2 files changed, 24 insertions, 0 deletions
diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
index 748827c4cfc..6c0ef66dea7 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -20,6 +20,7 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/IR/Intrinsics.h"
 #include <cctype>
 
@@ -531,6 +532,28 @@ bool SystemZTargetLowering::isLegalAddressingMode(const DataLayout &DL,
   return AM.Scale == 0 || AM.Scale == 1;
 }
 
+bool SystemZTargetLowering::isFoldableMemAccessOffset(Instruction *I,
+                                                      int64_t Offset) const {
+  // This only applies to z13.
+  if (!Subtarget.hasVector())
+    return true;
+
+  // * Use LDE instead of LE/LEY to avoid partial register
+  //   dependencies (LDE only supports small offsets).
+  // * Utilize the vector registers to hold floating point
+  //   values (vector load / store instructions only support small
+  //   offsets).
+
+  assert (isa<LoadInst>(I) || isa<StoreInst>(I));
+  Type *MemAccessTy = (isa<LoadInst>(I) ? I->getType() :
+                       I->getOperand(0)->getType());
+  if (!isUInt<12>(Offset) &&
+      (MemAccessTy->isFloatingPointTy() || MemAccessTy->isVectorTy()))
+    return false;
+
+  return true;
+}
+
 bool SystemZTargetLowering::isTruncateFree(Type *FromType, Type *ToType) const {
   if (!FromType->isIntegerTy() || !ToType->isIntegerTy())
     return false;
diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.h b/llvm/lib/Target/SystemZ/SystemZISelLowering.h
index b1de8936bee..423b246608c 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.h
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.h
@@ -394,6 +394,7 @@ public:
   bool isLegalAddImmediate(int64_t Imm) const override;
   bool isLegalAddressingMode(const DataLayout &DL, const AddrMode &AM, Type *Ty,
                              unsigned AS) const override;
+  bool isFoldableMemAccessOffset(Instruction *I, int64_t Offset) const override;
   bool allowsMisalignedMemoryAccesses(EVT VT, unsigned AS,
                                       unsigned Align,
                                       bool *Fast) const override;