Revert "[LLD] Set alignment as part of Characteristics in TLS table."

Revert individual wip commits and will instead follow up with a
single commit with all the changes. Makes cherry-picking easier
and will contain all the right tags.

This reverts commit 32a4ad3.
This reverts commit 7fe13af.
This reverts commit 51fbc1b.
This reverts commit f80950a.
This reverts commit 0778cad.
This reverts commit 8b70d52.

Author: luqmana

lld/COFF/Writer.cpp

@@ -241,7 +241,6 @@ class Writer {
   void addSyntheticIdata();
   void fixPartialSectionChars(StringRef name, uint32_t chars);
   bool fixGnuImportChunks();
-  void fixTlsAlignment();
   PartialSection *createPartialSection(StringRef name, uint32_t outChars);
   PartialSection *findPartialSection(StringRef name, uint32_t outChars);
 
@@ -268,7 +267,6 @@ class Writer {
   DelayLoadContents delayIdata;
   EdataContents edata;
   bool setNoSEHCharacteristic = false;
-  uint32_t tlsAlignment = 0;
 
   DebugDirectoryChunk *debugDirectory = nullptr;
   std::vector<std::pair<COFF::DebugType, Chunk *>> debugRecords;
@@ -635,11 +633,6 @@ void Writer::run() {
   writeSections();
   sortExceptionTable();
 
-  // Fix up the alignment in the TLS Directory's characteristic field,
-  // if a specific alignment value is needed
-  if (tlsAlignment)
-    fixTlsAlignment();
-
   t1.stop();
 
   if (!config->pdbPath.empty() && config->debug) {
@@ -873,10 +866,6 @@ void Writer::createSections() {
     StringRef name = c->getSectionName();
     if (shouldStripSectionSuffix(sc, name))
       name = name.split('$').first;
-
-    if (name.startswith(".tls"))
-      tlsAlignment = std::max(tlsAlignment, c->getAlignment());
-
     PartialSection *pSec = createPartialSection(name,
                                                 c->getOutputCharacteristics());
     pSec->chunks.push_back(c);
@@ -2049,33 +2038,3 @@ PartialSection *Writer::findPartialSection(StringRef name, uint32_t outChars) {
     return it->second;
   return nullptr;
 }
-
-void Writer::fixTlsAlignment() {
-  Defined *tlsSym =
-      dyn_cast_or_null<Defined>(symtab->findUnderscore("_tls_used"));
-  if (!tlsSym)
-    return;
-
-  OutputSection *sec = tlsSym->getChunk()->getOutputSection();
-  assert(sec && tlsSym->getRVA() >= sec->getRVA() &&
-         "no output section for _tls_used");
-
-  uint8_t *secBuf = buffer->getBufferStart() + sec->getFileOff();
-  uint64_t tlsOffset = tlsSym->getRVA() - sec->getRVA();
-  uint64_t directorySize = config->is64()
-                               ? sizeof(object::coff_tls_directory64)
-                               : sizeof(object::coff_tls_directory32);
-
-  if (tlsOffset + directorySize > sec->getRawSize())
-    fatal("_tls_used sym is malformed");
-
-  if (config->is64()) {
-    object::coff_tls_directory64 *tlsDir =
-        reinterpret_cast<object::coff_tls_directory64 *>(&secBuf[tlsOffset]);
-    tlsDir->setAlignment(tlsAlignment);
-  } else {
-    object::coff_tls_directory32 *tlsDir =
-        reinterpret_cast<object::coff_tls_directory32 *>(&secBuf[tlsOffset]);
-    tlsDir->setAlignment(tlsAlignment);
-  }
-}

lld/test/COFF/tls-alignment-32.ll

@@ -13,8 +13,7 @@
 ; RUN: llvm-readobj --coff-tls-directory %t.exe | FileCheck %s
 
 ; CHECK: TLSDirectory {
-; CHECK: Characteristics [ (0x600000)
-; CHECK-NEXT: IMAGE_SCN_ALIGN_32BYTES (0x600000)
+; CHECK: Characteristics [ (0x0)
 
 target triple = "i686-pc-windows-msvc"
 

lld/test/COFF/tls-alignment-64.ll

@@ -13,8 +13,7 @@
 ; RUN: llvm-readobj --coff-tls-directory %t.exe | FileCheck %s
 
 ; CHECK: TLSDirectory {
-; CHECK: Characteristics [ (0x700000)
-; CHECK-NEXT: IMAGE_SCN_ALIGN_64BYTES (0x700000)
+; CHECK: Characteristics [ (0x0)
 
 target triple = "x86_64-pc-windows-msvc"
 

llvm/include/llvm/Object/COFF.h

@@ -576,22 +576,11 @@ struct coff_tls_directory {
 
   uint32_t getAlignment() const {
     // Bit [20:24] contains section alignment.
-    uint32_t Shift = (Characteristics & COFF::IMAGE_SCN_ALIGN_MASK) >> 20;
+    uint32_t Shift = (Characteristics & 0x00F00000) >> 20;
     if (Shift > 0)
       return 1U << (Shift - 1);
     return 0;
   }
-
-  void setAlignment(uint32_t Align) {
-    uint32_t AlignBits = 0;
-    if (Align) {
-      assert(llvm::isPowerOf2_32(Align) && "alignment is not a power of 2");
-      assert(llvm::Log2_32(Align) <= 13 && "alignment requested is too large");
-      AlignBits = (llvm::Log2_32(Align) + 1) << 20;
-    }
-    Characteristics =
-        (Characteristics & ~COFF::IMAGE_SCN_ALIGN_MASK) | AlignBits;
-  }
 };
 
 using coff_tls_directory32 = coff_tls_directory<support::little32_t>;