[Clang] -fseparate-named-sections option (#91028)

When set, the compiler will use separate unique sections for global
symbols in named special sections (e.g. symbols that are annotated with
__attribute__((section(...)))). Doing so enables linker GC to collect
unused symbols without having to use a different section per-symbol.

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CommandFlags.cpp b/llvm/lib/CodeGen/CommandFlags.cpp
index 14ac4b21..677460a 100644
--- a/llvm/lib/CodeGen/CommandFlags.cpp
+++ b/llvm/lib/CodeGen/CommandFlags.cpp
@@ -96,6 +96,7 @@ CGOPT_EXP(bool, EmulatedTLS)
 CGOPT_EXP(bool, EnableTLSDESC)
 CGOPT(bool, UniqueSectionNames)
 CGOPT(bool, UniqueBasicBlockSectionNames)
+CGOPT(bool, SeparateNamedSections)
 CGOPT(EABI, EABIVersion)
 CGOPT(DebuggerKind, DebuggerTuningOpt)
 CGOPT(bool, EnableStackSizeSection)
@@ -419,6 +420,12 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
       cl::init(false));
   CGBINDOPT(UniqueBasicBlockSectionNames);
 
+  static cl::opt<bool> SeparateNamedSections(
+      "separate-named-sections",
+      cl::desc("Use separate unique sections for named sections"),
+      cl::init(false));
+  CGBINDOPT(SeparateNamedSections);
+
   static cl::opt<EABI> EABIVersion(
       "meabi", cl::desc("Set EABI type (default depends on triple):"),
       cl::init(EABI::Default),
@@ -569,6 +576,7 @@ codegen::InitTargetOptionsFromCodeGenFlags(const Triple &TheTriple) {
   Options.BBSections = getBBSectionsMode(Options);
   Options.UniqueSectionNames = getUniqueSectionNames();
   Options.UniqueBasicBlockSectionNames = getUniqueBasicBlockSectionNames();
+  Options.SeparateNamedSections = getSeparateNamedSections();
   Options.TLSSize = getTLSSize();
   Options.EmulatedTLS =
       getExplicitEmulatedTLS().value_or(TheTriple.hasDefaultEmulatedTLS());