Don't drop alignment info on local common symbols.

- On COFF the .lcomm directive has an alignment argument.
- On ELF we fall back to .local + .comm

Based on a patch by NAKAMURA Takumi.

Fixes PR9337, PR9483 and PR10128.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138976 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCAsmInfo.h

@@ -32,6 +32,10 @@ namespace llvm {
     enum ExceptionsType { None, DwarfCFI, SjLj, ARM, Win64 };
   }
 
+  namespace LCOMM {
+    enum LCOMMType { None, NoAlignment, ByteAlignment };
+  }
+
   /// MCAsmInfo - This class is intended to be used as a base class for asm
   /// properties and features specific to the target.
   class MCAsmInfo {
@@ -229,9 +233,9 @@ namespace llvm {
     /// .long a - b
     bool HasAggressiveSymbolFolding;           // Defaults to true.
 
-    /// HasLCOMMDirective - This is true if the target supports the .lcomm
+    /// LCOMMDirectiveType - Describes if the target supports the .lcomm
-    /// directive.
+    /// directive and whether it has an alignment parameter.
-    bool HasLCOMMDirective;                  // Defaults to false.
+    LCOMM::LCOMMType LCOMMDirectiveType;     // Defaults to LCOMM::None.
 
     /// COMMDirectiveAlignmentIsInBytes - True is COMMDirective's optional
     /// alignment is to be specified in bytes instead of log2(n).
@@ -479,7 +483,9 @@ namespace llvm {
     bool hasAggressiveSymbolFolding() const {
       return HasAggressiveSymbolFolding;
     }
-    bool hasLCOMMDirective() const { return HasLCOMMDirective; }
+    LCOMM::LCOMMType getLCOMMDirectiveType() const {
+      return LCOMMDirectiveType;
+    }
     bool hasDotTypeDotSizeDirective() const {return HasDotTypeDotSizeDirective;}
     bool getCOMMDirectiveAlignmentIsInBytes() const {
       return COMMDirectiveAlignmentIsInBytes;

include/llvm/MC/MCStreamer.h

@@ -304,7 +304,9 @@ namespace llvm {
     ///
     /// @param Symbol - The common symbol to emit.
     /// @param Size - The size of the common symbol.
-    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) = 0;
+    /// @param ByteAlignment - The alignment of the common symbol in bytes.
+    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                       unsigned ByteAlignment) = 0;
 
     /// EmitZerofill - Emit the zerofill section and an optional symbol.
     ///

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -290,10 +290,10 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
   // Handle common and BSS local symbols (.lcomm).
   if (GVKind.isCommon() || GVKind.isBSSLocal()) {
     if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
+    unsigned Align = 1 << AlignLog;
 
     // Handle common symbols.
     if (GVKind.isCommon()) {
-      unsigned Align = 1 << AlignLog;
       if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
         Align = 0;
 
@@ -307,17 +307,17 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
       const MCSection *TheSection =
         getObjFileLowering().SectionForGlobal(GV, GVKind, Mang, TM);
       // .zerofill __DATA, __bss, _foo, 400, 5
-      OutStreamer.EmitZerofill(TheSection, GVSym, Size, 1 << AlignLog);
+      OutStreamer.EmitZerofill(TheSection, GVSym, Size, Align);
       return;
     }
 
-    if (MAI->hasLCOMMDirective()) {
+    if (MAI->getLCOMMDirectiveType() != LCOMM::None &&
+        (MAI->getLCOMMDirectiveType() != LCOMM::NoAlignment || Align == 1)) {
       // .lcomm _foo, 42
-      OutStreamer.EmitLocalCommonSymbol(GVSym, Size);
+      OutStreamer.EmitLocalCommonSymbol(GVSym, Size, Align);
       return;
     }
 
