Move TryToFoldFastISelLoad to FastISel, where it belongs. In general, I'm

trying to move as much FastISel logic as possible out of the main path in
SelectionDAGISel - intermixing them just adds confusion.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179902 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 79 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 5aec6ac05a..e21f26e91c 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -835,84 +835,6 @@ void SelectionDAGISel::PrepareEHLandingPad() {
   if (Reg) MBB->addLiveIn(Reg);
 }
 
-/// TryToFoldFastISelLoad - We're checking to see if we can fold the specified
-/// load into the specified FoldInst.  Note that we could have a sequence where
-/// multiple LLVM IR instructions are folded into the same machineinstr.  For
-/// example we could have:
-///   A: x = load i32 *P
-///   B: y = icmp A, 42
-///   C: br y, ...
-///
-/// In this scenario, LI is "A", and FoldInst is "C".  We know about "B" (and
-/// any other folded instructions) because it is between A and C.
-///
-/// If we succeed in folding the load into the operation, return true.
-///
-bool SelectionDAGISel::TryToFoldFastISelLoad(const LoadInst *LI,
-                                             const Instruction *FoldInst,
-                                             FastISel *FastIS) {
-  // We know that the load has a single use, but don't know what it is.  If it
-  // isn't one of the folded instructions, then we can't succeed here.  Handle
-  // this by scanning the single-use users of the load until we get to FoldInst.
-  unsigned MaxUsers = 6;  // Don't scan down huge single-use chains of instrs.
-
-  const Instruction *TheUser = LI->use_back();
-  while (TheUser != FoldInst &&   // Scan up until we find FoldInst.
-         // Stay in the right block.
-         TheUser->getParent() == FoldInst->getParent() &&
-         --MaxUsers) {  // Don't scan too far.
-    // If there are multiple or no uses of this instruction, then bail out.
-    if (!TheUser->hasOneUse())
-      return false;
-
-    TheUser = TheUser->use_back();
-  }
-
-  // If we didn't find the fold instruction, then we failed to collapse the
-  // sequence.
-  if (TheUser != FoldInst)
-    return false;
-
-  // Don't try to fold volatile loads.  Target has to deal with alignment
-  // constraints.
-  if (LI->isVolatile()) return false;
-
-  // Figure out which vreg this is going into.  If there is no assigned vreg yet
-  // then there actually was no reference to it.  Perhaps the load is referenced
-  // by a dead instruction.
-  unsigned LoadReg = FastIS->getRegForValue(LI);
-  if (LoadReg == 0)
-    return false;
-
-  // Check to see what the uses of this vreg are.  If it has no uses, or more
-  // than one use (at the machine instr level) then we can't fold it.
-  MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(LoadReg);
-  if (RI == RegInfo->reg_end())
-    return false;
-
-  // See if there is exactly one use of the vreg.  If there are multiple uses,
-  // then the instruction got lowered to multiple machine instructions or the
-  // use of the loaded value ended up being multiple operands of the result, in
-  // either case, we can't fold this.
-  MachineRegisterInfo::reg_iterator PostRI = RI; ++PostRI;
-  if (PostRI != RegInfo->reg_end())
-    return false;
-
-  assert(RI.getOperand().isUse() &&
-         "The only use of the vreg must be a use, we haven't emitted the def!");
-
-  MachineInstr *User = &*RI;
-
-  // Set the insertion point properly.  Folding the load can cause generation of
-  // other random instructions (like sign extends) for addressing modes, make
-  // sure they get inserted in a logical place before the new instruction.
-  FuncInfo->InsertPt = User;
-  FuncInfo->MBB = User->getParent();
-
-  // Ask the target to try folding the load.
-  return FastIS->TryToFoldLoad(User, RI.getOperandNo(), LI);
-}
-
 /// isFoldedOrDeadInstruction - Return true if the specified instruction is
 /// side-effect free and is either dead or folded into a generated instruction.
 /// Return false if it needs to be emitted.
@@ -1113,7 +1035,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
           }
           if (BeforeInst != Inst && isa<LoadInst>(BeforeInst) &&
               BeforeInst->hasOneUse() &&
-              TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), Inst, FastIS)) {
+              FastIS->tryToFoldLoad(cast<LoadInst>(BeforeInst), Inst)) {
             // If we succeeded, don't re-select the load.
             BI = llvm::next(BasicBlock::const_iterator(BeforeInst));
             --NumFastIselRemaining;