[ThinLTO] Handle optional args in assembly format for ConstVCalls

Summary:
The AsmWriter was only writing the Args for a ConstVCall if it was
non-empty, however, the LLParser was always expecting it. To aid
in making it optional, surround the ConstVCall VFuncId and Args in
parentheses when writing, then make the Args optional when reading.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D49960

llvm-svn: 339637

2 files changed, 12 insertions, 4 deletions

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 7cf74dd16f5..8eede0a72eb 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -8027,12 +8027,18 @@ bool LLParser::ParseConstVCallList(
 }
 
 /// ConstVCall
-///   ::= VFuncId, Args
+///   ::= '(' VFuncId ',' Args ')'
 bool LLParser::ParseConstVCall(FunctionSummary::ConstVCall &ConstVCall,
                                IdToIndexMapType &IdToIndexMap, unsigned Index) {
-  if (ParseVFuncId(ConstVCall.VFunc, IdToIndexMap, Index) ||
-      ParseToken(lltok::comma, "expected ',' here") ||
-      ParseArgs(ConstVCall.Args))
+  if (ParseToken(lltok::lparen, "expected '(' here") ||
+      ParseVFuncId(ConstVCall.VFunc, IdToIndexMap, Index))
+    return true;
+
+  if (EatIfPresent(lltok::comma))
+    if (ParseArgs(ConstVCall.Args))
+      return true;
+
+  if (ParseToken(lltok::rparen, "expected ')' here"))
     return true;
 
   return false;
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 99a25a723b4..e19c7c20a5d 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2955,11 +2955,13 @@ void AssemblyWriter::printConstVCalls(
   FieldSeparator FS;
   for (auto &ConstVCall : VCallList) {
     Out << FS;
+    Out << "(";
     printVFuncId(ConstVCall.VFunc);
     if (!ConstVCall.Args.empty()) {
       Out << ", ";
       printArgs(ConstVCall.Args);
     }
+    Out << ")";
   }
   Out << ")";
 }