MC, COFF: Align section contents to a four byte boundary

llvm-svn: 228879

llvm/lib/MC/WinCOFFObjectWriter.cpp

@@ -939,7 +939,8 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
     Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(&Section);
 
     if (IsPhysicalSection(Sec)) {
-      Sec->Header.PointerToRawData = offset;
+      // Align the section data to a four byte boundary.
+      Sec->Header.PointerToRawData = RoundUpToAlignment(offset, 4);
 
       offset += Sec->Header.SizeOfRawData;
     }
@@ -1009,9 +1010,15 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
         continue;
 
       if ((*i)->Header.PointerToRawData != 0) {
-        assert(OS.tell() == (*i)->Header.PointerToRawData &&
+        assert(OS.tell() <= (*i)->Header.PointerToRawData &&
                "Section::PointerToRawData is insane!");
 
+        unsigned SectionDataPadding = (*i)->Header.PointerToRawData - OS.tell();
+        assert(SectionDataPadding < 4 &&
+               "Should only need at most three bytes of padding!");
+
+        WriteZeros(SectionDataPadding);
+
         Asm.writeSectionData(j, Layout);
       }
 

llvm/test/MC/COFF/directive-section-characteristics.ll

@@ -6,8 +6,14 @@ entry:
   ret void
 }
 
+; CHECK: Section {
+; CHECK:   Name: .text
+; CHECK:   PointerToRawData: 0xB4
+; CHECK: }
+
 ; CHECK: Section {
 ; CHECK:   Name: .drectve
+; CHECK:   PointerToRawData: 0xB8
 ; CHECK:   Characteristics [
 ; CHECK:     IMAGE_SCN_ALIGN_1BYTES
 ; CHECK:     IMAGE_SCN_LNK_INFO