Implement the missing pieces needed to support libstdc++4.7's <atomic>:

__atomic_test_and_set, __atomic_clear, plus a pile of undocumented __GCC_*
predefined macros.

Implement library fallback for __atomic_is_lock_free and
__c11_atomic_is_lock_free, and implement __atomic_always_lock_free.

Contrary to their documentation, GCC's __atomic_fetch_add family don't
multiply the operand by sizeof(T) when operating on a pointer type.
libstdc++ relies on this quirk. Remove this handling for all but the
__c11_atomic_fetch_add and __c11_atomic_fetch_sub builtins.

Contrary to their documentation, __atomic_test_and_set and __atomic_clear
take a first argument of type 'volatile void *', not 'void *' or 'bool *',
and __atomic_is_lock_free and __atomic_always_lock_free have an argument
of type 'const volatile void *', not 'void *'.

With this change, libstdc++4.7's <atomic> passes libc++'s atomic test suite,
except for a couple of libstdc++ bugs and some cases where libc++'s test
suite tests for properties which implementations have latitude to vary.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154640 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 26 deletions

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index ce41308344..01c9fe7cd8 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -4306,7 +4306,7 @@ bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E) {
 }
 
 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
-  switch (E->isBuiltinCall()) {
+  switch (unsigned BuiltinOp = E->isBuiltinCall()) {
   default:
     return ExprEvaluatorBaseTy::VisitCallExpr(E);
 
@@ -4365,6 +4365,7 @@ bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
       
     return Error(E);
 
+  case Builtin::BI__atomic_always_lock_free:
   case Builtin::BI__atomic_is_lock_free:
   case Builtin::BI__c11_atomic_is_lock_free: {
     APSInt SizeVal;
@@ -4382,32 +4383,31 @@ bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
 
     // Check power-of-two.
     CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue());
-    if (!Size.isPowerOfTwo())
-#if 0
-      // FIXME: Suppress this folding until the ABI for the promotion width
-      // settles.
-      return Success(0, E);
-#else
-      return Error(E);
-#endif
-
-#if 0
-    // Check against promotion width.
-    // FIXME: Suppress this folding until the ABI for the promotion width
-    // settles.
-    unsigned PromoteWidthBits =
-        Info.Ctx.getTargetInfo().getMaxAtomicPromoteWidth();
-    if (Size > Info.Ctx.toCharUnitsFromBits(PromoteWidthBits))
-      return Success(0, E);
-#endif
-
-    // Check against inlining width.
-    unsigned InlineWidthBits =
-        Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
-    if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits))
-      return Success(1, E);
+    if (Size.isPowerOfTwo()) {
+      // Check against inlining width.
+      unsigned InlineWidthBits =
+          Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
+      if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) {
+        if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
+            Size == CharUnits::One() ||
+            E->getArg(1)->isNullPointerConstant(Info.Ctx,
+                                                Expr::NPC_NeverValueDependent))
+          // OK, we will inline appropriately-aligned operations of this size,
+          // and _Atomic(T) is appropriately-aligned.
+          return Success(1, E);
+
+        QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()->
+          castAs<PointerType>()->getPointeeType();
+        if (!PointeeType->isIncompleteType() &&
+            Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) {
+          // OK, we will inline operations on this object.
+          return Success(1, E);
+        }
+      }
+    }
 
-    return Error(E);
+    return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
+        Success(0, E) : Error(E);
   }
   }
 }