[Alignment][NFC] use llvm::Align for AsmPrinter::EmitAlignment

Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: dschuff, sdardis, nemanjai, hiraditya, kbarton, jrtc27, MaskRay, atanasyan, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67443

llvm-svn: 371616

llvm/include/llvm/CodeGen/AsmPrinter.h

@@ -342,12 +342,11 @@ class AsmPrinter : public MachineFunctionPass {
   /// so, emit it and return true, otherwise do nothing and return false.
   bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
 
-  /// Emit an alignment directive to the specified power of two boundary. For
-  /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
+  /// Emit an alignment directive to the specified power of two boundary. If a
   /// global value is specified, and if that global has an explicit alignment
   /// requested, it will override the alignment request if required for
   /// correctness.
-  void EmitAlignment(unsigned NumBits, const GlobalObject *GV = nullptr) const;
+  void EmitAlignment(llvm::Align Align, const GlobalObject *GV = nullptr) const;
 
   /// Lower the specified LLVM Constant to an MCExpr.
   virtual const MCExpr *lowerConstant(const Constant *CV);
@@ -635,10 +634,9 @@ class AsmPrinter : public MachineFunctionPass {
   /// supported by the target.
   void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
 
-  /// Return the alignment in log2 form for the specified \p GV.
-  static unsigned getGVAlignmentLog2(const GlobalValue *GV,
-                                     const DataLayout &DL,
-                                     unsigned InBits = 0);
+  /// Return the alignment for the specified \p GV.
+  static llvm::Align getGVAlignment(const GlobalValue *GV, const DataLayout &DL,
+                                    llvm::Align InAlign = llvm::Align(1));
 
 private:
   /// Private state for PrintSpecial()

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -159,31 +159,31 @@ static gcp_map_type &getGCMap(void *&P) {
   return *(gcp_map_type*)P;
 }
 
-/// getGVAlignmentLog2 - Return the alignment to use for the specified global
-/// value in log2 form.  This rounds up to the preferred alignment if possible
-/// and legal.
-unsigned AsmPrinter::getGVAlignmentLog2(const GlobalValue *GV,
-                                        const DataLayout &DL,
-                                        unsigned InBits) {
-  unsigned NumBits = 0;
+/// getGVAlignment - Return the alignment to use for the specified global
+/// value.  This rounds up to the preferred alignment if possible and legal.
+llvm::Align AsmPrinter::getGVAlignment(const GlobalValue *GV,
+                                       const DataLayout &DL,
+                                       llvm::Align InAlign) {
+  llvm::Align Align;
   if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
-    NumBits = DL.getPreferredAlignmentLog(GVar);
+    Align = llvm::Align(DL.getPreferredAlignment(GVar));
 
-  // If InBits is specified, round it to it.
-  if (InBits > NumBits)
-    NumBits = InBits;
+  // If InAlign is specified, round it to it.
+  if (InAlign > Align)
+    Align = InAlign;
 
   // If the GV has a specified alignment, take it into account.
-  if (GV->getAlignment() == 0)
-    return NumBits;
+  const llvm::MaybeAlign GVAlign(GV->getAlignment());
+  if (!GVAlign)
+    return Align;
 
-  unsigned GVAlign = Log2_32(GV->getAlignment());
+  assert(GVAlign && "GVAlign must be set");
 
   // If the GVAlign is larger than NumBits, or if we are required to obey
   // NumBits because the GV has an assigned section, obey it.
-  if (GVAlign > NumBits || GV->hasSection())
-    NumBits = GVAlign;
-  return NumBits;
+  if (*GVAlign > Align || GV->hasSection())
+    Align = *GVAlign;
+  return Align;
 }
 
