[PowerPC] Recommit r340016 after fixing the reported issue

The internal benchmark failure reported by Google was due to a missing
check for the result type for the sign-extend and shift DAG. This commit
adds the check and re-commits the patch.

llvm-svn: 340734

1 files changed, 25 insertions, 1 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index fbeea91c92b..2b575317592 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1351,6 +1351,7 @@ const char *PPCTargetLowering::getTargetNodeName(unsigned Opcode) const {
   case PPCISD::QBFLT:           return "PPCISD::QBFLT";
   case PPCISD::QVLFSb:          return "PPCISD::QVLFSb";
   case PPCISD::BUILD_FP128:     return "PPCISD::BUILD_FP128";
+  case PPCISD::EXTSWSLI:        return "PPCISD::EXTSWSLI";
   }
   return nullptr;
 }
@@ -14131,7 +14132,30 @@ SDValue PPCTargetLowering::combineSHL(SDNode *N, DAGCombinerInfo &DCI) const {
   if (auto Value = stripModuloOnShift(*this, N, DCI.DAG))
     return Value;
 
-  return SDValue();
+  SDValue N0 = N->getOperand(0);
+  ConstantSDNode *CN1 = dyn_cast<ConstantSDNode>(N->getOperand(1));
+  if (!Subtarget.isISA3_0() ||
+      N0.getOpcode() != ISD::SIGN_EXTEND ||
+      N0.getOperand(0).getValueType() != MVT::i32 ||
+      CN1 == nullptr || N->getValueType(0) != MVT::i64)
+    return SDValue();
+
+  // We can't save an operation here if the value is already extended, and
+  // the existing shift is easier to combine.
+  SDValue ExtsSrc = N0.getOperand(0);
+  if (ExtsSrc.getOpcode() == ISD::TRUNCATE &&
+      ExtsSrc.getOperand(0).getOpcode() == ISD::AssertSext)
+    return SDValue();
+
+  SDLoc DL(N0);
+  SDValue ShiftBy = SDValue(CN1, 0);
+  // We want the shift amount to be i32 on the extswli, but the shift could
+  // have an i64.
+  if (ShiftBy.getValueType() == MVT::i64)
+    ShiftBy = DCI.DAG.getConstant(CN1->getZExtValue(), DL, MVT::i32);
+
+  return DCI.DAG.getNode(PPCISD::EXTSWSLI, DL, MVT::i64, N0->getOperand(0),
+                         ShiftBy);
 }
 
 SDValue PPCTargetLowering::combineSRA(SDNode *N, DAGCombinerInfo &DCI) const {