Force __pnacl_pso_root to be an external declaration.

src/IceGlobalInits.h

Index: src/IceGlobalInits.h
diff --git a/src/IceGlobalInits.h b/src/IceGlobalInits.h
index a11153648fb0d4c9a716d773e38947d15d84c9fb..ee2bc9e55a32bd3c72bdb4f05f13fefc067cefce 100644
--- a/src/IceGlobalInits.h
+++ b/src/IceGlobalInits.h
@@ -198,7 +198,7 @@ private:
 
   bool isPNaClABIExternalName() const {
     const char *Name = getName().c_str();
-    return strcmp(Name, "_start") == 0 || strcmp(Name, "__pnacl_pso_root") == 0;
+    return strcmp(Name, "_start") == 0;
   }
 
   bool isIntrinsicName(const GlobalContext *Ctx) const {
@@ -416,9 +416,22 @@ public:
 
   /// Returns true if linkage is correct for the variable declaration.
   bool verifyLinkageCorrect(const GlobalContext *Ctx) const {
+    if (isPNaClABIExternalName()) {
+      return Linkage == llvm::GlobalValue::ExternalLinkage;
+    }
     return verifyLinkageDefault(Ctx);
   }
 
+  /// Returns true if the linkage was updated.
+  bool forcePNaClABILinkage() {
+    if (isPNaClABIExternalName()) {
+      /// Force Linkage to be External for PNaCl ABI.

[Mark Seaborn, 2016/02/26 01:56:56]

Nit: Just "//"

Also you probably don't want to capitalise "linkage" and "external".

[Sean Klein, 2016/02/26 02:28:06]

Updated. Re: "//", I was just trying to match the style of the rest of the file.

+      setLinkage(llvm::GlobalValue::ExternalLinkage);

[Mark Seaborn, 2016/02/26 01:56:57]

A comment about why this is necessary would be good.  i.e. PNaCl bitcode has a
linkage field for Functions but not for GlobalVariables (because we didn't need
the latter for pexes and so we took it out).

Also, ideally we want to check that exactly one of _start and __pnacl_pso_root
is present...

[Sean Klein, 2016/02/26 02:28:06]

Comment added. Where would you recommend doing that check? There doesn't seem to
be an obvious spot that doesn't re-iterate over all the declarations/functions.

+      return true;
+    }
+    return false;
+  }
+
   static bool classof(const GlobalDeclaration *Addr) {
     return Addr->getKind() == VariableDeclarationKind;
   }
@@ -434,6 +447,11 @@ public:
   void discardInitializers() { Initializers = nullptr; }
 
 private:
+  bool isPNaClABIExternalName() const {
+    const char *Name = getName().c_str();
+    return strcmp(Name, "__pnacl_pso_root") == 0;
+  }
+
   /// List of initializers for the declared variable.
   std::unique_ptr<InitializerListType> Initializers;
   bool HasInitializer;