 AsmPrinter::AsmPrinter(TargetMachine &tm, std::unique_ptr<MCStreamer> Streamer)
@@ -502,7 +502,7 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
   // If the alignment is specified, we *must* obey it.  Overaligning a global
   // with a specified alignment is a prompt way to break globals emitted to
   // sections and expected to be contiguous (e.g. ObjC metadata).
-  unsigned AlignLog = getGVAlignmentLog2(GV, DL);
+  const llvm::Align Align = getGVAlignment(GV, DL);
 
   for (const HandlerInfo &HI : Handlers) {
     NamedRegionTimer T(HI.TimerName, HI.TimerDescription,
@@ -514,12 +514,11 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
   // Handle common symbols
   if (GVKind.isCommon()) {
     if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
-    unsigned Align = 1 << AlignLog;
-    if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
-      Align = 0;
-
     // .comm _foo, 42, 4
-    OutStreamer->EmitCommonSymbol(GVSym, Size, Align);
+    const bool SupportsAlignment =
+        getObjFileLowering().getCommDirectiveSupportsAlignment();
+    OutStreamer->EmitCommonSymbol(GVSym, Size,
+                                  SupportsAlignment ? Align.value() : 0);
     return;
   }
 
@@ -532,10 +531,9 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
       TheSection->isVirtualSection()) {
     if (Size == 0)
       Size = 1; // zerofill of 0 bytes is undefined.
-    unsigned Align = 1 << AlignLog;
     EmitLinkage(GV, GVSym);
     // .zerofill __DATA, __bss, _foo, 400, 5
-    OutStreamer->EmitZerofill(TheSection, GVSym, Size, Align);
+    OutStreamer->EmitZerofill(TheSection, GVSym, Size, Align.value());
     return;
   }
 
@@ -545,7 +543,6 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
       getObjFileLowering().getBSSSection() == TheSection) {
     if (Size == 0)
       Size = 1; // .comm Foo, 0 is undefined, avoid it.
-    unsigned Align = 1 << AlignLog;
 
     // Use .lcomm only if it supports user-specified alignment.
     // Otherwise, while it would still be correct to use .lcomm in some
@@ -555,17 +552,17 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
     // Prefer to simply fall back to .local / .comm in this case.
     if (MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
       // .lcomm _foo, 42
-      OutStreamer->EmitLocalCommonSymbol(GVSym, Size, Align);
+      OutStreamer->EmitLocalCommonSymbol(GVSym, Size, Align.value());
       return;
     }
 
-    if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
-      Align = 0;
-
     // .local _foo
     OutStreamer->EmitSymbolAttribute(GVSym, MCSA_Local);
     // .comm _foo, 42, 4
-    OutStreamer->EmitCommonSymbol(GVSym, Size, Align);
+    const bool SupportsAlignment =
+        getObjFileLowering().getCommDirectiveSupportsAlignment();
+    OutStreamer->EmitCommonSymbol(GVSym, Size,
+                                  SupportsAlignment ? Align.value() : 0);
     return;
   }
 
@@ -586,11 +583,11 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
 
     if (GVKind.isThreadBSS()) {
       TheSection = getObjFileLowering().getTLSBSSSection();
-      OutStreamer->EmitTBSSSymbol(TheSection, MangSym, Size, 1 << AlignLog);
+      OutStreamer->EmitTBSSSymbol(TheSection, MangSym, Size, Align.value());
     } else if (GVKind.isThreadData()) {
       OutStreamer->SwitchSection(TheSection);
 
-      EmitAlignment(AlignLog, GV);
+      EmitAlignment(Align, GV);
       OutStreamer->EmitLabel(MangSym);
 
       EmitGlobalConstant(GV->getParent()->getDataLayout(),
@@ -626,7 +623,7 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
   OutStreamer->SwitchSection(TheSection);
 
   EmitLinkage(GV, EmittedInitSym);
-  EmitAlignment(AlignLog, GV);
+  EmitAlignment(Align, GV);
 
   OutStreamer->EmitLabel(EmittedInitSym);
 
