Remove GlobalValue::getAlignment().

This function is deceptive at best: it doesn't return what you'd expect.
If you have an arbitrary GlobalValue and you want to determine the
alignment of that pointer, Value::getPointerAlignment() returns the
correct value.  If you want the actual declared alignment of a function
or variable, GlobalObject::getAlignment() returns that.

This patch switches all the users of GlobalValue::getAlignment to an
appropriate alternative.

Differential Revision: https://reviews.llvm.org/D80368

include/llvm/CodeGen/AsmPrinter.h

@@ -662,7 +662,7 @@ public:
   virtual void emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
 
   /// Return the alignment for the specified \p GV.
-  static Align getGVAlignment(const GlobalValue *GV, const DataLayout &DL,
+  static Align getGVAlignment(const GlobalObject *GV, const DataLayout &DL,
                               Align InAlign = Align(1));
 
 private:

include/llvm/IR/GlobalObject.h

@@ -76,6 +76,10 @@ public:
     return Align ? Align->value() : 0;
   }
 
+  /// Returns the alignment of the given variable or function.
+  ///
+  /// Note that for functions this is the alignment of the code, not the
+  /// alignment of a function pointer.
   MaybeAlign getAlign() const {
     unsigned Data = getGlobalValueSubClassData();
     unsigned AlignmentData = Data & AlignmentMask;
@@ -183,6 +187,13 @@ public:
   void setVCallVisibilityMetadata(VCallVisibility Visibility);
   VCallVisibility getVCallVisibility() const;
 
+  /// Returns true if the alignment of the value can be unilaterally
+  /// increased.
+  ///
+  /// Note that for functions this is the alignment of the code, not the
+  /// alignment of a function pointer.
+  bool canIncreaseAlignment() const;
+
 protected:
   void copyAttributesFrom(const GlobalObject *Src);
 

include/llvm/IR/GlobalValue.h

@@ -185,7 +185,6 @@ public:
 
   GlobalValue(const GlobalValue &) = delete;
 
-  unsigned getAlignment() const;
   unsigned getAddressSpace() const;
 
   enum class UnnamedAddr {
@@ -549,10 +548,6 @@ public:
     return !(isDeclarationForLinker() || isWeakForLinker());
   }
 
-  // Returns true if the alignment of the value can be unilaterally
-  // increased.
-  bool canIncreaseAlignment() const;
-
   const GlobalObject *getBaseObject() const;
   GlobalObject *getBaseObject() {
     return const_cast<GlobalObject *>(

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -1179,7 +1179,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
   std::map<std::string, unsigned> GCMap;
   unsigned MaxAlignment = 0;
   unsigned MaxGlobalType = 0;
-  for (const GlobalValue &GV : M.globals()) {
+  for (const GlobalVariable &GV : M.globals()) {
     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
     if (GV.hasSection()) {

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -157,7 +157,7 @@ static gcp_map_type &getGCMap(void *&P) {
 
 /// getGVAlignment - Return the alignment to use for the specified global
 /// value.  This rounds up to the preferred alignment if possible and legal.
-Align AsmPrinter::getGVAlignment(const GlobalValue *GV, const DataLayout &DL,
+Align AsmPrinter::getGVAlignment(const GlobalObject *GV, const DataLayout &DL,
                                  Align InAlign) {
   Align Alignment;
   if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))

lib/IR/ConstantFold.cpp

@@ -1239,8 +1239,8 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1,
             // Without a datalayout we have to assume the worst case: that the
             // function pointer isn't aligned at all.
             GVAlign = llvm::None;
-          } else {
-            GVAlign = MaybeAlign(GV->getAlignment());
+          } else if (isa<GlobalVariable>(GV)) {
+            GVAlign = cast<GlobalVariable>(GV)->getAlign();
           }
 
