[obj2yaml] [COFF] Write RVA instead of VA for sections, fix roundtripping executables

[mstorsjo]

Summary

This is an alternative to D54946, both fixing roundtripping executables. This patch changes the serialization format to be RVA, matching what's stored in files.

[zturner]

Ahh yes, this is the other patch you were referring to. I like this one too.

[majnemer]

LGTM

test/tools/yaml2obj/coff-arm64.yaml

 # RUN: yaml2obj %s -o %t
 # RUN: llvm-readobj -file-headers %t | FileCheck %s
+# RUN: obj2yaml %t | FileCheck %s --check-prefix=ROUNDTRIP
 
 # CHECK: OptionalHeaderSize: 240
 
+# ROUNDTRIP: VirtualAddress:  4096
+# ROUNDTRIP: VirtualAddress:  8192
+# ROUNDTRIP: VirtualAddress:  12288
+
 --- !COFF
 OptionalHeader:  
   AddressOfEntryPoint: 4096
   ImageBase:       1073741824
   SectionAlignment: 4096
   FileAlignment:   512
   MajorOperatingSystemVersion: 6
   MinorOperatingSystemVersion: 0
ClrRuntimeHeader:
     RelativeVirtualAddress: 0
     Size:            0
 header:          
   Machine:         IMAGE_FILE_MACHINE_ARM64
   Characteristics: [ IMAGE_FILE_EXECUTABLE_IMAGE, IMAGE_FILE_LARGE_ADDRESS_AWARE ]
 sections:        
   - Name:            .text
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
-    VirtualAddress:  1073745920
+    VirtualAddress:  4096
     VirtualSize:     4
     SectionData:     C0035FD6
   - Name:            .rdata
     Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
-    VirtualAddress:  1073750016
+    VirtualAddress:  8192
     VirtualSize:     12
     SectionData:     0100400800000000E4E3E3E3
   - Name:            .pdata
     Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
-    VirtualAddress:  1073754112
+    VirtualAddress:  12288
     VirtualSize:     8
     SectionData:     '0010000000200000'
 symbols:         []
 ...

tools/obj2yaml/coff2yaml.cpp

void COFFDumper::dumpSections(unsigned NumSections) {
   codeview::StringsAndChecksumsRef SC;
   initializeFileAndStringTable(Obj, SC);
 
   for (const auto &ObjSection : Obj.sections()) {
     const object::coff_section *COFFSection = Obj.getCOFFSection(ObjSection);
     COFFYAML::Section NewYAMLSection;
     ObjSection.getName(NewYAMLSection.Name);
     NewYAMLSection.Header.Characteristics = COFFSection->Characteristics;
-    NewYAMLSection.Header.VirtualAddress = ObjSection.getAddress();
+    NewYAMLSection.Header.VirtualAddress = COFFSection->VirtualAddress;
     NewYAMLSection.Header.VirtualSize = COFFSection->VirtualSize;
     NewYAMLSection.Header.NumberOfLineNumbers =
         COFFSection->NumberOfLinenumbers;
     NewYAMLSection.Header.NumberOfRelocations =
         COFFSection->NumberOfRelocations;
     NewYAMLSection.Header.PointerToLineNumbers =
         COFFSection->PointerToLinenumbers;
     NewYAMLSection.Header.PointerToRawData = COFFSection->PointerToRawData;