-    unsigned Align = 1 << AlignLog;
     if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
       Align = 0;
 

lib/MC/MCAsmInfo.cpp

@@ -65,7 +65,7 @@ MCAsmInfo::MCAsmInfo() {
   GlobalDirective = "\t.globl\t";
   HasSetDirective = true;
   HasAggressiveSymbolFolding = true;
-  HasLCOMMDirective = false;
+  LCOMMDirectiveType = LCOMM::None;
   COMMDirectiveAlignmentIsInBytes = true;
   HasDotTypeDotSizeDirective = true;
   HasSingleParameterDotFile = true;

lib/MC/MCAsmInfoCOFF.cpp

@@ -19,7 +19,7 @@ using namespace llvm;
 MCAsmInfoCOFF::MCAsmInfoCOFF() {
   GlobalPrefix = "_";
   COMMDirectiveAlignmentIsInBytes = false;
-  HasLCOMMDirective = true;
+  LCOMMDirectiveType = LCOMM::ByteAlignment;
   HasDotTypeDotSizeDirective = false;
   HasSingleParameterDotFile = false;
   PrivateGlobalPrefix = "L";  // Prefix for private global symbols

lib/MC/MCAsmStreamer.cpp

@@ -158,7 +158,9 @@ public:
   ///
   /// @param Symbol - The common symbol to emit.
   /// @param Size - The size of the common symbol.
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
+  /// @param Size - The alignment of the common symbol in bytes.
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment);
 
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             unsigned Size = 0, unsigned ByteAlignment = 0);
@@ -484,9 +486,16 @@ void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 ///
 /// @param Symbol - The common symbol to emit.
 /// @param Size - The size of the common symbol.
-void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
+void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
-  assert(MAI.hasLCOMMDirective() && "Doesn't have .lcomm, can't emit it!");
+                                          unsigned ByteAlign) {
+  assert(MAI.getLCOMMDirectiveType() != LCOMM::None &&
+         "Doesn't have .lcomm, can't emit it!");
   OS << "\t.lcomm\t" << *Symbol << ',' << Size;
+  if (ByteAlign > 1) {
+    assert(MAI.getLCOMMDirectiveType() == LCOMM::ByteAlignment &&
+           "Alignment not supported on .lcomm!");
+    OS << ',' << ByteAlign;
+  }
   EmitEOL();
 }
 

lib/MC/MCELFStreamer.cpp

@@ -220,14 +220,14 @@ void MCELFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
   SD.setSize(MCConstantExpr::Create(Size, getContext()));
 }
 
-void MCELFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
+void MCELFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                          unsigned ByteAlignment) {
   // FIXME: Should this be caught and done earlier?
   MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
   MCELF::SetBinding(SD, ELF::STB_LOCAL);
   SD.setExternal(false);
   BindingExplicitlySet.insert(Symbol);
-  // FIXME: ByteAlignment is not needed here, but is required.
+  EmitCommonSymbol(Symbol, Size, ByteAlignment);
-  EmitCommonSymbol(Symbol, Size, 1);
 }
 
 void MCELFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {

lib/MC/MCELFStreamer.h

@@ -74,7 +74,8 @@ public:
      SD.setSize(Value);
   }
 
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment);
 
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             unsigned Size = 0, unsigned ByteAlignment = 0) {

lib/MC/MCLoggingStreamer.cpp

@@ -133,9 +133,10 @@ public:
     return Child->EmitCommonSymbol(Symbol, Size, ByteAlignment);
   }
 
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment) {
     LogCall("EmitLocalCommonSymbol");
-    return Child->EmitLocalCommonSymbol(Symbol, Size);
+    return Child->EmitLocalCommonSymbol(Symbol, Size, ByteAlignment);
   }
   
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,

lib/MC/MCMachOStreamer.cpp

@@ -67,7 +67,8 @@ public:
   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
     assert(0 && "macho doesn't support this directive");
   }
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment) {
     assert(0 && "macho doesn't support this directive");
   }
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,

lib/MC/MCNullStreamer.cpp

@@ -59,8 +59,8 @@ namespace {
     virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
     virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                   unsigned ByteAlignment) {}
-    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {}
+    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
-
+                                       unsigned ByteAlignment) {}
     virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                               unsigned Size = 0, unsigned ByteAlignment = 0) {}
     virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,

lib/MC/MCPureStreamer.cpp

@@ -86,7 +86,8 @@ public:
   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
     report_fatal_error("unsupported directive in pure streamer");
   }
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment) {
     report_fatal_error("unsupported directive in pure streamer");
   }
   virtual void EmitFileDirective(StringRef Filename) {

lib/MC/WinCOFFStreamer.cpp

@@ -63,7 +63,8 @@ public:
   virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
   virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                 unsigned ByteAlignment);
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment);
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
                             unsigned Size,unsigned ByteAlignment);
   virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
@@ -304,11 +305,12 @@ void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
   AddCommonSymbol(Symbol, Size, ByteAlignment, true);
 }
 