           if (GVAlign && *GVAlign > 1) {

lib/IR/Core.cpp

@@ -2003,7 +2003,7 @@ LLVMTypeRef LLVMGlobalGetValueType(LLVMValueRef Global) {
 
 unsigned LLVMGetAlignment(LLVMValueRef V) {
   Value *P = unwrap<Value>(V);
-  if (GlobalValue *GV = dyn_cast<GlobalValue>(P))
+  if (GlobalObject *GV = dyn_cast<GlobalObject>(P))
     return GV->getAlignment();
   if (AllocaInst *AI = dyn_cast<AllocaInst>(P))
     return AI->getAlignment();
@@ -2013,7 +2013,7 @@ unsigned LLVMGetAlignment(LLVMValueRef V) {
     return SI->getAlignment();
 
   llvm_unreachable(
-      "only GlobalValue, AllocaInst, LoadInst and StoreInst have alignment");
+      "only GlobalObject, AllocaInst, LoadInst and StoreInst have alignment");
 }
 
 void LLVMSetAlignment(LLVMValueRef V, unsigned Bytes) {

lib/IR/Globals.cpp

@@ -108,20 +108,6 @@ bool GlobalValue::canBenefitFromLocalAlias() const {
          !isa<GlobalIFunc>(this) && !hasComdat();
 }
 
-unsigned GlobalValue::getAlignment() const {
-  if (auto *GA = dyn_cast<GlobalAlias>(this)) {
-    // In general we cannot compute this at the IR level, but we try.
-    if (const GlobalObject *GO = GA->getBaseObject())
-      return GO->getAlignment();
-
-    // FIXME: we should also be able to handle:
-    // Alias = Global + Offset
-    // Alias = Absolute
-    return 0;
-  }
-  return cast<GlobalObject>(this)->getAlignment();
-}
-
 unsigned GlobalValue::getAddressSpace() const {
   PointerType *PtrTy = getType();
   return PtrTy->getAddressSpace();
@@ -252,7 +238,7 @@ bool GlobalValue::isDeclaration() const {
   return false;
 }
 
-bool GlobalValue::canIncreaseAlignment() const {
+bool GlobalObject::canIncreaseAlignment() const {
   // Firstly, can only increase the alignment of a global if it
   // is a strong definition.
   if (!isStrongDefinitionForLinker())

lib/IR/Verifier.cpp

@@ -570,8 +570,9 @@ void Verifier::visitGlobalValue(const GlobalValue &GV) {
   Assert(!GV.isDeclaration() || GV.hasValidDeclarationLinkage(),
          "Global is external, but doesn't have external or weak linkage!", &GV);
 
-  Assert(GV.getAlignment() <= Value::MaximumAlignment,
-         "huge alignment values are unsupported", &GV);
+  if (const GlobalObject *GO = dyn_cast<GlobalObject>(&GV))
+    Assert(GO->getAlignment() <= Value::MaximumAlignment,
+           "huge alignment values are unsupported", GO);
   Assert(!GV.hasAppendingLinkage() || isa<GlobalVariable>(GV),
          "Only global variables can have appending linkage!", &GV);
 

lib/LTO/LTOModule.cpp

@@ -414,9 +414,8 @@ void LTOModule::addDefinedFunctionSymbol(StringRef Name, const Function *F) {
 
 void LTOModule::addDefinedSymbol(StringRef Name, const GlobalValue *def,
                                  bool isFunction) {
-  // set alignment part log2() can have rounding errors
-  uint32_t align = def->getAlignment();
-  uint32_t attr = align ? countTrailingZeros(align) : 0;
+  const GlobalObject *go = dyn_cast<GlobalObject>(def);
+  uint32_t attr = go ? Log2(go->getAlign().valueOrOne()) : 0;
 
