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

This reverts commit r282241. It caused http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/19882.

llvm-svn: 282249

1 files changed, 0 insertions, 170 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 018fb1617d6..434b4546483 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -37,7 +37,6 @@
 #include "llvm/IR/CallingConv.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instruction.h"
@@ -60,28 +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));
-static cl::opt<unsigned> ConstpoolPromotionMaxTotal(
-    "arm-promote-constant-max-total", cl::Hidden,
-    cl::desc("Maximum size of ALL constants to promote into a constant pool"),
-    cl::init(128));
-
 namespace {
   class ARMCCState : public CCState {
   public:
@@ -2980,154 +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;
-}
-
-/// Return true if all users of V are within some (any) function, looking through
-/// ConstantExprs. In other words, are there any global constant users?
-static bool allUsersAreInFunctions(const Value *V) {
-  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;
-    }
-
-    if (!isa<Instruction>(U))
-      return false;
-  }
-  return true;
-}
-
-// Return true if T is an integer, float or an array/vector of either.
-static bool isSimpleType(Type *T) {
-  if (T->isIntegerTy() || T->isFloatingPointTy())
-    return true;
-  Type *SubT = nullptr;
-  if (T->isArrayTy())
-    SubT = T->getArrayElementType();
-  else if (T->isVectorTy())
-    SubT = T->getVectorElementType();
-  else
-    return false;
-  return SubT->isIntegerTy() || SubT->isFloatingPointTy();
-}
-
-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();
-  
-  // We rely on this decision to inline being idemopotent and unrelated to the
-  // use-site. We know that if we inline a variable at one use site, we'll
-  // inline it elsewhere too (and reuse the constant pool entry). Fast-isel
-  // doesn't know about this optimization, so bail out if it's enabled else
-  // we could decide to inline here (and thus never emit the GV) but require
-  // the GV from fast-isel generated code.
-  if (!EnableConstpoolPromotion ||
-      DAG.getMachineFunction().getTarget().Options.EnableFastISel)
-      return SDValue();
-
-  auto *GVar = dyn_cast<GlobalVariable>(GV);
-  if (!GVar || !GVar->hasInitializer() ||
-      !GVar->isConstant() || !GVar->hasGlobalUnnamedAddr() ||
-      !GVar->hasLocalLinkage())
-    return SDValue();
-
-  // Ensure that we don't try and inline any type that contains pointers. If
-  // we inline a value that contains relocations, we move the relocations from
-  // .data to .text which is not ideal.
-  auto *Init = GVar->getInitializer();
-  if (!isSimpleType(Init->getType()))
-    return SDValue();
-
-  // 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 *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)
-    return SDValue();
-
-  unsigned PaddedSize = Size + ((RequiredPadding == 4) ? 0 : RequiredPadding);
-  MachineFunction &MF = DAG.getMachineFunction();
-  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-
-  // We can't bloat the constant pool too much, else the ConstantIslands pass
-  // may fail to converge. If we haven't promoted this global yet (it may have
-  // multiple uses), and promoting it would increase the constant pool size (Sz
-  // > 4), ensure we have space to do so up to MaxTotal.
-  if (!AFI->getGlobalsPromotedToConstantPool().count(GVar) && Size > 4)
-    if (AFI->getPromotedConstpoolIncrease() + PaddedSize - 4 >=
-        ConstpoolPromotionMaxTotal)
-      return SDValue();
-
-  // This is only valid if all users are in a single function OR it has users
-  // in multiple functions but it no larger than a pointer. We also check if
-  // GVar has constant (non-ConstantExpr) users. If so, it essentially has its
-  // address taken.
-  if (!allUsersAreInFunction(GVar, F) &&
-      !(Size <= 4 && allUsersAreInFunctions(GVar)))
-    return SDValue();
-
-  // We're going to inline this global. Pad it out if needed.
-  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);
-  }
-
-  auto CPVal = ARMConstantPoolConstant::Create(GVar, Init);
-  SDValue CPAddr =
-    DAG.getTargetConstantPool(CPVal, PtrVT, /*Align=*/4);
-  if (!AFI->getGlobalsPromotedToConstantPool().count(GVar)) {
-    AFI->markGlobalAsPromotedToConstantPool(GVar);
-    AFI->setPromotedConstpoolIncrease(AFI->getPromotedConstpoolIncrease() +
-                                      PaddedSize - 4);
-  }
-  ++NumConstpoolPromoted;
-  return DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
-}
-
 SDValue ARMTargetLowering::LowerGlobalAddressELF(SDValue Op,
                                                  SelectionDAG &DAG) const {
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
@@ -3139,11 +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);