PNaCl ABI: Convert "private" linkage to "internal"

This simplifies the ABI by reducing the number of linkage types we
have to check for and represent in the wire format.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3495
TEST=*.ll tests + PNaCl toolchain trybots

Review URL: https://codereview.chromium.org/17084003

3 files changed, 30 insertions, 12 deletions

diff --git a/lib/Analysis/NaCl/PNaClABIVerifyModule.cpp b/lib/Analysis/NaCl/PNaClABIVerifyModule.cpp
index baa072f390..c0a5e4bcc2 100644
--- a/lib/Analysis/NaCl/PNaClABIVerifyModule.cpp
+++ b/lib/Analysis/NaCl/PNaClABIVerifyModule.cpp
@@ -110,7 +110,6 @@ void PNaClABIVerifyModule::checkGlobalValueCommon(const GlobalValue *GV) {
     case GlobalValue::ExternalLinkage:
     case GlobalValue::AvailableExternallyLinkage:
     case GlobalValue::InternalLinkage:
-    case GlobalValue::PrivateLinkage:
       break;
     default:
       Reporter->addError() << GVTypeName << GV->getName()
diff --git a/lib/Transforms/NaCl/StripAttributes.cpp b/lib/Transforms/NaCl/StripAttributes.cpp
index a28aee3ad1..5c2ff72daa 100644
--- a/lib/Transforms/NaCl/StripAttributes.cpp
+++ b/lib/Transforms/NaCl/StripAttributes.cpp
@@ -135,12 +135,25 @@ static void CheckAttributes(AttributeSet Attrs) {
   }
 }
 
+void stripGlobalValueAttrs(GlobalValue *GV) {
+  GV->setUnnamedAddr(false);
+
+  // Convert "private" linkage to "internal" to reduce the number of
+  // linkage types that need to be represented in PNaCl's wire format.
+  //
+  // We convert "private" to "internal" rather than vice versa because
+  // "private" symbols are omitted from the nexe's symbol table, which
+  // would get in the way of debugging when an unstripped pexe is
+  // translated offline.
+  if (GV->getLinkage() == GlobalValue::PrivateLinkage)
+    GV->setLinkage(GlobalValue::InternalLinkage);
+}
+
 void stripFunctionAttrs(Function *Func) {
   CheckAttributes(Func->getAttributes());
   Func->setAttributes(AttributeSet());
   Func->setCallingConv(CallingConv::C);
   Func->setAlignment(0);
-  Func->setUnnamedAddr(false);
 
   for (Function::iterator BB = Func->begin(), E = Func->end();
        BB != E; ++BB) {
@@ -169,12 +182,14 @@ bool StripAttributes::runOnModule(Module &M) {
     // constructor for Functions just adds them back again.  It would
     // be confusing if the attributes were sometimes present on
     // intrinsics and sometimes not.
-    if (!Func->isIntrinsic())
+    if (!Func->isIntrinsic()) {
+      stripGlobalValueAttrs(Func);
       stripFunctionAttrs(Func);
+    }
   }
   for (Module::global_iterator GV = M.global_begin(), E = M.global_end();
        GV != E; ++GV) {
-    GV->setUnnamedAddr(false);
+    stripGlobalValueAttrs(GV);
   }
   return true;
 }
diff --git a/test/NaCl/PNaClABI/linkagetypes.ll b/test/NaCl/PNaClABI/linkagetypes.ll
index f19ed48796..61a5286838 100644
--- a/test/NaCl/PNaClABI/linkagetypes.ll
+++ b/test/NaCl/PNaClABI/linkagetypes.ll
@@ -5,15 +5,16 @@ target datalayout = "e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64
 target triple = "le32-unknown-nacl"
 
 
+@gv_internal = internal global [1 x i8] c"x"
+; CHECK-NOT: disallowed
+
 @gv_private = private global [1 x i8] c"x"
+; CHECK: Variable gv_private has disallowed linkage type: private
 @gv_linker_private = linker_private global [1 x i8] c"x"
-; CHECK-NOT: disallowed
 ; CHECK: Variable gv_linker_private has disallowed linkage type: linker_private
 @gv_linker_private_weak = linker_private_weak global [1 x i8] c"x"
 ; CHECK: gv_linker_private_weak has disallowed linkage type: linker_private_weak
-@gv_internal = internal global [1 x i8] c"x"
 @gv_linkonce = linkonce global [1 x i8] c"x"
-; CHECK-NOT: disallowed
 ; CHECK: gv_linkonce has disallowed linkage type: linkonce
 @gv_linkonce_odr = linkonce_odr global [1 x i8] c"x"
 ; CHECK: gv_linkonce_odr has disallowed linkage type: linkonce_odr
@@ -35,15 +36,18 @@ target triple = "le32-unknown-nacl"
 ; CHECK: gv_extern_weak has disallowed linkage type: extern_weak
 @gv_avilable_externally = available_externally global [1 x i8] c"x"
 
-; CHECK-NOT: private_func
-define private void @private_func() {
-  ret void
-}
-; internal linkage is allowed, and should not appear in error output.
+
+; CHECK-NOT: disallowed
 ; CHECK-NOT: internal_func
+; internal linkage is allowed, and should not appear in error output.
 define internal void @internal_func() {
   ret void
 }
+
+; CHECK: Function private_func has disallowed linkage type: private
+define private void @private_func() {
+  ret void
+}
 ; CHECK: Function external_func is declared but not defined (disallowed)
 declare external void @external_func()
 ; CHECK: linkonce_func has disallowed linkage type: linkonce