   // set permissions part
   if (isFunction) {

lib/Object/IRSymtab.cpp

@@ -264,9 +264,13 @@ Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
   Sym.Flags |= unsigned(GV->getVisibility()) << storage::Symbol::FB_visibility;
 
   if (Flags & object::BasicSymbolRef::SF_Common) {
+    auto *GVar = dyn_cast<GlobalVariable>(GV);
+    if (!GVar)
+      return make_error<StringError>("Only variables can have common linkage!",
+                                     inconvertibleErrorCode());
     Uncommon().CommonSize = GV->getParent()->getDataLayout().getTypeAllocSize(
         GV->getType()->getElementType());
-    Uncommon().CommonAlign = GV->getAlignment();
+    Uncommon().CommonAlign = GVar->getAlignment();
   }
 
   const GlobalObject *Base = GV->getBaseObject();

lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

@@ -904,16 +904,9 @@ bool AArch64DAGToDAGISel::SelectAddrModeIndexed(SDValue N, unsigned Size,
     if (!GAN)
       return true;
 
-    if (GAN->getOffset() % Size == 0) {
-      const GlobalValue *GV = GAN->getGlobal();
-      unsigned Alignment = GV->getAlignment();
-      Type *Ty = GV->getValueType();
-      if (Alignment == 0 && Ty->isSized())
-        Alignment = DL.getABITypeAlignment(Ty);
-
-      if (Alignment >= Size)
-        return true;
-    }
+    if (GAN->getOffset() % Size == 0 &&
+        GAN->getGlobal()->getPointerAlignment(DL) >= Size)
+      return true;
   }
 
   if (CurDAG->isBaseWithConstantOffset(N)) {

lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp

@@ -5161,13 +5161,8 @@ AArch64InstructionSelector::tryFoldAddLowIntoImm(MachineInstr &RootDef,
   if (GV->isThreadLocal())
     return None;
 
-  unsigned Alignment = GV->getAlignment();
-  Type *Ty = GV->getValueType();
   auto &MF = *RootDef.getParent()->getParent();
-  if (Alignment == 0 && Ty->isSized())
-    Alignment = MF.getDataLayout().getABITypeAlignment(Ty);
-
-  if (Alignment < Size)
+  if (GV->getPointerAlignment(MF.getDataLayout()) < Size)
     return None;
 
   unsigned OpFlags = STI.ClassifyGlobalReference(GV, MF.getTarget());

lib/Target/AMDGPU/AMDGPUISelLowering.cpp

@@ -1321,7 +1321,7 @@ SDValue AMDGPUTargetLowering::LowerGlobalAddress(AMDGPUMachineFunction* MFI,
 
     // TODO: We could emit code to handle the initialization somewhere.
     if (!hasDefinedInitializer(GV)) {
-      unsigned Offset = MFI->allocateLDSGlobal(DL, *GV);
+      unsigned Offset = MFI->allocateLDSGlobal(DL, *cast<GlobalVariable>(GV));
       return DAG.getConstant(Offset, SDLoc(Op), Op.getValueType());
     }
   }
@@ -4589,11 +4589,10 @@ void AMDGPUTargetLowering::computeKnownBitsForTargetNode(
   }
   case AMDGPUISD::LDS: {
     auto GA = cast<GlobalAddressSDNode>(Op.getOperand(0).getNode());
-    unsigned Align = GA->getGlobal()->getAlignment();
+    Align Alignment = GA->getGlobal()->getPointerAlignment(DAG.getDataLayout());
 
     Known.Zero.setHighBits(16);
-    if (Align)
-      Known.Zero.setLowBits(Log2_32(Align));
+    Known.Zero.setLowBits(Log2(Alignment));
     break;
   }
   case ISD::INTRINSIC_WO_CHAIN: {

lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp

@@ -2099,7 +2099,9 @@ bool AMDGPULegalizerInfo::legalizeGlobalValue(
         return true; // Leave in place;
       }
 
