[SystemZ] Improve isFoldableMemAccessOffset().

A store of an extracted element or a load which gets inserted into a vector,
will be combined into a vector load/store element instruction.

Therefore, isFoldableMemAccessOffset(), which is called by LSR, should
return false in these cases.

Reviewer: Ulrich Weigand
llvm-svn: 291673

1 files changed, 20 insertions, 2 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
index 2081809def7..2d0a06af18a 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -547,8 +547,26 @@ bool SystemZTargetLowering::isFoldableMemAccessOffset(Instruction *I,
   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()))
+  bool IsFPAccess = MemAccessTy->isFloatingPointTy();
+  bool IsVectorAccess = MemAccessTy->isVectorTy();
+
+  // A store of an extracted vector element will be combined into a VSTE type
+  // instruction.
+  if (!IsVectorAccess && isa<StoreInst>(I)) {
+    Value *DataOp = I->getOperand(0);
+    if (isa<ExtractElementInst>(DataOp))
+      IsVectorAccess = true;
+  }
+
+  // A load which gets inserted into a vector element will be combined into a
+  // VLE type instruction.
+  if (!IsVectorAccess && isa<LoadInst>(I) && I->hasOneUse()) {
+    User *LoadUser = *I->user_begin();
+    if (isa<InsertElementInst>(LoadUser))
+      IsVectorAccess = true;
+  }
+
+  if (!isUInt<12>(Offset) && (IsFPAccess || IsVectorAccess))
     return false;
 
   return true;