Handle /align option.

[ruiu]

Summary

Previously, this option was simply ignored.

[MaskRay]

lld/test/COFF/align.s

28

Align the values?

[ruiu]

lld/test/COFF/align.s

28

This is as-is, and I guess that this is actually aligned vertically by some rule, as it looks like this line is aligned vertically with the following "CheckSum" and "Number" lines.

[rnk]

lgtm with question, no need to re-review

lld/COFF/Writer.cpp

1201

Should this be alignTo(sizeOfHeaders, config->align)? I assume sizeOfHeaders was less than 4096, so this shouldn't be a behavior change for a default alignment.

[ruiu]

lld/COFF/Writer.cpp

1201

Yeah, I think you are right. Fixed.

lld/COFF/Config.h

struct Configuration {
   llvm::StringRef thinLTOIndexOnlyArg;
 
   // Used for /thinlto-object-prefix-replace:
   std::pair<llvm::StringRef, llvm::StringRef> thinLTOPrefixReplace;
 
   // Used for /thinlto-object-suffix-replace:
   std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace;
 
+  uint64_t align = 4096;
   uint64_t imageBase = -1;
   uint64_t fileAlign = 512;
   uint64_t stackReserve = 1024 * 1024;
   uint64_t stackCommit = 4096;
   uint64_t heapReserve = 1024 * 1024;
   uint64_t heapCommit = 4096;
   uint32_t majorImageVersion = 0;
   uint32_t minorImageVersion = 0;

lld/COFF/Driver.cpp

 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/COFFModuleDefinition.h"
 #include "llvm/Object/WindowsMachineFlag.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/LEB128.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/TarWriter.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ToolDrivers/llvm-lib/LibDriver.h"
 #include <algorithm>
 #include <future>
if (config->mingw) {
     parseMerge(".dtors=.rdata");
     parseMerge(".CRT=.rdata");
   }
 
   // Handle /section
   for (auto *arg : args.filtered(OPT_section))
     parseSection(arg->getValue());
 
+  // Handle /align
+  if (auto *arg = args.getLastArg(OPT_align)) {
+    parseNumbers(arg->getValue(), &config->align);
+    if (!isPowerOf2_64(config->align))
+      error("/align: not a power of two: " + StringRef(arg->getValue()));
+  }
+
   // Handle /aligncomm
   for (auto *arg : args.filtered(OPT_aligncomm))
     parseAligncomm(arg->getValue());
 
   // Handle /manifestdependency. This enables /manifest unless /manifest:no is
   // also passed.
   if (auto *arg = args.getLastArg(OPT_manifestdependency)) {
     config->manifestDependency = arg->getValue();

lld/COFF/Writer.cpp

 // file offsets.
 void Writer::assignAddresses() {
   sizeOfHeaders = dosStubSize + sizeof(PEMagic) + sizeof(coff_file_header) +
                   sizeof(data_directory) * numberOfDataDirectory +
                   sizeof(coff_section) * outputSections.size();
   sizeOfHeaders +=
       config->is64() ? sizeof(pe32plus_header) : sizeof(pe32_header);
   sizeOfHeaders = alignTo(sizeOfHeaders, config->fileAlign);
-  uint64_t rva = pageSize; // The first page is kept unmapped.
+  uint64_t rva = config->align; // The first page is kept unmapped.
   fileSize = sizeOfHeaders;
 
   for (OutputSection *sec : outputSections) {
     if (sec == relocSec)
       addBaserels();
     uint64_t rawSize = 0, virtualSize = 0;
     sec->header.VirtualAddress = rva;
 
for (Chunk *c : sec->chunks) {
         rawSize = alignTo(virtualSize, config->fileAlign);
     }
     if (virtualSize > UINT32_MAX)
       error("section larger than 4 GiB: " + sec->name);
     sec->header.VirtualSize = virtualSize;
     sec->header.SizeOfRawData = rawSize;
     if (rawSize != 0)
       sec->header.PointerToRawData = fileSize;
-    rva += alignTo(virtualSize, pageSize);
+    rva += alignTo(virtualSize, config->align);
     fileSize += alignTo(rawSize, config->fileAlign);
   }
-  sizeOfImage = alignTo(rva, pageSize);
+  sizeOfImage = alignTo(rva, config->align);
 
   // Assign addresses to sections in MergeChunks.
   for (MergeChunk *mc : MergeChunk::instances)
     if (mc)
       mc->assignSubsectionRVAs();
 }
 
 template <typename PEHeaderTy> void Writer::writeHeader() {
template <typename PEHeaderTy> void Writer::writeHeader() {
   // reason signing the resulting PE file with Authenticode produces a
   // signature that fails to validate on Windows 7 (but is OK on 10).
   // Set it to 14.0, which is what VS2015 outputs, and which avoids
   // that problem.
   pe->MajorLinkerVersion = 14;
   pe->MinorLinkerVersion = 0;
 
   pe->ImageBase = config->imageBase;
-  pe->SectionAlignment = pageSize;
+  pe->SectionAlignment = config->align;
   pe->FileAlignment = config->fileAlign;
   pe->MajorImageVersion = config->majorImageVersion;
   pe->MinorImageVersion = config->minorImageVersion;
   pe->MajorOperatingSystemVersion = config->majorOSVersion;
   pe->MinorOperatingSystemVersion = config->minorOSVersion;
   pe->MajorSubsystemVersion = config->majorOSVersion;
   pe->MinorSubsystemVersion = config->minorOSVersion;
   pe->Subsystem = config->subsystem;

lld/test/COFF/align.s

+# RUN: yaml2obj < %s > %t.obj
+# RUN: lld-link /out:%t.exe /entry:main /align:32 %t.obj
+# RUN: llvm-readobj --file-headers %t.exe | FileCheck %s
+
+# CHECK: SectionAlignment: 32
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4096
+    SectionData:     0000000000000000
+    Relocations:
+      - VirtualAddress:  0
+        SymbolName:      __ImageBase
+        Type:            IMAGE_REL_AMD64_ADDR64
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          8
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          0
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            __ImageBase
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...