-      B.buildConstant(DstReg, MFI->allocateLDSGlobal(B.getDataLayout(), *GV));
+      B.buildConstant(
+          DstReg,
+          MFI->allocateLDSGlobal(B.getDataLayout(), *cast<GlobalVariable>(GV)));
       MI.eraseFromParent();
       return true;
     }

lib/Target/AMDGPU/AMDGPUMachineFunction.cpp

@@ -38,7 +38,7 @@ AMDGPUMachineFunction::AMDGPUMachineFunction(const MachineFunction &MF) :
 }
 
 unsigned AMDGPUMachineFunction::allocateLDSGlobal(const DataLayout &DL,
-                                                  const GlobalValue &GV) {
+                                                  const GlobalVariable &GV) {
   auto Entry = LocalMemoryObjects.insert(std::make_pair(&GV, 0));
   if (!Entry.second)
     return Entry.first->second;

lib/Target/AMDGPU/AMDGPUMachineFunction.h

@@ -77,7 +77,7 @@ public:
     return WaveLimiter;
   }
 
-  unsigned allocateLDSGlobal(const DataLayout &DL, const GlobalValue &GV);
+  unsigned allocateLDSGlobal(const DataLayout &DL, const GlobalVariable &GV);
 };
 
 }

lib/Target/PowerPC/PPCAsmPrinter.cpp

@@ -1143,8 +1143,11 @@ void PPCAsmPrinter::emitInstruction(const MachineInstr *MI) {
     // can be enabled for those subtargets.
     unsigned OpNum = (MI->getOpcode() == PPC::STD) ? 2 : 1;
     const MachineOperand &MO = MI->getOperand(OpNum);
-    if (MO.isGlobal() && MO.getGlobal()->getAlignment() < 4)
-      llvm_unreachable("Global must be word-aligned for LD, STD, LWA!");
+    if (MO.isGlobal()) {
+      const DataLayout &DL = MO.getGlobal()->getParent()->getDataLayout();
+      if (MO.getGlobal()->getPointerAlignment(DL) < 4)
+        llvm_unreachable("Global must be word-aligned for LD, STD, LWA!");
+    }
     // Now process the instruction normally.
     break;
   }

lib/Target/PowerPC/PPCISelDAGToDAG.cpp

@@ -6659,7 +6659,8 @@ void PPCDAGToDAGISel::PeepholePPC64() {
     int MaxDisplacement = 7;
     if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(ImmOpnd)) {
       const GlobalValue *GV = GA->getGlobal();
-      MaxDisplacement = std::min((int) GV->getAlignment() - 1, MaxDisplacement);
+      Align Alignment = GV->getPointerAlignment(CurDAG->getDataLayout());
+      MaxDisplacement = std::min((int)Alignment.value() - 1, MaxDisplacement);
     }
 
     bool UpdateHBase = false;
@@ -6725,10 +6726,10 @@ void PPCDAGToDAGISel::PeepholePPC64() {
       if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(ImmOpnd)) {
         SDLoc dl(GA);
         const GlobalValue *GV = GA->getGlobal();
+        Align Alignment = GV->getPointerAlignment(CurDAG->getDataLayout());
         // We can't perform this optimization for data whose alignment
         // is insufficient for the instruction encoding.
-        if (GV->getAlignment() < 4 &&
-            (RequiresMod4Offset || (Offset % 4) != 0)) {
+        if (Alignment < 4 && (RequiresMod4Offset || (Offset % 4) != 0)) {
           LLVM_DEBUG(dbgs() << "Rejected this candidate for alignment.\n\n");
           continue;
         }

lib/Target/PowerPC/PPCInstrInfo.cpp

@@ -3591,9 +3591,11 @@ bool PPCInstrInfo::isImmElgibleForForwarding(const MachineOperand &ImmMO,
     // not just an immediate but also a multiple of 4, or 16 depending on the
     // load. A DForm load cannot be represented if it is a multiple of say 2.
     // XForm loads do not have this restriction.
-    if (ImmMO.isGlobal() &&
-        ImmMO.getGlobal()->getAlignment() < III.ImmMustBeMultipleOf)
-      return false;
+    if (ImmMO.isGlobal()) {
+      const DataLayout &DL = ImmMO.getGlobal()->getParent()->getDataLayout();
+      if (ImmMO.getGlobal()->getPointerAlignment(DL) < III.ImmMustBeMultipleOf)
+        return false;
+    }
 
