[FastISel][X86] Add MachineMemOperand to load/store instructions.

This commit adds MachineMemOperands to load and store instructions. This allows
the peephole optimizer to fold load instructions. Unfortunatelly the peephole
optimizer currently doesn't run at -O0.

llvm-svn: 210858

1 files changed, 44 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 94d3be90cb9..21fcbd61617 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1737,3 +1737,47 @@ bool FastISel::canFoldAddIntoGEP(const User *GEP, const Value *Add) {
   return isa<ConstantInt>(cast<AddOperator>(Add)->getOperand(1));
 }
 
+MachineMemOperand *
+FastISel::createMachineMemOperandFor(const Instruction *I) const {
+  const Value *Ptr;
+  Type *ValTy;
+  unsigned Alignment;
+  unsigned Flags;
+  bool IsVolatile;
+
+  if (const auto *LI = dyn_cast<LoadInst>(I)) {
+    Alignment = LI->getAlignment();
+    IsVolatile = LI->isVolatile();
+    Flags = MachineMemOperand::MOLoad;
+    Ptr = LI->getPointerOperand();
+    ValTy = LI->getType();
+  } else if (const auto *SI = dyn_cast<StoreInst>(I)) {
+    Alignment = SI->getAlignment();
+    IsVolatile = SI->isVolatile();
+    Flags = MachineMemOperand::MOStore;
+    Ptr = SI->getPointerOperand();
+    ValTy = SI->getValueOperand()->getType();
+  } else {
+    return nullptr;
+  }
+
+  bool IsNonTemporal = I->getMetadata("nontemporal") != nullptr;
+  bool IsInvariant = I->getMetadata("invariant.load") != nullptr;
+  const MDNode *TBAAInfo = I->getMetadata(LLVMContext::MD_tbaa);
+  const MDNode *Ranges = I->getMetadata(LLVMContext::MD_range);
+
+  if (Alignment == 0)  // Ensure that codegen never sees alignment 0.
+    Alignment = DL.getABITypeAlignment(ValTy);
+
+  unsigned Size = TM.getDataLayout()->getTypeStoreSize(ValTy);
+
+  if (IsVolatile)
+    Flags |= MachineMemOperand::MOVolatile;
+  if (IsNonTemporal)
+    Flags |= MachineMemOperand::MONonTemporal;
+  if (IsInvariant)
+    Flags |= MachineMemOperand::MOInvariant;
+
+  return FuncInfo.MF->getMachineMemOperand(MachinePointerInfo(Ptr), Flags, Size,
+                                           Alignment, TBAAInfo, Ranges);
+}