2 files changed, 22 insertions, 0 deletions
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 6b24c21c8bc..e93c7819b1a 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -9780,6 +9780,26 @@ bool PPCTargetLowering::isTruncateFree(EVT VT1, EVT VT2) const {
   return NumBits1 == 64 && NumBits2 == 32;
 }
 
+bool PPCTargetLowering::isZExtFree(SDValue Val, EVT VT2) const {
+  // Generally speaking, zexts are not free, but they are free when they can be
+  // folded with other operations.
+  if (LoadSDNode *LD = dyn_cast<LoadSDNode>(Val)) {
+    EVT MemVT = LD->getMemoryVT();
+    if ((MemVT == MVT::i1 || MemVT == MVT::i8 || MemVT == MVT::i16 ||
+         (Subtarget.isPPC64() && MemVT == MVT::i32)) &&
+        (LD->getExtensionType() == ISD::NON_EXTLOAD ||
+         LD->getExtensionType() == ISD::ZEXTLOAD))
+      return true;
+  }
+
+  // FIXME: Add other cases...
+  //  - 32-bit shifts with a zext to i64
+  //  - zext after ctlz, bswap, etc.
+  //  - zext after and by a constant mask
+
+  return TargetLowering::isZExtFree(Val, VT2);
+}
+
 bool PPCTargetLowering::isLegalICmpImmediate(int64_t Imm) const {
   return isInt<16>(Imm) || isUInt<16>(Imm);
 }
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index 6149a21f443..db5a3e42d52 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -526,6 +526,8 @@ namespace llvm {
     bool isTruncateFree(Type *Ty1, Type *Ty2) const override;
     bool isTruncateFree(EVT VT1, EVT VT2) const override;
 
+    bool isZExtFree(SDValue Val, EVT VT2) const override;
+
     /// \brief Returns true if it is beneficial to convert a load of a constant
     /// to just the constant itself.
     bool shouldConvertConstantLoadToIntImm(const APInt &Imm,