shuffle mask for the second input, shuffle it, and
@@ -5820,10 +5803,7 @@
pshufbMask.clear();
for (unsigned i = 0; i != 16; ++i) {
int EltIdx = MaskVals[i];
- if (EltIdx < 16) {
- pshufbMask.push_back(DAG.getConstant(0x80, MVT::i8));
- continue;
- }
+ EltIdx = (EltIdx < 16) ? 0x80 : EltIdx - 16;
pshufbMask.push_back(DAG.getConstant(EltIdx - 16, MVT::i8));
}
V2 = DAG.getNode(X86ISD::PSHUFB, dl, MVT::v16i8, V2,
@@ -5837,7 +5817,7 @@
// the 16 different words that comprise the two doublequadword input vectors.
V1 = DAG.getNode(ISD::BITCAST, dl, MVT::v8i16, V1);
V2 = DAG.getNode(ISD::BITCAST, dl, MVT::v8i16, V2);
- SDValue NewV = V2Only ? V2 : V1;
+ SDValue NewV = V1;
for (int i = 0; i != 8; ++i) {
int Elt0 = MaskVals[i*2];
int Elt1 = MaskVals[i*2+1];
@@ -5847,9 +5827,7 @@
continue;
// This word of the result is already in the correct place, skip it.
- if (V1Only && (Elt0 == i*2) && (Elt1 == i*2+1))
- continue;
- if (V2Only && (Elt0 == i*2+16) && (Elt1 == i*2+17))
+ if ((Elt0 == i*2) && (Elt1 == i*2+1))
continue;
SDValue Elt0Src = Elt0 < 16 ? V1 : V2;