Improve obvious-most-derived-type devirtualization:

  * if the base is produced by a series of derived-to-base conversions, check
    the expression inside them when looking for an expression with a known
    dynamic type
  * step past MaterializeTemporaryExprs when checking for a known dynamic type
  * when checking for a known dynamic type, treat all class prvalues as having
    a known dynamic type after skipping all relevant rvalue subobject
    adjustments
  * treat callees formed by pointer-to-member access for a non-reference member
    type like callees formed by member access.

llvm-svn: 285954

1 files changed, 26 insertions, 2 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 9cf9e86c4f4..53ab5cfd58b 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -35,9 +35,33 @@
 #include <cstring>
 using namespace clang;
 
-const CXXRecordDecl *Expr::getBestDynamicClassType() const {
-  const Expr *E = ignoreParenBaseCasts();
+const Expr *Expr::getBestDynamicClassTypeExpr() const {
+  const Expr *E = this;
+  while (true) {
+    E = E->ignoreParenBaseCasts();
+
+    // Follow the RHS of a comma operator.
+    if (auto *BO = dyn_cast<BinaryOperator>(E)) {
+      if (BO->getOpcode() == BO_Comma) {
+        E = BO->getRHS();
+        continue;
+      }
+    }
 
+    // Step into initializer for materialized temporaries.
+    if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E)) {
+      E = MTE->GetTemporaryExpr();
+      continue;
+    }
+
+    break;
+  }
+
+  return E;
+}
+
+const CXXRecordDecl *Expr::getBestDynamicClassType() const {
+  const Expr *E = getBestDynamicClassTypeExpr();
   QualType DerivedType = E->getType();
   if (const PointerType *PTy = DerivedType->getAs<PointerType>())
     DerivedType = PTy->getPointeeType();