-void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
+void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                            unsigned ByteAlignment) {
   assert((Symbol->isInSection()
          ? Symbol->getSection().getVariant() == MCSection::SV_COFF
          : true) && "Got non COFF section in the COFF backend!");
-  AddCommonSymbol(Symbol, Size, 1, false);
+  AddCommonSymbol(Symbol, Size, ByteAlignment, false);
 }
 
 void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,

lib/Target/ARM/MCTargetDesc/ARMMCAsmInfo.cpp

@@ -72,7 +72,7 @@ ARMELFMCAsmInfo::ARMELFMCAsmInfo() {
   Code32Directive = ".code\t32";
 
   WeakRefDirective = "\t.weak\t";
-  HasLCOMMDirective = true;
+  LCOMMDirectiveType = LCOMM::NoAlignment;
 
   HasLEB128 = true;
   SupportsDebugInformation = true;

lib/Target/PTX/PTXMCAsmStreamer.cpp

@@ -132,7 +132,9 @@ public:
   ///
   /// @param Symbol - The common symbol to emit.
   /// @param Size - The size of the common symbol.
-  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
+  /// @param ByteAlignment - The alignment of the common symbol in bytes.
+  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                     unsigned ByteAlignment);
 
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             unsigned Size = 0, unsigned ByteAlignment = 0);
@@ -283,7 +285,8 @@ void PTXMCAsmStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
 void PTXMCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                         unsigned ByteAlignment) {}
 
-void PTXMCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {}
+void PTXMCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                             unsigned ByteAlignment) {}
 
 void PTXMCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
                                     unsigned Size, unsigned ByteAlignment) {}

lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp

@@ -60,7 +60,7 @@ PPCLinuxMCAsmInfo::PPCLinuxMCAsmInfo(bool is64Bit) {
     
   ZeroDirective = "\t.space\t";
   Data64bitsDirective = is64Bit ? "\t.quad\t" : 0;
-  HasLCOMMDirective = true;
+  LCOMMDirectiveType = LCOMM::NoAlignment;
   AssemblerDialect = 0;           // Old-Style mnemonics.
 }
 

test/CodeGen/ARM/2010-12-15-elf-lcomm.ll

@@ -5,7 +5,7 @@
 
 
 @dummy = internal global i32 666
-@array00 = internal global [20 x i32] zeroinitializer
+@array00 = internal global [80 x i8] zeroinitializer, align 1
 @sum = internal global i32 55
 @STRIDE = internal global i32 8
 
@@ -28,8 +28,9 @@
 
 define i32 @main(i32 %argc) nounwind {
   %1 = load i32* @sum, align 4
-  %2 = getelementptr  [20 x i32]* @array00, i32 0, i32 %argc
+  %2 = getelementptr [80 x i8]* @array00, i32 0, i32 %argc
-  %3 = load i32* %2, align 4
+  %3 = load i8* %2
-  %4 = add i32 %1, %3
+  %4 = zext i8 %3 to i32
-  ret i32 %4;
+  %5 = add i32 %1, %4
+  ret i32 %5
 }

test/CodeGen/ARM/elf-lcomm-align.ll

@@ -0,0 +1,14 @@
+; RUN: llc < %s -mtriple=arm-linux-gnueabi -O0 | FileCheck %s
+; run with -O0 to avoid arm global merging.
+
+@c = internal global i8 0, align 1
+@x = internal global i32 0, align 4
+
+; CHECK: .lcomm c,1
+; .lcomm doesn't support alignment.
+; CHECK: .local x
+; CHECK-NEXT: .comm x,4,4
+
+define i32 @foo() nounwind {
+  ret i32 sub (i32 ptrtoint (i8* @c to i32), i32 ptrtoint (i32* @x to i32))
+}

tools/lto/LTOModule.cpp

@@ -581,7 +581,8 @@ namespace {
       markDefined(*Symbol);
     }
     virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
-    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {}
+    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                       unsigned ByteAlignment) {}
     virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
                                 uint64_t Size, unsigned ByteAlignment) {}
     virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}