@@ -667,7 +664,7 @@ void AsmPrinter::EmitFunctionHeader() {
 
   EmitLinkage(&F, CurrentFnSym);
   if (MAI->hasFunctionAlignment())
-    EmitAlignment(Log2(MF->getAlignment()), &F);
+    EmitAlignment(MF->getAlignment(), &F);
 
   if (MAI->hasDotTypeDotSizeDirective())
     OutStreamer->EmitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
@@ -1421,7 +1418,7 @@ bool AsmPrinter::doFinalization(Module &M) {
       OutStreamer->SwitchSection(TLOF.getDataSection());
       const DataLayout &DL = M.getDataLayout();
 
-      EmitAlignment(Log2_32(DL.getPointerSize()));
+      EmitAlignment(llvm::Align(DL.getPointerSize()));
       for (const auto &Stub : Stubs) {
         OutStreamer->EmitLabel(Stub.first);
         OutStreamer->EmitSymbolValue(Stub.second.getPointer(),
@@ -1448,7 +1445,7 @@ bool AsmPrinter::doFinalization(Module &M) {
                 COFF::IMAGE_SCN_LNK_COMDAT,
             SectionKind::getReadOnly(), Stub.first->getName(),
             COFF::IMAGE_COMDAT_SELECT_ANY));
-        EmitAlignment(Log2_32(DL.getPointerSize()));
+        EmitAlignment(llvm::Align(DL.getPointerSize()));
         OutStreamer->EmitSymbolAttribute(Stub.first, MCSA_Global);
         OutStreamer->EmitLabel(Stub.first);
         OutStreamer->EmitSymbolValue(Stub.second.getPointer(),
@@ -1730,7 +1727,7 @@ void AsmPrinter::EmitConstantPool() {
 
       if (CurSection != CPSections[i].S) {
         OutStreamer->SwitchSection(CPSections[i].S);
-        EmitAlignment(Log2_32(CPSections[i].Alignment));
+        EmitAlignment(llvm::Align(CPSections[i].Alignment));
         CurSection = CPSections[i].S;
         Offset = 0;
       }
@@ -1777,7 +1774,7 @@ void AsmPrinter::EmitJumpTableInfo() {
     OutStreamer->SwitchSection(ReadOnlySection);
   }
 
-  EmitAlignment(Log2_32(MJTI->getEntryAlignment(DL)));
+  EmitAlignment(llvm::Align(MJTI->getEntryAlignment(DL)));
 
   // Jump tables in code sections are marked with a data_region directive
   // where that's supported.
@@ -1990,7 +1987,7 @@ void AsmPrinter::EmitXXStructorList(const DataLayout &DL, const Constant *List,
   }
 
   // Emit the function pointers in the target-specific order
-  unsigned Align = Log2_32(DL.getPointerPrefAlignment());
+  const llvm::Align Align = llvm::Align(DL.getPointerPrefAlignment());
   llvm::stable_sort(Structors, [](const Structor &L, const Structor &R) {
     return L.Priority < R.Priority;
   });
@@ -2114,23 +2111,21 @@ void AsmPrinter::EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
 //===----------------------------------------------------------------------===//
 
 // EmitAlignment - Emit an alignment directive to the specified power of
-// two boundary.  For example, if you pass in 3 here, you will get an 8
-// byte alignment.  If a global value is specified, and if that global has
+// two boundary.  If a global value is specified, and if that global has
 // an explicit alignment requested, it will override the alignment request
 // if required for correctness.
-void AsmPrinter::EmitAlignment(unsigned NumBits, const GlobalObject *GV) const {
+void AsmPrinter::EmitAlignment(llvm::Align Align,
+                               const GlobalObject *GV) const {
   if (GV)
-    NumBits = getGVAlignmentLog2(GV, GV->getParent()->getDataLayout(), NumBits);
+    Align = getGVAlignment(GV, GV->getParent()->getDataLayout(), Align);
 
-  if (NumBits == 0) return;   // 1-byte aligned: no need to emit alignment.
+  if (Align == 1)
+    return; // 1-byte aligned: no need to emit alignment.
 
