[mach-o] remove __compact_unwind atoms once __unwind_info has been generated

The job of the CompactUnwind pass is to turn __compact_unwind data (and
__eh_frame) into the compressed final form in __unwind_info. After it's done,
the original atoms are no longer relevant and should be deleted (they cause
problems during actual execution, quite apart from the fact that they're not
needed).

llvm-svn: 221301

8 files changed, 28 insertions, 16 deletions

diff --git a/lld/include/lld/Core/File.h b/lld/include/lld/Core/File.h
index 2e9dbaaddf4..8ab44528c6a 100644
--- a/lld/include/lld/Core/File.h
+++ b/lld/include/lld/Core/File.h
@@ -17,6 +17,7 @@
 #include "lld/Core/UndefinedAtom.h"
 #include "lld/Core/range.h"
 #include "llvm/Support/ErrorHandling.h"
+#include <functional>
 #include <vector>
 
 namespace lld {
@@ -222,6 +223,9 @@ public:
   typedef range<std::vector<const DefinedAtom *>::iterator> DefinedAtomRange;
   virtual DefinedAtomRange definedAtoms() = 0;
 
+  virtual void
+  removeDefinedAtomsIf(std::function<bool(const DefinedAtom *)> pred) = 0;
+
 protected:
   /// \brief only subclasses of MutableFile can be instantiated
   MutableFile(StringRef p) : File(p, kindObject) {}
diff --git a/lld/include/lld/Core/Resolver.h b/lld/include/lld/Core/Resolver.h
index 64f962e8234..e001b499a15 100644
--- a/lld/include/lld/Core/Resolver.h
+++ b/lld/include/lld/Core/Resolver.h
@@ -89,8 +89,12 @@ private:
     void addAtoms(std::vector<const Atom*>& atoms);
 
     void addAtom(const Atom& atom) override;
+
     DefinedAtomRange definedAtoms() override;
 
+    void removeDefinedAtomsIf(
+        std::function<bool(const DefinedAtom *)> pred) override;
+
   private:
     atom_collection_vector<DefinedAtom>         _definedAtoms;
     atom_collection_vector<UndefinedAtom>       _undefinedAtoms;
diff --git a/lld/include/lld/Core/Simple.h b/lld/include/lld/Core/Simple.h
index ee29f5b214b..a8282d11fee 100644
--- a/lld/include/lld/Core/Simple.h
+++ b/lld/include/lld/Core/Simple.h
@@ -40,6 +40,12 @@ public:
     }
   }
 
+  void removeDefinedAtomsIf(std::function<bool(const DefinedAtom *)> pred) {
+    auto &atoms = _definedAtoms._atoms;
+    auto newEnd = std::remove_if(atoms.begin(), atoms.end(), pred);
+    atoms.erase(newEnd, atoms.end());
+  }
+
   const atom_collection<DefinedAtom> &defined() const override {
     return _definedAtoms;
   }
diff --git a/lld/lib/Core/Resolver.cpp b/lld/lib/Core/Resolver.cpp
index 16578661602..e4a1b53cc33 100644
--- a/lld/lib/Core/Resolver.cpp
+++ b/lld/lib/Core/Resolver.cpp
@@ -445,6 +445,13 @@ MutableFile::DefinedAtomRange Resolver::MergedFile::definedAtoms() {
       _definedAtoms._atoms.begin(), _definedAtoms._atoms.end());
 }
 
