From bf83659d11cfa81de18d87288cd2c48468aa0c95 Mon Sep 17 00:00:00 2001
From: Stuart Hastings <stuart@apple.com>
Date: Wed, 23 Feb 2011 02:27:05 +0000
Subject: [PATCH] Omit private_extern declarations of extern symbols; followup
 to r124468.  Patch by Rafael Avila de Espindola!

llvm-svn: 126297
---
 llvm/include/llvm/CodeGen/AsmPrinter.h     |  3 ++-
 llvm/include/llvm/MC/MCAsmInfo.h           |  8 ++++++++
 llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp | 10 +++++++---
 llvm/lib/MC/MCAsmInfo.cpp                  |  1 +
 llvm/lib/MC/MCAsmInfoDarwin.cpp            |  1 +
 5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/AsmPrinter.h b/llvm/include/llvm/CodeGen/AsmPrinter.h
index 357b933db54c..a071febb102f 100644
--- a/llvm/include/llvm/CodeGen/AsmPrinter.h
+++ b/llvm/include/llvm/CodeGen/AsmPrinter.h
@@ -445,7 +445,8 @@ namespace llvm {
 
     /// EmitVisibility - This emits visibility information about symbol, if
     /// this is suported by the target.
-    void EmitVisibility(MCSymbol *Sym, unsigned Visibility) const;
+    void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
+                        bool IsDefinition = true) const;
 
     void EmitLinkage(unsigned Linkage, MCSymbol *GVSym) const;
 
diff --git a/llvm/include/llvm/MC/MCAsmInfo.h b/llvm/include/llvm/MC/MCAsmInfo.h
index 9cfd0048a607..0bf364a6dfcf 100644
--- a/llvm/include/llvm/MC/MCAsmInfo.h
+++ b/llvm/include/llvm/MC/MCAsmInfo.h
@@ -246,6 +246,11 @@ namespace llvm {
     /// declare a symbol as having hidden visibility.
     MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
 
+    /// HiddenDeclarationVisibilityAttr - This attribute, if not MCSA_Invalid,
+    /// is used to declare an undefined symbol as having hidden visibility.
+    MCSymbolAttr HiddenDeclarationVisibilityAttr;   // Defaults to MCSA_Hidden.
+
+
     /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
     /// to declare a symbol as having protected visibility.
     MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
@@ -425,6 +430,9 @@ namespace llvm {
     const char *getLinkOnceDirective() const { return LinkOnceDirective; }
 
     MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
+    MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
+      return HiddenDeclarationVisibilityAttr;
+    }
     MCSymbolAttr getProtectedVisibilityAttr() const {
       return ProtectedVisibilityAttr;
     }
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 43e8990a9da1..9cb882e6a1bb 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -764,7 +764,7 @@ bool AsmPrinter::doFinalization(Module &M) {
       continue;
 
     MCSymbol *Name = Mang->getSymbol(&F);
-    EmitVisibility(Name, V);
+    EmitVisibility(Name, V, false);
   }
 
   // Finalize debug and EH information.
@@ -1820,13 +1820,17 @@ void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock *MBB) const {
   }
 }
 
-void AsmPrinter::EmitVisibility(MCSymbol *Sym, unsigned Visibility) const {
+void AsmPrinter::EmitVisibility(MCSymbol *Sym, unsigned Visibility,
+                                bool IsDefinition) const {
   MCSymbolAttr Attr = MCSA_Invalid;
   
   switch (Visibility) {
   default: break;
   case GlobalValue::HiddenVisibility:
-    Attr = MAI->getHiddenVisibilityAttr();
+    if (IsDefinition)
+      Attr = MAI->getHiddenVisibilityAttr();
+    else
+      Attr = MAI->getHiddenDeclarationVisibilityAttr();
     break;
   case GlobalValue::ProtectedVisibility:
     Attr = MAI->getProtectedVisibilityAttr();
diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
index cc1afbd08926..8199fb2e158a 100644
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -65,6 +65,7 @@ MCAsmInfo::MCAsmInfo() {
   WeakDefDirective = 0;
   LinkOnceDirective = 0;
   HiddenVisibilityAttr = MCSA_Hidden;
+  HiddenDeclarationVisibilityAttr = MCSA_Hidden;
   ProtectedVisibilityAttr = MCSA_Protected;
   HasLEB128 = false;
   SupportsDebugInformation = false;
diff --git a/llvm/lib/MC/MCAsmInfoDarwin.cpp b/llvm/lib/MC/MCAsmInfoDarwin.cpp
index 13776f04437d..526ad0da42aa 100644
--- a/llvm/lib/MC/MCAsmInfoDarwin.cpp
+++ b/llvm/lib/MC/MCAsmInfoDarwin.cpp
@@ -45,6 +45,7 @@ MCAsmInfoDarwin::MCAsmInfoDarwin() {
   HasAggressiveSymbolFolding = false;
 
   HiddenVisibilityAttr = MCSA_PrivateExtern;
+  HiddenDeclarationVisibilityAttr = MCSA_Invalid;
   // Doesn't support protected visibility.
   ProtectedVisibilityAttr = MCSA_Global;