Some improvements to the handling of C11 atomic types:
- Add atomic-to/from-nonatomic cast types
- Emit atomic operations for arithmetic on atomic types
- Emit non-atomic stores for initialisation of atomic types, but atomic stores and loads for every other store / load
- Add a __atomic_init() intrinsic which does a non-atomic store to an _Atomic() type. This is needed for the corresponding C11 stdatomic.h function.
- Enables the relevant __has_feature() checks. The feature isn't 100% complete yet, but it's done enough that we want people testing it.
Still to do:
- Make the arithmetic operations on atomic types (e.g. Atomic(int) foo = 1; foo++;) use the correct LLVM intrinsic if one exists, not a loop with a cmpxchg.
- Add a signal fence builtin
- Properly set the fenv state in atomic operations on floating point values
- Correctly handle things like _Atomic(_Complex double) which are too large for an atomic cmpxchg on some platforms (this requires working out what 'correctly' means in this context)
- Fix the many remaining corner cases
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148242 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index b94a08d..bffcccc 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1092,6 +1092,8 @@
case CK_Dependent:
case CK_LValueToRValue:
case CK_NoOp:
+ case CK_AtomicToNonAtomic:
+ case CK_NonAtomicToAtomic:
case CK_PointerToBoolean:
case CK_IntegralToBoolean:
case CK_FloatingToBoolean:
@@ -1204,6 +1206,10 @@
return "ARCReclaimReturnedObject";
case CK_ARCExtendBlockObject:
return "ARCCExtendBlockObject";
+ case CK_AtomicToNonAtomic:
+ return "AtomicToNonAtomic";
+ case CK_NonAtomicToAtomic:
+ return "NonAtomicToAtomic";
}
llvm_unreachable("Unhandled cast kind!");
@@ -2536,6 +2542,18 @@
case CStyleCastExprClass: {
const CastExpr *CE = cast<CastExpr>(this);
+ // If we're promoting an integer to an _Atomic type then this is constant
+ // if the integer is constant. We also need to check the converse in case
+ // someone does something like:
+ //
+ // int a = (_Atomic(int))42;
+ //
+ // I doubt anyone would write code like this directly, but it's quite
+ // possible as the result of macro expansions.
+ if (CE->getCastKind() == CK_NonAtomicToAtomic ||
+ CE->getCastKind() == CK_AtomicToNonAtomic)
+ return CE->getSubExpr()->isConstantInitializer(Ctx, false);
+
// Handle bitcasts of vector constants.
if (getType()->isVectorType() && CE->getCastKind() == CK_BitCast)
return CE->getSubExpr()->isConstantInitializer(Ctx, false);