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, 6 insertions, 4 deletions

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 0c33fb5371..c92cbb2010 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -2904,13 +2904,11 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) {
 
   case AtomicExpr::AO__c11_atomic_fetch_add:
   case AtomicExpr::AO__c11_atomic_fetch_sub:
-  case AtomicExpr::AO__atomic_fetch_add:
-  case AtomicExpr::AO__atomic_fetch_sub:
-  case AtomicExpr::AO__atomic_add_fetch:
-  case AtomicExpr::AO__atomic_sub_fetch:
     if (MemTy->isPointerType()) {
       // For pointer arithmetic, we're required to do a bit of math:
       // adding 1 to an int* is not the same as adding 1 to a uintptr_t.
+      // ... but only for the C11 builtins. The GNU builtins expect the
+      // user to multiply by sizeof(T).
       QualType Val1Ty = E->getVal1()->getType();
       llvm::Value *Val1Scalar = EmitScalarExpr(E->getVal1());
       CharUnits PointeeIncAmt =
@@ -2921,6 +2919,10 @@ RValue CodeGenFunction::EmitAtomicExpr(AtomicExpr *E, llvm::Value *Dest) {
       break;
     }
     // Fall through.
+  case AtomicExpr::AO__atomic_fetch_add:
+  case AtomicExpr::AO__atomic_fetch_sub:
+  case AtomicExpr::AO__atomic_add_fetch:
+  case AtomicExpr::AO__atomic_sub_fetch:
   case AtomicExpr::AO__c11_atomic_store:
   case AtomicExpr::AO__c11_atomic_exchange:
   case AtomicExpr::AO__atomic_store_n: