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

5 files changed, 16 insertions, 18 deletions

diff --git a/llvm/include/llvm/IR/GlobalValue.h b/llvm/include/llvm/IR/GlobalValue.h
index 7823eefecdc..1d8025d4a9b 100644
--- a/llvm/include/llvm/IR/GlobalValue.h
+++ b/llvm/include/llvm/IR/GlobalValue.h
@@ -437,8 +437,7 @@ public:
   void setLinkage(LinkageTypes LT) {
     if (isLocalLinkage(LT)) {
       Visibility = DefaultVisibility;
-      if (getValueID() != Value::GlobalIFuncVal)
-        setDSOLocal(true);
+      setDSOLocal(true);
     }
     Linkage = LT;
   }
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 6f425721c1b..f94b616e596 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -756,11 +756,6 @@ bool LLParser::parseIndirectSymbol(const std::string &Name, LocTy NameLoc,
     return Error(NameLoc,
                  "symbol with local linkage must have default visibility");
 
-  if (DSOLocal && !IsAlias) {
-    return Error(NameLoc,
-                 "dso_local is invalid on ifunc");
-  }
-
   Type *Ty;
   LocTy ExplicitTypeLoc = Lex.getLoc();
   if (ParseType(Ty) ||
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();
   }
diff --git a/llvm/test/Assembler/ifunc-dsolocal-daig.ll b/llvm/test/Assembler/ifunc-dsolocal.ll
index 86e941d6cac..63242cb3f24 100644
--- a/llvm/test/Assembler/ifunc-dsolocal-daig.ll
+++ b/llvm/test/Assembler/ifunc-dsolocal.ll
@@ -1,7 +1,7 @@
-; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
 
 @foo = dso_local ifunc i32 (i32), i64 ()* @foo_ifunc
-; CHECK: error: dso_local is invalid on ifunc
+; CHECK: @foo = dso_local ifunc i32 (i32), i64 ()* @foo_ifunc
 
 define internal i64 @foo_ifunc() {
 entry: