Fix the meaning of an "empty" record for the case of a zero-length array. Use isEmptyRecord for arguments on x86-32; there are structs of size 0 which don't count as empty.

llvm-svn: 144971

2 files changed, 15 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 33291dd5527..a2e15107f50 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -117,10 +117,14 @@ static bool isEmptyField(ASTContext &Context, const FieldDecl *FD,
 
   QualType FT = FD->getType();
 
-    // Constant arrays of empty records count as empty, strip them off.
+  // Constant arrays of empty records count as empty, strip them off.
+  // Constant arrays of zero length always count as empty.
   if (AllowArrays)
-    while (const ConstantArrayType *AT = Context.getAsConstantArrayType(FT))
+    while (const ConstantArrayType *AT = Context.getAsConstantArrayType(FT)) {
+      if (AT->getSize() == 0)
+        return true;
       FT = AT->getElementType();
+    }
 
   const RecordType *RT = FT->getAs<RecordType>();
   if (!RT)
@@ -684,7 +688,7 @@ ABIArgInfo X86_32ABIInfo::classifyArgumentType(QualType Ty) const {
     }
 
     // Ignore empty structs/unions.
-    if (Ty->isRecordType() && getContext().getTypeSize(Ty) == 0)
+    if (isEmptyRecord(Context, Ty, true))
       return ABIArgInfo::getIgnore();
 
     // Expand small (<= 128-bit) record types when we know that the stack layout
diff --git a/clang/test/CodeGen/x86_32-arguments-darwin.c b/clang/test/CodeGen/x86_32-arguments-darwin.c
index 31802ab8a32..cc10580f8f4 100644
--- a/clang/test/CodeGen/x86_32-arguments-darwin.c
+++ b/clang/test/CodeGen/x86_32-arguments-darwin.c
@@ -316,3 +316,11 @@ int f63(int i, ...) {
   __builtin_va_end(ap);
   return s.y;
 }
+
+// CHECK: define i32 @f64(%struct.s64* nocapture byval align 4 %x)
+struct s64 { signed char a[0]; signed char b[]; };
+void f64(struct s64 x) {}
+
+// CHECK: define float @f65()
+struct s65 { signed char a[0]; float b; };
+struct s65 f65() { return (struct s65){{},2}; }