Move the uglier parts of deciding not to emit a

UsedDirective for some symbols in llvm.used into
Darwin-specific code.  I've decided LessPrivateGlobal
is potentially a useful abstraction and left it in
the target-independent area, with improved comment.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56024 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 14 insertions, 3 deletions

diff --git a/include/llvm/Target/DarwinTargetAsmInfo.h b/include/llvm/Target/DarwinTargetAsmInfo.h
index 0ed9b38703..4abf4b7cfd 100644
--- a/include/llvm/Target/DarwinTargetAsmInfo.h
+++ b/include/llvm/Target/DarwinTargetAsmInfo.h
@@ -22,6 +22,7 @@ namespace llvm {
   class GlobalValue;
   class GlobalVariable;
   class Type;
+  class Mangler;
 
   struct DarwinTargetAsmInfo: public virtual TargetAsmInfo {
     const Section* TextCoalSection;
@@ -33,6 +34,8 @@ namespace llvm {
     virtual const Section* SelectSectionForGlobal(const GlobalValue *GV) const;
     virtual std::string UniqueSectionForGlobal(const GlobalValue* GV,
                                                SectionKind::Kind kind) const;
+    virtual bool emitUsedDirectiveFor(const GlobalValue *GV,
+                                      Mangler *Mang) const;
     const Section* MergeableConstSection(const GlobalVariable *GV) const;
     const Section* MergeableConstSection(const Type *Ty) const;
     const Section* MergeableStringSection(const GlobalVariable *GV) const;
diff --git a/include/llvm/Target/TargetAsmInfo.h b/include/llvm/Target/TargetAsmInfo.h
index bbb58527eb..589c9a6efc 100644
--- a/include/llvm/Target/TargetAsmInfo.h
+++ b/include/llvm/Target/TargetAsmInfo.h
@@ -100,6 +100,7 @@ namespace llvm {
   class CallInst;
   class GlobalValue;
   class Type;
+  class Mangler;
 
   class Section {
     friend class TargetAsmInfo;
@@ -220,9 +221,9 @@ namespace llvm {
     /// have names in the .o file.  This is often "." or "L".
     const char *PrivateGlobalPrefix;      // Defaults to "."
     
-    /// LessPrivateGlobalPrefix - This prefix is used for some Objective C
-    /// metadata symbols that should be passed through the assembler but be
-    /// removed by the linker.  This is "l" on Darwin.
+    /// LessPrivateGlobalPrefix - This prefix is used for symbols that should
+    /// be passed through the assembler but be removed by the linker.  This
+    /// is "l" on Darwin, currently used for some ObjC metadata.
     const char *LessPrivateGlobalPrefix;      // Defaults to ""
     
     /// JumpTableSpecialLabelPrefix - If not null, a extra (dead) label is
@@ -543,6 +544,13 @@ namespace llvm {
       return false;
     }
 
+    /// emitUsedDirectiveFor - This hook allows targets to selectively decide
+    /// not to emit the UsedDirective for some symbols in llvm.used.
+    virtual bool emitUsedDirectiveFor(const GlobalValue *GV,
+                                      Mangler *Mang) const {
+      return (GV!=0);
+    }
+
     /// PreferredEHDataFormat - This hook allows the target to select data
     /// format used for encoding pointers in exception handling data. Reason is
     /// 0 for data, 1 for code labels, 2 for function pointers. Global is true