     return true;
   }

lib/Target/SystemZ/SystemZSubtarget.cpp

@@ -74,9 +74,12 @@ bool SystemZSubtarget::enableSubRegLiveness() const {
 
 bool SystemZSubtarget::isPC32DBLSymbol(const GlobalValue *GV,
                                        CodeModel::Model CM) const {
-  // PC32DBL accesses require the low bit to be clear.  Note that a zero
-  // value selects the default alignment and is therefore OK.
-  if (GV->getAlignment() == 1)
+  // PC32DBL accesses require the low bit to be clear.
+  //
+  // FIXME: Explicitly check for functions: the datalayout is currently
+  // missing information about function pointers.
+  const DataLayout &DL = GV->getParent()->getDataLayout();
+  if (GV->getPointerAlignment(DL) == 1 && !GV->getValueType()->isFunctionTy())
     return false;
 
   // For the small model, all locally-binding symbols are in range.

lib/Target/XCore/XCoreISelLowering.cpp

@@ -435,7 +435,7 @@ SDValue XCoreTargetLowering::LowerLOAD(SDValue Op, SelectionDAG &DAG) const {
                                                     Offset, DAG);
     }
     if (TLI.isGAPlusOffset(BasePtr.getNode(), GV, Offset) &&
-        MinAlign(GV->getAlignment(), 4) == 4) {
+        GV->getPointerAlignment(DAG.getDataLayout()) >= 4) {
       SDValue NewBasePtr = DAG.getGlobalAddress(GV, DL,
                                                 BasePtr->getValueType(0));
       return lowerLoadWordFromAlignedBasePlusOffset(DL, Chain, NewBasePtr,

test/CodeGen/AArch64/funcptr_cast.ll

@@ -1,10 +1,12 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc < %s -mtriple=aarch64-none-linux-gnu | FileCheck %s
 
 define i8 @test() {
-; CHECK-LABEL: @test
-; CHECK: adrp {{x[0-9]+}}, foo
-; CHECK: add {{x[0-9]+}}, {{x[0-9]+}}, :lo12:foo
-; CHECK: ldrb w0, [{{x[0-9]+}}]
+; CHECK-LABEL: test:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    adrp x8, foo
+; CHECK-NEXT:    ldrb w0, [x8, :lo12:foo]
+; CHECK-NEXT:    ret
 entry:
   %0 = load i8, i8* bitcast (void (...)* @foo to i8*), align 1
   ret i8 %0

test/CodeGen/AArch64/global-alignment.ll

@@ -51,11 +51,11 @@ define i64 @test_var32_alias() {
 ; CHECK-LABEL: test_var32_alias:
   %addr = bitcast [3 x i32]* @alias to i64*
 
-  ; Test that we can find the alignment for aliases.
+  ; We don't know anything about the alignment of aliases.
   %val = load i64, i64* %addr
 ; CHECK: adrp x[[HIBITS:[0-9]+]], alias
-; CHECK-NOT: add x[[HIBITS]]
-; CHECK: ldr x0, [x[[HIBITS]], {{#?}}:lo12:alias]
+; CHECK: add x[[ADDR:[0-9]+]], x[[HIBITS]], {{#?}}:lo12:alias
+; CHECK: ldr x0, [x[[ADDR]]]
 
   ret i64 %val
 }

test/CodeGen/PowerPC/atomics-constant.ll

@@ -8,11 +8,10 @@ target triple = "powerpc64le-unknown-linux-gnu"
 define i64 @foo() {
 ; CHECK-LABEL: foo:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    addis 3, 2, a@toc@ha
 ; CHECK-NEXT:    li 4, 0
-; CHECK-NEXT:    addi 3, 3, a@toc@l
+; CHECK-NEXT:    addis 3, 2, a@toc@ha
+; CHECK-NEXT:    ld 3, a@toc@l(3)
 ; CHECK-NEXT:    cmpd 7, 4, 4
-; CHECK-NEXT:    ld 3, 0(3)
 ; CHECK-NEXT:    li 3, 0
 ; CHECK-NEXT:    bne- 7, .+4
 ; CHECK-NEXT:    isync