IRgen/i386/C++: Fix isSingleElementStruct computation for C++ record decls.

- Fixes PR7098.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103514 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/TargetInfo.cpp

@@ -130,6 +130,30 @@ static const Type *isSingleElementStruct(QualType T, ASTContext &Context) {
     return 0;
 
   const Type *Found = 0;
+  
+  // If this is a C++ record, check the bases first.
+  if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
+    for (CXXRecordDecl::base_class_const_iterator i = CXXRD->bases_begin(),
+           e = CXXRD->bases_end(); i != e; ++i) {
+      const CXXRecordDecl *Base =
+        cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
+      // Ignore empty records.
+      if (Base->isEmpty())
+        continue;
+
+      // If we already found an element then this isn't a single-element struct.
+      if (Found)
+        return 0;
+
+      // If this is non-empty and not a single element struct, the composite
+      // cannot be a single element struct.
+      Found = isSingleElementStruct(i->getType(), Context);
+      if (!Found)
+        return 0;
+    }
+  }
+
+  // Check for single element.
   for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
          i != e; ++i) {
     const FieldDecl *FD = *i;

test/CodeGenCXX/x86_32-arguments.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple i386-apple-darwin9 -emit-llvm -o - %s | FileCheck %s
 
 // Non-trivial dtors, should both be passed indirectly.
 struct S {
@@ -13,6 +13,7 @@ void f(S) { }
 
 // Non-trivial dtors, should both be passed indirectly.
 class C {
+public:
   ~C();
   double c;
 };
@@ -51,3 +52,34 @@ struct BasicAliasAnalysis : public ModulePass, public AliasAnalysis {
 
 void BasicAliasAnalysis::getModRefInfo(CallSite CS) {
 }
+
+// Check various single element struct type conditions.
+//
+// PR7098.
+
+// CHECK: define i64 @_Z2f0v()
+struct s0_0 { int x; };
+struct s0_1 : s0_0 { int* y; };
+s0_1 f0() { return s0_1(); }
+
+// CHECK: define i32 @_Z2f1v()
+struct s1_0 { int x; };
+struct s1_1 : s1_0 { };
+s1_1 f1() { return s1_1(); }
+
+// CHECK: define double @_Z2f2v()
+struct s2_0 { double x; };
+struct s2_1 : s2_0 { };
+s2_1 f2() { return s2_1(); }
+
+// CHECK: define double @_Z2f3v()
+struct s3_0 { };
+struct s3_1 { double x; };
+struct s3_2 : s3_0, s3_1 { };
+s3_2 f3() { return s3_2(); }
+
+// CHECK: define i64 @_Z2f4v()
+struct s4_0 { float x; };
+struct s4_1 { float x; };
+struct s4_2 : s4_0, s4_1 { };
+s4_2 f4() { return s4_2(); }