Fix a subtle bug in CodeGen for the increment of a bitfield.

llvm-svn: 67499

2 files changed, 14 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 80aa755e189..89f28bea6d3 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -620,9 +620,8 @@ Value *ScalarExprEmitter::VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
 Value *ScalarExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
                                              bool isInc, bool isPre) {
   LValue LV = EmitLValue(E->getSubExpr());
-  // FIXME: Handle volatile!
-  Value *InVal = CGF.EmitLoadOfLValue(LV, // false
-                                     E->getSubExpr()->getType()).getScalarVal();
+  QualType ValTy = E->getSubExpr()->getType();
+  Value *InVal = CGF.EmitLoadOfLValue(LV, ValTy).getScalarVal();
   
   int AmountVal = isInc ? 1 : -1;
   
@@ -667,8 +666,11 @@ Value *ScalarExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
   }
   
   // Store the updated result through the lvalue.
-  CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV, 
-                             E->getSubExpr()->getType());
+  if (LV.isBitfield())
+    CGF.EmitStoreThroughBitfieldLValue(RValue::get(NextVal), LV, ValTy,
+                                       &NextVal);
+  else
+    CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV, ValTy);
 
   // If this is a postinc, return the value read from memory, otherwise use the
   // updated value.
diff --git a/clang/test/CodeGen/2009-03-22-increment-bitfield.c b/clang/test/CodeGen/2009-03-22-increment-bitfield.c
new file mode 100644
index 00000000000..7a18cea28d4
--- /dev/null
+++ b/clang/test/CodeGen/2009-03-22-increment-bitfield.c
@@ -0,0 +1,7 @@
+// RUN: clang -emit-llvm -O1 < %s | grep "ret i32 0"
+
+int a(void) {
+  return ++(struct x {unsigned x : 2;}){3}.x;
+}
+
+