COFF: Preserve section type when processing /section flag.

[pcc]

Summary

It turns out that we were dropping this before.

Depends on D45801

[ruiu]

LGTM

lld/COFF/Chunks.h

45 ↗

(On Diff #143046)

Thank you for correcting the bit masks (from 0xF to 0xE).

COFF/Chunks.h

 class Baserel;
 class Defined;
 class DefinedImportData;
 class DefinedRegular;
 class ObjFile;
 class OutputSection;
 class Symbol;
 
-// Mask for section types (code, data, bss, disacardable, etc.)
-// and permissions (writable, readable or executable).
-const uint32_t PermMask = 0xFF0000F0;
+// Mask for permissions (discardable, writable, readable, executable, etc).
+const uint32_t PermMask = 0xFE000000;
+
+// Mask for section types (code, data, bss).
+const uint32_t TypeMask = 0x000000E0;
 
 // A Chunk represents a chunk of data that will occupy space in the
 // output (if the resolver chose that). It may or may not be backed by
 // a section of an input file. It could be linker-created data, or
 // doesn't even have actual data (if common or bss).
 class Chunk {
 public:
   enum Kind { SectionKind, OtherKind };

COFF/Chunks.cpp

void SectionChunk::getBaserels(std::vector<Baserel> *Res) {
   }
 }
 
 bool SectionChunk::hasData() const {
   return !(Header->Characteristics & IMAGE_SCN_CNT_UNINITIALIZED_DATA);
 }
 
 uint32_t SectionChunk::getOutputCharacteristics() const {
-  return Header->Characteristics & PermMask;
+  return Header->Characteristics & (PermMask | TypeMask);
 }
 
 bool SectionChunk::isCOMDAT() const {
   return Header->Characteristics & IMAGE_SCN_LNK_COMDAT;
 }
 
 void SectionChunk::printDiscardedMessage() const {
   // Removed by dead-stripping. If it's removed by ICF, ICF already

COFF/Writer.cpp

 void writeResult() { Writer().run(); }
 
 void OutputSection::addChunk(Chunk *C) {
   Chunks.push_back(C);
   C->setOutputSection(this);
 }
 
 void OutputSection::setPermissions(uint32_t C) {
-  Header.Characteristics = C & PermMask;
+  Header.Characteristics &= ~PermMask;
+  Header.Characteristics |= C;
 }
 
 void OutputSection::merge(OutputSection *Other) {
   for (Chunk *C : Other->Chunks)
     C->setOutputSection(this);
   Chunks.insert(Chunks.end(), Other->Chunks.begin(), Other->Chunks.end());
   Other->Chunks.clear();
 }

test/COFF/output-chars.test

 # CHECK: Characteristics [
 # CHECK-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
 # CHECK-NEXT: IMAGE_SCN_MEM_READ
 # CHECK-NEXT: IMAGE_SCN_MEM_WRITE
 # CHECK-NEXT: ]
 
 # SECTION: Name: .foo
 # SECTION: Characteristics [
+# SECTION-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
 # SECTION-NEXT: IMAGE_SCN_MEM_EXECUTE
 # SECTION-NEXT: IMAGE_SCN_MEM_READ
 # SECTION-NEXT: IMAGE_SCN_MEM_WRITE
 # SECTION-NEXT: ]
 
 # SECTION: Name: .foo
 # SECTION: Characteristics [
+# SECTION-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
 # SECTION-NEXT: IMAGE_SCN_MEM_EXECUTE
 # SECTION-NEXT: IMAGE_SCN_MEM_READ
 # SECTION-NEXT: IMAGE_SCN_MEM_WRITE
 # SECTION-NEXT: ]
 
 # MERGE: Name: .bar
 # MERGE: Characteristics [
 # MERGE-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA

 # MERGE-SECTION: Characteristics [
 # MERGE-SECTION-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
 # MERGE-SECTION-NEXT: IMAGE_SCN_MEM_READ
 # MERGE-SECTION-NEXT: IMAGE_SCN_MEM_WRITE
 # MERGE-SECTION-NEXT: ]
 
 # MERGE-SECTION: Name: .foo
 # MERGE-SECTION: Characteristics [
+# MERGE-SECTION-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
 # MERGE-SECTION-NEXT: IMAGE_SCN_MEM_EXECUTE
 # MERGE-SECTION-NEXT: IMAGE_SCN_MEM_READ
 # MERGE-SECTION-NEXT: IMAGE_SCN_MEM_WRITE
 # MERGE-SECTION-NEXT: ]
 
 --- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64

test/COFF/section.test

 # RUN:   /section:.foo,e %t.obj
 # RUN: llvm-readobj -sections %t.exe | FileCheck -check-prefix=E %s
 
 # RUN: lld-link /out:%t.exe /entry:main /subsystem:console /force \
 # RUN:   /section:.foo,s %t.obj
 # RUN: llvm-readobj -sections %t.exe | FileCheck -check-prefix=S %s
 
 # R:      Characteristics [
+# R-NEXT:   IMAGE_SCN_CNT_INITIALIZED_DATA
 # R-NEXT:   IMAGE_SCN_MEM_READ
 # R-NEXT: ]
 
 # W:      Characteristics [
+# W-NEXT:   IMAGE_SCN_CNT_INITIALIZED_DATA
 # W-NEXT:   IMAGE_SCN_MEM_WRITE
 # W-NEXT: ]
 
 # E:      Characteristics [
+# E-NEXT:   IMAGE_SCN_CNT_INITIALIZED_DATA
 # E-NEXT:   IMAGE_SCN_MEM_EXECUTE
 # E-NEXT: ]
 
 # S:      Characteristics [
+# S-NEXT:   IMAGE_SCN_CNT_INITIALIZED_DATA
 # S-NEXT:   IMAGE_SCN_MEM_SHARED
 # S-NEXT: ]
 
 --- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: []
 sections: