commit 7a7ee3033e44b45630981355460ef89efa0bdcc4
author David Chisnall <csdavec@swan.ac.uk> Mon Jan 16 17:27:18 2012 +0000
committer David Chisnall <csdavec@swan.ac.uk> Mon Jan 16 17:27:18 2012 +0000
tree 2d566bcdd0dc4e2f73b95747eac6a198b1dfc619
parent 52e4c60e31fee851e2988f7909aebf488e57fc12

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

lib/AST/Expr.cpp

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);

lib/AST/ExprConstant.cpp

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index ae68e19..89e8ab7 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -2277,6 +2277,8 @@
     default:
       break;
 
+    case CK_AtomicToNonAtomic:
+    case CK_NonAtomicToAtomic:
     case CK_NoOp:
       return StmtVisitorTy::Visit(E->getSubExpr());
 
@@ -4531,6 +4533,8 @@
     return Error(E);
 
   case CK_LValueToRValue:
+  case CK_AtomicToNonAtomic:
+  case CK_NonAtomicToAtomic:
   case CK_NoOp:
     return ExprEvaluatorBaseTy::VisitCastExpr(E);
 
@@ -4997,6 +5001,8 @@
     llvm_unreachable("invalid cast kind for complex value");
 
   case CK_LValueToRValue:
+  case CK_AtomicToNonAtomic:
+  case CK_NonAtomicToAtomic:
   case CK_NoOp:
     return ExprEvaluatorBaseTy::VisitCastExpr(E);
 
@@ -5855,6 +5861,8 @@
     }
     switch (cast<CastExpr>(E)->getCastKind()) {
     case CK_LValueToRValue:
+    case CK_AtomicToNonAtomic:
+    case CK_NonAtomicToAtomic:
     case CK_NoOp:
     case CK_IntegralToBoolean:
     case CK_IntegralCast:

lib/AST/StmtPrinter.cpp

diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index 836f192..ecf8ed7 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -1052,6 +1052,9 @@
 void StmtPrinter::VisitAtomicExpr(AtomicExpr *Node) {
   const char *Name = 0;
   switch (Node->getOp()) {
+    case AtomicExpr::Init:
+      Name = "__atomic_init(";
+      break;
     case AtomicExpr::Load:
       Name = "__atomic_load(";
       break;
@@ -1094,7 +1097,8 @@
     PrintExpr(Node->getVal2());
     OS << ", ";
   }
-  PrintExpr(Node->getOrder());
+  if (Node->getOp() != AtomicExpr::Init)
+    PrintExpr(Node->getOrder());
   if (Node->isCmpXChg()) {
     OS << ", ";
     PrintExpr(Node->getOrderFail());