+void Resolver::MergedFile::removeDefinedAtomsIf(
+    std::function<bool(const DefinedAtom *)> pred) {
+  auto &atoms = _definedAtoms._atoms;
+  auto newEnd = std::remove_if(atoms.begin(), atoms.end(), pred);
+  atoms.erase(newEnd, atoms.end());
+}
+
 void Resolver::MergedFile::addAtoms(std::vector<const Atom *> &all) {
   ScopedTask task(getDefaultDomain(), "addAtoms");
   DEBUG_WITH_TYPE("resolver", llvm::dbgs() << "Resolver final atom list:\n");
diff --git a/lld/lib/ReaderWriter/MachO/CompactUnwindPass.cpp b/lld/lib/ReaderWriter/MachO/CompactUnwindPass.cpp
index f440cede201..9280ec43320 100644
--- a/lld/lib/ReaderWriter/MachO/CompactUnwindPass.cpp
+++ b/lld/lib/ReaderWriter/MachO/CompactUnwindPass.cpp
@@ -337,11 +337,15 @@ private:
             << " has " << entriesInPage << " entries\n");
     } while (pageStart < unwindInfos.size());
 
-    // FIXME: we should also erase all compact-unwind atoms; their job is done.
     UnwindInfoAtom *unwind = new (_file.allocator())
         UnwindInfoAtom(_archHandler, _file, _isBig, std::vector<uint32_t>(),
                        personalities, pages, numLSDAs);
     mergedFile->addAtom(*unwind);
+
+    // Finally, remove all __compact_unwind atoms now that we've processed them.
+    mergedFile->removeDefinedAtomsIf([](const DefinedAtom *atom) {
+      return atom->contentType() == DefinedAtom::typeCompactUnwindInfo;
+    });
   }
 
   void collectCompactUnwindEntries(
diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
index 4a4ba792028..dc015c5f296 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
@@ -231,12 +231,6 @@ const MachOFinalSectionFromAtomType sectsToAtomType[] = {
   ENTRY("__DATA", "___got",           S_NON_LAZY_SYMBOL_POINTERS,
                                                           typeGOT),
   ENTRY("__DATA", "___bss",           S_ZEROFILL,         typeZeroFill),
-
-  // FIXME: __compact_unwind actually needs to be processed by a pass and put
-  // into __TEXT,__unwind_info. For now, forwarding it back to
-  // __LD,__compact_unwind is harmless (it's ignored by the unwinder, which then
-  // proceeds to process __TEXT,__eh_frame for its instructions).
-  ENTRY("__LD",   "__compact_unwind", S_REGULAR,         typeCompactUnwindInfo),
 };
 #undef ENTRY
 
diff --git a/lld/test/mach-o/unwind-info-simple-x86_64.yaml b/lld/test/mach-o/unwind-info-simple-x86_64.yaml
index 2c42ada405e..8886e527166 100644
--- a/lld/test/mach-o/unwind-info-simple-x86_64.yaml
+++ b/lld/test/mach-o/unwind-info-simple-x86_64.yaml
@@ -24,6 +24,7 @@
 # CHECK:       [2]: function offset=0x00000efd, encoding=0x04000018
 # CHECK:       [3]: function offset=0x00000efe, encoding=0x04000040
 # CHECK:       [4]: function offset=0x00000eff, encoding=0x00000000
+# CHECK-NOT: Contents of __compact_unwind section
 
 --- !native
 path:            '<linker-internal>'
diff --git a/lld/test/mach-o/write-final-sections.yaml b/lld/test/mach-o/write-final-sections.yaml
index 8701f405bea..b8b8cc67d91 100644
--- a/lld/test/mach-o/write-final-sections.yaml
+++ b/lld/test/mach-o/write-final-sections.yaml
@@ -140,17 +140,9 @@ defined-atoms:
 # CHECK-NEXT: 0000: 0D000000 00000000
 # CHECK-NEXT: )
 
-# FIXME: this should really end up in __TEXT,__unwind_info after being
-# processed. Most important fact here is that its presence doesn't trigger an
-# assert, but __LD,__compact_unwind is a harmless enough place to stash it.
-
   - type:            compact-unwind
     content:         [ 0E, 00, 00, 00, 00, 00, 00, 00 ]
-# CHECK: Name: __compact_unwind
-# CHECK: Segment: __LD
-# CHECK: SectionData (
-# CHECK-NEXT: 0000: 0E000000 00000000
-# CHECK-NEXT: )
+# CHECK-NOT: Name: __compact_unwind
 
 
 --- !mach-o