-  assert(NumBits <
-             static_cast<unsigned>(std::numeric_limits<unsigned>::digits) &&
-         "undefined behavior");
   if (getCurrentSection()->getKind().isText())
-    OutStreamer->EmitCodeAlignment(1u << NumBits);
+    OutStreamer->EmitCodeAlignment(Align.value());
   else
-    OutStreamer->EmitValueToAlignment(1u << NumBits);
+    OutStreamer->EmitValueToAlignment(Align.value());
 }
 
 //===----------------------------------------------------------------------===//
@@ -2905,8 +2900,9 @@ void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock &MBB) {
   }
 
   // Emit an alignment directive for this block, if needed.
-  if (unsigned LogAlign = MBB.getLogAlignment())
-    EmitAlignment(LogAlign);
+  const llvm::Align Align = MBB.getAlignment();
+  if (Align > 1)
+    EmitAlignment(Align);
   MCCodePaddingContext Context;
   setupCodePaddingContext(MBB, Context);
   OutStreamer->EmitCodePaddingBasicBlockStart(Context);

llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp

@@ -426,7 +426,7 @@ MCSymbol *EHStreamer::emitExceptionTable() {
   // EHABI). In this case LSDASection will be NULL.
   if (LSDASection)
     Asm->OutStreamer->SwitchSection(LSDASection);
-  Asm->EmitAlignment(2);
+  Asm->EmitAlignment(llvm::Align(4));
 
   // Emit the LSDA.
   MCSymbol *GCCETSym =
@@ -602,11 +602,11 @@ MCSymbol *EHStreamer::emitExceptionTable() {
   }
 
   if (HaveTTData) {
-    Asm->EmitAlignment(2);
+    Asm->EmitAlignment(llvm::Align(4));
     emitTypeInfos(TTypeEncoding, TTBaseLabel);
   }
 
-  Asm->EmitAlignment(2);
+  Asm->EmitAlignment(llvm::Align(4));
   return GCCETSym;
 }
 

llvm/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp

@@ -72,7 +72,7 @@ void ErlangGCPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
      **/
 
     // Align to address width.
-    AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
+    AP.EmitAlignment(IntPtrSize == 4 ? llvm::Align(4) : llvm::Align(8));
 
     // Emit PointCount.
     OS.AddComment("safe point count");

llvm/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp

@@ -129,7 +129,7 @@ void OcamlGCMetadataPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
     report_fatal_error(" Too much descriptor for ocaml GC");
   }
   AP.emitInt16(NumDescriptors);
-  AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
+  AP.EmitAlignment(IntPtrSize == 4 ? llvm::Align(4) : llvm::Align(8));
 
   for (GCModuleInfo::FuncInfoVec::iterator I = Info.funcinfo_begin(),
                                            IE = Info.funcinfo_end();
@@ -180,7 +180,7 @@ void OcamlGCMetadataPrinter::finishAssembly(Module &M, GCModuleInfo &Info,
         AP.emitInt16(K->StackOffset);
       }
 
-      AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
+      AP.EmitAlignment(IntPtrSize == 4 ? llvm::Align(4) : llvm::Align(8));
     }
   }
 }

llvm/lib/CodeGen/AsmPrinter/WinException.cpp

@@ -203,8 +203,8 @@ void WinException::beginFunclet(const MachineBasicBlock &MBB,
 
     // We want our funclet's entry point to be aligned such that no nops will be
     // present after the label.
-    Asm->EmitAlignment(
-        Log2(std::max(Asm->MF->getAlignment(), MBB.getAlignment())), &F);
+    Asm->EmitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()),
+                       &F);
 
     // Now that we've emitted the alignment directive, point at our funclet.
     Asm->OutStreamer->EmitLabel(Sym);

llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

@@ -692,7 +692,7 @@ void AArch64AsmPrinter::EmitJumpTableInfo() {
     if (JTBBs.empty()) continue;
 
     unsigned Size = AFI->getJumpTableEntrySize(JTI);
-    EmitAlignment(Log2_32(Size));
+    EmitAlignment(llvm::Align(Size));
     OutStreamer->EmitLabel(GetJTISymbol(JTI));
 
     for (auto *JTBB : JTBBs)