Implement ONLY_IF_RO/ONLY_IF_RW like bfd.

The actual logic is to keep the output section if the output section
would have been ro/rw.

This is both simpler and more practical, as the intention is linker
scripts is to always keep of of a pair of ONLY_IF_RO/ONLY_IF_RW.

llvm-svn: 282099

2 files changed, 36 insertions, 9 deletions

diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 3917c6ef1f3..a8ed92513fb 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -138,22 +138,17 @@ getComparator(SortSectionPolicy K) {
   }
 }
 
-static bool checkConstraint(uint64_t Flags, ConstraintKind Kind) {
-  bool RO = (Kind == ConstraintKind::ReadOnly);
-  bool RW = (Kind == ConstraintKind::ReadWrite);
-  bool Writable = Flags & SHF_WRITE;
-  return !(RO && Writable) && !(RW && !Writable);
-}
-
 template <class ELFT>
 static bool matchConstraints(ArrayRef<InputSectionBase<ELFT> *> Sections,
                              ConstraintKind Kind) {
   if (Kind == ConstraintKind::NoConstraint)
     return true;
-  return llvm::all_of(Sections, [=](InputSectionData *Sec2) {
+  bool IsRW = llvm::any_of(Sections, [=](InputSectionData *Sec2) {
     auto *Sec = static_cast<InputSectionBase<ELFT> *>(Sec2);
-    return checkConstraint(Sec->getSectionHdr()->sh_flags, Kind);
+    return Sec->getSectionHdr()->sh_flags & SHF_WRITE;
   });
+  return (IsRW && Kind == ConstraintKind::ReadWrite) ||
+         (!IsRW && Kind == ConstraintKind::ReadOnly);
 }
 
 static void sortSections(InputSectionData **Begin, InputSectionData **End,
diff --git a/lld/test/ELF/linkerscript/sections-constraint5.s b/lld/test/ELF/linkerscript/sections-constraint5.s
new file mode 100644
index 00000000000..ea14aad5247
--- /dev/null
+++ b/lld/test/ELF/linkerscript/sections-constraint5.s
@@ -0,0 +1,32 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "SECTIONS { \
+# RUN:         bar : ONLY_IF_RO { sym1 = .; *(foo*) } \
+# RUN:         bar : ONLY_IF_RW { sym2 = .; *(foo*) } \
+# RUN:       }" > %t.script
+
+# RUN: ld.lld -o %t -T %t.script %t.o
+# RUN: llvm-readobj -s -t %t | FileCheck %s
+
+# CHECK: Sections [
+# CHECK:      Name: bar
+# CHECK-NEXT: Type: SHT_PROGBITS
+# CHECK-NEXT: Flags [
+# CHECK-NEXT:   SHF_ALLOC
+# CHECK-NEXT:   SHF_WRITE
+# CHECK-NEXT: ]
+# CHECK-NEXT: Address:
+# CHECK-NEXT: Offset:
+# CHECK-NEXT: Size: 2
+
+# CHECK: Symbols [
+# CHECK-NOT: sym1
+# CHECK:     sym2
+# CHECK-NOT: sym1
+
+.section foo1,"a"
+.byte 0
+
+.section foo2,"aw"
+.byte 0
+