From c68dda815e64fb2fb463318d1eaa304e22199d50 Mon Sep 17 00:00:00 2001
From: Preston Gurd <preston.gurd@intel.com>
Date: Thu, 12 Apr 2012 20:13:57 +0000
Subject: This patch improves the MCJIT runtime dynamic loader by adding new
 handling of zero-initialized sections, virtual sections and common symbols
 and preventing the loading of sections which are not required for execution
 such as debug information.

Patch by Andy Kaylor!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154610 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Object/MachOObjectFile.cpp | 55 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 51 insertions(+), 4 deletions(-)

(limited to 'lib/Object/MachOObjectFile.cpp')

diff --git a/lib/Object/MachOObjectFile.cpp b/lib/Object/MachOObjectFile.cpp
index ac90d5ccb4..1078faa481 100644
--- a/lib/Object/MachOObjectFile.cpp
+++ b/lib/Object/MachOObjectFile.cpp
@@ -175,7 +175,12 @@ error_code MachOObjectFile::getSymbolSize(DataRefImpl DRI,
     BeginOffset = Entry->Value;
     SectionIndex = Entry->SectionIndex;
     if (!SectionIndex) {
-      Result = UnknownAddressOrSize;
+      uint32_t flags = SymbolRef::SF_None;
+      getSymbolFlags(DRI, flags);
+      if (flags & SymbolRef::SF_Common)
+        Result = Entry->Value;
+      else
+        Result = UnknownAddressOrSize;
       return object_error::success;
     }
     // Unfortunately symbols are unsorted so we need to touch all
@@ -198,7 +203,12 @@ error_code MachOObjectFile::getSymbolSize(DataRefImpl DRI,
     BeginOffset = Entry->Value;
     SectionIndex = Entry->SectionIndex;
     if (!SectionIndex) {
-      Result = UnknownAddressOrSize;
+      uint32_t flags = SymbolRef::SF_None;
+      getSymbolFlags(DRI, flags);
+      if (flags & SymbolRef::SF_Common)
+        Result = Entry->Value;
+      else
+        Result = UnknownAddressOrSize;
       return object_error::success;
     }
     // Unfortunately symbols are unsorted so we need to touch all
@@ -265,19 +275,22 @@ error_code MachOObjectFile::getSymbolFlags(DataRefImpl DRI,
                                            uint32_t &Result) const {
   uint16_t MachOFlags;
   uint8_t MachOType;
+  uint8_t MachOSectionIndex;
   if (MachOObj->is64Bit()) {
     InMemoryStruct<macho::Symbol64TableEntry> Entry;
     getSymbol64TableEntry(DRI, Entry);
     MachOFlags = Entry->Flags;
     MachOType = Entry->Type;
+    MachOSectionIndex = Entry->SectionIndex;
   } else {
     InMemoryStruct<macho::SymbolTableEntry> Entry;
     getSymbolTableEntry(DRI, Entry);
     MachOFlags = Entry->Flags;
     MachOType = Entry->Type;
+    MachOSectionIndex = Entry->SectionIndex;
   }
 
-  // TODO: Correctly set SF_ThreadLocal and SF_Common.
+  // TODO: Correctly set SF_ThreadLocal
   Result = SymbolRef::SF_None;
 
   if ((MachOType & MachO::NlistMaskType) == MachO::NListTypeUndefined)
@@ -286,8 +299,11 @@ error_code MachOObjectFile::getSymbolFlags(DataRefImpl DRI,
   if (MachOFlags & macho::STF_StabsEntryMask)
     Result |= SymbolRef::SF_FormatSpecific;
 
-  if (MachOType & MachO::NlistMaskExternal)
+  if (MachOType & MachO::NlistMaskExternal) {
     Result |= SymbolRef::SF_Global;
+    if ((MachOType & MachO::NlistMaskType) == MachO::NListTypeUndefined)
+      Result |= SymbolRef::SF_Common;
+  }
 
   if (MachOFlags & (MachO::NListDescWeakRef | MachO::NListDescWeakDef))
     Result |= SymbolRef::SF_Weak;
@@ -566,6 +582,37 @@ error_code MachOObjectFile::isSectionBSS(DataRefImpl DRI,
   return object_error::success;
 }
 
+error_code MachOObjectFile::isSectionRequiredForExecution(DataRefImpl Sec,
+                                                          bool &Result) const {
+  // FIXME: Unimplemented
+  Result = true;
+  return object_error::success;
+}
+
+error_code MachOObjectFile::isSectionVirtual(DataRefImpl Sec,
+                                            bool &Result) const {
+  // FIXME: Unimplemented
+  Result = false;
+  return object_error::success;
+}
+
+error_code MachOObjectFile::isSectionZeroInit(DataRefImpl DRI,
+                                              bool &Result) const {
+  if (MachOObj->is64Bit()) {
+    InMemoryStruct<macho::Section64> Sect;
+    getSection64(DRI, Sect);
+    Result = (Sect->Flags & MachO::SectionTypeZeroFill ||
+              Sect->Flags & MachO::SectionTypeZeroFillLarge);
+  } else {
+    InMemoryStruct<macho::Section> Sect;
+    getSection(DRI, Sect);
+    Result = (Sect->Flags & MachO::SectionTypeZeroFill ||
+              Sect->Flags & MachO::SectionTypeZeroFillLarge);
+  }
+
+  return object_error::success;
+}
+
 error_code MachOObjectFile::sectionContainsSymbol(DataRefImpl Sec,
                                                   DataRefImpl Symb,
                                                   bool &Result) const {
-- 
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