Allow dso_local on ifunc.

It was never fully disallowed. We were rejecting it in the asm parser,
but not in the verifier.

Currently TargetMachine::shouldAssumeDSOLocal returns true for hidden
ifuncs. I considered changing it and moving the check from the asm
parser to the verifier.

The reason for deciding to allow it instead is that all linkers handle
a direct reference just fine. They use the plt address as the address
of the function. In fact doing that means that clang doesn't have the
same bug as gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83782.

This patch then removes the check from the asm parser and updates the
bitcode reader and writer.

llvm-svn: 322378

2 files changed, 13 insertions, 9 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 95291a1caf9..1b029bf8885 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -3054,14 +3054,17 @@ Error BitcodeReader::parseGlobalIndirectSymbolRecord(
       // FIXME: Change to an error if non-default in 4.0.
       NewGA->setVisibility(getDecodedVisibility(Record[VisInd]));
   }
-  if (OpNum != Record.size())
-    NewGA->setDLLStorageClass(getDecodedDLLStorageClass(Record[OpNum++]));
-  else
-    upgradeDLLImportExportLinkage(NewGA, Linkage);
-  if (OpNum != Record.size())
-    NewGA->setThreadLocalMode(getDecodedThreadLocalMode(Record[OpNum++]));
-  if (OpNum != Record.size())
-    NewGA->setUnnamedAddr(getDecodedUnnamedAddrType(Record[OpNum++]));
+  if (BitCode == bitc::MODULE_CODE_ALIAS ||
+      BitCode == bitc::MODULE_CODE_ALIAS_OLD) {
+    if (OpNum != Record.size())
+      NewGA->setDLLStorageClass(getDecodedDLLStorageClass(Record[OpNum++]));
+    else
+      upgradeDLLImportExportLinkage(NewGA, Linkage);
+    if (OpNum != Record.size())
+      NewGA->setThreadLocalMode(getDecodedThreadLocalMode(Record[OpNum++]));
+    if (OpNum != Record.size())
+      NewGA->setUnnamedAddr(getDecodedUnnamedAddrType(Record[OpNum++]));
+  }
   if (OpNum != Record.size())
     NewGA->setDSOLocal(getDecodedDSOLocal(Record[OpNum++]));
   ValueList.push_back(NewGA);
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index a7201ed9735..f3f33c4474b 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1302,7 +1302,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
   // Emit the ifunc information.
   for (const GlobalIFunc &I : M.ifuncs()) {
     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
-    //         val#, linkage, visibility]
+    //         val#, linkage, visibility, DSO_Local]
     Vals.push_back(addToStrtab(I.getName()));
     Vals.push_back(I.getName().size());
     Vals.push_back(VE.getTypeID(I.getValueType()));
@@ -1310,6 +1310,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     Vals.push_back(VE.getValueID(I.getResolver()));
     Vals.push_back(getEncodedLinkage(I));
     Vals.push_back(getEncodedVisibility(I));
+    Vals.push_back(I.isDSOLocal());
     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
     Vals.clear();
   }