[llvm] 27e2c8f - Add Record::getValueAsOptionalDef().

[John McCall via llvm-commits]

Author: John McCall
Date: 2019-10-25T16:39:21-07:00
New Revision: 27e2c8faec6926fafdbd4d9b5b2f827f002e1c8e

URL: https://github.com/llvm/llvm-project/commit/27e2c8faec6926fafdbd4d9b5b2f827f002e1c8e
DIFF: https://github.com/llvm/llvm-project/commit/27e2c8faec6926fafdbd4d9b5b2f827f002e1c8e.diff

LOG: Add Record::getValueAsOptionalDef().

Using `?` as an optional marker is very useful in Clang's AST-node
emitters because otherwise we need a separate class just to encode
the presence or absence of a base node reference.

Added: 
    

Modified: 
    llvm/include/llvm/TableGen/Record.h
    llvm/lib/TableGen/Record.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/TableGen/Record.h b/llvm/include/llvm/TableGen/Record.h
index 73ed342a6101..f490c7c80c60 100644
--- a/llvm/include/llvm/TableGen/Record.h
+++ b/llvm/include/llvm/TableGen/Record.h
@@ -1663,6 +1663,12 @@ class Record {
   /// the value is not the right type.
   Record *getValueAsDef(StringRef FieldName) const;
 
+  /// This method looks up the specified field and returns its value as a
+  /// Record, returning null if the field exists but is "uninitialized"
+  /// (i.e. set to `?`), and throwing an exception if the field does not
+  /// exist or if its value is not the right type.
+  Record *getValueAsOptionalDef(StringRef FieldName) const;
+
   /// This method looks up the specified field and returns its
   /// value as a bit, throwing an exception if the field does not exist or if
   /// the value is not the right type.

diff  --git a/llvm/lib/TableGen/Record.cpp b/llvm/lib/TableGen/Record.cpp
index 835ef8c7141b..2ab7b98ca030 100644
--- a/llvm/lib/TableGen/Record.cpp
+++ b/llvm/lib/TableGen/Record.cpp
@@ -2277,6 +2277,21 @@ Record *Record::getValueAsDef(StringRef FieldName) const {
     FieldName + "' does not have a def initializer!");
 }
 
+Record *Record::getValueAsOptionalDef(StringRef FieldName) const {
+  const RecordVal *R = getValue(FieldName);
+  if (!R || !R->getValue())
+    PrintFatalError(getLoc(), "Record `" + getName() +
+      "' does not have a field named `" + FieldName + "'!\n");
+
+  if (DefInit *DI = dyn_cast<DefInit>(R->getValue()))
+    return DI->getDef();
+  if (isa<UnsetInit>(R->getValue()))
+    return nullptr;
+  PrintFatalError(getLoc(), "Record `" + getName() + "', field `" +
+    FieldName + "' does not have either a def initializer or '?'!");
+}
+
+
 bool Record::getValueAsBit(StringRef FieldName) const {
   const RecordVal *R = getValue(FieldName);
   if (!R || !R->getValue())