Revert "[ARM] Promote small global constants to constant pools"

This reverts commit r281213. It made a bot go bang: http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15-full/builds/14625

llvm-svn: 281228

1 files changed, 0 insertions, 89 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index fd757d882b3..3441688daa5 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -59,24 +59,12 @@ using namespace llvm;
 STATISTIC(NumTailCalls, "Number of tail calls");
 STATISTIC(NumMovwMovt, "Number of GAs materialized with movw + movt");
 STATISTIC(NumLoopByVals, "Number of loops generated for byval arguments");
-STATISTIC(NumConstpoolPromoted,
-  "Number of constants with their storage promoted into constant pools");
 
 static cl::opt<bool>
 ARMInterworking("arm-interworking", cl::Hidden,
   cl::desc("Enable / disable ARM interworking (for debugging only)"),
   cl::init(true));
 
-static cl::opt<bool> EnableConstpoolPromotion(
-    "arm-promote-constant", cl::Hidden,
-    cl::desc("Enable / disable promotion of unnamed_addr constants into "
-             "constant pools"),
-    cl::init(true));
-static cl::opt<unsigned> ConstpoolPromotionMaxSize(
-    "arm-promote-constant-max-size", cl::Hidden,
-    cl::desc("Maximum size of constant to promote into a constant pool"),
-    cl::init(64));
-
 namespace {
   class ARMCCState : public CCState {
   public:
@@ -2975,78 +2963,6 @@ ARMTargetLowering::LowerGlobalTLSAddress(SDValue Op, SelectionDAG &DAG) const {
   llvm_unreachable("bogus TLS model");
 }
 
-/// Return true if all users of V are within function F, looking through
-/// ConstantExprs.
-static bool allUsersAreInFunction(const Value *V, const Function *F) {
-  SmallVector<const User*,4> Worklist;
-  for (auto *U : V->users())
-    Worklist.push_back(U);
-  while (!Worklist.empty()) {
-    auto *U = Worklist.pop_back_val();
-    if (isa<ConstantExpr>(U)) {
-      for (auto *UU : U->users())
-        Worklist.push_back(UU);
-      continue;
-    }
-
-    auto *I = dyn_cast<Instruction>(U);
-    if (!I || I->getParent()->getParent() != F)
-      return false;
-  }
-  return true;
-}
-
-static SDValue promoteToConstantPool(const GlobalValue *GV, SelectionDAG &DAG,
-                                     EVT PtrVT, SDLoc dl) {
-  // If we're creating a pool entry for a constant global with unnamed address,
-  // and the global is small enough, we can emit it inline into the constant pool
-  // to save ourselves an indirection.
-  //
-  // This is a win if the constant is only used in one function (so it doesn't
-  // need to be duplicated) or duplicating the constant wouldn't increase code
-  // size (implying the constant is no larger than 4 bytes).
-  const Function *F = DAG.getMachineFunction().getFunction();
-  auto *GVar = dyn_cast<GlobalVariable>(GV);
-  if (EnableConstpoolPromotion && GVar && GVar->hasInitializer() &&
-      GVar->isConstant() && GVar->hasGlobalUnnamedAddr()) {
-    // The constant islands pass can only really deal with alignment requests
-    // <= 4 bytes and cannot pad constants itself. Therefore we cannot promote
-    // any type wanting greater alignment requirements than 4 bytes. We also
-    // can only promote constants that are multiples of 4 bytes in size or
-    // are paddable to a multiple of 4. Currently we only try and pad constants
-    // that are strings for simplicity.
-    auto *Init = GVar->getInitializer();
-    auto *CDAInit = dyn_cast<ConstantDataArray>(Init);
-    unsigned Size = DAG.getDataLayout().getTypeAllocSize(Init->getType());
-    unsigned Align = DAG.getDataLayout().getABITypeAlignment(Init->getType());
-    unsigned RequiredPadding = 4 - (Size % 4);
-    bool PaddingPossible =
-        RequiredPadding == 4 || (CDAInit && CDAInit->isString());
-
-    if (PaddingPossible && Align <= 4 && Size <= ConstpoolPromotionMaxSize &&
-        (allUsersAreInFunction(GVar, F) || Size <= 4)) {
-      if (RequiredPadding != 4) {
-        StringRef S = CDAInit->getAsString();
-
-        SmallVector<uint8_t,16> V(S.size());
-        std::copy(S.bytes_begin(), S.bytes_end(), V.begin());
-        while (RequiredPadding--)
-          V.push_back(0);
-        Init = ConstantDataArray::get(*DAG.getContext(), V);
-      }
-      
-      SDValue CPAddr =
-        DAG.getTargetConstantPool(Init, PtrVT, Align);
-
-      MachineFunction &MF = DAG.getMachineFunction();
-      ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-      AFI->markGlobalAsPromotedToConstantPool(GVar);
-      return DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
-    }
-  }
-  return SDValue();
-}
-
 SDValue ARMTargetLowering::LowerGlobalAddressELF(SDValue Op,
                                                  SelectionDAG &DAG) const {
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
@@ -3058,11 +2974,6 @@ SDValue ARMTargetLowering::LowerGlobalAddressELF(SDValue Op,
   bool IsRO =
       (isa<GlobalVariable>(GV) && cast<GlobalVariable>(GV)->isConstant()) ||
       isa<Function>(GV);
-  
-  if (TM.shouldAssumeDSOLocal(*GV->getParent(), GV))
-    if (SDValue V = promoteToConstantPool(GV, DAG, PtrVT, dl))
-      return V;
-
   if (isPositionIndependent()) {
     bool UseGOT_PREL = !TM.shouldAssumeDSOLocal(*GV->getParent(), GV);