TableGen: Add IsOptional field to AsmOperandClass

Summary:
This makes it possible to specify some operands as optional to the AsmMatcher.
Setting this field to true will prevent the AsmMatcher from emitting
'too few operands' errors when there are missing optional operands.

Reviewers: olista01, ab

Subscribers: nhaustov, arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D15755

llvm-svn: 259913

1 files changed, 15 insertions, 1 deletions

diff --git a/llvm/utils/TableGen/AsmMatcherEmitter.cpp b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
index 07dbd285305..103ed99e35c 100644
--- a/llvm/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
@@ -200,6 +200,10 @@ struct ClassInfo {
 
   /// For custom match classes: the diagnostic kind for when the predicate fails.
   std::string DiagnosticType;
+
+  /// Is this operand optional and not always required.
+  bool IsOptional;
+
 public:
   /// isRegisterClass() - Check if this is a register class.
   bool isRegisterClass() const {
@@ -1115,6 +1119,7 @@ ClassInfo *AsmMatcherInfo::getTokenClass(StringRef Token) {
     Entry->RenderMethod = "<invalid>";
     Entry->ParserMethod = "";
     Entry->DiagnosticType = "";
+    Entry->IsOptional = false;
   }
 
   return Entry;
@@ -1249,6 +1254,7 @@ buildRegisterClasses(SmallPtrSetImpl<Record*> &SingletonRegisters) {
     CI->Registers = RS;
     // FIXME: diagnostic type.
     CI->DiagnosticType = "";
+    CI->IsOptional = false;
     RegisterSetClasses.insert(std::make_pair(RS, CI));
     ++Index;
   }
@@ -1363,6 +1369,10 @@ void AsmMatcherInfo::buildOperandClasses() {
     if (StringInit *SI = dyn_cast<StringInit>(DiagnosticType))
       CI->DiagnosticType = SI->getValue();
 
+    Init *IsOptional = Rec->getValueInit("IsOptional");
+    if (BitInit *BI = dyn_cast<BitInit>(IsOptional))
+      CI->IsOptional = BI->getValue();
+
     ++Index;
   }
 }
@@ -2102,6 +2112,7 @@ static void emitMatchClassEnumeration(CodeGenTarget &Target,
      << "/// instruction matching.\n";
   OS << "enum MatchClassKind {\n";
   OS << "  InvalidMatchClass = 0,\n";
+  OS << "  OptionalMatchClass = 1,\n";
   for (const auto &CI : Infos) {
     OS << "  " << CI.Name << ", // ";
     if (CI.Kind == ClassInfo::Token) {
@@ -2188,6 +2199,8 @@ static void emitIsSubclass(CodeGenTarget &Target,
   bool EmittedSwitch = false;
   for (const auto &A : Infos) {
     std::vector<StringRef> SuperClasses;
+    if (A.IsOptional)
+      SuperClasses.push_back("OptionalMatchClass");
     for (const auto &B : Infos) {
       if (&A != &B && A.isSubsetOf(B))
         SuperClasses.push_back(B.Name);
@@ -3100,7 +3113,8 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   OS << "      auto Formal = static_cast<MatchClassKind>(it->Classes[i]);\n";
   OS << "      if (i" << (HasMnemonicFirst ? "+1" : "")
      << " >= Operands.size()) {\n";
-  OS << "        OperandsValid = (Formal == " <<"InvalidMatchClass);\n";
+  OS << "        OperandsValid = (Formal == " <<"InvalidMatchClass) || "
+                                 "isSubclass(Formal, OptionalMatchClass);\n";
   OS << "        if (!OperandsValid) ErrorInfo = i"
      << (HasMnemonicFirst ? "+1" : "") << ";\n";
   OS << "        break;\n";