Improve the representation of the atomic builtins in a few ways. First, we make

their call expressions synthetically have the "deduced" types based on their
first argument. We only insert conversions in the AST for arguments whose
values require conversion to match the value type expected. This keeps PR7600
closed by maintaining the return type, but avoids assertions due to unexpected
implicit casts making the type unsigned (test case added from Daniel).

The magic is moved into the codegen for the atomic builtin which inserts the
casts as needed at the IR level to raise the type to an integer suitable for
the LLVM intrinsic. This shouldn't cause any real change in functionality, but
now we can make the builtin be more truly polymorphic.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108638 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 34 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 370d350329..bedea18203 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -512,19 +512,10 @@ Sema::SemaBuiltinAtomicOverloaded(OwningExprResult TheCallResult) {
   FunctionDecl *NewBuiltinDecl =
     cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
                                            TUScope, false, DRE->getLocStart()));
-  const FunctionProtoType *BuiltinFT =
-    NewBuiltinDecl->getType()->getAs<FunctionProtoType>();
 
-  QualType OrigValType = ValType;
-  ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType();
-
-  // If the first type needs to be converted (e.g. void** -> int*), do it now.
-  if (BuiltinFT->getArgType(0) != FirstArg->getType()) {
-    ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast);
-    TheCall->setArg(0, FirstArg);
-  }
-
-  // Next, walk the valid ones promoting to the right type.
+  // The first argument is by definition correct, we use it's type as the type
+  // of the entire operation. Walk the remaining arguments promoting them to
+  // the deduced value type.
   for (unsigned i = 0; i != NumFixed; ++i) {
     Expr *Arg = TheCall->getArg(i+1);
 
@@ -564,28 +555,10 @@ Sema::SemaBuiltinAtomicOverloaded(OwningExprResult TheCallResult) {
   UsualUnaryConversions(PromotedCall);
   TheCall->setCallee(PromotedCall);
 
-  // Change the result type of the call to match the result type of the decl.
-  TheCall->setType(NewBuiltinDecl->getCallResultType());
-
-  // If the value type was converted to an integer when processing the
-  // arguments (e.g. void* -> int), we need to convert the result back.
-  if (!Context.hasSameUnqualifiedType(ValType, OrigValType)) {
-    Expr *E = TheCallResult.takeAs<Expr>();
-
-    assert(ValType->isIntegerType() &&
-           "We always convert atomic operation values to integers.");
-    // FIXME: Handle floating point value type here too.
-    CastExpr::CastKind Kind;
-    if (OrigValType->isIntegerType())
-      Kind = CastExpr::CK_IntegralCast;
-    else if (OrigValType->hasPointerRepresentation())
-      Kind = CastExpr::CK_IntegralToPointer;
-    else
-      llvm_unreachable("Unhandled original value type!");
-
-    ImpCastExprToType(E, OrigValType, Kind);
-    return Owned(E);
-  }
+  // Change the result type of the call to match the original value type. This
+  // is arbitrary, but the codegen for these builtins ins design to handle it
+  // gracefully.
+  TheCall->setType(ValType);
 
   return move(TheCallResult);
 }